Document dQbG64kO1yBdLQyKQQ0GgrQa5

12 141 BRAKING SYSTEM Airpak August 1979 12 283 Page 43 O Series (c) The fluid in the reservoit should he of the correct specification (ic.-SM 6C 1002A) and topped up level with the mark on the reservoir. Id) All brake pipe unions should be free from visible signs of leakage. To Bleed the System 1. By repeatedly depressing the brake pedal, reduce the air pressure in the system until a gauge reading of between 2,0 to 3,5 kp/cm2 (28,5 to 50 lb/in2) is indicated. NOTE: It may be necessary to start and run the engine occasionally during the bleeding process to retain the above air pressure reading. 2. Commence to bleed at the bleed screw on the top of the Servo end cover, followed by the screw on the end-cap of the hydraulic (slave) cylinder. 3. Remove the rubber dust cap on the bleed valve and fit a rubber tube on the valve. 4. Immerse the end of the bleed tube in a dean jar containing new brake fluid. Keep the end of the tube below the surface of the fluid during the brake bleeding operation. 5. Open the bleed valve and slowly depress and release the brake pedal several times. Pause for an instant between each depression of the pedal to ensure full recuperation of the master cylinder. (If the master cylinder is sticking, overhaul the master c^inder as detailed in Operation 12 343 8). For each depression of the brake pedal some fluid or air should be emitted from the tube, if neither fluid nor air emerges, the bleed valve has not been opened properly or there is a blockage in the pipe line. 6. Continue depressing the brake pedal, until no more air bubbles emerge from the tube. NOTE: It is important that the fluid level in the reservoir is maintained during the brake bleeding operation. NEVER replenish the reservoir with fluid drained from the system as it may be contaminated or aerated. If the fluid in the system is dirty it is advisable to drain it completely and refill with fresh fluid. 7. When, with each depression of the brake pedal, fluid alone comes out of the bleed tube, hold the footbrake pedal in the fully depressed position and tighten the bleed valve. CAUTION: Do not use excessive force when tightening the valve. 8. Remove the tube and refit the rubber cap on the bleed valve. 3. Repeal operations 3 to 8 to bleed the wheel cylinders, starting at the wheel having the shortest pipeline run from the slave cylinder. Bleed at the wheel having the longest pipe line run last. NOTE: The load apportioning valve must be bled before the rear wheel cylinders, using the same procedure as that for bleeding all other valves. 10. Top up the reservoir to the correct level and refit the cap. 122S3 SHOES - FRONT BRAKES - REMOVE AND INSTALL (One Side) (Includes: Adjust Both Sides) WARNING: Brake lining dust is injurious to health if inhaled and proper care must be taken when cleaning the brake drums and/or back plates.__________________ ___ To Remove 1. Ensure that the park brake is applied. 2. Position a jack under the centre of the front axle and raise the vehicle sufficiently to fit stands under each end of the axle. 3. Using a wheel trolley, remove the wheel and brake drum assembly as one unit, as detailed in Operation 14 371. 4. Using the Brake Shoe Horn (Tool No. 64947016), prise one of the shoes from its abutment slot on the wheel cylinder. 5. Gradually release the tension on the shoe to enable the other shoe to be removed from its abutment slot on the other wheel cylinder. 6. Remove both shoes complete with the retracting springs. 7. Note the positions of the retracting springs and remove the springs from the shoes. 8 Wire the wheel cylinder pistons to keep them retracted. To Install NOTE: Ensure that the brake shoe lining material of the replacement shoes is of the correct specification. Check the letter code on the side of the brake shoe lining (see SPECIFICATIONS). 9. Refit the brake shoe retracting springs in the positions noted during removal. 10. Locate the shoe web of each brake shoe leading edge into the slot at the end of the wheel cylinder piston. 8006 1271 HFM- 005857