TIP AS- 5106289 - Caterpillar

Purge Procedure For Power Assist Brakes
Personal injury or death can result if two persons are not used in the following procedure.
Escaping fluid under pressure, even a pinhole size leak, can penetrate body tissue, causing serious injury, and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury.Always use a board or cardboard when checking for a leak.
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids.Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat products.Dispose of all fluids according to local regulations and mandates.
Note: Refer to the Operation and Maintenance Manual for your machine.Two people are needed for this procedure.
Illustration 1 g01200158
Rear Axle (1) Left air purge screw (2) Right air purge screw
Fill the hydraulic tank with oil. Add oil to the hydraulic tank during the purge procedure in order to maintain the proper level. Refer to Operation and Maintenance Manual, "Recommended Oils" and Operation and Maintenance Manual, "Refill Capacities".
Open the left air purge screw (1) and the right air purge screw (2) .
Fasten one end of a transparent tube that is 6.4 mm (.25 inch) in diameter to the left air purge screw (1) and the right air purge screw (2). Put the other end of the tubes into a suitable container for collecting the hydraulic oil. The tube may also be routed back to the hydraulic oil tank.
Permit only one operator on the machine. Keep all other personnel away from the machine or in the operators sight.
Engage the parking brake.
Start the engine. Place the machine in neutral.
Illustration 2 g01200166
Brake Pedals (3) Left brake pedal (4) Right brake pedal (5) Lock bar
Unlock the lock bar (5) .
Depress both pedals five times in a rapid manner. This process is called stroking.
Stroke the left pedal (3) fifty times in a steady manner.
As the hydraulic oil flows through the tube, look for air bubbles in the oil. Allow the oil to flow into the container until no air bubbles are visible.
Stroke the right pedal (4) fifty times in a steady manner.
As the hydraulic oil flows through the tube, look for air bubbles in the oil. Allow the oil to flow into the container until no air bubbles are visible.
Stroke both pedals ten times in a steady manner. Hold down pedals on the last stroke.
Close the left air purge screw (1) and close the right air purge screw (2). Remove the transparent tubes from the purge screws.
Stroke both pedals ten times in a rapid manner.
Inspect the brake system for leaks.
Fill the hydraulic tank with oil.
Lock the lock bar (5) .
Perform the braking system test. Refer to Operation and Maintenance Manual, "Braking System - Test".Note: If the brake pedal is spongy during the first hours of