SLEEVE 7C2116 - Caterpillar

Testing Brake System (50S1-50S2451, 55U1-55U521 And 94U1-94U537)
Operational Check
Master Cylinder
(1) Stroke rod indicator.A need for brake repair is indicated by stroke indicator rod (1). With the pedal depressed, note the stroke of the rod on each master cylinder. Brake repair is necessary when the stroke indicator rod extends 36.6 mm (1.44 in.).1. Start the diesel engine and charge the air reservoir to operating pressure.2. Depress the brake pedal and hold it in the depressed position.3. Observe the stroke indicator rods. (a) Stroke indicator rod creep indicates leakage in the hydraulic portion of the brake system.(b) Excessive indicator rod travel (with brake pads in proper contact) indicates air in the hydraulic portion of the system.4. Release the brake pedal. (a) Failure of one or both master cylinder stroke indicator rods to retract indicates a master cylinder with a bypass port blocked by dirt, corrosion or a swollen primary cup. A primary cup which has become too large is an indication of wrong or dirty hydraulic fluid in the system. If hydraulic fluid is dirty, remove and repair all components in the hydraulic system of the brakes. Flush the brake lines with clean hydraulic fluid.Leakage Check
Depress the brake pedal and hold it in the depressed position. Coat air line connections at the air chambers with soap suds and check for air leakage. Release the brake pedal. Coat the exhaust ports of the brake control valve with soap suds. When pedal is depressed leakage must not exceed a 25.4 mm (1 in.) soap bubble in one minute. Repair any air leaks that may exist.Bleeding The Brakes (Machines Before 50S2452, 55U522 And 94U538)
Master Cylinders Location
(1) Driveline brake cylinder. (2) Front wheel brake cylinder.Bleed the front wheel brake system which is actuated by master cylinder (2).1. Check the fluid level in the reservoir. The initial level should be within 12 mm (.5 in.) from the top of the reservoir. To prevent an air lock from developing in the master cylinder, fluid must always be visible in the reservoir while the system is being bled.
Checking Reservoir Fluid Level2. Attach a 6.3 mm (.25 in.) I.D. hose to the bleed valve. Place loose end of hose into a jar containing enough fluid to submerge the end of the hose.
Wheel Brake Bleed Valve3. Repeatedly depress the brake pedal until a shorter stroke is observed on the stroke indicator rods.4. Hold the brake pedal down and observe the stroke indicator rod.5. Open the bleed valve and observe the brake fluid escaping from the bleed line. Close the bleed valve when the stroke indicator rod is extended 36.6 mm (1.44 in.)6. Repeat Steps 3, 4, and 5 until the brake fluid escaping through the bleed line contains no air bubbles.7. Refill the reservoir to within 12 mm (.5 in.) from the top of the reservoir.8. Repeat procedure for the driveline brake system if necessary. Remember that the brake pedal will have to be depressed all the way to the floor since this is a sequencing system which actuates the