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Rebuild HFB70 - Centennial College

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2. Figure 162 Re adjust if worm shaft input shaft torque exceeds 20 in Ibs 2 3 N m 5 Adjust worm shaft input shaft adjusting screw 38 a 5 16 inch Allen wrench or screwdriver required to increase maximum worm shaft input shaft 16 torque noted in procedure 4 by 10 to 15 in Ibs 1 1 to 1 7 N m Torque sealing nut 39 to 70 80 ft Ibs 95 108 N m using a 1 1 16 inch socket and check worm shaft input shaft torque again Readjust if worm shaft input shaft torque exceeds 35 in Ibs 4 0 N m SEE FIGURE 163 This completes the final adjustments of the HFB70 gear to be made before it is installed into the vehicles steering system Install the gear by following instructions in the vehicle shop manual Then follow the succeeding sections of this service manual HFB70 on HYDRAULIC FLUID and FILLING AND AIR BLEEDING THE SYSTEM which also includes instructions for adjustment of the optional adjustable poppet l valve Figure 163 49 o0 Hydraulic Fluid The steering system should be kept filled with one of the following fluids AUTOMATIC TRANSMISSION FLUID TYPE E or F FORD SPEC M2C138CJ AUTOMATIC TRANSMISSION FLUID DEXRON 11 Oe AE ELIA Fi es ee EE SAE 30 AA SAE 10W30 720 AA SAE 10W40 LINEN oe oe AA te SAE 10W40 AN AA NAA AA AANO SAE 10W40 IE MED NAGANO Pe SAE 15W40 aaa ana aaa RE OE N SAE 10W40 Psa AAAH PA SAE 15W40 JNICALGAURDOL iss oe EE Ee SAE 30 NN SAE 15W40 Ga Ge a ee O E SAE 1
3. minimum flow is required based on the size of the auxiliary cylinder and the vehicles steering geometry Operation What Happens During a Steering Maneuver Bleed Systems When the driver turns the steering wheel he transmits force from the wheel to the steering gear input shaft A torsion bar pinned at its one end to the input shaft and at its other end to the worm shaft turns with the input shaft and exerts a rotational force on the worm shaft In response to this rotational force the worm shaft acting through the recirculating ball mechanism tries to move the rack piston axially through the gear housing cylinder bore Some HFB 0 gears which are mounted with the output shaft above the rack piston bore are equipped with a manual bleed screw The procedure for servicing the manual bleed screw Is described under Filling and Air Bleeding page 50 in this manual The rack piston s axial movement is resisted by its engagement to the sector shaft which is connected by linkage to the steered wheels Because of this resistance the torsion bar is twisted by the input shaft thereby actuating the control valve Pressurized fluid directed by the control valve assists in moving the rack piston axially through the cylinder bore The rack piston then turns the sector shaft to steer the vehicle Shock Loads to the Gear If the steered wheels receive a shock load the shock forces are transmitted through the sector shaft
4. 61 NOTE The valve sleeve 14 will probably remain in the valve housing WARNING DO NOT DISASSEMBLE THE WORM SHAFT INPUT SHAFT ASSEMBLY 16 WHICH INGLUDES THE WORM SHAFT INPUT SHAFT TORSION BAR TORSION BAR PINS DRIVE RING AND DRIVE RING RETAINER AND INSERT DO NOT UNBEND THE DRIVE RING RETAINER TANGS THAT HOLD THE DRIVE RING IN PLAGE SEE FIGURE 62 DOING EITHER WILL ALTER THE VALVE TIMING WHICH COULD CAUSE THE VEHICLE TO PULL TO ONE SIDE OR THE OTHER Remove the valve sleeve 14 from the valve housing 8 SEE FIGURE 63 Remove the first thrust washer 10 and the thrust bearing 11 and then the second thrust washer 10 from the valve housing SEE FIGURE 64 NOTE The first thrust washer may stay on the end of the valve sleeve Figure 63 Figure 64 25 remove seal rings remove dirt 4 water seal remove retaining ring remove valve housing seal pack NOTE remove seal rings remove 0 rings 26 26 Remove and discard the valve housing seal ring 9 from the valve housing 8 27 Remove and discard the dirt and water seal 4 SEE FIGURE 65 28 Remove retaining ring 5 SEE FIGURE 66 29 Remove steel backup washer 6 and two piece input shaft seal 7 from the valve housing 8 SEE FIGURE 67 Discard seal NOTE The poppet adjusting screw 3 and sealing nut 2 do not have to be removed from valve housing unless apparent leaks at the adjusting screw indicate seal
5. DAMAGE TO GUIDES CAN RESULT IN SUBSEQUENT LOCK UP OR LOSS OF STEERING Assemble 34 balls 43 into the ball return guides 44 and rack piston 29 Drop the balls through the hole provided in the ball return guides As you drop the balls rotate the worm shaft input shaft 16 to pull the balls down into the grooves SEE FIGURE 109 Read warning then go to step 10 WARNING MAKE SURE THE BALL RETURN GUIDES STAY DOWN IN PLACE WHILE YOU ASSEMBLE THE BALLS FAILURE TO HOLD THE GUIDES DOWN MAY RESULT IN A BALL BEING TRAPPED OUTSIDE THE CLOSED LOOP A TRAPPED BALL CAN RESULT INA STEERING LOCKUP WHICH COULD CAUSE AN ACCIDENT For ball return guides which do not have the hole in top follow this procedure Insert the eraser end of a pencil into one ball return guide hole of the rack piston as far as it will go Drop 22 balls of the 34 total into the other ball return guide hole of the rack piston SEE FIGURE 110 Turn the worm shaft input shaft 16 to advance the balls toward the other hole You will feel resistance at the pencil after you drop the 22nd ball At this time a ball will be visible at the base of each hole Remove the pencil Figure 108 Figure 109 Figure 110 WARNING install ball return guide halves NOTE assemble ball return guide clip NOTE WARNING DO NOT TURN THE WORM SHAFT OR ALLOW THE RACK PISTON TO MOVE AFTER YOU REMOVE THE PENCIL IF THE WORM SHAFT OR RACK PISTON MOVE BEFORE BALL RETUR
6. Place the trunnion cover 25 on a bench to install the new seal package Start with the new Teflon backup washer 24 install new seal 1 7 Install the new two piece sector shaft seal 23 so that the words oll side are visible after seal is in place SEE FIGURE 12 WARNING WARNING THE WORDS OIL SIDE MUST BE VISIBLE ON THE SEAL AFTER IT IS IN PLACE IF NOT THE SEAL WILL NOT FUNCTION AND A LOSS OF POWER STEERING ASSIST MAY OCCUR install new seal 7 1 8 Grease the new trunnion cover seal ring 22 and install it into the ring cover groove Figure 13 tape sector 1 9 Cover the serrations of the sector shaft 48 with tape to avoid shaft damaging the seals during installation SEE FIGURE 13 NOTE NOTE Use only one layer of tape Teflon is a registered trademark of DuPont Corporation Figure 14 install trunnion cover washers 4 bolts install new dirt 4 water seal assemble protector boot amp fitting install pitman arm WARNING 1 10 Install the trunnion cover 25 and four trunnion cover washers 27 and bolts 28 Torque bolts to 15 22 ft Ibs 20 30 N m if dry or 11 16 ft Ibs 15 22 N m if lubricated 1 2 inch socket required SEE FIGURES 14 15 16 1 11 Pack clean high temperature industrial grease per Ross specification 045231 Mobil temp 1 or 2 or equivalent around seal area of sector shaft 48 Install a new dirt and water seal 26 using a suitable blunt end drift SEE FIGU
7. Seal Compression Tool J26740 Seal installation Tool J26741 Seal Compression Tool J26742 Seal Driving Tool J28490 Bearing Mandrel J26 43 Adjustable wrench Knife Chisel Torque Wrench in Ibs IN m Torque Wrench ft Ibs IN m soft Punch Retaining Ring pliers Ratchet sockets 112 13 16 15 16 inch Allen sockets 5 16 5 32 inch 12 point sockets 11 16 314 13 16 inch Torx sockets 1 30 Pitman arm puller screw driver Slot type screwdriver socket NOTE SPECIAL TOOLS ARE AVAILABLE FROM Kent Moore Tool Division 29784 Little Mack Roseville MI 48066 Phone 313 574 2332 or 1 800 328 6657 For complete HFB 0 service tool set order Part No J26837 Mobile Temp is a Registered Trademark of Mobile Oil Co Disassembly Preparation THOROUGHLY CLEAN OFF ALL OUTSIDE DIRT ESPECIALLY FROM AROUND FITTINGS AND HOSE CONNECTIONS BEFORE YOU REMOVE THE GEAR Drain the steering gear assembly Remove input and output shaft connections per 1 1 and 2 1 Page 11 and 14 Remove the supply and return lines from the gear and immediately plug all port holes and fluid lines WARNING THIS STEERING GEAR WEIGHS APPROXIMATELY 112 POUNDS 51 KG DRY EXERCISE CAUTION WHEN YOU REMOVE LIFT OR CARRY IT DO NOT POUND THE UNIVERSAL JOINT OR INPUT SHAFT COUPLING ON OR OFF THE INPUT SHAFT INTERNAL DAMAGE TO THE STEERING GEAR CAN RESULT Remove the steering gear from the vehicle and take it to a clean surface a pi
8. approximately two turns An 11 16 inch box end required remove end cover bolts remove end cover NOTE remove seal ring remove seal protector clean input shaft loosen poppet nut amp screw remove valve housing bolts 24 1b 17 20 21 22 Remove the four end cover bolts 41 with a 13 16 inch socket and remove four washers 40 SEE FIGURE 56 Remove the end cover 37 Some fluid will drain SEE FIGURE 57 NOTE The worm shaft adjusting screw and sealing nut and poppet adjusting screw and sealing nut do not have to be removed from the end cover 37 unless apparent fluid leaks at the adjusting screws indicate the sealing nuts and or screws be replaced Remove and discard the end cover seal ring 9 from the end cover 37 SEE FIGURE 58 Remove seal protector 62 from worm shaft input shaft 16 and discard Clean any paint or foreign material from the input shaft with a fine grade emery paper SEE FIGURE 59 Loosen the poppet adjusting screw sealing nut 2 and the poppet adjusting screw 3 in the valve housing 8 approximately two turns Remove the four valve housing bolts 1 with a 13 16 inch socket SEE FIGURE 60 Figure bb Figure 58 Figure 59 Figure 60 remove valve housing NOTE WARNING remove valve sleeve remove thrust washers 4 bearing NOTE 23 24 20 Remove the valve housing 8 Some fluid will drain SEE FIGURE
9. but it may also be glazed and a slipping belt doesn t always squeal If you adjust the belt check the specifications These are just some of the checks you should make before you turn to the steering gear or pump The Troubleshooting Guide on pages 8 thru 10 explains what to diagnose for a particular steering problem Match the trouble symptom against the chart and follow the recommended troubleshooting sequence Doing so will most likely save you time and may prevent unnecessary repairs and costs Hydraulic Tests If the checks described above all prove satisfactory it is possible that the cause of the steering problem can be traced to a lack of pressure or Insufficient flow In this case you may have to do more detailed troubleshooting that involves conducting hydraulic tests Preparation for Hydraulic Tests To conduct the following hydraulic tests first install a flow meter pressure gage and load shut off valve in the fluid supply line to the steering gear as indicated by the instructions that come with the flow meter Steering system analyzers are available with the 3 units integral Place a thermometer in the reservoir FIG 2 You must use a flow meter and it is recommended that you use a thermometer if you are to troubleshoot the hydraulic system accurately Start the engine and warm the hydraulic system up by partially closing the load valve until the pressure gage reads 1000 psi 69 0 Bar When the fluid temperature as i
10. m making sure that the worm shaft preload adjusting screw 38 does not move SEE FIGURE 36 NOTE NOTE If the sealing material in the sealing nut has separated remove the adjusting screw and replace the sealing nut with a new one onto the nonslotted pd end of the adjusting screw Figure 36 set axle stops install flow meter rotate sector shaft CAUTION NOTE loosen sealing nut and adjusting Screw set adjusting screw 4 tighten sealing nut repeat for other poppet 4 Poppet Valve Adjustment With vehicle engine on 41 Before adjustment properly set the axle stops manufacturer s specifications 4 2 Install a pressure gage flow meter package in the supply line from the pump to the gear Make sure the flow meter can be pressurized Bring the fluid temperature up to approximately 130 F 54 C using the method described in the troubleshooting section page 6 4 3 With the engine at idle have someone turn the steering wheel to full lock axle against axle stop while you observe the rotation of the sector shaft 48 SEE FIGURE 37 If the sector shaft rotates counter clockwise as shown adjust the poppet adjusting screw identified in FIGURE 37 If the sector shaft rotates clockwise adjust the other poppet adjusting screw CAUTION If relief pressure is reached while the steering wheel is at full lock axle against axle stop release the steering wheel from this position At no time should relief
11. or b any repairs or service of a particular HFB70 steering gear will result in a properly functioning steering gear If inspection or testing reveals evidence of abnormal wear or damage to the HFB70 steering gear or if you encounter circumstances not covered in the Manual STOP CONSULT THE VEHICLE MANUFACTURER S SERVICE MANUAL AND WARRANTY DO NOT TRY TO REPAIR OR SERVICE AN HFB70 STEERING GEAR WHICH HAS BEEN DAMAGED OR INCLUDES ANY PART THAT SHOWS EXCESSIVE WEAR UNLESS THE DAMAGED AND WORN PARTS ARE REPLACED WITH ORIGINAL TRW REPLACEMENT AND SERVICE PARTS AND THE UNIT IS RESTORED TO TRW s SPECIFICATIONS FOR THE HFB70 STEERING GEAR It is the responsibility of the mechanic performing the maintenance repairs or service on a particular HFB70 steering gear to a inspect the steering gear for abnormal wear and damage b choose a repair procedure which will not endanger his her safety the safety of others the vehicle or the safe operation of the vehicle and c fully inspect and test the HFB70 steering gear and the vehicle steering system to insure that the repair or service of the steering gear has been properly performed and that the steering gear and system will function properly This TRW Ross Gear Division vehicle power steering gear is covered by one or more of United States patent numbers 3 896 702 3 606 819 3 741 074 3 773 081 3 955 473 3 935 790 and 3 921 669 Other United States patent applications are pending and correspond
12. other end of the rack piston install one poppet 32 the spring 34 the nylon spacer rod 33 the other poppet 32 and the other poppet seat 31 Torque both poppet seats to 20 25 ft lbs 27 34 N m Install both retaining rings 30 SEE FIGURES 106 107 Figure 107 35 install worm shaft input shaft into rack piston CAUTION NOTE assemble ball return guides WARNING assemble balls WARNING assemble balls 36 When the 10 minute compression time has elapsed remove the compression tool from the worm shaft input shaft assembly 16 Grease the worm shaft seal ring 18 and the sealing surface inside the rack piston 29 Install the worm shaft input shaft assembly into the rack piston end that will position the worm seal ring in the rack bore and the worm ball track grooves to accept the set of balls through the rack piston ball guide holes SEE FIGURE 108 CAUTION Steps 6 11 describe the installation of the rack piston balls guides and caps or clips Read through each step carefully to determine which ones you should follow NOTE If your ball return guides do not have a hole in the top for loading balls then proceed to step 8 If your ball return guides do have a hole in the top then follow steps 6 amp 7 SEE FIGURE 77 Page 28 Assemble the ball return guides 44 into the rack piston 29 Make sure that the ball return guides are seated WARNING DO NOT SEAT GUIDES WITH A HAMMER
13. ring groove Using seal installation tool J26739 assemble the new worm shaft o ring 17 and then the new seal ring 18 SEE FIGURE 99 100 Next compress the seal ring by pulling the compression tool back over the seal ring Allow the worm shaft input shaft to set with compression tool in place for at least ten minutes SEE FIGURE 101 CAUTION Be sure the compression tool is assembled correctly before assembly of the seal ring If the tool is backwards it cannot be pulled over the new seal ring for compression or for tool removal without destroying the seal ring CAUTION Allow for the 10 minutes to insure that the O ring and seal ring are properly seated when you install the worm shaft into the rack piston If you do not allow for this time the seal may tear or be cut when you place the worm into the rack If you are installing a new housing bearing 20 or using the old housing and bearing assembly apply a generous amount of clean grease to the bearing race to retain the bearing rolls Then place the rolls into the race being sure you have the correct quantity of rolls for your particular bearing assembly To install the NEW bearing assembly 20 into the housing first install the a N al NP a 39 2 145 Figure 98 Figure 99 Figure 100 Figure 101 Figure 102 NOTE CAUTION NOTE install rack piston seal and O ring WARNING install poppet assembly retaining ring 21 into the gr
14. that the gear box contains a manual steering mechanism a hydraulic control valve and a hydraulic power cylinder all in a single compact package Rotary Control Valve The rotary control valve combines simplicity of construction with desirable performance characteristics The speed at which the driver can turn the steering wheel with power assist is dependent upon the pump flow measured in gallons per minute gpm or Liters Min directed to a cylinder cavity The pressure measured in pounds per square inch psi or bar required for the gear to Steer the vehicle is created by the power steering pump to overcome resistance at the steered wheels The control valve senses these requirements and directs fluid to the cylinder cavity at the proper flow rate and pressure Pressure Means Work Flow Means Speed The higher pressure a gear can withstand the more work it can perform The HFB 0 can steer a vehicle with a front end weight rating of about 16 000 pounds 7257 Kg through a turn at low vehicle speed and engine idle As the driver turns the steering wheel faster or slower more or less fluid will be required by the gear in one minute For the HFB70 maximum operating pressure is 2000 psi 137 9 bar maximum flow rate 8 gpm 30 Liters Min NOTE The recommended minimum flow at 1 1 2 hand wheel turns second must be no less than 3 4 gom 13 Liters Min If the HFB70 steering gear is controlling an auxiliary cylinder increased
15. the opposite direction of turn If internal leakage is greater than 1 0 gpm 3 8 Liters Min and there is no auxiliary hydraulic cylinder in the system repair the gear If the internal leakage is greater than 1 5 gpm 5 7 Liters Min and there is an auxiliary hydraulic cylinder in the system controlled by the HFB70 gear isolate the auxiliary cylinder from the system by disconnecting 05 1 0 15 GPM the auxiliary cylinder hydraulic lines at the HFB 0 units auxiliary ports Plug those ports with suitable pressure plugs or caps Connect 18 3 B 7 7 Liters Min the disconnected lines together if a rotary auxiliary cylinder is in the ALLOWABLE INTERNAL LEAKAGE system Plug the disconnected lines if a linear auxiliary cylinder is in STEERING GEAR 130 F 64 4 C the system and disconnect the linear cylinder from the steering link age making sure it will clear the steered axle Repeat the internal 4 ENGINE IDLE 130 F 54 4 C m Pai ka a a o o o a I i o EE Lk Ha j kan E gt Li leakage test If the internal leakage is less than 1 0 gpm 3 8 Figure 4 Liters Min repair the auxiliary cylinder If the internal leakage is i f greater than 1 0 gpm 3 8 Liters Min repair the HFB70 gear See NOTE If all seals as included in the complete seal kit internal leakage diagram FIGURE 4 have been correctly replaced and the HFB70 steering gear camnot pass the internal leakage test or if intermi
16. to the rack piston and onto the worm shaft The internal geometry of the steering gear causes the control valve to send high pressure fluid to the correct cylinder cavity to resist the shock forces By absorbing the shock forces hydraulically the steering gear prevents objectionable kickback at the steering wheel Unloading Poppet Valves The HFB 0 gears are equipped with two unloading valves one at each end of the rack piston One valve or the other depending on the direction of turn will trip as the steered wheels approach the axle stops which must be set according to manufacturer s specification The tripped valve reduces pressure in the gear and helps to reduce heat generated by the pump At the same time the valves also reduce forces on the steering linkage Troubleshooting Information Preliminary Checks When a customer comes to you with a problem related to his truck s steering you can save a lot of time and work if you first verify the problem Make sure you re both talking the same language about the same problem If he says the truck s hard to steer find out exactly what he means Is it hard steering into a right or left turn Only when turning the steering wheel while the truck is sitting still Is there only intermittent power steering Or is there no power assist at all If at all possible and if its safe to do so test drive the truck If you re not familiar with the rig let the customer drive it while you s
17. valves This will allow full pump relief pressure to develop To prevent operation of the poppets place an unhardened steel spacer block about 1 inch thick and long enough to keep your fingers clear between the axle and stop at one wheel see FIG 3 Figure 3 With the fluid temperature between 125 F 51 7 C and 135 F 57 22C turn the steering wheel until the axle stops bottom on the spacer block FIG 3 CAUTION When running this test do not hold the steering wheel in the full turn position for longer than 5 to 10 seconds at a time to avoid damaging the pump WARNING KEEP YOUR FINGERS CLEAR OF THE AXLE STOPS AND SPACER BLOCK DURING THIS TEST MAKE SURE THAT THE SPACER BLOCK CONTACTS THE AXLE STOP SQUARELY CONTACT THAT IS NOT SQUARE COULD BREAK THE AXLE STOPS OR DANGEROUSLY THROW OR EJECT THE SPACER BLOCK Apply 20 Ibs 9 1 KG to the rim of the steering wheel during this test to be sure that the steering gear control valve is fully closed The pressure gage should now read pump relief pressure as noted during the pump pressure test You can now read steering gear internal leakage on the flow meter PUMP FLOW RATE V5 ALLOWABLE INTERNAL LEAKAGE HFB7O GEAR VARIOUS SPEEDS OF STEERING AS NOTED Litara Min GPM 22 7 6 a ae FOR 2 HWT SEC 15 1 4 FOR 1 5 HWT SEC 11 4 3 FOR 1 0 HWT SEC 7 8 2 an aa 1 Acceptable internal leakage can range from 0 to 1 5 gpm 5 7 Liters Min Repeat this test for
18. 16 inch Allen wrench socket required Apply clean grease to the end cover seal ring groove on the end cover 37 Install the new end cover seal ring 9 into the end cover seal ring groove SEE FIGURE 119 NOTE When installed the end cover seal ring should extend slightly above the machined surface of the end cover CAUTION When performing step 17 make sure that the rack piston 29 teeth are fully visible in the sector shaft cavity of the housing This is necessary to insure proper location of the poppets and to insure that the poppet adjusting screw will contact the poppets Position the end cover 37 so that the poppet adjusting screw 42 is aligned with the end of the poppet 32 SEE FIGURE 120 Install the four end cover bolts 41 1 625 in 41 mm long and washers 40 and torque the bolts to 150 170 ft Ibs 203 230 N m if dry or 108 128 ft Ibs 146 174 N m if lubricated A 13 16 inch socket required SEE FIGURE 121 Grease the two new backup O rings 13 and the two new Teflon seal rings 12 Using seal installation tool J26741 assemble the backup O rings and then the Teflon seal rings onto the valve sleeve 14 SEE FIGURES 122 123 NOTE Assemble each 0 ring and seal ring from the end closest to its groove Figure 121 Figure 122 Figure 123 dy compress rings CAUTION assemble poppet adjusting screw install valve housing seal ring NOTE install thrust
19. 5W40 EMERY FRIGID GO OW 02 SYNTHETIC WARNING COMPLETELY FLUSH THE STEERING SYSTEM WITH ONE OF THE RECOMMENDED FLUIDS ABOVE ONLY DO NOT MIX OIL TYPES ANY MIXTURE OR ANY UNAPPROVED OIL COULD LEAD TO SEAL DETERIORATION AND LEAKS A LEAK COULD ULTIMATELY CAUSE THE LOSS OF FLUID WHICH COULD RESULT IN A LOSS OF POWER STEERING ASSIST Filling and Air Bleeding the System CAUTION For steps 1 and 2 do not turn the steering wheel Otherwise air may be induced into the system 1 Fill the reservoir nearly full Crank the engine for 10 seconds without if possible allowing it to start If the engine does start shut it off immediately Check and refill the reservoir Repeat at least three times each time checking and refilling the reservoir CAUTION Do not allow the fluid to drop significantly or run out of the reservoir This may induce air into the system 2 start the engine and let it idle for 2 minutes Shut the engine off and check the fluid level in the reservoir 3 Start the engine again Steer the vehicle from full left to full right turn several times Add fluid as necessary to the fill line on the dipstick NOTE Poppets if equipped on the gear must be adjusted so that they relieve pressure at full left and right turns to aid in the removing of air from the system At this time make sure any poppets are properly adjusted If they are not adjust them in accordance with section 4 page 18 and repeat step 3 The above
20. 9 teeth for cracks and wear If you can piston teeth detect a step by running your fingernail horizontally across the teeth surface you must replace both the rack piston and sector shaft 48 and use a set of 34 service balls 43 SEE FIGURE 87 Figure 88 inspect rack 2 Inspect the rack piston internal ball track grooves for brinelling piston internal dents or spalling flaking SEE FIGURE 88 If either condition grooves exists you must replace all of the following parts the rack piston 29 the worm shaft input shaft assembly 16 the valve sleeve 14 and the set of 34 balls 43 inspect worm 3 Inspect the worm shaft input shaft assembly 16 ball track shaft grooves for brinelling or spalling SEE FIGURE 89 If either condition exists you must replace all of the following parts the worm shaft input shaft assembly 16 the rack piston 29 the valve sleeve 14 the set of 34 balls Visually inspect the upper shaft seal area near the input shaft serrations for nicks and run your fingernail edge across the sealing surface to detect steps SEE FIGURE 90 Visually inspect the sleeve 14 contact area of the worm shaft input shaft for discoloration from excess heat If either of these conditions exist you must replace the worm shaft input shaft assembly 16 and valve sleeve 14 as a matched set Figure 89 Figure 90 NOTE NOTE The input shaft is pinned to the worm shaft by the torsion bar pin and the assembl
21. E AND LIMB ITEMS AS SUCH IT IS IMPERATIVE THAT THE INSTRUCTIONS IN THIS BOOKLET ARE FOLLOWED TO THE LETTER FAILURE TO OBSERVE THE PROCEDURES SET OUT IN THIS PAMPHLET MAY RESULT IN LOSS OF STEERING Introduction Service Manual for Model HFB70 This service manual has one purpose to guide you in maintaining troubleshooting and servicing the HFB70 Hydrapower integral power steering gear Material in this manual is organized so you can work on the HFB 0 and get results without wasting time or being confused To get these results you should review the contents of this manual before you begin any work on the HFB 0 The section of this manual on General Design and Operation treats the major parts of the HFB70 and explains how they function together The knowledge you acquire from reviewing this section should assist you in solving your steering problem This manual also contains troubleshooting information and checklists With them you can diagnose a steering problem without removing the HFB70 from the vehicle If you must service the HFB 0 the checklists will help you to determine where the problem may be The three column format of the Repairs Adjustments Disassembly Inspection and Assembly sections will make it easier for you to service the HFB70 Column 1 gives a brief key for each procedure Column 2 explains in detail the procedure you should follow Column 3 illustrates this procedure with photographs Pay special attention t
22. E THRUST WASHER COULD BREAK WHEN YOU ASSEMBLE THE VALVE HOUSING INTO THE GEAR HOUSING 19 SEE FIGURE 128 A BROKEN WASHER COULD CAUSE UNCONTROLLABLE STEERING POSSIBLY RESULTING IN AN ACCIDENT Figure 124 Figure 125 Figure 126 Figure 127 Figure 128 install thrust washer WARNING assemble valve sleeve onto valve housing WARNING position rack piston amp rotate worm shaft WARNING 25 When the 10 minute compression time has elapsed remove the compression tool J26742 from the valve sleeve 14 Apply more grease to the valve sleeve seals and grease the thrust washer face on the end of the valve sleeve without the drive slots Place the other thrust washer 10 onto the valve sleeve end without the drive slots SEE FIGURE 129 WARNING THIS THRUST WASHER MUST BE SECURELY IN PLACE ON THE VALVE SLEEVE IF IT IS Figure 129 NOT IT CAN BREAK AND CAUSE UNCONTROLLABLE STEERING POSSIBLY RESULTING IN AN ACCIDENT 26 Assemble the valve sleeve 14 with attached thrust washer down Into the valve housing 8 SEE FIGURE 130 When the valve sleeve is in place it should measure between 370 and 400 inches 9 40 10 16 mm above the face of the valve housing to the end of the valve sleeve nose SEE FIGURE 131 WARNING DO NOT FORCE VALVE SLEEVE DOWN INTO THE VALVE HOUSING MAKE SURE VALVE SLEEVE SEAL RINGS ARE COMPRESSED MISASSEMBLY OR INCORRECT MEASUREMENT MAY CAUSE THE THRUST WASHERS OR THRUST BEAR
23. ING TO BREAK DURING GEAR OPERATION WHICH WILL RESULT IN UNCONTROLLABLE STEERING Figure 130 21 Position the rack piston 29 so that it is flush with the open end of the gear housing 19 Rotate the worm shaft 16 until it extends out of the rack piston as far as it will go WARNING WORM SHAFT AND VALVE SLEEVE UNITS ARE ASSEMBLED AND SOLD AS MATCHED SETS 370 TO 400 In USE ONLY PREMATCHED SETS FOR REPLACEMENT 9 40 TO 10 16 mm NEVER MATE AN OLD SLEEVE WITH A NEW WORM OR AN OLD WORM WITH A NEW SLEEVE TO DO SO MAY DAMAGE THE GEAR OR INJURE THE DRIVER OR DO BOTH DURING OPERATION Figure 131 41 install valve assembly onto worm shaft input shaft assembly NOTE WARNING finish valve housing installation install valve housing bolts assemble adjusting screw and retainer 42 28 29 30 31 Locate the timing mark on the valve sleeve 14 a faint punched mark on the chamfered edge of the valve sleeve or an indented mark on the front face of the sleeve SEE FIGURE 132 Locate the scribed timing mark on the worm shaft SEE FIGURE 62 page 25 Next grasp the valve housing valve sleeve assembly with your thumbs on the valve housing face and your fingers applying pressure to keep the valve sleeve in the valve housing SEE FIGURE 133 Align the previously located timing marks and place the valve housing valve sleeve assembly onto the input shaft end of the worm shaft input shaft 16 unt
24. ITOT TU AUTOMO Commercial Steering Systems HFB Steering Gear Service M anual HFB70 SERIES HFB70 Integral Hydraulic Power Steering Gear This steering gear was specifically designed for motor trucks new design features and our design experience with previous models of integral hydraulic power steering gears have been combined into this new product MF ES ng __ _ __ _ 7 7 b ANS l A l x f EE sg d rd pe A lt NE N pod Ve Nae LNG MG NG NG NG Ga CET les de eg a d a SS ES Ono oe _ A l med RE i S E eZ SAN NG ee MY bu BISE Ba ASAN YEY a N LIFE C3 ye N Design Features 1 Rotary Valve his device provides responsive steering Balanced Area Cylinder Back pressures cannot affect control steering stability ra Precision Roller Bearings Allow the steering gear to High Temperature Seals These specially developed seals operate with high efficiency and reversibility Unloading Valves Furnish power steering pump protection and reduce pressure to unload steering linkage at the ends of steering gear travel Recirculating Balls Combines high mechanical efficiency with smooth operation Dirt and Water Seals Lip type seals on both input and output shafts Torsion Bar Provides positive valve centering with definitive feel of the road may be operated intermitten
25. N ARM FROM THE SHAFT WITH A CHISEL AND YOUR HANDS REMOVE THE CHISEL FROM THE PITMAN ARM AND USE A PULLER ONLY TO REMOVE THE PITMAN ARM remove 1 2 Remove protector boot 60 grease fitting 61 and dirt and water protector boot seal 26 SEE FIGURE 7 8 Discard protector boot and dirt and fitting and dirt water seal and water seal Figure 8 clean sector 1 3 Clean the sector shaft 48 with a fine grade of emery paper Be shaft sure to remove any paint SEE FIGURE 9 Figure 9 11 remove trunnion cover 4 seal 1 4 Next remove the four trunnion cover bolts 28 washers 27 and trunnion cover 25 SEE FIGURE 10 A 1 2 inch socket required package Be prepared for fluid loss Then remove and discard the sector shaft seal package consisting of the two piece sector shaft seal 23 the Teflon backup washer 24 and the trunnion cover seal ring 22 SEE FIGURE 11 clean and 1 5 Clean the trunnion cover 25 with petroleum based solvent blow Inspect trunnion dry and inspect the seal cavity and sealing face for nicks or cover corrosion Replace the trunnion cover with a new one if these conditions exist Figure 10 WARNING WARNING SINCE THEY ARE FLAMMABLE BE EXTREMELY CAREFUL WHEN USING ANY SOLVENT EVEN A SMALL EXPLOSION OR FIRE COULD CAUSE INJURY OR DEATH WARNING WARNING WEAR EYE PROTECTION AND BE SURE TO COMPLY WITH OSHA OR OTHER MAXIMUM AIR PRESSURE REQUIREMENTS Figure 11 install new washer 1 6
26. N GUIDES ARE IN PLACE A BALL MAY MOVE INTO THE DEAD TRACK BEYOND THE BALL RETURN GUIDES THIS CAN RESULT IN A STEERING LOCKUP WHICH COULD CAUSE AN ACCIDENT Coat the ball return guides 44 liberally with grease and insert the remaining 12 balls into a guide half SEE FIGURES 111 112 Join the guide halves together and install this subassembly into the rack piston NOTE For models with the ball return clip 46A per form step 10 SEE FIGURE 72 For models with the ball return guide cap 46 perform step 11 SEE FIGURE 74 If your gear is equipped with the ball return guide clip 46A install it so that both bolt hole faces are in full contact with the rack piston 29 surface Install the two lock tabs 47A and the two hexagon head bolts 47B Torque the bolts to 14 22 ft Ibs 19 30 N m Finish by bending up the lock tabs against the bolt heads SEE FIGURES 113 114 1 2 inch socket required NOTE The current ball return guide clip 46A 47A will have integral lock tabs and be included in current service seal kits Figure 111 Figure 112 Figure 114 3 assemble ball return guide cap WARNING install rack piston worm shaft assembly into housing CAUTION NOTE assemble worm shaft poppet adjusting screws amp sealing nuts assemble poppet screw assembly into end cover 38 Dl If your gear is equipped with the ball return guide cap 46 instead of the clip grease the new ball re
27. NY STEERING COMPONENT WHICH HAS BEEN OR IS SUSPECTED TO HAVE BEEN SUBJECTED TO IMPACT REPLACE ANY DAMAGED OR QUESTIONABLE COMPONENT ol Steering System Maintenance Tips of Prevent internal bottoming of the steering gear Carefully check axle stops to be sure that they meet the manufacturer s specifications Regularly check the fluid and the fluid level in the power steering reservoir Keep tires inflated to correct pressure Always use a puller never a hammer or torch to remove pitman arms Investigate and immediately correct the cause of any play rattle or shimmy in any part of the steering linkage or steering mechanism Remove the cause of steering column misalignment Encourage all drivers to report any malfunctions or accidents that could have damaged steering components Do not attempt to weld any broken steering component Replace the component with original equipment only Do not cold straighten hot straighten or bend any steering system component Always clean off around the reservoir filler cap before you remove it Prevent dirt or other foreign matter from entering the hydraulic systems Investigate and correct any external leaks no matter how minor Replace filters and pumps in compliance with specification If extended stationary use of vehicle is developing excessive hydraulic fluid temperatures consult vehicle manufacturer for auxiliary cooling method Maintain grease pack applied behind the input
28. RE 17 1 12 Apply a generous amount of the same grease to protector boot 60 in the area inside of the smaller diameter ring Assemble protector boot onto sector shaft 48 and trunnion cover 25 locating the grease fitting hole toward the input shaft end of gear assembly Insert grease fitting 61 into protector boot Remove tape from sector shaft serrations SEE FIGURE 18 1 13 Reconnect the pitman arm making sure the timing mark on the pitman arm aligns with the timing mark on the sector shaft SEE FIGURE 19 WARNING WHEN USING A CHISEL TO SPREAD THE PITMAN ARM BOSS FOR ASSEMBLY ONTO THE SECTOR SHAFT 48 MAINTAIN A FIRM GRIP ON THE CHISEL AT ALL TIMES FAILURE TO DO THIS MAY RESULT IN THE CHISEL FLYING LOOSE WHICH COULD CAUSE AN INJURY NEVER LEAVE THE CHISEL WEDGED IN THE PITMAN ARM BOSS Mobil Temp is a Registered Trademark of Mobil Oil Co Figure 15 Figure 16 Figure 18 Figure 19 13 install and torque pitman arm bolt CAUTION fill and bleed system remove input coupling amp protector clean input shaft WARNING remove and plug the return line 1 14 Insert the pitman arm clamp bolt and nut assembly using a 3 4 16 grade 8 bolt SEE FIGURE 20 If the bolt is lubricated or plated torque its to 300 320 ft Ibs 407 434 N m If dry and unplated torque to 380 420 ft Ibs 515 569 N m CAUTION Be sure there is no spreading wedge left in the pitman arm boss before torquing
29. RE 77 36 Remove the worm shaft input shaft 16 from the rack piston 29 SEE FIGURE 78 37 Remove and discard the rack piston seal ring 36 SEE FIGURE 79 Figure 78 Figure 79 remove rack piston 0 ring remove Worm shaft seal and 0 ring CAUTION WARNING remove poppets if necessary 38 39 40 Remove and discard the rack piston backup 0 ring 35 from the rack piston SEE FIGURE 80 Remove and discard the worm shaft seal ring 18 Then remove and discard the worm shaft O ring 17 from the worm shaft input shaft 16 SEE FIGURE 81 CAUTION This completes the extent that the worm shaft input shaft 16 may be disassembled for service See Warning on Page 25 WARNING DURING STEP 40 YOU SHOULD WEAR EYE PROTECTION AS THE SPRING LOADED POPPETS COULD EJECT AND CAUSE EYE INJURY It is not usually required to service the poppet assembly If required however position the rack piston 29 carefully in a vise equipped with soft jaws Then remove two retaining rings 30 two poppet seats 31 two poppets 32 nylon spacer rod 33 and spring 34 SEE FIGURES 82 83 84 Figure 80 Figure 81 Figure 84 29 remove housing bearing if necessary CAUTION NOTE remove bleed SCrew 30 41 42 The housing bearing assembly 20 or race should only be removed if you determine that the bearing must be replaced after following inspection pr
30. Refer to Vehicle Service Manual for proper torque WARNING WARNING MISTIMED U JOINTS CAN RESULT INA BUMPY SENSATION AT THE STEERING WHEEL AND POSSIBLY AFFECT STEERING CONTROL fill and bleed 2 13 Before operating the steering gear fill the system with the system recommended fluid only and bleed the system following the filling and bleeding instructions on page 50 Adjustments You can make three adjustments to the gear while it is mounted on the vehicle the worm shaft preload adjustment the poppet valve adjustment and the sector shaft adjustment 3 Worm Shaft Preload Adjustment With vehicle engine off loosen sealing 3 1 Back off the worm shaft adjusting screw sealing nut 39 three nut and adjusting turns SEE FIGURE 33 Back off the worm shaft preload adjusting screw screw 38 at least one turn SEE FIGURE 34 Inspect the threads between the jam nut and end cover 37 for foreign matter Clean the threads or replace the sealing nut if necessary SEE FIGURE 35 Figure 34 torque adjusting 3 2 While torquing the worm shaft preload adjusting screw 38 to screw 60 70 in Ibs 81 95 N m have someone lightly move the steering wheel back and forth about one inch 25 mm total NOTE NOTE While torquing the adjusting screw make sure that the worm shaft adjusting screw sealing nut 39 does not tighten against end cover torque sealing 3 3 Torque the worm shaft adjusting screw sealing nut 39 to 70 80 nut ft Ibs 95 108 N
31. TE If the seal kit being used includes a ball return guide clip 46A 47A with integral lock tabs discard the ball return guide clip removed from the unit For a rack piston with the ball return guide cap 46 instead of the clip remove the two special screws 47 which will require either a 5 32 inch allen wrench or a I 30 Torx wrench SEE FIGURE 73 Remove the ball return guide cap and the ball return cap seal 45 SEE FIGURE 74 Discard screws and cap seal Figure 70 Figure 71 Figure 72 Figure 73 Figure 74 21 remove guides amp balls CAUTION WARNING NOTE remove Worm shaft remove seal ring 28 35 Remove the two ball return guide halves 44 SEE FIGURE 7b Remove the balls 43 from the rack piston 29 by rotating the worm shaft input shaft 16 until the 34 balls fall out SEE FIGURE 76 CAUTION Assembly contains a set of 34 matched balls and you must take special care not to lose any If any balls are lost a complete new set of matched balls will be required WARNING INCORRECT MATCHING OF BALLS WORMSCREW AND RACK PISTON CAN RESULT IN LOSS OF STEERING WHICH COULD RESULT IN AN ACCIDENT NOTE Ball return guides are closely fitted with the rack piston and you may have to remove them by carefully inserting a screw driver between the rack piston and the ball return guides See composite picture of both types of rack piston assemblies and two types of ball guides SEE FIGU
32. TEM DESCRIPTION ITEM DESCRIPTION NO NO 42 Poppet Adjusting Screw 51 Retaining Ring 43 Balls 34 52 Side Cover Seal Two piece 44 Ball Return Guides 2 53 Teflon Backup Washer 45 Ball Return Guide Cap Seal 54 Steel Backup Washer 46 Ball Return Guide Cap 55 Side Cover Gasket 46A Ball Return Guide Clip 56 Side Cover Ass y 47 Allen or Torx Head Screws 2 57 Vent Plug 47A Lock Tabs 2 58 Jam Nut 47B Hex Head Bolts 2 59 Special Ring Head Bolts 8 48 Sector Shaft 60 Seal Protector Boot 49 Sector Shaft Adjusting Screw 61 Grease Fitting 50 Retainer 62 Seal Protector ALTERNATE CONSTRUCTION NOTE Teflon Backup Washer 53 is an Integral Part of 2 Piace Seal 52 and Lock Tabs 474 are an Integral Part of Ball Return Guide Clip 465A in Latest Saal Kits ALTERNATE SERVICE CONSTRUCTION 19B SHY 26 156 87 Ut Yop NOILINHLSNOD dyg aping wnay jeg 40 oo Hey Jeifieul we ase Yip JANIS 3LVNHINY 5 cS SQEL 4307 pug 7G 1895 8261 2 JO Weg Efe we S EG 1ause n dnyoeg Wola 310M Rbag t L Buoj 929 pasn y sijog 48A09 pug y SBYSeAA 19 A09 pug INN Buljeas Malas Bunsnfpy yeys WOM M S Bunsnipy peojaig HEYS WOM 1809 pu e3S UO1SId JOEY U0 J3 Buly 0 dnyaeg uolsig J984 Buds poy 4a9ede Z syaddod Z sjeas jaddod z sbuiy Bululeyay UO SIq Y3eY y SUO9 19A09 U0lUunI y SBYSeAA 13409 UOIUUNII jeas J9 EM pue UIG Jano U0lUUNI
33. and rolls for brinelling or spalling If either condition exists replace the damaged housing bearing 20 For the housing bearing follow disassembly step 41 and assembly step 2 Pages 30 and 34 If the side cover bearing is damaged replace side cover assembly SEE FIGURES 94 95 WARNING FOR BEARING TYPE WITH UNCAGED LOOSE ROLLS DO NOT MIX THE ROLLS FROM THE SIDE COVER BEARING WITH THE ROLLS FROM THE HOUSING BEARING THE BEARING RACE AND ROLLERS ARE A MATCHED SET INTERCHANGING THE ROLLS COULD RESULT IN PREMATURE BEARING OR SEAL FAILURE WHICH COULD CAUSE A LOSS OF POWER STEERING Figure 95 inspect sector shaft assembly NOTE inspect adjusting screw and retainer inspect thrust washers and bearing ip 8 9 This completes inspection of the HFB70 steering gear Inspect the sector shaft 48 bearing and sealing areas and sector INSPECTION AREAS teeth contact surfaces for brinelling or spalling SEE FIGURE 96 Run your fingernail edge across these areas to detect steps Inspect also for cracks Remove any masking tape from the shaft serrations and inspect for twisted or otherwise damaged serrations If any of these conditions exist replace the sector shaft NOTE A service shaft assembly will have the adjusting screw 49 and retainer 50 assembled into it The screw 49 and retainer 50 can be serviced separately if required Inspect the sector shaft assembly for damaged adjusting screw 49 threads T
34. and output shaft s dirt and water seal and seal protector as a general maintenance procedure Grease fitting provided in output shaft seal protector TRW Automotive Commercial Steering Systems 800 Heath Street Lafayette IN 47904 Tel 765 423 5377 Fax 765 429 1868 http ww w trw com commercialsteering TRW Inc 2000 TRW 1109 Rev 3 00
35. assemble into the side cover bearing 41 rolls BR 970 42 rolls BR 970 1 Do not these rolls for the side cover with the rolls for the trunnion cover side of the gear housing If the side cover does not have a caged bearing assembly assemble 41 or 42 rolls into the side cover bearing race Grease must retain rolls SEE FIGURE 138 NOTE If the service replacement Teflon backup washer 53 is not an integral part of the service replacement seal 52 see alternate service construction 52 53 on exploded assembly foldout page examine the lead in chamfer or radius on the side cover short end of sector shaft 48 bearing diameter SEE FIGURE 139 If rough edges can be felt by drawing a thumb nail across the lead in chamfer or radius on the end of sector shaft skip procedures 34 35 36 and follow procedures 37 38 39 Figure 137 Figure 138 Figure 139 43 CAUTION assemble side cover seal pack CAUTION WARNING assemble retaining ring install sector shaft into side CAUTION assemble steel 4 Teflon washers into side cover alternate assemble retaining ring and seal alternate 44 34 35 36 af 38 CAUTION Following procedures 34 35 36 with a sector shaft that does not pass the thumb nail test and a replacement seal 52 that does not have the Teflon washer 53 integral to it can result in the seal being destroyed when assembling sector shaft into si
36. ble retaining ring 51 onto the side cover end of sector shaft 48 Assemble the two piece seal 52 onto the end of the sector shaft about 1 inch 25 4 mm The words oil side on the seal must face toward the sector shaft SEE FIGURE 144 Figure 140 Figure 141 Figure 142 Figure 144 ALTERNATE CAUTION install sector shaft into side cover alternate assemble vent plug WARNING assemble jam nut install side cover gasket center rack piston CAUTION 39 40 4 ma 42 43 CAUTION Be sure the two piece seal and the side cover bearing rolls remain correctly assembled and that the vent plug 57 has been removed during these procedures Be sure the side cover bearing the sector shaft bearing diameter and seal are well greased then insert sector shaft 48 assembly into the side cover 56 bearing only until the shaft will retain the loose side cover bearing rolls in place about 8 turns of adjusting screw Slowly and carefully work the two piece seal 52 down the sector shaft and squarely into the side cover until it is past the retaining ring groove Then work the retaining ring 51 into the retaining ring groove Use an appropriate blunt end punch or punches SEE FIGURE 145 Carefully turn the adjusting screw 49 through side cover until it reaches solid height then back screw one turn so that the side cover rotates freely on sector shaft Assemble the vent plug 57 i
37. boot 60 grease fitting 61 and the dirt and boot amp dirt and water seal 26 from the trunnion cover 25 SEE FIGURE 41 water seal Discard boot and seal 20 Figure 41 TIMING MARK clean sector shaft and loosen jam nut remove trunnion cover bolts 4 washers remove trunnion cover and seal package tape sector shaft remove side cover bolts NOTE di 4 Remove any paint or corrosion from the exposed area of the sector shaft 48 and loosen the jam nut 58 on the sector shaft adjusting screw 49 3 4 inch socket required Remove the four bolts 28 and washers 27 from the trunnion cover with a 1 2 inch socket SEE FIGURE 42 5 Remove the trunnion cover 25 Remove and discard the seal ring 22 the two piece sector shaft seal 23 and the Teflon back up washer 24 from the trunnion cover SEE FIGURE 43 6 Tape the serrations and bolt groove of the sector shaft 48 with one layer of masking tape to prevent loose bearing rolls from hanging up the sector shaft during its removal The tape should not extend on to the sector shaft bearing diameter SEE FIGURE 44 7 Prepare for fluid to drain and remove eight special ring head bolts 59 from the side cover 56 with a 13 16 inch socket SEE FIGURE 45 NOTE These bolts are special because they are equipped with either a ring or washer design on the underside of the head If you replace one or more bolts you must use bolts of eit
38. ctor boot 60 in the area inside of the smaller diameter ring Assemble the protector boot onto the sector shaft and trunnion cover Locate the boot grease fitting hole toward the input shaft end of gear assembly SEE FIGURE 156 Insert grease fitting 61 into protector boot Apply clean grease in the input shaft seal assembly 7 washer 6 and to the input shaft Install the new two piece input shaft seal 7 flat side out and the steel backup washer 6 using seal driving tool J28490 Install the retaining ring 5 SEE FIGURES 157 158 Pack the area around the input shaft with high temperature industrial grease per Ross specification 045231 Mobil Temp 1 or 2 or equivalent and install the dirt and water seal 4 using seal driving tool J28490 or suitable blunt ended drift Mobil Temp is a Registered Trademark of Mobil Oil Co Figure 158 4 assemble seal protector install manual bleed screw if equipped 48 54 Apply more of the special grease to the cupped side of the new seal protector 62 and assemble it cupped side in on to the worm shaft input shaft 16 and into the serration relief groove SEE FIGURE 159 55 If your gear is equipped with the manual bleed screw I9A install it into the gear housing 19 and torque it to 27 33 in Ibs 3 1 3 7 N m SEE FIGURE 160 5 16 inch hex socket required This completes assembly of the HFB 0 steering gear Before you install the gear onto the vehicle
39. de cover Assemble the steel back up washer 54 into side cover 56 Assemble a new Teflon washer 53 then a new two piece seal 52 or a new two piece seal that has the integral Teflon washer 52 53 into the side cover such that the words Oil side are visible after the seal is assembled SEE FIGURE 140 CAUTION Be sure that a separate Teflon washer 53 is not used with a two piece seal 52 53 that has the Teflon washer integral to it WARNING THE WORDS OIL SIDE MUST BE VISIBLE ON THE SEAL AFTER IT IS IN PLACE IF NOT THE SEAL WILL NOT FUNCTION AND A LOSS OF POWER STEERING ASSIST MAY OCCUR Assemble retaining ring 51 into the ring groove in the side cover SEE FIGURE 141 Apply a generous amount of clean grease to the short bearing area of the sector shaft 48 and insert the sector shaft into the side cover 56 Screw the adjusting screw into the side cover until it reaches solid height Then back out the adjusting screw One turn so that the side cover rotates freely on the sector shaft SEE FIGURE 142 CAUTION Be sure that one or more bearing rolls do not become dislodged during assembly of sector shaft into side cover If the replacement Teflon washer 53 is not an integral part of the two piece seal 52 and the sector shaft 48 did not pass the thumb nail test assemble the steel backup washer 54 and then the Teflon washer 53 into the side cover 56 bearing bore SEE FIGURE 143 Assem
40. e Trunnion Cover Bolts Trunnion Cover Bolts Worm Shaft Preload Adjusting Screw Worm Shaft Adjusting Screw Sealing Nut Poppet Adjusting Screw Sealing Nuts Poppet Seats Hex Head Bolts Allen or Torx Head Screws End Cover Bolts End Cover Bolts Valve Housing Bolts Valve Housing Bolts special Bolts special Bolts Bleed Screw Pitman Arm Clamp Bolt Pitman Arm Clamp Bolt Jam Nut Item Number 28 28 If Lubricated 38 39 2 31 47B 47 41 41 If Lubricated 1 1 If lubricated 59 59 If lubricated 19A Lubricated Plated Dry Unplated 58 Torque 15 22 ft Ibs 20 30 N m 11 16 ft Ibs 15 22 N m 60 70 in Ibs 6 8 7 9 N m 70 80 ft Ibs 95 108 N m 12 18 ft Ibs 16 24 N m 20 25 ft Ibs 27 34 N m 14 22 ft Ibs 19 30 N m 14 22 ft Ibs 19 30 N m 150 170 ft Ibs 203 230 N m 108 128 ft Ibs 146 174 N m 150 170 ft Ibs 203 230 N m 108 128 ft Ibs 146 174 N m 150 170 ft Ibs 203 230 N m 108 128 ft Ibs 146 174 N m 27 33 in lbs 3 1 3 7 N m 300 320 ft Ibs 407 434 N m 380 420 ft Ibs 515 569 N m 40 45 ft Ibs 54 61 N m Universal joint bolts torque to vehicle manufacturer s specifications All torques specified in this manual are for dry unplated parts unless otherwise specified Tools and Materials Required for Servicing 19D Manual Tape Grease Wheel bearing grease Grease Mobil Temp 1 or 2 or equivalent Special Tools Seal Installation Tool J26739
41. ece of wrapping paper makes an excellent disposable top Clean and dry the gear before you start to disassemble it As you disassemble the gear clean all parts in clean petroleum based solvent and blow them dry only WARNING SINCE THEY ARE FLAMMABLE BE EXTREMELY CAREFUL WHEN USING ANY SOLVENT EVEN A SMALL EXPLOSION OR FIRE COULD CAUSE INJURY OR DEATH WARNING WEAR EYE PROTECTION AND BE SURE TO COMPLY WITH OSHA OR OTHER MAXIMUM AIR PRESSURE REQUIREMENTS CAUTION Never steam clean or high pressure wash hydraulic steering com ponents Do not force or abuse closely fitted parts Keep each part separate to avoid nicks and burrs Discard all seals O rings and gaskets removed from the gear Replace them with new parts only Disassembly position gear amp 1 Position the steering gear firmly in a vise with the gear s worm sector shaft shaft input shaft 16 in a horizontal direction Prepare for fluid drainage and unplug fluid line ports Rotate worm shaft input shaft with an 11 16 inch or 3 4 inch 12 point socket or box end wrench through the gear travel several times to purge hydraulic fluid from the unit Then position the timing mark located on the end of the sector shaft 48 to a vertical direction SEE FIGURE 40 CAUTION CAUTION Clamp only against housing mounting bosses or attach a plate to the mounting bosses for this purpose Do not clamp against the body of housing remove protector 2 Remove protector
42. ed by the vehicle manufacturer you should follow those instructions rather than the procedure described below With the engine idling and the fluid temperature between 125 F 51 7 C and 135 F 57 2 C check the pump manufacturer s specifications for flow rate Compare these specifications with the flow rate on the flow meter Now fully close the load valve until the pressure gage registers the pressure at which the pump is relieving When pump relief is reached flow rate must be zero IMMEDIATELY OPEN THE LOAD VALVE The flow rate must instantly return to the original reading If this rate does not return immediately the pump is malfunctioning which can result in intermittent power assist Now set the engine at governed rpm and fully close the load valve again until pump relief is reached At pump relief the flow rate must be zero IMMEDIATELY OPEN THE LOAD VALVE The flow rate must instantly return to the original reading If this rate does not return immediately the pump is malfunctioning which can result in intermittent power assist NOTE Conduct the pump flow test once at idle rpm and three times at governed rpm CAUTION Do not allow the fluid temperature to exceed 180 F 82 2 C Run each phase of this test between 125 F 51 7 C and 135 F 57 2 C Steering Gear Internal Leakage Test To test the steering gear for internal leakage you must first prevent operation of the gear s internal unloading poppet
43. f the gear and some fluid will squirt out of the gear SEE FIGURE 28 Discard the seal Disconnect the shop air as soon as the seal assembly is out Figure 28 15 install seal package grease input shaft install seal assemble seal protector reconnect line 2 7 Apply clean grease to the new input shaft seal assembly 7 washer 6 and the input shaft Install the new two piece input shaft seal flat side up and the steel backup washer using the seal driving tool J28490 SEE FIGURE 29 Install the retaining ring 5 2 8 Pack the area around the worm shaft input shaft 16 and dirt and water seal 4 cavity with high temperature industrial grease per Ross specification 045231 Mobil Temp 1 or 2 or equivalent SEE FIGURE 30 2 9 Install the new dirt and water seal 4 with tool J28490 or a suitable blunt end drift SEE FIGURE 31 2 10 Add more grease to seal area and assemble seal protector 62 onto worm shaft input shaft 16 seating it in the relief groove just beyond the input shaft serrations with cupped side toward the gear SEE FIGURE 32 2 11 Remove the plug and reconnect the return line Mobil Temp is a Registered Trademark of Mobil Oil Co Figure 31 Pd sas i Figure 32 reconnect input 2 12 Reconnect the input coupling If the input coupling male coupling assembly slides free of the female end during reassembly realign the timing marks to insure proper phasing of the U joints
44. from the sector shaft 48 clamp the sector shaft into a soft faced vise by gripping the serrated end Coat the expanded end of the new Figure 133 ki Figure 136 WARNING grease side bearing cover bearing CAUTION NOTE assemble side cover bearing NOTE 32 JU adjusting screw with a suitable grade of wheel bearing grease and insert into recess in end of sector shaft Thread a new sector shaft screw retainer 50 into the sector shaft and adjust to permit free rotation of sector shaft adjusting screw by hand without perceptible end play 000 to 002 in 05 mm loose Stake the new retainer into the two slots provided using a suitable punch and again check freedom of adjusting screw movement and end play SEE FIGURE 137 WARNING USE CARE IN SECURELY STAKING THE RETAINER 50 INTO THE SECTOR SHAFT SLOTS A RETAINER THAT IS BROKEN OR CRACKED DURING THE STAKING PROCEDURE MUST BE REPLACED AS IT COULD RESULT IN THE SECTOR SHAFT NOT BEING RETAINED AND THE LOSS OF MANUAL AND POWER STEERING CONTROL Apply a generous amount of clean wheel grease do not substitute another type of grease to the bearing race or caged bearing assembly inside the side cover 56 CAUTION Use only wheel bearing grease This bearing is sealed and will receive no lubrication from the hydraulic fluid in the gear Failure to use wheel bearing grease could result in premature bearing wear NOTE You will have 41 or 42 rolls to
45. haft input shaft adjusting screw 38 using a 5 16 inch Allen wrench socket into solid height 15 to 20 ft Ibs 20 3 to 27 1 N m Then loosen the adjusting screw 1 4 to 1 2 turn and note torque required to rotate worm shaft input shaft 16 through 90 each side of center using an 12 point socket that will fit input shaft serrations and an appropriate torque wrench SEE FIGURE 150 Loosen adjusting screw if noted input shaft torque exceeds 15 in Ibs 17 N m Return rack piston to center position WARNING AS YOU PLACE THE SECTOR SHAFT THROUGH THE HOUSING BEARING 20 BE CAREFUL NOT TO KNOCK OUT ANY OF THE BEARING ROLLS SEE FIGURE 151 BE CAREFUL ALSO NOT TO PINCH THE SIDE COVER GASKET 55 SHOULD THE BEARING ROLLS BE KNOCKED OUT OR THE SIDE COVER GASKET PINCHED PREMATURE BEARING AND SEAL FAILURE MAY OCCUR WHICH COULD RESULT IN A LOSS OF POWER STEERING ASSIST Clean off any old tape on the sector shaft 48 serrations Retape the serrations and bolt groove with one layer of tape Assemble the sector shaft 48 side cover 56 assembly into the gear housing 19 with the center tooth of the sector shaft engaging the tooth space between the second and third teeth on the rack piston SEE FIGURE 152 Assemble the eight special ring head bolts 59 and torque them to 150 170 ft Lbs 203 230 N m if dry or 108 125 ft Ibs 146 174 N m if lubricated 13 16 inch socket required Place the trunnion cover 25 on a bench to install
46. he staked retainer 50 must be locked in place and have no cracks The adjusting screw must rotate by hand with no perceptible end play lash Replace adjusting screw if damaged Replace the retainer if damaged or if the adjusting screw requires replacement or adjustment Inspect the thrust bearing 11 rollers for any deterioration Inspect the two thrust washers for brinelling spalling or cracks SEE FIGURE Replace any part with these conditions Figure 97 33 Assembly Preparation Wash all parts in clean petroleum based solvent Blow them dry only WARNING WARNING WARNING SINCE THEY ARE FLAMMABLE EXTREMELY CAREFUL WHEN USING ANY SOLVENT EVEN A SMALL EXPLOSION OR FIRE COULD CAUSE INJURY OR DEATH WARNING WEAR EYE PROTECTION AND BE SURE TO COMPLY WITH OSHA OR OTHER MAXIMUM AIR PRESSURE REQUIREMENTS Replace all seals seal rings and gaskets with new ones each time you disassemble the gear Ross Gear does provide individual seals seal rings and gaskets as well as complete and partial seal kits SEE FIGURE 98 These parts should be available thru most QEM parts distributors Contact your local dealer for availability 9 Assembly assemble worm 1 shaft O ring amp seal ring CAUTION CAUTION install housing ra bearing and retaining ring 34 Slide compression tool J26740 small diameter end first onto the worm end of worm shaft input shaft 16 until it is beyond the seal
47. her design and of the SAME SPECIAL TYPE AND LENGTH AS THOSE YOU REMOVED Do not use a substitute You can get these bolts through your OEM parts distributor SEE FIGURE 46 NN es Om an Oe Na Png Reid De ire BOT aii po ed po df a p dd a Le gF _ dd AN Figure 46 21 begin to remove side cover amp sector shaft NOTE CAUTION remove side cover and sector shaft CAUTION remove bearing rolls remove jam nut remove sector shaft 22 8 10 Begin to remove the side cover 56 and sector shaft 48 as an assembly SEE FIGURE 47 Stop removal when the bearing rolls in the housing bearing 20 are half exposed Coat the bearing rolls with grease As a means of starting the removal of the side cover and sector shaft assembly you may use a soft hammer or wooden hammer handle SEE FIGURE 48 NOTE When the bearing rolls are half exposed and it is evident that the unit has a caged bearing rolls retained the following caution note does not apply CAUTION Take care to remove this assembly slowly or it may come out too quickly for you to retain the loose bearing rolls in the housing bearing race Follow the shaft end with the bearing tool J26743 to retain the rolls or when the rolls are half exposed be sure to coat them with grease to retain them in the housing bearing If one or more of the rolls is lost you must replace the entire bea
48. il the drive lugs are fully engaged in the valve sleeve slots SEE FIGURE 134 NOTE Valve sleeves are identified and matched to a right or left hand lead of the worm screw If the screw has a right hand thread that is goes into the rack piston when turned clockwise the valve sleeve will have the letter R stamped between the seal lands For a left hand worm lead which will come out of the rack piston when turned clockwise the mating valve sleeve has no identifying letter or has the letter L stamped between the seal lands WARNING IF YOU PLACE AN INCORRECT VALVE SLEEVE ON A WORM AND ASSEMBLE THIS INTO THE GEAR THE GEAR WILL NOT FUNCTION PROPERLY INSTEAD THE MECHANISM WILL JERK THE STEERING WHEEL WITH SUCH FORCE THAT IT COULD INJURE THE DRIVER Maintain pressure on the valve end of the valve housing 8 to insure continued engagement of the drive lugs and thrust bearing package SEE FIGURE 135 While maintaining pressure rotate the valve housing to align the poppet adjusting screw 3 with the poppet 32 in the rack piston 29 Continue pressure and rotate the input shaft to bring the valve housing into contact with the gear housing face Assemble four valve housing bolts 1 2 125 in 53 98 mm long into the housing 19 and torque to 150 170 ft Ibs 203 230 N m if dry or 108 128 ft Ibs 146 174 N m if lubricated A 13 16 inch socket required SEE FIGURE 136 If the adjusting screw 49 has been removed
49. ing foreign patents are pending and issued TRW INC 1989 Table of Contents Page HFB 0 Design Features and Phantom View 0 0000 0 eae Inside front cover Definitions and sc ld AR ee eae ad obs GLAD NE RE EK N 1 GUO 2 024256 kanta SE A LG BA by pane DE Ee nee POLL BG OR EDE DEE DES 3 HFB70 Oil Flow Illustration sco oase dee Geena aan pA LAG KAY ADD ow ed Grech ws 4 HFB70 General Design and Operation eee 5 Troubleshooting Information teen tenes 6 Troubleshooting Guide 8 Repairs and Adjustments on Vehicle SS teen 11 The Sector Shaft and Trunnion Cover 0 00 00 eee 11 The Worm Shaft Input Shaft Seal 2 eee 14 Worm Shaft Preload Adjustment SS SS Se ee ee 17 Poppet Valve Adjustment a 18 Cross Shaft or Sector Shaft Adjustment SS SS Se eee 19A HFB 0 Exploded Assembly View Typical SS SS SS SS SeSe 19B Torgue Chat 3b nba bee neha so he ee pate PD RE RD ue ee GED sues 19D Tools and Materials Required for Servicing 00 00 ccc eee 19D BEER AA MAA Ge eee es 20 IPELUDN soe EE caress AG WALA DN haa OE N N N LG NG ER NN N 31 AO Eman pama SS LG ERG NAMI DE Ge Ee E DAG pi ALA Up AT 34 Final Adjustment AA 49 Para at eieae e EN AE RE oe E EE A EE e eet 50 Filling and Air Bleeding the SYSTEM a 50 WARNINGS for Proper Steering Gear Operation SS ee 50 Steering System Maintenance Tips SS SS See ee 52 WARNING ALL STEERING MECHANISMS ARE LIF
50. ing nut and or adjusting screw be replaced 30 Remove and discard the two Teflon seal rings 12 from valve Sleeve 14 SEE FIGURE 68 31 Remove the two backup O rings 13 from the valve sleeve grooves SEE FIGURE 69 Figure 65 Figure 66 Figure 67 Figure 68 Figure 69 remove rack piston amp worm shaft NOTE remove ball return guide clip if equipped NOTE NOTE remove ball return guide cap if equipped 32 dy 34 Remove the rack piston 29 worm shaft input shaft 16 assembly from the gear housing 19 SEE FIGURE 70 Lay the rack piston 29 worm shaft 6 assembly on a clean rag to keep the piston from rolling NOTE The worm shaft part of the assembly will be inside the rack piston with the input shaft part of the worm protruding from the rack piston Take care when removing this assembly from the housing To prevent the teflon rack piston seal 36 from getting caught in the sector shaft cavity remove the worm shaft rack piston assembly from the long end of the housing For rack pistons with the ball return guide clip 46A bend the tangs down that are on the clip or on the two locking tabs 47A SEE FIGURE 68 Remove the two hex head bolts 47B lock tabs and clip Discard lock tabs SEE FIGURE 72 1 2 inch hex socket required NOTE The current HFB70 units and seal kits will utilize a ball return guide clip 46A 47A with the two tabs integral to it NO
51. it beside him Take hold of the wheel while he drives to get a feel for the problem he s talking about Since most of his driving will be with his truck hauling a load arrange for a load If one is required to reproduce the steering problem Typical Steering System Figure 1 Typical Steering System with Auxiliary Cylinder ni Figure 1A Once you ve determined the problem and its symptoms don t jump right in to tear the steering gear or pump apart In most cases in fact the gear should be the last component you check There are many other components in the steering system that could be causing the problem see FIG 1 amp 1A These you should check first Begin then by checking the steered wheels make sure that the tires are at correct pressure and equal all around that they are properly sized and that they are not worn or damaged Next have the front end alignment checked and look for abnormal looseness or tightness in the steering linkage ball joints and king pins A service replacement hose or fluid line may be misrouted or may be too small in diameter or it may be restricted in some ether way Reroute any hose that is kinked or bent sharply Replace any hoses that are not the same as original equipment Continue by checking the power steering fluid reservoir to make sure that oil is up to the correct level Also check the pump drive belt if one is used to see If it is slipping The belt may be tight
52. make final adjustments described on next page All ports should be plugged until unit is installed on vehicle Figure 160 Final Adjustment Sr TIMING MARK center steering gear NOTE tighten adjusting Screw NOTE loosen adjusting screw and note torque adjust adjusting screw adjust worm shaft input shaft adjusting screw 1 To center the steering gear rotate worm shaft input shaft 16 until the timing mark on the end of sector shaft 48 is perpendicular to the worm shaft input shaft SEE FIGURE 161 A 12 point box end or socket wrench required NOTE Initial worm preload adjustment was accomplished in assembly procedure 44 page 46 before assembly of sector shaft 48 Figure 161 2 Tighten sector shaft adjusting screw 49 to provide 25 to 30 in Ibs 2 8 to 3 4 N m of torque required to rotate the worm shaft input shaft 16 through 180 each side of center SEE FIGURE 162 NOTE This procedure will properly mesh and seat the rack piston teeth and sector shaft teeth for final adjustments 3 Loosen sector shaft adjusting screw 49 one turn and note maximum torque required to rotate the worm shaft input shaft 16 through 180 each side of center 4 Adjust sector shaft adjusting screw 49 to increase maximum torque noted in procedure 3 by 2 to 4 in Ibs 23 to 45 N m Torque jam nut 58 using a 3 4 inch socket to 40 to 45 ft Ibs 54 to 61 N m and check worm shaft input shaft torque again
53. ndicated on the thermometer reaches between 125 F 51 7 C and 135 F 57 2 C open the load valve The system is warmed up and you can conduct the tests EP THERMOMETER BRECSIIME KA RESERVOIR GAGE 16 FILTER Via LOAD 54 Nae SHUTOFF POWER STEERING PUMP FLOW METER STEERING GEAR Figure 2 CAUTION Do not close the load valve completely and leave it closed or you may damage the pump At no time allow fluid temperature to exceed 180 F 82 2 C Run all the tests at the prescribed temperature range of 125 F 51 7 C 135 F 57 2 C Power Steering Pump Pressure Test With the engine idling close the load valve and read the pressure gage If the pressure reads below the minimum specified by the pump manufacturer repair or replace the pump CAUTION Do not keep the load valve closed for longer than 5 seconds to avoid damaging the pump Closing the load valve causes the pump to operate at relief pressure and the fluid temperature to increase rapidly Allow fluid to cool between 125 F 51 7 C and 135 F 57 2 C before you resume with the other tests Power Steering Pump Flow Test WARNING MAXIMUM FLOW RATE FOR THE HFB70 STEERING GEAR IS 8 GPM 30 LITER MIN FLOW RATE SHOULD NOT EXCEED 8 GPM 30 LITER MIN EXCESSIVE FLOW CAN CAUSE DAMAGE TO INTERNAL PARTS OF THE STEERING GEAR WHICH COULD RESULT IN A LOSS OF POWER STEERING NOTE If flow specifications and methods of checking flow rate are provid
54. nto the hole provided on the side cover 56 Press the vent plug in flush with the side cover SEE FIGURE 146 WARNING DO NOT WELD OR OTHERWISE PLUG THIS HOLE IN ANY PERMANENT MANNER THIS IS A SAFETY VENT WHICH FUNCTIONS ONLY IF THE SIDE COVER SEAL FAILS IF THE SEAL FAILS AND THE PLUG CANNOT VENT THE STEERING GEAR MAY LOCKUP OR OTHERWISE MALFUNCTION Assemble the jam nut 58 onto the adjusting screw 49 a few threads Final adjustment will be made later Apply clean grease to the new side cover gasket 55 and assemble it onto the side cover 56 There must be enough grease to hold the gasket in place SEE FIGURE 147 There are four teeth on the rack piston 29 SEE FIGURE 148 Position the tooth space between the second and third teeth in the center of the housing sector shaft cavity SEE FIGURE 149 This will center the rack piston in the cavity CAUTION If the rack piston is not centered when sector shaft is installed the gear travel will be severely limited in one direction of travel and significant internal damage to the steering gear can occur when the gear Is operated Figure 146 Figure 147 45 make initial worm preload adjustment WARNING install sector shaft side cover into housing install side cover bolts assemble trunnion cover seal pack assemble seal WARNING 46 AA Ad 46 Al AB With the rack piston 29 in its center position torgue the worm s
55. o the notes cautions and warnings A foldout page with the same typical HFB70 exploded assembly view on both sides is provided in this manual The component part names and item numbers assigned on this exploded assembly view correspond with names and item numbers in parentheses used in the disassembly assembly and other procedures set forth in this manual When this exploded assembly view page is folded out you can easily identify components and locate their relative position on the exploded assembly view as you follow the disassembly assembly and other procedures As you gain experience in servicing the HFB 0 you may find that some information in this manual could be clearer and more complete If so let us know about it Don t try to second guess the manual if you are stuck contact us Servicing the HFB70 should be a safe and productive procedure HFB70 OIL FLOW ILLUSTRATION STEERING WHEEL INPUT CLOCKWISE ROTATION LI a MEN a il a i a meee Neutral No Steering Action NS N E ar Cd N DOY LU TIN L H mam a EE rd Elk al ll se ad De Ba STEERING WHEEL INPUT COUNTER CLOCKWISE ROTATION Left Hand Turn Ea Supply Pressure ba Return Pressure HFB70 General Design and Operation Design Integral Power Steering The HFB 0 power steering gear is the latest design in the Ross family of integral hydraulic power steering gears Integral hydraulic power steering means
56. ocedures 4 5 and 6 on page 32 Remove the bearing in the following manner Use bearing mandrel special tool J26743 to apply pressure from the side cover opening and press the bearing out through the trunnion cover opening SEE FIGURE 85 Maintain a good square contact between the housing and press base to avoid damaging the housing bearing bore Remove retaining ring 21 from bearing Discard bearing CAUTION If the bearing is cocked while you press it out it will burnish the bore causing it to become oversized You will then have to replace the gear housing NOTE Service housing assembly includes housing 19 bearing assembly 20 retaining ring 21 and bleed screw 19A Remove bleed screw 19A A 5 16 inch socket required SEE FIGURE 86 This completes the disassembly of the HFB70 steering gear Figure 85 Figure 86 Inspection Check to make sure that all sealing surfaces and seal cavities are free from nicks and corrosion If any part is nicked or corroded where sealing occurs you must replace the part to insure proper sealing Wash all parts in clean petroleum based solvent Blow them dry only WARNING WARNING SINCE THEY ARE FLAMMABLE BE EXTREMELY CAREFUL WHEN USING ANY SOLVENT EVEN A SMALL EXPLOSION OR FIRE COULD CAUSE INJURY OR DEATH WARNING WARNING WEAR EYE PROTECTION AND BE SURE TO COMPLY WITH OSHA OR OTHER MAXIMUM AIR PRESSURE REQUIREMENTS inspect rack 1 Inspect the rack piston 2
57. of turn only verify with internal leakage test High Steering Effort in Both Directions Low tire pressure Vehicle overloaded Low hydraulic fluid level Low pressure or flow from pump Components of steering system binding Restriction in return line or line too small in diameter Excessive internal leakage verify with internal leakage test Oversize tires check manufacturer s specifications Lost Motion Lash at the Steering Wheel steering wheel loose on the shaft Loose connection between the steering gear intermediate column and steering column Steering gear loose on frame Pitman arm loose on output shaft Components in steering linkage loose or worn steering gear improperly adjusted Excessive Heat 150 F 65 6 C Over Ambient Not to Exceed 250 F 121 C Continuously Excessive pump flow Vehicle overloaded Undersized replacement hose or line Restricted hose or line that is kinked or severely bent or internally blocked Restricted recentering of gear valve caused by column bind or side load on the Input shaft Poppet not adjusted properly only for gears equipped with poppets Prolonged stationary vehicle operation WARNING IF THE HYDRAULIC SYSTEM FLUID BECOMES OVERHEATED IT CAN CAUSE THE SEALS IN THE STEERING GEAR AND PUMP TO SHRINK HARDEN OR CRACK AND LOSE THEIR SEALING ABILITY Repairs and Adjustments on Vehicle When you have conducted the checks and tests described in the tr
58. oove on the bearing s outside diameter Then press the bearing into the housing from the trunnion side using bearing mandrel special tool J26743 against the lettered end of the bearing shell so that the retaining ring is away from the housing bore SEE FIGURE 102 During this procedure be sure that the housing is square with press base and the bearing Is not cocked NOTE Bearing BR 970 requires 41 rolls and Bearing BR 970 1 requires 42 rolls Figure 103 CAUTION The bearing rolls must be in place to insure proper installation of the bearing If the rolls are improperly installed the bearing race may col lapse and fail The flange may break causing premature failure of the bearing Again do not mix the housing bearing rolls with the side cover bearing rolls Be sure the bearing mandrel used is clean NOTE The bearing assembly 20 may be of caged Figure 104 retained roll type therefore not requiring reassembly of the rolls Install the new rack piston backup O ring 35 and the new Teflon rack piston seal ring 36 into the rack piston 29 ring groove SEE FIGURES 103 104 Do not over stretch the rings as you install them Coat with a liberal amount of grease WARNING DURING STEP 4 YOU SHOULD WEAR EYE PROTECTION AS THE SPRING LOADED POPPETS COULD EJECT AND CAUSE EYE INJURY If the poppets were removed position rack piston 29 in a soft jawed vise and install one poppet seat 31 SEE FIGURE 105 From the
59. oubleshooting sections you may find it necessary to repair or adjust the steering gear Since removing the gear from the vehicle is usually difficult and time consuming you will probably find it easier to perform the following repairs and adjustments with the gear on the vehicle The photographs in this sec tion show a gear mounted on a mock up frame for clearer illustration Figure 5 1 The Sector Shaft And Trunnion Cover remove pitman 1 1 If a leak is detected in the trunnion cover area on many HFB70 arm installations you can remove the trunnion cover to gain access to the sector shaft seal package while the steering gear is on the vehicle First remove the pitman arm nut and bolt and then the pitman arm from the sector shaft 48 SEE FIGURES 5 amp 6 Check the radial position of the pitman arm to the sector shaft prior to removal of pitman arm Add timing marks to the arm and shaft if necessary to insure correct alignment at reassembly Figure 6 NOTE NOTE A chisel will help you loosen the pitman arm Use only a puller if you cannot remove the pitman arm with your hands WARNING WARNING WHEN USING A CHISEL TO SPREAD THE PITMAN ARM BOSS IN ORDER TO LOOSEN THE PITMAN ARM FOR REMOVAL FROM THE SHAFT MAINTAIN A FIRM GRIP ON THE CHISEL AT ALL TIMES FAILURE TO DO THIS MAY RESULT IN THE CHISEL FLYING LOOSE WHICH COULD CAUSE AN Figure 7 INJURY NEVER LEAVE THE CHISEL WEDGED IN THE PITMAN ARM BOSS IF YOU CANNOT REMOVE THE PITMA
60. pitman arm clamp bolt 1 15 Before operating the steering gear fill the with the recommended fluid and bleed air the system by following the Filling and Air Bleeding instructions on page 50 2 The Worm Shaft Input Shaft Seal 2 1 If there is a leak in the shaft seal you can usually replace the input shaft seal assembly with the gear on the vehicle Start by removing the input coupling per the vehicle manufacturers instructions SEE FIGURE 21 Remove seal protector 62 and clean the area around the input shaft with a fine grade of emery paper SEE FIGURE 22 amp 23 WARNING DO NOT DRIVE OR PRY COUPLING FROM WORM SHAFT INPUT SHAFT INTERNAL DAMAGE TO THE STEERING GEAR CAN RESULT IF COUPLING IS TIGHT INSERT SCREWDRIVER INTO SLOT TO RELEASE 2 2 Remove and plug the return line SEE FIGURE 24 Figure 20 Figure 24 remove seal remove retaining ring apply air pressure to port WARNING remove seal 4 washer 2 3 Remove and discard the dirt and water seal 4 SEE FIGURE 25 2 4 Remove the seal retaining ring 5 from the valve housing 8 SEE FIGURE 26 2 5 Hold a shop rag over the worm shaft input shaft and apply shop air pressure to the valve housing 8 return port SEE FIGURE 27 WARNING BE SURE TO WEAR EYE PROTECTION AND TO COMPLY WITH OSHA OR OTHER MAXIMUM AIR PRESSURE REQUIREMENTS 2 6 The air pressure will force the two piece input shaft seal 7 and the steel backup washer 6 to pop out o
61. pressure be maintained for longer than 5 seconds as damage to the pump may result NOTE You must maintain enough force on the steering wheel to assure that the steering gear control valve is completely closed when reading pressure gage 4 4 Once you have determined which poppet to adjust and the steering wheel is in full lock axle stop to axle stop loosen the poppet adjusting screw sealing nut 2 and the poppet adjusting screw 3 or 42 until the pressure gage reads maximum pump relief pressure SEE FIGURE 38 11 16 inch box end wrench and screw driver required 4 5 Manually no power tool and carefully screw in the poppet adjusting screw 3 or 42 until the pressure gage shows a Significant drop in pressure 200 400 psi 13 8 27 6 Bar with the steering wheel in full lock Tighten the poppet adjusting sealing nut 2 to 12 18 ft Ibs 16 24 N m 46 To adjust the other poppet repeat these instructions for full lock in the other direction SEE FIGURE 39 ADJUST THIS POPPET SCREW ADJUST THIS POPPET SCREW Figure 37 Figure 38 locate adjusting nut remove the drag link CAUTION NOTE center the sector shaft check for lash position adjusting screw check for lash eliminate lash recheck for lash connect drag link 5 Cross shaft or Sector shaft Adjustment With vehicle engine off 5 1 If the sector shaft adjusting screw jam nut 58 located on the side cover is not accessible the stee
62. procedures should remove all the air from the steering system unless the gear is mounted in an inverted position and is equipped with the manual bleed screw I9A SEE FIGURE 160 Page 48 If this is so refer to step 4 Remove the air from a gear mounted in an inverted position and equipped with a manual bleed screw I9A by following steps 1 2 and 3 above Then with the engine idling steer the gear from full left turn to full right turn several times With the steering gear in neutral no steering action loosen the manual bleed screw about one turn allowing air and aerated fluid to bleed out around the bleed screw until only clear non aerated fluid is bleeding out then close the bleed screw 5 16 inch socket required Check and refill reservoir Repeat this procedure 3 or 4 times starting with the steering maneuver with bleed screw closed until only clear non aerated fluid is discharged when bleed screw is loosened Torque the manual bleed screw to 27 33 in Ibs 3 1 3 7 N m Check and refill reservoir CAUTION Do not turn steering wheel with bleed screw loosened as this could induce air into the system Warnings for Proper Steering Gear Operation WARNING DO NOT WELD BRAZE OR SOLDER ANY STEERING GEAR OR SYSTEM ARM COMPONENTS WARNING MAXIMUM FLOW UNDER ANY CONDITIONS MUST NOT EXCEED 8 GPM 30 LITERS MIN WARNING MAXIMUM OPERATING PRESSURE MUST NOT EXCEED 2000 PSI 137 9 BAR WARNING ALWAYS CAREFULLY INSPECT A
63. ring Finish removing the side cover 56 and sector shaft 48 as an assembly Remove side cover gasket 55 and discard CAUTION The bearing may contain 41 or 42 rolls depending upon the type used Bearing BR 970 has 41 rolls Bearing BR 9701 has 42 rolls The identification number can be found on the outside edge of the bearing race flange There is also a set of bearing rolls in the side cover with either 41 or 42 rolls The quantity may not be the same as in the housing bearing Do not mix these rolls If the housing 19 bearing has loose rolls the bearing rolls from the bearing 20 race count them and put them aside as a set for cleaning Inspecting and reassembly Remove the sector shaft adjusting screw jam nut 58 SEE FIGURE 49 3 4 inch socket required Screw the sector shaft adjusting screw 49 through the side cover 56 SEE FIGURE 50 Place the side cover exterior face down and lift the sector shaft 48 out vertically SEE FIGURE 51 US ULV UG apa E SSO YO E z sa lt BANAAG Figure 48 Figure 49 Figure 50 Figure 51 NOTE NOTE If the side cover bearing assembly has uncaged loose rolls the vertical position will allow the side cover bearing rolls to fall into the side cover where you may easily collect and count them Immediately gather all of the side cover bearing rolls and count them CAUTION CAUTION Take care not to lose any rolls during disassembly and assembl
64. ring gear must be removed prior to adjustment 5 2 If the sector shaft adjusting screw 49 is accessible remove the drag link from the pitman arm CAUTION This adjustment must be performed with the sector shaft on its center of travel NOTE Because of pitman arm or internal stops or poppet adjustment the center of travel for this adjustment may not be the center of sector shaft or handwheel rotation 5 3 To position the sector shaft 48 on center of travel for this adjustment rotate steering wheel worm shaft input shaft until the timing mark across the end of the sector shaft is perpendicular to the worm shaft input shaft 16 SEE FIGURE 40 page 20 5 4 With the sector shaft 48 in the center position grasp the pitman arm and gently try to move this arm back and forth in the direction of travel Finger tip force is adequate to detect lash of a loose sector shaft There must be no movement of the input shaft or sector shaft If no lash is detected do not adjust 5 5 If lash is detected loosen jam nut 58 with a 3 4 inch socket and move the adjusting screw 49 clockwise until the sector shaft and rack piston 29 are in contact Use no more than 10 ft Ibs 14 N m of torque Then turn the adjusting screw counterclockwise one turn 5 6 At this point there should be lash at the pitman arm 5 7 To adjust slowly turn the adjusting screw 49 clockwise until no lash is felt at the pitman arm Hold the adjusting
65. rm shaft input shaft adjusting screw sealing nut 39 onto the solid nonslotted end of the worm shaft preload adjusting screw 38 so that the seal on the sealing nut will face the end cover 37 Assemble one NEW poppet valve adjusting screw sealing nut 2 onto the poppet valve adjusting screw 42 and assemble the other NEW poppet valve adjusting screw sealing nut 2 onto the other poppet valve adjusting screw 3 in the same manner as described for parts 39 and 38 Assemble poppet adjusting screw 42 and nut 2 assembly into end cover 37 a few turns Final adjustments will be made later Figure 115 Figure 118 NOTE WARNING install worm shaft preload adjusting screw install end cover seal ring NOTE CAUTION install end cover install end cover bolts install valve sleeve rings amp seals NOTE 18 NOTE The poppet valve adjusting screws may or may not be of the same length If not the same length assemble the shorter adjusting screw 42 2 25 in 57 mm long into the end cover 37 WARNING IF THE SCREWS ARE OF UNEQUAL LENGTH YOU MUST INSTALL THE SHORTER SCREW INTO END COVER OTHERWISE THE POPPET ASSEMBLY MAY BREAK AND CAUSE THE STEERING GEAR TO LOCKUP POSSIBLY RESULTING IN AN ACCIDENT Assemble the worm shaft preload adjusting screw 38 and nut 39 assembly into the end cover 37 a few turns Final adjustments will be made later A slot screw driver or 5
66. screw in place and tighten the jam nut 58 Final torque 40 45 ft Ibs 54 61 N m 5 8 Recheck the pitman arm for lash Turn the steering wheel 1 4 turn each side of center No lash should be felt If lash exists repeat adjustments 5 3 5 8 5 9 Re connect drag link to pitman arm 19A HFB70 Exploded Assembly View Typical ITEM NO EL a RE Dt ER ER ER ER ER ER AR ma Q 19A 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 DESCRIPTION Valve Housing Bolts 4 used 2 125 long Poppet Screw Sealing Nuts 2 Poppet Adjusting Screw Dirt and Water Seal Retaining Ring Steel Backup Washer Input Shaft Seal Two piece Valve Housing End Cover and Valve Housing Seal Rings Trust Washer 2 Thrust Bearing Teflon Seal Rings 2 Backup O Rings 2 Valve Sleeve Worm Shaft Input Shaft Worm Shaft Backup O Ring Teflon Worm Shaft Seal Housing Bleed Screw Housing Bearing Retaining Ring Trumnion Cover Seal Ring Sector Shaft Seal Two piece Backup Washer Trumnion Cover Dirt and Water Seal Trunnion Cover Washers 4 Trunnion Cover Bolts 4 Rack Piston Retaining Rings 2 Poppet Seats 2 Poppets 2 Spacer Rod Spring Rack Piston Backup O Ring Teflon Rack Piston Seal End Cover Worm Shaft Preload Adjusting Screw Worm Shaft Adjusting Screw Sealing Nut End Cover Washers 4 End Cover Bolts 4 used 1 625 long I
67. t tent loss of power steering occurs a service worm NOTE When hydraulic tests are completed and fluid shaft input shaft valve sleeve assembly is required lines are reconnected check fluid level and air bleed the system Reference page 50 Troubleshooting Guide Normal Noises e You or the driver may hear a hissing noise from the control valve when It is actuated during a steering maneuver e You or the driver may hear a noise as fluid bypasses through the poppets at full turn e You or the driver may hear a noise from the system relief valve when it is required to actuate e You or the driver may hear pump growl from some types of power steering pumps ll Abnormal Noises e f the power steering pump is belt driven a squealing noise may indicate that the belts should be tightened or replaced e A clicking noise heard during a turn or when changing directions may indicate that some component Is loose and shifting under load e A change in the normal noise of the pump may indicate that air has been induced into the system or that fluid level is low lll Possible Steering Problems and Causes Road Wander No Recovery Shimmy External Oil Leakage Tire pressure incorrect or unequal left to right Components in steering linkage loose or worn Steering wheel to road wheel Wheel bearings improperly adjusted or worn Front end alignment out of specification Dry fifth wheel or poor finish on fif
68. th wheel or trailer plate steering gear mounting bolts loose on frame Steering gear improperly adjusted Looseness in rear axle assemblies or trailer bogies Tire pressure low Front end components binding Front end alignment incorrect Tight front axle king pins Dry fifth wheel or poor finish on fifth wheel or trailer plate Steering column binding Pump flow insufficient Steering gear improperly adjusted Steering gear control valve sleeve sticking Badly worn or unevenly worn tires Improperly mounted tire or wheel Wheel bearings improperly adjusted or worn Components in steering linkage loose or worn Wheels or brake drums out of balance Front end alignment incorrect Air in the hydraulic system Finding the location of leak may be difficult since oil may run away from leak source the fittings hoses pump or gear to a low point on the gear or chassis A leak from the vent plug at the side cover indicates failure of the sector shaft oil seal inside the side cover Oversteering or Darting Dry fifth wheel or poor finish on fifth wheel or trailer plate Front end components binding or loose Steering column binding Steering gear improperly adjusted Steering gear control valve sleeve sticking Rear axle mounts rear steer High Steering Effort in One Direction Unequal tire pressure Vehicle overloaded Inadequate hydraulic system pressure Excessive internal leakage in one direction
69. the new seal package Start with the Teflon backup washer 24 Assemble the two piece sector shaft seal 23 so that the words oil side are visible SEE FIGURE 153 WARNING THE WORDS OIL SIDE MUST BE VISIBLE IF NOT THE SEAL WILL NOT FUNCTION AND A LOSS OF POWER STEERING ASSIST MAY OCCUR Figure 152 Figure 153 install trunnion cover seal ring install trunnion cover bolts washers amp seal assemble seal protector boot amp grease fitting install input shaft seal pack pack with grease and install dirt and water seal 49 50 gl 52 53 Grease the new trunnion cover seal ring 22 and install it into the trunnion cover seal ring groove Before installing the trunnion cover 25 and seal assembly onto the housing 19 visually inspect the housing bearing 20 to insure that all bearing rolls are properly in place Then install the trunnion cover SEE FIGURE 154 Install four trunnion cover bolts 28 and washers 27 and torque the bolts to 15 22 ft Ibs 20 30 N m if dry or 11 16 ft Ibs 15 22 N m if lubricated SEE FIGURE 155 A 1 2 inch socket required Pack clean high temperature industrial grease per Ross specification 045231 Mobil Temp 1 or 2 grease or equivalent around the seal area of sector shaft 48 Install a new dirt and water seal 26 using a Suitable blunt end drift Apply more of the special grease around the seal area of sector shaft and to the new prote
70. tly at 300 F 148 9 C Manual Steering Capability Provides for steering control in the event of hydraulic failure Compactness Lowest weight to output torque ratio in the industry Auxiliary Porting Available For auxiliary cylinder control Seal Protectors Provide protection from harsh environment Definitions Disclaimer NOTE A NOTE gives key information to make procedures easier or clearer CAUTION A CAUTION refers to those procedures which must be followed to avoid damage to the gear WARNING A WARNING REFERS TO THOSE PROCEDURES WHICH MUST BE FOLLOWED FOR THE SAFETY OF THE DRIVER AND THE PERSON INSPECTING OR REPAIRING THE GEAR This Service Manual has been prepared by TRW Ross Gear Division for reference and use by mechanics who have been trained to repair and service steering components and systems on heavy commercial vehicles TRW Ross Gear Division has exercised reasonable care and diligence to present accurate clear and complete information and instructions regarding the techniques and tools required for maintaining repairing and servicing the complete line of TRW Ross Gear HFB70 Integral Power Steering Gears However despite the care and effort taken in preparing this general Service Manual TRW makes no warranties that a the Service Manual or any explanations illustrations information techniques or tools described herein are either accurate complete or correct as applied to a specific HFB70 steering gear
71. turn guide cap seal 45 and place it in the seal groove of the cap Assemble the cap so that the seal makes full contact with the rack piston surface SEE FIGURE 115 Install the two new Allen head or Torx head screws 47 and torque them to 14 22 ft Ibs 19 30 N m A 5 32 inch Allen socket or a T 30 Torx socket required SEE FIGURE 116 WARNING ROTATE THE WORM SHAFT FROM END OF TRAVEL TO END OF TRAVEL TO MAKE CERTAIN THAT YOU HAVE INSTALLED THE BALLS PROPERLY IF YOU CANNOT ROTATE THE SHAFT YOU WILL HAVE TO REMOVE THE BALLS AND REASSEMBLE THEM IF YOU INSTALL THE GEAR ON A TRUCK WITH THE SHAFT UNABLE TO ROTATE THE GEAR WILL NOT FUNCTION Position the housing 19 securely in a vise as it was for the disassembly procedures SEE FIGURE 40 page 20 Apply a generous amount of clean grease to the Teflon rack piston seal 36 and to the housing cylinder bore SEE FIGURE 117 Install the rack piston 29 worm shaft input shaft 16 assembly into the long end of the housing so that the Teflon rack piston seal goes in last SEE FIGURE 118 CAUTION Be certain that the seal enters the long end last otherwise a large section of the seal will be cut and the vehicle will have no power steering assist NOTE To ease the later assembly of the sector shaft 48 rotate the rack piston worm shaft assembly in the housing so that the rack piston teeth are exposed in the sector shaft cavity of the housing If disassembled assemble a new wo
72. washer install thrust bearing WARNING 40 20 21 22 23 24 Use compression tool J26 42 to compress the Teflon seal rings SEE FIGURE 124 Leave the compression tool on for 10 minutes CAUTION A minimum of ten minutes with the compression tool in place is required to ensure that the seal rings are properly seated Otherwise the valve sleeve will be difficult to assemble into the valve housing and the seal rings may be damaged during installation Assemble the poppet valve adjusting screw 3 and nut 2 assembly into the valve housing 8 4 or 5 turns Final adjustments will be made later Be sure you have the correct length adjusting Screw Apply clean grease to the valve housing 8 seal ring groove Install a new valve housing seal ring 9 into valve housing seal ring groove SEE FIGURE 125 NOTE When installed the valve housing seal ring should extend slightly above the machined surface of the valve housing Apply a generous amount of clean grease to one thrust washer 10 Install the thrust washer into the valve housing 8 making Sure to center the washer SEE FIGURE 126 Apply a generous amount of clean grease to the thrust bearing 11 Install the thrust bearing into the valve housing onto the thrust washer making sure to center the bearing on the washer SEE FIGURE 127 WARNING THE THRUST WASHER AND THRUST BEARING MUST BE FLAT AND CENTERED IN THE COUNTERBORE SURFACE OTHERWISE TH
73. y or you will have to replace the complete side cover assembly Figure 52 WARNING WARNING IF THE BEARING IS THE UNCAGED LOOSE ROLL TYPE DO NOT MIX THE ROLLS FROM THE SIDE COVER WITH THE ROLLS FROM THE HOUSING BEARING THE BEARING RACE AND ROLLS ARE A MATCHED SET INTERCHANGING THE ROLLS COULD RESULT IN PREMATURE BEARING OR SEAL FAILURE WHICH COULD CAUSE A LOSS OF POWER TALET So _ 3 STEERING Figure 53 remove side 13 Remove the retaining ring 51 the two piece side cover seal 52 cover seal pack the Teflon backup washer 53 and the steel backup washer 54 from the side cover Discard seal and Teflon washer SEE FIGURES 52 53 Remove and discard vent plug 57 remove retainer 14 Only if replacement of the retainer 50 and or adjusting screw and adjusting 49 is required see inspection procedure 8 page 33 place the screw sector shaft 48 firmly in a soft jawed vise and unstake the retainer using a suitable chisel Turn the retainer out of the sector Figure 54 shaft pocket and remove the adjusting screw Discard the retainer SEE FIGURE 54 loosen worm 15 Loosen the worm shaft adjusting screw sealing nut 39 with a shaft amp poppet 1 1 16 inch box end wrench and loosen the worm shaft preload nuts amp screws adjusting screw 38 approximately two turns with a 5 16 inch allen socket or screw driver SEE FIGURE 55 Loosen the poppet adjusting screw sealing nut 2 and the poppet adjusting screw 42
74. y is flexible and may appear slightly bent at this joint This slight bend is normal SEE FIGURE 91 Figure 91 31 inspect housing cylinder bore NOTE inspect housing faces inspect housing and side cover bearings WARNING 32 4 D 6 Inspect the housing 19 cylinder bore SEE FIGURE 92 You will probably notice normal scoring marks running lengthwise through the bore Since this scoring is normal you should not compare it to the scoring considered detrimental in the cylinder bores of an internal combustion engine Replace the housing only if you ve tested it for internal leakage as described in the troubleshooting section on page 7 and you ve determined that the scoring and not damaged seals is responsible for the excessive internal leakage greater than 1 5 gpm 5 7 liters min NOTE In running the internal leakage test after reassembly of the unit make sure that internal leakage exceeding 1 0 gpm 3 8 liters min can only be attributed to the housing and not to the improper assembly of the new seals in the worm shaft rack piston and valve assembly before you decide to replace the housing Inspect the housing 19 faces for nicks that would prevent proper sealing Replace the gear housing if these nicks are present and cannot be easily removed with a fine toothed flat file without changing the dimensional characteristics SEE FIGURE 93 Inspect the housing bearing and the side cover bearing race

Rebuild HFB70 - Centennial College

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