TUBE AS 3543297 - Caterpillar

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, "Caterpillar Tools and Shop Products Guide" for tools and supplies suitable to collect and contain fluids on Caterpillar products.Dispose of all fluids according to local regulations and mandates.
Machine Preparation
Prepare the machine for testing by completing the procedure that is specified in the Service Manual module Testing and Adjusting, "Machine Preparation for Troubleshooting" for the machine that is being serviced.Testing Procedure
Note: Make sure that the precharge pressure of the brake accumulators are within specifications before running this procedure.For more information on testing the pressure of the accumulators, refer to the appropriate Service Manual modules for the machine that is being serviced.
Specifications, "Brake Accumulator"
Testing and Adjusting, "Brake Accumulator - Test and Charge"
Illustration 1 g00465247
Location of the Brake Components (1) Parking brake control valve.Parking brake control valve (1) is located under the operator's platform on the right side of the machine.
Illustration 2 g00491485
(1) Parking brake control valve. (2) Drain line.
Start the engine. The brake oil pressure indicator light should turn OFF.
Stop the engine.
Release the parking brake.Note: If the pressure has been relieved from the system the parking brake will not disengage.
Remove drain line (2) at parking brake control valve (1) .
Start the engine. Bring the hydraulic oil to operating temperature.
Measure the flow rate from the drain port of the parking brake valve. Flow must be less than 0.1 L/min (0.03 US gpm).
If the flow rate is not correct, then the parking brake control valve may have excessive internal leakage back to the hydraulic oil tank. Repair or replacement of the parking brake control valve may be required.