1800566, OPR, HYSTER, Hyster2, SRM

//-->.pos {position:absolute; z-index: 0; left: 0px; top: 0px;}INTRODUCTIONGENERALThis section has a description and the serviceprocedures for the parts of the brake system. The brakesystem includes the following parts: master cylinder,brake shoes, wheel cylinders, and the parking brakesystem. A troubleshooting section is included at the endof this section.operate in the single bore of the master cylinder. The res-ervoir for the fluid is pressed into the two ports on top ofthe master cylinder and held in position by seals. Whenthe brake pedal is pushed, the push rod moves the pistonassemblies. The operation of the master cylinder is de-scribed in FIGURE 1.If a failure occurs in one of the dual circuits, the othercircuit will apply one of the service brakes. This failurewill cause the brake pedal to travel farther when thebrakes are applied, but the service brakes on one drivewheel will operate. This failure of one of the brake cir-cuits can cause the lift truck to turn toward the drivewheel with the good brake when the brakes are applied.The operator must control the direction of the lift truckwith the steering when the brakes are applied during thiscondition.The reservoir is equipped with an indicator for low fluidlevel. A float in the reservoir moves up and down withthe fluid level. When the fluid level is low, a magnet onthe float activates a switch in the bottom of the reservoir.This switch energizes a warning light on the instrumentcluster.DESCRIPTION AND OPERATIONService Brakes (See FIGURE 8.)A service brake assembly is installed on the mounts ateach end of the drive axle. The parts of the service brakeassembly are shown in FIGURE 2. and FIGURE 3.When the brake pedal is pushed, fluid pressure from themaster cylinder causes the pistons in the wheel cylindersto extend. The pistons expand the brake shoes againstthe drums.The clearance between the brake shoes and the brakedrum is adjusted automatically. An adjuster linkageturns the adjuster wheel to adjust the clearance. Whenthe lift truck moves in the REVERSE direction and thebrakes are applied, the rear brake shoe and the adjusterlinks move with the drum. This linkage moves the ad-juster lever to rotate the adjuster wheel. The adjusterwheel can turn only when there is clearance between thelining of the brake shoe and the brake drum. The ad-juster wheel can also be turned with a tool. A hole in thebrake drum gives access to the adjuster wheel.Parking Brake (See FIGURE 9.)The parking brake system uses the service brake shoes.Additional linkage activates the parking brake system.When the pedal is moved to apply the parking brake, thecables and linkage expand the brake shoes against thedrums. The design of the parking brake linkage adjustseach cable so that the tension is the same when the pedalis moved to apply parking brake.Master Cylinder (See FIGURE 1.)The master cylinder is designed for a dual circuit sys-tem. The master cylinder has two separate pistons that1BRAKE “OFF”When the brakes are “OFF,” the hydraulic fluidcan move freely between the dual circuit systemand the separate chambers of the fluid reservoir.BRAKE “RELEASED”When the brake pedal is released, the re-turn springs cause the pistons to retractfaster than the fluid. This action causes avacuum between the fluid in chambersAandC.The vacuum causes the seals (2)to change shape. When the seals changeshape, they permit the fluid in chambersBandDto flow through the holes in thepistons and past the seals into chambersAandC.The supply holes in the cylinderbody supplies fluid as the flow movesfrom the one chamber to the other cham-ber. The fluid returns to the reservoirthrough the bypass holes when the pis-tons are fully retracted.7698982A12B345CDFLUID WITH NO PRESSUREFLUID UNDER PRESSURE1.2.3.4.5.SECONDARY SPRINGSEALSECONDARY PISTONPRIMARY SPRINGPRIMARY PISTON6.7.8.9.PRIMARY FLUID CHAMBERSECONDARY FLUID CHAMBERBYPASS HOLESSUPPLY HOLESBRAKE “APPLIED”When the brake pedal is pressed, the primarypiston moves in the cylinder bore. This move-ment creates hydraulic pressure that combineswith the force of the primary spring. These com-bined forces overcome the secondary springforce and move the secondary piston in thebore with the primary piston. The first move-ment of both pistons pushes the seals (2) pastthe bypass holes in the chambersAandC.This action applies pressure to the fluid in thosechambers and causes fluid to flow to the cham-bers of the two separate systems. The fluid inchambersBandDis not effected by movementof the pistons. This fluid can move freely be-tween the piston chambers and the chambersof the fluid reservoir, before and during brakeapplication.ABCD12595FIGURE 1. OPERATION OF MASTER CYLINDER2SERVICE BRAKESRemoval And Disassembly3. Remove the capscrews that hold the axle shaft to thehub. Remove the axle shaft.4. Release the parking brake. Bend the lock plate and re-move the nut that holds the axle bearing. Remove thewasher and the bearing cone.5. Put grease on the floor so that the wheel assembly willslide easily from the axle tube. Pull the wheel assemblyfrom the lift truck. If the wheel assembly cannot be re-moved easily, remove the wheel and use a small screw-driver to push the adjuster actuator away from the ad-juster wheel. Use a brake adjustment tool or a screw-driver to turn the adjuster wheel to loosen the brakeshoes. Install the wheel and then remove the hub anddrum assembly. Do not damage the grease seal when re-moving the hub.WARNINGBrake linings can contain dangerous fibers. Breath-ing the dust from these brake linings is a cancer orlung disease hazard. Do not create dust! Do not cleanbrake parts with compressed air or by brushing. Usevacuum equipment approved for brake dust or fol-low the cleaning procedure in this section. When thebrake drums are removed, do not create dust.Do not sand, grind, chisel, hammer, or change liningsin any way that will create dust. Any changes tobrake linings must be done in a restricted area withspecial ventilation. Protective clothing and arespirator must be used.1. See the procedure “HOW TO PUT A LIFT TRUCKON BLOCKS” in the PERIODIC MAINTENANCEsection of the service manual or theOPERATINGMANUAL.Tilt the mast fully backward. Put blocks un-der the mast. Tilt the mast forward until the wheels justtouch the floor. Stop the motor. Put blocks under theframe of the lift truck.2. If tilt does not function use a hydraulic jack, crane oranother lift truck to lift the drive wheels until they justtouch the floor. Put blocks under the frame of the lifttruck.DANGERWhen the brake shoes are removed do not createdust in the air. See the cleaning procedure in this sec-tion.6. See FIGURE 2. Remove the return springs (2 and 14)with spring pliers.NOTE:The return springs (2 and 14) are not the samepart number. Make sure the springs are installed in thesame positions from which they were removed.121214LEFT SIDE SHOWN35111341113121010987695241.2.3.4.5.6.7.8.9.10.11.12.13.14.WHEEL CYLINDERRETURN SPRING, MAROONPIVOT PLATELINKANCHORADJUSTER WHEEL ACTUATORADJUSTER WHEELADJUSTER NUTCABLE, PARKING BRAKERETAINERLEVER, PARKING BRAKEBRAKE SHOEPIN, HOLD DOWNRETURN SPRING, GREYFIGURE 2. BRAKE ASSEMBLY (LEFT BRAKE ASSEMBLY SHOWN)37. Remove the retainers, springs, and retainer pins thathold the brake shoes to the back plate. See FIGURE 3.Remove the brake shoes and adjuster assembly.NOTE:The adjuster wheel for the left brake is not thesame as the adjuster wheel for the right brake. The ad-juster wheel for the right brake has left–hand threads.8. Remove the brake line from the wheel cylinder. Re-move the wheel cylinder.9. Remove the dust covers, pistons, cups, and springsfrom the wheel cylinder. See FIGURE 4.1417*121110. Remove the snap rings from the parking brake lev-ers. Remove the parking brake levers from the backplate.NOTE:The back plate is not normally removed fromthe axle housing for brake repairs. Six special capscrewsare used to fasten the back plate to the axle mount andthe locking function of the capscrews is reduced if theyare removed. The five capscrews with5/8inch thread aretightened to 245 N.m (180 lbfft). The capscrew with1/2inch thread is tightened to 125 N.m (92 lbfft).DO NOT BEND OR PUT STRESS ON THEUPPER LINK (17) BY FORCING THE HOOKEND ON OR AROUND THE POST ON THESPECIAL CAPSCREW (15).LEFT SIDE SHOWN109821620157623118192281 5211.2.3.4.5.6.7.8.9.10.11.12.13.14.15.SNAP RINGRETURN SPRING, MAROONBACK PLATECABLECABLE GUIDESPECIAL CAPSCREWCAPSCREWSLEVER, PARKING BRAKEWHEEL CYLINDERPIVOT PINBRAKE SHOE, REARPIVOT PLATEHOLD–DOWN PIN (2)RETURN SPRING, GREYSPECIAL CAPSCREW43242516.17.18.19.20.21.ADJUSTER LINKADJUSTER LINK*RETAINER SPRING ASSEMBLYBRAKE SHOE, FRONTSPRINGADJUSTER NUT13122. ADJUSTER WHEEL23. ADJUSTER WHEELACTUATOR24. CABLE RETAINER25. CRANKFIGURE 3. PARTS OF THE SERVICE BRAKE43467851.2.3.4.5.6.7.8.PORT FOR SPECIAL FITTINGINLET PORTBRAKE SHOEDUST COVERWHEEL CYLINDERSPRINGCUPPISTON ASSEMBLY124FIGURE 4. WHEEL CYLINDERCleaningWARNINGDO NOT use an oil solvent to clean the master cylin-der, wheel cylinder, or the brake linings. Use a sol-vent approved for cleaning of brake parts. Do notpermit oil or grease in the brake fluid or on the brakelinings. Oil and grease will cause damage and leaksin the seals of a brake system. The brakes will not op-erate correctly if oil, grease, or brake fluid is on thebrake linings.Cleaning solvents can be flammable and toxic, andcan cause skin irritation. When using cleaning sol-vents, always follow the safety instructions of the sol-vent manufacturer.1. Do not release brake lining dust from the brake liningsinto the air when the brake drum is removed.2. Use a solvent approved for cleaning of brake parts towet the brake lining dust. Follow the instructions andcautions of the manufacturer for the use of the solvent. Ifa solvent spray is used, do not create brake lining dustwith the spray.3. When the brake lining dust is wet, clean the parts. Putany cloth or towels in a plastic bag or an airtight con-tainer while they are still wet. Put an “DANGEROUSFIBERS” warning label on the plastic bag or airtightcontainer.4. Any cleaning cloths that will be washed must becleaned so that fibers are not released into the air.CAUTIONDo not permit oil or grease on the brake linings. Use abrake cleaning fluid as necessary to clean linings thatwill not be replaced.Inspection1. Inspect the bore of the wheel cylinder for holes orscratches. Replace the wheel cylinder assembly if thereis any damage.2. Inspect the return springs for wear or damage. Inspectthe back plate for wear where the brake shoes touch theback plate. Remove any grooves or replace a worn ordamaged back plate.3. Inspect the brake shoes for cracks or damage. If thelinings or shoes are worn or damaged, replace the brakeshoes. Maximum wear is to within 1 mm (0.025 in) ofcontact with the rivets, or the metal shoe on bonded lin-ings. Brake shoes must be replaced in complete sets. In-spect the brake drums for cracks or damage. Replaceany damaged parts.5

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