1800452, OPR, HYSTER, Hyster2, SRM

//-->.pos {position:absolute; z-index: 0; left: 0px; top: 0px;}INTRODUCTIONGENERAL (See FIGURE 1.)This section has a description and the repair proceduresfor the parts of the brake system. These parts include thebrake booster, master cylinder and brake shoe assem-blies.The brake system on this series of lift trucks uses a hy-draulic actuator (brake booster) (1) to actuate the mastercylinder (4). The operation of the brake booster (1) de-creases the foot effort necessary to apply the brakes. Theoil flow from the outlet of the steering control unit isused to operate the brake booster (1).DESCRIPTIONThe brake system consists of service brakes and theparking brake. The service brakes have the brake pedal,booster and master cylinder and a brake assembly ateach drive wheel. The parking brake has the hand leverassembly, cables to each service brake assembly and alever in the service brake assembly to mechanicallymove the brake shoes.OPERATIONThe operator pushes the brake pedal to apply the brake.This action pushes the push rod of the booster to movethe plunger. When the plunger moves, it moves the pis-ton. When the piston moves, it allows the pressure fromthe steering pump to enter the booster and help move thepiston. As the piston moves, it moves the piston rod tomove the piston of the master cylinder. Brake fluid isforced through the brake lines to the wheel cylinders.The fluid forces the pistons of the wheel cylinders tomove the brake shoes against the brake drums to stop thelift truck.When the operator releases the latch and pulls the park-ing brake lever, the cables move the lever to move thebrake shoes against the brake drum to keep the lift truckfrom moving.122461.2.3.4.5.6.BRAKE BOOSTERINLET FROM STEERING CONTROL UNITOUTLET TO HYDRAULIC TANKMASTER CYLINDERINLET FROM RESERVOIROUTLET TO WHEEL CYLINDERSBRAKE BOOSTER AND MASTERCYLINDERThe operation of the brake booster and master cylinderis shown and described in FIGURE 2.FIGURE 1. BRAKE BOOSTER AND MASTERCYLINDER121673BRAKES NOT APPLIED4Hydraulic oil flows from the steering control unit to the inlet (2) of the brake valve. The hydraulicoil flows freely between the plunger (3) and the piston (4) and returns to the hydraulic tank fromthe outlet (6)109812874BRAKES APPLIED115When the brakes are applied and the engine is not running, the plunger (3) pushes against thepiston (4). The piston and piston rod (5) push against the piston in the master cylinder to actu-ate the brakes.When the engine is running, there is hydraulic oil flowing through the brake valve.The movement of the plunger (3) makes a restriction in the flow of oil between the plunger (3)and the piston (4). The hydraulic pressure behind the piston increases and pushes on the pis-ton (4) and piston rod (5) to move the piston in the master cylinder. The oil pressure behind thepiston decreases the effort at the brake pedal to apply the brakes. As the piston (8) for themaster cylinder moves, brake fluid flows from the outlet (9) to the wheel cylinders. The reliefvalve (11) gives a 2300 kPa (332 psi) limit to the hydraulic pressure in the brake valve.1.2.3.4.5.BRAKE VALVE (BOOSTER)INLETPLUNGERPISTON (BRAKE VALVE)PISTON ROD6. OUTLET TO HYDRAULICTANK7. MASTER CYLINDER8. PISTON (MASTER CYL-INDER)9. OUTLET TO WHEELCYLINDERS10. INLET FROM BRAKERESERVOIR11. RELIEF VALVEFIGURE 2. OPERATION OF THE BRAKE BOOSTER AND THE MASTER CYLINDER2SERVICE BRAKE ASSEMBLY(See FIGURE 3.)A service brake assembly is used at each end of the driveaxle housing. Each service brake assembly has a wheelcylinder (3) at the top of each back plate (1). A shoeguide (2) and guide springs (5) keep the shoes (6)against the back plate. Return springs (4) hold the brakeshoes tight against the wheel cylinder and the adjustermechanism (7).moves away from the adjuster plate. When there isclearance between the shoe and drum, the adjuster platecan move and engage the next tooth of the adjusterwheel. The springs on the adjuster plate cause the ad-juster plate to rotate when the brake pressure is released.PARKING BRAKE (See FIGURE 4.)The parking brake uses the service brake shoes. Addi-tional linkage pushes the shoes apart when the handlever (1) pulls the cables (2). On units with a powershifttransmission and a Monotrol pedal, the hand lever alsooperates a switch (3) to allow the key switch to energizethe starting circuit for the engine. When the parkingbrake is applied, the switch deenergizes the circuit forthe Monotrol pedal and the Forward and Reverse sole-noids. This action puts the transmission inNEUTRAL.The starting circuit for the engine is energized when theparking brake is applied.1. HAND LEVER2. CABLES TO BRAKE SHOES3. SWITCH1.2.3.4.5.6.BACK PLATESHOE GUIDEWHEEL CYLINDERRETURN SPRINGGUIDE SPRINGBRAKE SHOE7. AUTOMATICADJUSTERMECHANISM8. BRAKE LEVER9. BRAKE LINKFIGURE 3. SERVICE BRAKE ASSEMBLYWhen the piston of the wheel cylinder is moved by fluidpressure from the master cylinder, the piston moves thebrake shoes to contact the drum. The primary shoe startsto turn with the brake drum. This action pushes the sec-ondary shoe tight against the brake drum. This servo ac-tion increases the force applied to the brake drums.The automatic adjuster mechanism turns the adjusterwheels to adjust the clearance between the brake shoesand the drum. The adjuster mechanism operates whenthe the lift truck is traveling in forward or reverse. Whenthe brakes are applied, the brake shoes move toward thebrake drum. When the bottom of a brake shoe movesaway from the adjuster mechanism, the adjuster wheelFIGURE 4. PARKING BRAKE ASSEMBLY3REPAIRSBRAKE SHOE ASSEMBLIESRemoval And Disassembly (See FIGURE 5.)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 a respira-tor must be used.1. Tilt the upright back and put blocks under the outerupright weldments. Tilt the upright forward to raise thetires from the floor.2. The wheels (16), hub (3) and brake drum (6) can beremoved as an assembly.3. Remove the capscrews that hold the axle shaft (2) tothe hub. Remove the axle shaft.4. Remove the seal (7) from the hub. Remove the nutsfor the bearings (8 and 10) from the axle housing (1).Slide the wheel, hub and brake drum from the axle hous-ing.5. See FIGURE 3. Use spring pliers to remove the shoereturn springs (4). Remove the clips at the back plate (1)for the guide springs (5). Remove the guide springs.6. See FIGURE 3. Disconnect the parking brake cablefrom the parking brake lever. Remove the brake shoes(6).7. See FIGURE 3. If necessary, the adjuster mechanism(7) and wheel cylinder (3) can be removed from the backplate. The back plate can be removed from the axlehousing.41.2.3.4.5.6.7.8.AXLE HOUSINGAXLE SHAFTHUBBEARING CUPBEARING CONEBRAKE DRUMSEALLOCKNUT9.10.11.12.13.14.15.16.LOCKWASHERADJUSTMENT NUTWHEEL NUTBRAKE ASSEMBLYWEAR SLEEVEGASKETTAPERED CAPSCREWWHEELFIGURE 5. DRIVE AXLE AND BRAKEASSEMBLYCleaning1. Do not release brake lining dust into the air when thebrake drum is removed.2. Use a solvent to wet the brake lining dust on the partsof the brake. If a solvent spray is used, do not create dustwith the spray.3. When the dust is wet, clean the parts. Put any cloth ortowels in a plastic bag or an airtight container while theyare still wet. Put an “ASBESTOS” warning label on theplastic bag or airtight container.4. Any cleaning cloths that will be washed must becleaned so that the fibers are not released into the air.CAUTIONDo not use solvent to clean the wheel cylinder. Do notget oil or grease in the brake fluid or on the brake lin-ings. Use a brake cleaning fluid to clean the liningsand the brake hydraulic parts.Inspection1. Clean all metal parts except the linings and the wheelcylinder with solvent.2. Check the bore of the wheel cylinder for corrosion,pitting or scratches. Replace the wheel cylinder if thereis any damage.3. Check the return springs for defects. Inspect the backplate for wear where the brake shoes touch the backplate.4. Inspect the brake shoes for cracks or damage. If thelinings or shoes are worn or damaged, replace the brakeshoes. It is recommended that if one brake shoe is re-placed, both brake shoes on the wheel be replaced.5. Inspect the brake drum for deep grooves or other dam-age on the surface for the brake shoes. Use sandpaper tosmooth the grooves on the brake drum surface.NOTE:If the brake drums require turning on a lathe, donot remove more than 1.5 mm (0.060 in) from the di-ameter. The maximum inside diameter of the brakedrum, including wear, is 316.82 mm (12.473 in). If thediameter is larger than this, replace the brake drum.Assembly And Installation1. See FIGURE 3. Install the wheel cylinder (3) andshoe guide (2) on the back plate (1). Install the adjustermechanism (7) on the back plate. Use the following pro-cedure to adjust the adjuster mechanism:a. See FIGURE 6. Check the clearance between theadjuster plate (2) and the adjuster wheels (1). Useshims (3) between the adjuster wheels and thehousing until the clearance is 1.04 to 1.34 mm(0.041 to 0.053 in). This adjustment is importantfor the correct operation of the automatic brakeadjuster.2. Install the back plate on the axle housing. Install thetapered sleeves and the nuts. Tighten the nuts in thecross pattern to 55 to 80 N.m (41 to 59 lbf ft), thentighten the nuts in the same cross pattern to 110 to 125N.m (81 to 92 lbf ft).1. ADJUSTER WHEEL2. ADJUSTER PLATE3. SHIMSFIGURE 6. AUTOMATIC ADJUSTERMECHANISM3. See FIGURE 3. Install the lever for the parking brake(8) on the brake shoe (6). Install the brake shoe. Installthe parking brake link (9). Connect the parking brake ca-ble to the lever.4. See FIGURE 3. Install the guide springs (5) and in-stall the clips on the back of the brake plate. Install theshoe return springs (4).5. See FIGURE 5. If removed, install the hub, brakedrum (6) and wheels (16) on the hub (3). Tighten thenuts for the brake drum and wheels (11) to 610 to 680N.m (450 to 500 lbf ft).6. See FIGURE 5. Lubricate the inner wheel bearing (5)with grease, then install the inner seal (7) in the hub.7. See FIGURE 5. Slide the wheel and hub assembly onthe axle housing (1). Lubricate the outer wheel bearing(5) with grease and install the bearing on the axle hous-ing.CAUTIONDo not damage the seal when installing the wheel andhub assembly.8. See FIGURE 5. Install the bearing adjusting nut (10).Tighten the nut to 200 N.m (150 lbf ft) while turning thehub. Loosen the nut to less than 27 N.m (20 lbf ft).Tighten the nut to 35 N.m (26 lbf ft). Lock the adjustingnut at this position or tighten the nut to the first positionwhere the lock washer (9) fits. Install the locknut (8) andtighten it to 135 N.m (100 lbf ft).9. See FIGURE 5. Use a sealant on the flange of the oilseal and install the outer seal in the hub. Use a sealant on5

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