TR-SERVICE MANUAL-06.pmd
Contents
1. in any direction at any point in the stroke of the chamber If the PUSH ROD is not square make corrections by repositioning the chamber on the mounting bracket and or by shimming the slack adjuster to the right or left on the camshaft as required Inspect the YOKE ASSEMBLY being sure YOKE PIN is installed and locked into place with a COTTER PIN Replace any damaged worn or missing parts MGM Brakes recommends the YOKE LOCKNUT be tightened to 25 50 Lbs Ft torque Not Shown On units equipped with a DUST BOOT check the BOOT for damage and replace as necessary Not Shown On units equipped with an external BREATHER TUBE Figure 2 be sure both ends of the connector tube are engaged a minimum of 1 2 inch into each of the flexible eloows The tube must be glued to both of the elbows with a high quality rubber adhesive or secured with a clamp that may be purchased with the MGM Brakes BREATHER TUBE KIT These units must be mounted with the BREATHER TUBE in the upper half of the non pressure chamber facing away from the road surface Figure 10 O0 Model TR T Series IMPORTANT Failure to operate any MGM Brakes Model Series TR T or TR TS chamber without the EXTERNAL BREATHER TUBE and END CAP with O ring being present and in good condition will void the MGM Brakes Warranty without remedy SECTION 2 MANUAL RELEASE PARKING BRAKES a Before releasing the parking brakes chock wheels of the vehicle to prevent a r2. the air line fittings and inspect for air leaks If bubbles appear tighten fittings slightly but not over 30 Lbs Ft torque IMPORTANT If the service brake clamp ring was loosened to reposition air inlet ports in Step e above apply air to the spring brake and then apply and hold foot brake treadle valve down to charge the service brake chamber Test for air leaks around the circumference of the service clamp ring using soapy water or leak detection solution If bubbles appear firmly tap the circumference of the clamp ring with a hammer and retighten the clamp nuts until leaks cease Figure 19 MGM Brakes recommends 30 35 Lbs Ft torque on clamp hex nuts Completely exhaust air from both of the chambers when complete j With air pressure now exhausted from the service chamber but still applied on the spring brake remove release nut washer and release bolt for all TR models Replace these parts in their storage pocket Figure 4 on chamber or in vehicle tool box if storage pocket is not present on chamber and tighten nut against flat washer to 10 Lbs Ft torque k Replace the END CAP properly Figure 13 Operating units equipped with the EXTERNAL BREATHER TUBE without the END CAP and O RING securely in place will void the MGM Brakes Warranty without remedy IMPORTANT If chamber is fitted with an external breather tube be sure both ends of the connector tube are engaged a minimum of 1 2 inch into each of the flexible elbows Th
3. EATHER TUBE wipe the open end of the connector tube clean to be sure that no oil is present apply a high quality rubber cement to the tube and re insert tube into flexible elbow a minimum 1 2 inch engagement Figure 14 If the old single unit was not equipped with an EXTERNAL BREATHER TUBE drill a 1 2 inch diameter hole 1 inch from the top of the non pressure chamber Figure 18 at a point closest to the centerline between the air ports but in the upper half of the chamber facing away from the road surface Figure 10 Remove any burrs around the hole install a new rubber elbow in the non pressure chamber wipe the open end of connector tube clean to be sure no oil is present Apply a high quality rubber cement to the tube and insert the tube into the flexible elbow with a minimum 1 2 inch engagement Figure 18 IMPORTANT These units must be mounted with the BREATHER TUBE in the upper half of the non pressure chamber facing away from the road surface Figure 10 and the tube glued or clamped securely into the rubber elbows Figure 14 Failure to comply with these installation instructions will void the MGM Brakes Warranty without remedy k With air pressure exhausted from the service chamber but with line pressure still on the spring brake remove the release nut washer and bolt for all TR models Replace these parts in their storage pocket Figure 4 on the chamber or in the vehicle tool box if a storage pocket is not on the chambe
4. MODEL TR SERIES E MODEL TR T SERIES MGM Brakes Service Manual MODEL TR TS SERIES MODEL TR HD SERIES MODEL TR LP3 SERIES 50 Years of Leadership For Tamper Resistant S Cam Double Diaphragm Combination Service and Spring Brake Chambers The MGM Brakes Tamper Resistant spring brake chambers are an important part of your braking system While they do not require scheduled servicing it is good preventative maintenance to make the following routine inspections while they are in the shop for regular servicing of other components or at a minimum of every 50 000 miles WARNING YOUR MGM BRAKES TAMPER RESISTANT SPRING BRAKE HAS BEEN FACTORY SEALED FOR YOUR PROTECTION THERE ARE NO USER SERVICEABLE PARTS INSIDE THE SPRING BRAKE CHAMBER IF YOU EXPERIENCE ANY DAMAGE OR FAILURE OF YOUR SPRING BRAKE CHAMBER REMOVE EITHER THE ENTIRE ACTUATOR AS IN SECTION 3 OF THIS Figure 1 MANUAL OR THE SINGLE PIGGYBACK AS IN SECTION 5 OF THIS MANUAL SEE SECTION J 8 OF THIS MANUAL FOR DISPOSAL INSTRUCTIONS NEVER ATTEMPT TO DISASSEMBLE THE SPRING BRAKE CHAMBER AS SERIOUS PERSONAL INJURY COULD RESULT FROM ACCIDENTAL SUDDEN RELEASE OF THE HIGH ENERGY SPRING SECTION 1 RECOMMENDED INSPECTION POINTS The plastic END CAP on all TR and TR T models requires no positioning or maintenance but must be snapped tightly into place Inspect the cap for damage and replace as necessary TR T units equipped with a breather tube and the white WEATHE
5. R SEAL END CAP must be equipped with a rubber O ring Figure 12 to ensure proper sealing of the spring chamber Operating units equipped with the BREATHER TUBE without the END CAP or DUST CAP securely in place will void the MGM Brakes warranty without remedy Visually inspect the exterior surfaces of the unit for signs of damage from outside sources corrosion and or rust If any of these are seen or suspected cautiously remove the complete combination chamber by following the directions in Section 3 of this manual Per CVSA out of service criteria any non manufactured hole or crack will place the vehicle out of service Not Shown Inspect SERVICE BRAKE CLAMP RING to be sure it is securely in place and damage free If any Model TR Series damage is seen or suspected cautiously remove the complete piggyback spring brake chamber by following directions in Section 5 of this manual MGM Brakes recommends 30 35 Lbs Ft torque on CLAMP BOLTS Check to ensure the MOUNTING STUD NUTS are tightened to 133 155 Lbs Ft torque clockwise and washers are in place between the nut and bracket Figure 2 Inspect air lines hoses and fittings attached to chamber Replace any damaged or leaking parts MGM Brakes recommends the fittings be tightened to 25 30 Lbs Ft torque into the chamber air inlet ports OO Inspect the PUSH ROD to be sure it is working free not bent not binding and is square to the chamber bottom within 3
6. ad yoke onto the push rod Yoke from removed unit may be reused provided yoke pin hole is not worn Adjust yoke to the same Y dimension as measured from the removed unit k Hold yoke to prevent it from turning and tighten locknut against yoke 25 35 Lbs Ft torque TO INSTALL NEW UNIT ON VEHICLE Refer to MGM Brakes Service Manual for the model that is being installed SECTION 5 REMOVAL AND INSTALLATION INSTRUCTIONS FOR SINGLE PIGGYBACK SPRING BRAKES The removal and installation of a single spring brake chamber without removal of the service brake chamber can be made easier by locking off the service chamber piston To do this apply the service brake by applying the driver s foot brake treadle valve and while applied clamp vise grip pliers on push rod so that vice grips abut mounting bracket to prevent rod from retracting when air pressure is released Figure 15 a Determine manufacturer of the single spring brake to be removed from the vehicle and following that manufacturer s instructions exactly manually release the spring brake completely Instructions for all MGM Brakes Model Series TR TR T and single spring brakes having removable release bolts are given in Section 2 of this manual Service Manuals for all other design series of MGM Brakes single spring brakes are also available upon request to MGM Brakes b Remove both air lines from the chamber c On all MGM Brakes models fitted wit
7. del with the breather tube it is mandatory to position the non pressure chamber end of the breather tube in upper half of chamber facing away from the road surface Figure 10 Failure to comply will void the MGM Brakes Warranty on these models f Reconnect yoke to the slack adjuster being sure that the correct diameter and length of yoke pin is installed into the correct hole in the slack adjuster Secure the yoke pin with a new cotter pin IMPORTANT When making a reconnection to an automatic slack adjuster follow the vehicle manufacturer s recommendations for installation and set up 9 Inspect the push rod to be sure that it is working free not bent not binding an is square to the chamber bottom within 3 in any direction at any point in the stroke of the chamber If the push rod is not square make corrections by repositioning the chamber on the mounting bracket and or by shimming the slack adjuster to the right or left on the camshaft as required h Apply a non hardening sealing compound to the hose fittings and re install both of the air lines to the chamber being sure each is mated to the correct air inlet port according to the markings made earlier MGM Brakes recommends the fittings be tightened to 25 30 Lbs Ft torque into the chamber air inlet ports i Using the vehicle system air charge the spring brake with full line pressure minimum 100 psi Spray only soapy water or leak detection solution NEVER ANY TYPE OF OIL to
8. e piggyback spring brakes having removable bolts are given in Section 2 of this manual Service Manuals for all other design series of MGM Brakes piggyback spring brakes are also available upon request to MGM Brakes b Remove the cotter pin from the yoke pin knock out the yoke pin and remove both air lines from the assembly IMPORTANT Be sure to mark the air line from the inlet port marked SPRING BRAKE for later re installation reference Figure 8 Figure 9 x i Figure 11 LE c Using a 15 16 inch wrench unscrew hex nuts on mounting bolts and cautiously remove the old chamber from the mounting bracket d Follow procedure to cut the service push rod to proper length Refer to Section 4 e Remove the hex nut and the flat washers on the mounting bolts of the new chamber clean the face of the mounting bracket and install the chamber on the bracket with close attention given to positioning the chamber air inlet ports for correct alignment to the vehicle lines Then install one flat washer and hex nut on each mounting bolt and using a 15 16 inch hand wrench DO NOT USE AN IMPACT WRENCH tighten nuts to MGM Brakes recommended 133 155 Lbs Ft torque IMPORTANT If it is required to repostition the air inlet ports to assure proper mating and alignment with vehicle air lines refer to Section 5 of this manual and follow Steps c through f very carefully IMPORTANT When installing any MGM Brakes mo
9. e tube must be glued to both of the elbows with a high quality rubber adhesive or secured with a clamp that may be purchased with the MGM Brakes Breather Tube Kit These units must be mounted with the BREATHER TUBE in the upper half of the non pressure chamber facing away from the road surface Figure 10 WARNING AFTER REPLACEMENT OF ANY BRAKE CHAMBER THE CHAMBER PUSH ROD STROKE AND ACTUATING ALIGNMENT MUST BE CHECKED TO ASSURE CORRECT INSTALLTION AND FOUNDATION BRAKE ADJUSTMENT IT IS VERY IMPORTANT TO RECOGNIZE THAT NO FOUNDATION ADJUSTMENTS CAN BE MADE AT EITHER THE SPRING BRAKE CHAMBER OR AT THE SERVICE BRAKE CHAMBER AND THAT ALL STROKE ADJUSTMENTS MUST BE MADE AT THE SLACK ADJUSTER ACCORDING TO THE SPECIFIC RECOMMENDATIONS OF THE FOUNDATION BRAKE MANUFACTURER OR THE VEHICLE MANUFACTURER A SECTION 4 PROCEDURE TO CUT THE SERVICE PUSH ROD TO PROPER LENGTH WARNING DO NOT ATTEMPT TO SERVICE OR DISASSEMBLE THE SPRING CHAMBER OR ANY SPRING BRAKE ACTUATOR ALARGE SPRING IN THE SPRING CHAMBER HAVING EXTREME FORCE COULD CAUSE SERIOUS BODILY INJURY IF IT WERE SUDDENLY RELEASED DUE TO INADVERTENT REMOVAL OF THIS CLAMP OR TAMPER RESISTANT HEAD IMPORTANT Place blocks under wheels to prevent vehicle runaway before removing air brake actuators a REMOVE WORN OR NON FUNCTIONAL UNIT FROM VEHICLE Determine manufacturer and model of unit to be replaced Refer to that manufacturer s service manual for caging and removal in
10. f the high energy spring as much as 2700 Lbs of force in the parking chamber To disarm the unit remove it from the vehicle following the instructions in Section 3 for combination chambers or Section 5 for single piggyback chambers Be sure to release the brake per Section 2 of this manual Never attempt to remove the head which contains the power spring Observe all safety precautions Place the unit in a steel container and use an acetylene torch to cut a hole through the head housing the power spring Cut completely through at least two spring coils The steel container must have openings to expose the head where it is to be cut with the acetylene torch and it must be strong enough to prevent parts from hurtling out should the unit suddenly separate before it is safely disarmed It is the users responsibility to ensure the steel container is safe Information concerning a suitable container is available through your MGM Brakes Representative Form 5011 A Division of Indian Head Industries Inc MGM 8530 Cliff Cameron Drive Charlotte NC 28269 9786 704 547 7411 800 527 1534 704 547 9367 Fax All Rights Reserved 50 Years of Leadership e mail mail mgmbrakes com www MGMBrakes com Printed in U S A 1991 MGM Brakes Revised 2 2006
11. gth of bolt extends above the nut Figure 7 3 25 inch Type 2430 Chamber 4 00 inch Type 3036 Chamber 3 25 inch Type 3030 Chamber 4 00 inch Type 3636 Chamber WARNING DO NOT EXCEED THESE LENGTHS AND DO NOT EXCEED 50 Lbs Ft TORQUE ON RELEASE NUT AT ANY TIME OR DAMAGE MAY OCCUR WHICH COULD PREVENT ANY FUTURE CORRECT MANUAL RELEASING OF THE PIGGYBACK SPRING BRAKE CHAMBER NOTES For easier manual releasing apply 90 125 psi air pressure to inlet port marked SPRING BRAKE before Step d above but be sure to exhaust all air pressure after Step g is completed To reactivate the piggyback spring brake from its manually released position reverse the order of Steps a through g above When re installing the release bolt flat washer and release nut into the storage pocket MGM Brakes recommends 10 Lbs Ft torque on nut against the flat washer See Figure 11 SECTION 3 REMOVAL AND INSTALLATION INSTRUCTIONS FOR COMBINATION CHAMBERS NOTE Refer to Section 7 before removing air brake chamber to be replaced to ensure that the brake chamber being replaced was properly installed with the correct rod length a Determine the manufacturer of the single piggyback spring brake or combination chamber to be removed from the vehicle and following that manufacturer s instructions exactly manually release the spring brake completely Instructions for all MGM Brakes Model Series TR TR T and singl
12. h external breather tubes Figure 2 disconnect the tube and elbow from the service chamber housing Figure 18 Figure 12 Figure 13 Figure 14 Figure 15 Adhesive 1 2 inch Minimum Engagement Tyree stati Nien ett Apply Adhesive Here 1 2 inch Minimum Engagement 1 2 inch Diam Hole d Using a 9 16 inch wrench or socket remove the clamp nuts on the service clamp ring Then while holding the single spring brake securely in place remove the clamp ring to allow removal of the single brake from the service chamber Figure 16 IMPORTANT At this time take the opportunity to inspect all parts in the service chamber especially the diaphragm and replace the return spring and any other parts which may be damaged or worn Use only genuine MGM Brakes Engineered replacement parts e Make sure the new single piggyback spring brake is fully released as outlined in Section 2 of this manual Position the diaphragm in the bottom recess of the chamber Figure 17 and with very close attention taken to assure all mating parts are aligned straight and the air lines are positioned to mate with the vehicle air supply lines replace the service clamp ring Figure 16 f Re install the clamp bolts and nuts Alternately tighten each nut in 5 10 Lbs Ft torque increments while constantly rechecking mating parts alignment If re alignment is required loosen clamp nuts and repeat Step e above Firmly tap around c
13. ircumference of the clamp ring with ahammer to assure the full seating of the clamp Figure 19 and tighten the nuts to 30 35 Lbs Ft torque g Apply a non hardening sealing compound to the hose fittings and re install both of the air lines to the chamber being sure each is mated to the correct air inlet port according to the markings made earlier MGM Brakes recommends the fittings be tightened to 25 30 Lbs Ft torque into the chamber air inlet ports h Using the vehicle system air charge the spring brake with full line pressure minimum 100 psi Spray only soapy water or leak detection solution NEVER ANY TYPE OF OIL to the air line fittings and inspect for air leaks If bubbles appear tighten fittings slightly but not over 30 Lbs Ft torque i With the spring brake still fully charged with full line pressure apply and hold foot brake treadle valve down to charge the service brake chamber IMPORTANT At this time remove the vise grip pliers Figure 15 from the service push rod so that the piston can return to a normal position in the chamber Now test for air leaks around the circumference of the service clamp ring by spraying with soapy water or leak detection solution If bubbles appear firmly tap the circumference of the clamp ring with a hammer and retighten the clamp nuts until leaks cease Figure 19 MGM Brakes recommends 30 35 Lbs Ft torque on the clamp hex nuts j On all MGM Brakes models fitted with an EXTERNAL BR
14. r and tighten the nut against the flat washer to 10 Lbs Ft torque I Replace the end cap properly Figure 13 Operating these units without the END CAP securely in place will void the MGM Brakes Warranty without remedy SECTION 6 REMOVAL AND INSTALLATION INSTRUCTIONS FOR SERVICE BRAKE DIAPHRAGM a Follow all instructions given in Section 5 of this manual and install the new diaphragm in Step 5 e Use only genuine MGM Brakes Engineered replacement diaphragms WARNING WHEN SERVICING A3 INCH LONG STROKE MODEL BRAKE BE SURE TO REPLACE WITH THE CORRECT DIAPHRAGM INSTALLATION OF A STANDARD 2 50 INCH STROKE DIAPHRAGM INA 3 INCH LONG STROKE CHAMBER COULD RESULT IN CATASTROPHIC FAILURE OF THE UNIT SECTION 7 CAM BRAKE ADJUSTMENT ALL MODELS SPRING BRAKE AND SERVICE BRAKE ACTUATORS NOTE The last half of an air chamber stroke is less efficient than the first half Therefore the following adjustments are recommended for maximum efficiency when using manually adjusted slack adjusters BRAKES OFF NOT APPLIED PROPERLY ADJUSTED BRAKES ON APPLIED Angle must always be greater than 90 due to various slack yi To check brake adjustment apply 90 to 100 psi air pressure to adjuster lengths and installation setups Refer to axle or the service chamber Consult the vehicle manufacturer for the OEM manufacturer s manual for recommended angle correct angle between the slack adjuster a
15. rm and push rod and or the push rod length This is necessary since different dimensions are required for automatic or manual slacks various slack lengths and different slack adjuster manufacturers IMPROPERLY ADJUSTED BRAKES ON APPLIED ive Maximum B MV MA Stroke with Recommended Maximum recommended readjustment stroke has been exceeded Maxin J Brakes Readjustment Adjusted Stroke MGM Brakes Stroke Alert Inches MM Excessive Stroke Warning Stroke should be as short as possible with no lining to drum contact POSSIBLE WITHOUT LINING TO 24LP3 24 7 00 175 3 00 76 8 00 200 250 64 SOURCE MVMA Motor Vehicle Manufacturers Association See chart on right for recommended reagjusIMEnT Stoke Note The push rod must remain perpendicular to the bottom surface of the non pressure chamber NPC within 3 zero to full stroke SECTION 8 RECOMMENDED SPRING BRAKE ACTUATOR DISARMING PROCEDURE WARNING THIS PROCEDURE MUST BE STRICTLY ADHERED TO NEVER ATTEMPT TO REMOVE THE SPRING CHAMBER CLAMP RING FROM A DOUBLE DIAPHRAGM ACTUATOR OR THE SPRING CHAMBER RETAINING RING FROM A PISTON ACTUATOR BOTH ACTUATORS EMPLOY A HIGH ENERGY POWER SPRING THAT COULD CAUSE SERIOUS BODILY INJURY IF THE SPRING WERE SUDDENLY RELEASED DUE TO IMPROPER DISASSEMBLY All retired spring brake actuators must be safely disarmed before they are disposed of to prevent serious personal injury from accidental sudden release o
16. structions b Make sure the spring chamber of the removed actuator is fully released power spring caged and the service brake push rod is fully retracted to zero stroke position i e brake fully released c Measure and record the X and Y dimensions Figure 8 X Dimension The dimension from bottom of actuator to end of push rod Y Dimension The dimension from bottom of actuator to centerline of yoke pin NOTE If for some reason the spring chamber power spring cannot be caged and fully released then the X and Y dimensions will need to be measured from another actuator of the exact type from the same vehicle provided it is retracted to its zero stroke position brake fully released and was operating correctly d Before marking push rod to be cut on a new unit be sure the spring chamber and push rod are fully retracted to the zero position This may be done with the manual caging bolt or by applying 90 100 psi air pressure to the spring chamber air inlet port e Take measured X dimension from the removed unit and mark push rod of new unit from the bottom of the actuator f Thread yoke jam nut past mark on push rod Align bottom edge of nut with mark 9 Use a sharp hack saw and cut push rod on the mark Figure 9 h After cutting rod thread jam nut off to clean up the thread i Thread jam nut back onto the push rod a suffient length to allow assembly of the yoke j Thre
17. unaway b Remove the plastic end cap from the spring brake chamber Figure 3 c Using a 3 4 inch 15 16 inch for TR3036 and TR3636 models wrench unscrew the release nut and remove the nut flat washer and release bolt from their storage pocket on side of chamber for all TR series brakes Figure 4 IMPORTANT If these parts are not stored on the chamber they must be obtained from vehicle tool box or service department as the piggyback spring brake cannot be manually released without them d Insert the release bolt into the centerhole of the head Figure 5 and being sure that the formed end of the bolt has entered the hole in the piston inside the chamber continue to insert the bolt until it bottoms out IMPORTANT If you are not absolutely sure of correct bolt to piston engagement repeat this step until you are sure e Turn the release bolt 1 4 turn clockwise and pull the bolt out to lock the formed end into the piston IMPORTANT If the bolt does not lock into the piston in less than 1 2 inch outward movement repeat steps d and e until you are sure it does lock f Holding the bolt locked into the piston install the flat washer and the release nut on the end of the release bolt and turn down the nut against the flat washer until finger tight Figure 6 g Using a 3 4 inch 15 16 inch for TR3036 and TR3636 models handwrench DO NOT USE AN IMPACT WRENCH turn the release nut clockwise until the following len
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