TAS Steering Gear Service Manual
Contents
1. remove and discard them 4 Onboth the master gear and the rotary cylinder tum the adjusting screw and sealing nut assembly without rotating the nut on the screw into the housing until the nut is firmly against the housing using a 2 allen wrench Tighten the sealing nut against the housing 5 Refill system reservoir with approved hydraulic fluid Do not mix fluid types Mixing of transmission fluid motor oil or other hydraulic fluids will cause seals to deteriorate faster 6 Place a jack under the center of the front axle and jack up the front end of the vehicle so the steer axle tires are off the ground This resetting procedure will work in most cases with at least 134 hand wheel turns from each side of center If you re making a large reduction in wheelcut and this procedure does not work you may have to replace or internally reset the poppets using the procedure de scribed in the Poppet Component section of this Service M anual 7 a Start the engine and let it run at idle speed b Tum the steering wheel in the direction that makes the timing mark on the master gear move toward the adjusting screw just installed Tum in this direction until axle stop contact is made c Pull hard on the steering wheel put 40 Ibs rim pull on a 20 dia steering wheel after the axle Stop is contacted 8 a Tum the steering wheel in the opposite direction end of timing mark on the master gear away from adjusti2. back the nut off of the adjusting screw until it is flush with the end of the adjusting screw M ake sure the engine is off and the road wheels are in straight ahead position Remove and discard the poppet fixed stop bolt if equipped and washer if equipped from the lower end of the housing If the unit has a poppet adjusting screw and sealing nut that need to be replaced remove and discard them Tum the adjusting screw and sealing nut assembly without rotating the nut on the screw into the housing until the nut is firmly against the housing using a 72 Allen wrench Tighten the sealing nut against the housing If the drive end of the screw is below the face of the nut the popet seat flange will break during step 7d Refill reservoir 5 Refill the system reservoir with approved hydraulic fluid Hydraulic fluid Do not mix fluid types Mixing of transmission fluid motor oil or other hydraulic fluids will cause seals to deteriorate faster J ack up vehicle 6 Place a jack under the center of the front axle and jack up the front end of the vehicle so the steer axle tires are off the ground Push upper poppet 7 a Start the engine and let it run at idle speed out to prepare it for b Note which output shaft timing mark is nearest setting the housing piston bore c Tum the steering wheel in the direction that makes this timing mark move toward the adjust ing screw just installed Turn in this direc
3. beyond the sealing nut may be different for each vehicle Poppet Readjustment Dual Gears Reversed Image Tools Required Materials Required 732 Allen wrench 7e Open end wrench 4 Open end wrench y4 Socket Lbf eb Torque wrench Hydraulic fluid J ack 1 Set the axle stops to vehicle manufacturer s wheelcut or clearance specifications Start the engine and allow the vehicle to idle for 5 10 minutes to warm the hydraulic fluid Shut off the engine 2 If new poppet adjusting screws and nuts are being used tum the screws into the non sealing end of the jam nuts until the drive end of screw is flush with the nut Your steering gear and rotary cylinder will have either fixed stop bolts or adjusting screws If the adjusting screw is already part of the steering gear or cylinder back the nut off of the adjusting screw until it is flush with the end of the adjusting screw 3 Make sure the engine is off and the road wheels are in straight ahead position Remove and discard the poppet fixed stop bolts if equipped and washers if equipped from the lower end of housing on both the master gear and the rotary cylinder If the unit has poppet adjusting screws and Sealing nuts that need to be replaced remove and discard them 4 Tum the adjusting screws and sealing nut assem blies without rotating the nut on the screw into the housing until the nut is firmly against the housing on both the master gear a
4. place with a wrench b Turn the adjusting screw in clockwise using finger pressure only don t use a ratchet until the Allen wrench comes to a stop Do not attempt to tum it in farther Pause the tuming in process each time the driver releases the steering wheel Continue tuming only while the wheel is held at full tum c Back off the adjusting screw 3 turns and tighten the sealing nut Torque nut to 33 37 Ibf dt 13 The poppets on both the master gear and rotary cylinder have now been completely reset Lower the vehicle Check the reservoir and fill if required The length of the adjusting screw beyond the nut must be no more than 1 for proper thread engagement NOTE The length of adjusting screw beyond the sealing nut may be different for each vehicle TRW Automotive Commercial Steering Systems 800 Heath Street Lafayette IN 47904 Tel 765 423 5377 Fax 765 429 1868 htto www trw com commercialsteering TRW Inc 2000 TRW 1108 Rev 3 00
5. al column and remove the input shaft seal E T RSS Heat Damaged Seal Lit BERAR RARR Ag ml Inspect seal area Inspect old seal Install new seal Hammer J 37073 Install retaining ring Install dirt amp water seal 10 11 12 13 14 Check the seal area of the valve housing for any seal fragments Remove any that are found Check the seal for heat damage If the seal is stiff and brittle and not pliable like the new seal it is probably heat damaged Determine and fix the cause of excessive heat in the vehicle Put clean grease 406038 on the inside dia of the new input shaft seal and place it over the input shaft With the small dia of tool J 37073 against the seal tap the tool until the tool shoulder is square against the valve housing Remove any seal material that may have sheared off in the seal bore or retaining ring groove Do not use a socket to install this seal because you will not be able to control seal installation depth possibly causing a leak Insert new retaining ring into the groove Pack the end of the valve housing bore around the input shaft with grease 406038 Choose the correct size dirt amp water seal by comparing the choices to the old seal or by measuring the major diameter of the input shaft serrations see chart next page Apply more grease 406038 to the new dirt amp water seal and install it over the input shaft Seat it in the groove behind the ser
6. ash pitman arm and gently try to rotate it back and forth If looseness or lash is felt at this point the sector Shaft is out of adjustment Loosen jam nut 4 Loosen the jam nut 74 Socket If the gear is removed from the vehicle to adjust the lash e Leave the pitman arm connected to the gear e Best option is to follow the Final Adjustment procedure on page 67 e Alternate option is to continue with step 5 of this procedure da a screw Screwdriver M Screwdriver y4 Open end wrench Position adjusting 5 Adjust shaft 6 Recheck for lash 7 Connect drag link 8 If no lash was detected in step 3 turn the shaft adjusting screw counterclockwise until you feel lash at the output shaft Slowly tum the shaft adjusting screw clockwise until you feel no lash at the output shaft without using more than 10 lbf ft 14 Nem of torque From this position tum the screw clockwise s to 6 of a tum more Hold the adjusting screw in place and tighten the jam nut Final jam nut torque 43 Ibf dt 58 Nem Tum the steering wheel tum each side of center then back to center and recheck the pitman arm for lash You should feel no lash if there is lash repeat steps 4 6 and 7 Reconnect the drag link to the pitman arm according to manufacturer s specifications Maintain grease in the sector shaft bearing through the grease fitting in the housing using only a hand operated grease gun Add grea
7. elease the steering wheel and shut off the engine Loosen the sealing nut and back out the adjusting screw on the rotary cylinder until 1 is past the nut Tighten the sealing nut against the housing a Start the engine and let it idle b Tum the steering wheel in the opposite direction end of timing mark on master gear away from adjusting screw until axle stop contact is made c Hold the steering wheel in this position put up to 40 Ib nm pull on a 20 dia steering wheel for 10 seconds then release Repeat this hold and release process as many times as necessary while completing step 14 a With steering wheel held at full turn loosen the jam nut on the rotary cylinder and hold it in place with a wrench b Turn the adjusting screw in clockwise using finger pressure only don t use a ratchet until the Allen wrench comes to a stop Do not attempt to tum it in farther Pause the tuming in process each time the driver releases the steering wheel Continue tuming only while the wheel is held at full tum c Back off the adjusting screw 3 turns and tighten the sealing nut Torque the sealing nut to 33 37 Ibf ft d Release the steering wheel and shut off the engine The poppets have now been completely reset Lower the vehicle Check the reservoir and fill if required The length of the adjusting screw beyond the nut must be no more than 1y1s for proper thread engagement NOTE The length of adjusting screw
8. gine and let it idle for 2 minutes Do not minutes turn off steer Shut off the engine and check the fluid level and fill reservoir in the reservoir Refill as required Hydraulic fluid o Steer vehicle 3 Start the engine again Steer the vehicle from full i left to full right several times Add fluid as neces Sary to the full line on the dip stick Automatic bleed systems should now be free from 7 trapped air Manual bleed systems continue with step 4 Auto Bleed Plug Do Not Remove Allow airto bleed 4 With engine idling steer from full left tum to full out from bleed right turn several times Stop steering and loosen screw the manual bleed screw about one tum Allow air and aerated fluid to bleed out until only clear fluid is seen Close the bleed screw refill the reservoir if required M anual Bleed Screw Lbfen Torque wrench 716 Socket Repeat step 4 three to four times until all the air is discharged Torque manual bleed screw to 45 Ibf n N Do not turn steering w heel with bleed screw loosened Input Shaft Seal Replacement This procedure uses the vehicle s power steering pump to force out the input shaft seal To use this procedure the power steering pump should have a minimum of 1 500 psi available Materials Required Tools Required Clean cloth Drip pan High pressure fitting Hydraulic fluid Plug Shop towel Hammer J 37073 Screwdriver
9. h point toward the poppet screws or both point toward the end opposite the poppet screws you have a reversed image system Low er Poppet Upper Poppets a Low er Poppet WE Poppet Readjustment Dual Gears Mirror Image Tools Required Materials Required 732 Allen wrench 7e Open end wrench 4 Open end wrench y4 Socket Lbf eb Torque wrench Hydraulic fluid J ack 1 Set the axle stops to vehicle manufacturer s wheelcut or clearance specifications Start the engine and allow the vehicle to idle for 5 10 minutes to warm the hydraulic fluid Shut off the engine 2 If new poppet adjusting screws and nuts will be used tum each screw into the non sealing end of the jam nut until the drive end of screw is flush with the nut Your steering gear and rotary cylinder will both have either fixed stop bolts or adjusting screws If the adjusting screw Is already part of the gear or cylin der back the nut off of the adjusting screw until it is flush with the end of the adjusting screw 3 Make sure the engine is off and the road wheels are in straight ahead position Remove and discard the poppet fixed stop bolt if equipped and washer if equipped from the lower end of housing on both the gear and the cylinder If either unit has a poppet adjusting screw and Sealing nut that need to be replaced
10. he Safety of others the vehicle or the safe operation of the vehicle and c fully inspect and test the TAS steering gear and the vehicle steering system to ensure that the repair or service of the steering gear has been properly performed and that the steering gear and system will function properly Patents TRW Commercial Steering Division TAS power steering gears are covered by several United States and foreign patents either issued or pending TRW Inc 1998 Section 3 On Vehicle Service Filling and Air Bleeding the System ccccsssseessseeeeeeeees 21 Input Shaft Seal Replacement cccccsseeeesesseeeeeeeeesaeees 22 Sector Shaft Adjustment ee ee RR ER EE ee EE Ee 26 Poppet Readjustment Single Gears EK N N sir conianmnreeteniial 28 Dual Gears ss EER RE EE ee ER RR EE Ge 31 9 Filling and Air Bleeding the System Tools Required Materials Required Vis Socket Hydraulic fluid Lof sn Torque wrench Make sure poppets are set correctly before beginning this Run engine for 10 1 Fill the reservoir nearly full Do not steer Start and seconds turn off run the engine for 10 seconds then shut it off and fill reservoir Check and refill the reservoir Repeat at least three times checking the reservoir each time Hydraulic fluid Do not allow the fluid level to drop significantly or run out of the reservoir This may induce air into the system Run engine for 2 2 Start the en
11. line High pressure fitting ring Clean cloth Screwdriver Disconnect return 1 Disconnect 2 column Remove dirt amp 3 water seal Remove retaining 4 Disconnect retum line from the steering gear and plug the line Also cap the retum port of the gear with a high pressure fitting Remove the steering column from the gear input Shaft Remove the dirt and water seal from the steering gear Save this seal to match the new seal to the correct size Wipe out the grease and then remove the spiral retaining ring Use a screwdriver inserted into the notch formed in the end of the ring Be careful not to scratch the bore with the screwdriver Replace column 5 Slip the steering column back onto the input shaft with the pinch bolt installed but not tightened Wrap exposed 6 Tie or wrap a shop towel around the input shaft area area and place a drip pan under the vehicle to catch the oil Drip pan Shop towel Fill reservoir 7 Add fluid as necessary to the full line on the dip stick Do not mix fluid types Any mixture of fluid types or use of any unapproved fluid could lead to seal deterioration and leaks A leak could ultimately cause the loss of fluid which could resultin a loss of power steering assist Force out the seal 8 With the vehicle in neutral momentarily tum the starter quickly tum off the engine if it starts Remove inputshaft 9 Remove the shop towel Disconnect the steering se
12. nd the rotary cylinder using a 72 allen wrench Tighten the sealing nut against the housing 5 Refill system reservoir with approved hydraulic fluid Do not mix fluid types Mixing of transmission fluid motor oil or other hydraulic fluids will cause seals to deteriorate faster 6 Place a jack under the center of the front axle and jack up the front end of the vehicle so the steer axle tires are off the ground This resetting procedure will work in most cases with at least 134 hand wheel turns from each side of center If you re making a large reduction in wheelcut and this procedure does not work you may have to replace or internally reset the poppets using the procedure de scribed in the Poppet Component section of this Service M anual 7 a Start the engine and let it run at idle speed b Note which output shaft timing mark is nearest the housing piston bore c Turn the steering wheel in the direction that makes this timing mark move toward the adjusting screws just installed on both the gear and the cylinder Tum in this direction until axle stop contact is made d Pull hard on the steering wheel put 40 Ibs rim pull on a 20 dia steering wheel after the axle Stop is contacted 8 a Turm the steering wheel in the opposite direction end of timing mark away from adjusting screw until the other axle stop is contacted b Pull hard on the steering wheel put 40 Ibs rim pull on a 20 dia steeri
13. ng screw until the other axle stop is contacted b Pull hard on the steering wheel put 40 Ibs rim pull on a 20 dia steering wheel c Release the steering wheel and shut off the engine 9 Loosen the sealing nut and back out the adjusting screw on the master gear until 1 is past the nut Tighten the sealing nut against the housing Do not hold the steering wheel at full turn for more than 10 seconds ata time the heat build up at pump relief pressure may damage components 10 a Start the engine and let it idle b Tum the steering wheel in the original direction end of timing mark on the gears toward adjusting screw until axle stop contact is made c Hold the steering wheel in this position with 40 lbs rim pull for 10 seconds then release Repeat this hold and release process as many times as necessary while completing steps 11 amp 12 11 12 13 14 a With steering wheel held at full turn loosen the 15 jam nut on the master gear and hold it in place with a wrench b Turn the adjusting screw in clockwise using finger pressure only don t use a ratchet until the Allen wrench comes to a stop Do not attempt to tum it in farther Pause the tuming in process each time the driver releases the steering wheel Continue tuming only while the wheel is held at full tum c Back off the adjusting screw 3 turns and tighten the sealing nut Torque the sealing nut to 33 37 Ibf ft d R
14. ng wheel c Release the steering wheel and shut off the engine 9 Loosen the sealing nut and back out the adjusting screw until 1 is past the nut on both the master gear and the rotary cylinder Tighten the sealing nuts against both housings Do not hold the steering wheel at full turn for more than 10 seconds ata time the heat build up at pump relief pressure may damage components 10 a Start the engine and let it idle b Tum the steering wheel in the original direction end of timing mark toward adjusting screw until axle stop contact is made c Hold the steering wheel in this position with 40 Ibs rim pull for 10 seconds then release Repeat this hold and release process as many times as necessary while completing steps 11 and 12 first on the master gear then on the rotary cylinder 11 a With steering wheel held at full tum loosen the jam nut on the master gear and hold it in place with a wrench b Tum the adjusting screw in clockwise using finger pressure only don t use a ratchet until the Allen wrench comes to a stop Do not attempt to tum it in farther Pause the tuming in process each time the driver releases the steering wheel Continue tuming only while the wheel is held at full tum c Back off the adjusting screw 3 4 turns and tighten the sealing nut Torque nut to 33 37 Ibf ft 12 a With steering wheel held at full turn loosen the jam nut on the rotary cylinder and hold it in
15. r or quicker Disclaimer This Service M anual has been prepared by TRW Commercial Steering Division for reference and use by mechanics who have been trained to repair and service steering components and systems on heavy commercial vehicles TRW Commercial Steering Division has exercised reasonable care and diligence to present accurate clear and complete information and instructions regarding the TRW Commercial Steering TAS Series Integral Power Steering Gears Since this is a general Service Manual the photographs and illustrations may not look exactly like the steering gear being ser viced The procedures therefore must be carefully read and understood before Servicing If inspection or testing reveals evidence of abnormal wear or damage to the TAS steering gear or if you encounter circumstances not covered in the M anual Stop Consult the vehicle manufacturer s Service Manual and warranty Do nottry to repair or service a TAS steering gear which has been damaged or includes any part that shows exces sive wear unless the damaged and worn parts are replaced with original TRW replacement and service parts and the unitis restored to TRW s specifications for the TAS steering gear It is the responsibility of the mechanic performing the maintenance repairs or service on a particular TAS 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 t
16. rations and against the valve housing Reconnectcolumn 15 Reconnect the steering column to the input shaft and tighten the pinch bolt to torque level specified Reconnect return 16 Reconnect the retum line to the steering gear retum line port Air bleed system 17 Air bleed the system using the procedure on page 21 Seal PartNo Serration Size Major Serration Dia 478044 13 16 x 36 0 807 0 799 478060 7 8 x 36 0 866 0 857 478050 1 x 36 0 987 0 977 478050 1 x 79 1 008 1 000 Sector Shaft Adjustment Tools Required Materials Required This adjustment can only be completed on the vehicle if the adjusting screw jam nut is accessible This nut is located on the side cover Screwdriver Va Socket A Photos in this section were taken on a mock frame rail for 3a Open end wrench clarity Center the sector 1 With the engine on rotate the steering wheel input shaft shaft until the timing mark on the sector shaft lines up with the mark on the housing The line on the sector shaft should be at a 90 angle from the input shaft The sector shaft is now on its center of travel Tum the vehicle off Remove the drag 2 Remove the drag link from the pitman arm link To avoid resetting the poppets do not rotate the input shaft more than 1 2 turns from the center of travel position while the drag link is disconnected Check for sector 3 From the center of travel position grasp the Shaft l
17. se until it begins to extrude past the dirt and water seal Do notuse a power grease gun because it will supply grease too fast this could adversely affect the high pressure seal and contaminate the hydraulic fluid Poppet Readjustment Single Gears Tools Required Materials Required 732 Allen wrench 7e Open end wrench 4 Open end wrench y4 Socket Lbf eb Torque wrench Hydraulic fluid J ack Set axle stops 1 warm up system Assemble adjust 2 ing screw into nut Remove poppet 3 stop bolt 5 Open end wrench Turn adjusting 4 screw assembly into housing This resetting procedure will work in most cases with at least 134 hand wheel tums from each side of center If you re making a large reduction in wheelcut and this procedure does not work you may have to replace or internally reset the poppets using the procedure de scribed in the Poppet Component section of this Service M anual Set the axle stops to vehicle manufacturer s wheelcut or clearance specifications Start the engine and allow the vehicle to idle for 5 10 minutes to warm the hydraulic fluid Shut off the engine If a new poppet adjusting screw and nut are being used tum the screw into the non sealing end of the jam nut until the drive end of screw is flush with the nut Your steering gear will have either a fixed stop bolt or an adjusting screw If the adjusting screw is already part of the steering gear
18. tion until axle stop contact is made d Pull hard on the steering wheel put up to 40 Ib rim pull on a 20 dia steering wheel after the axle stop is contacted Set upper poppet 8 a Tum the steering wheel in the opposite direction end of timing mark away from adjusting screw until the other axle stop is contacted b Pull hard on the steering wheel put up to 40 Ib nm pull on a 20 dia steering wheel c Release the steering wheel and shut off the engine Back outadjusting 9 Loosen the sealing nut and back out the adjusting screw screw until L is past the nut Tighten the sealing nut against the housing 732 Allen wrench Do not hold the steering wheel at 4 Open end full turn for more than 10 seconds wrench ata time the heat build up at pump relief pressure may damage components Set lower poppet 10 a Start the engine and let it idle i b Tum the steering wheel in the orginal direction end of timing mark toward adjusting screw until axle stop contact is made c Hold the steering wheel in this position with up to 40 Ib rim pull for 10 seconds then release Repeat this hold and release process as many times as necessary while completing step 11 Position adjusting 11 a With steering wheel held tightly at full turn loosen screw the jam nut and hold it in place with a wrench b Tum the adjusting screw in clockwise using 732 Allen finger pressure only don t use a ratchet until the
19. tw RW Automotive Commercial Steering Systems TAS Steering Gear Service M anual TAS 40 55 65 AND 85 SERIES STANDARD STEP BORE Design Features Q Rotary Valve This device provides responsive steering control Poppets optional These unloading valves are automatically set to furnish power steering pump protection and reduce pressure to unload steering linkage at vehicle axle stop settings Recirculating Balls Combine high mechanical efficiency with smooth operation Dirt amp Water Seals Lip type seals on both input and output shafts Torsion Bar Provides positive valve centering with definitive feel of the road Relief valves fumish pump protection by limiting maximum pressure optional Balanced area cylinder so back pressures cannot affect steering stability High temperature seals were developed to with stand temperatures of 250 F M anual steering capability provides for steering control in the event of hydraulic failure Auxiliary porting available for auxiliary cylinder control Seal protectors provide protection from harsh environment conditions Hazard Warning Definitions A warning describes hazards or unsafe practices which could result in severe personal injury or death A caution describes hazards or unsafe practices which could result in personal injury or product or property damage NOTE A note gives key information to make following a procedure easie
20. wrench Allen wrench stops Do not attempt to turn it in 34 Open end further Pause the turning in process each time wrench the driver releases the steering wheel continue 3 Socket turning only while the wheel is held at full turn Lbf sft Torque c Back off the adjusting screw 34 turns and tighten wrench the sealing nut Torque sealing nut to 35 Ibf ft The procedure is 12 The poppets have now been completely reset complete Lower the vehicle Check the reservoir and fill if required The length of the adjusting screw beyond the nut must be no more than 1 s for proper thread engagement The length of adjusting screw beyond the sealing nut may be different for each vehicle Poppet Readjustment Dual Gears Mirror Image Systems and Reversed Image Systems Before setting poppets on a dual gear system you must determine whether the system has mirror image gears or reversed image gears The procedures are slightly different for each type of system 1 Park the vehicle with the wheels turned all the way to the axle stop in either direction Turn the vehicle off 2 Look at the output shaft timing mark nearest the housing piston bore on the master gear Is this mark pointing toward the poppet screw or away from it 3 Now check the same timing mark on the rotary cylinder Does it point toward the poppet screw or away from it If they point to opposite ends of the gears you have a mirror image system If they bot
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