CLAMP 7D1519 - Caterpillar

Cut-in and Cut out
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(A) Test port for the service brakes (B) Test port for the parking brakes (1) Service brake accumulator (2) Parking brake accumulatorsNote: The brake pressure can be checked at location (A) and location (B) .
Connect a hose assembly with an 8T-0860 Pressure Gauge (0 to 40000 kPa (0 to 5800 psi)) to pressure tap (A) for the service brake accumulators.
Start the engine. Allow the brake accumulators to charge fully.
Run the engine at low idle. The pressure in the brake accumulators will decrease because of leakage in the system and lubrication. The solenoid valve (unloader) controls the charge cycle for the brake accumulators. Allow the charge cycle for the brake accumulators to occur at least ten times before any measurements are made.Note: If a gauge is used, note the gauge reading at the cut-in pressure and at the cutout pressure.
Observe the pressure at the cut-in pressure and at the cutout pressure.Note: The pressure setting for the cutout is 20685 483 kPa (3000 70 psi). The cut-in pressure is 70 percent of the cutout pressure. The cut-in pressure will be 14480 483 kPa (2100 70 psi).
Illustration 3 g03423229
Typical view
Check Cat ET in order to verify that the pressures from Step 4 are accurate.
Illustration 4 g01951101
Control valve (brake) (3) Diverter valve (unloader) (4) Solenoid valve (unloader) (C) Port for the service brake accumulators (D) Port for the parking brake accumulatorNote: The cutout pressure and the cut-in pressure are not adjustable. The cutout and the cut-in pressures are controlled by diverter valve (3) , and by solenoid valve (4) .Note: If the pump pressure does not reach cut-in pressure inspect diverter valve (3) and solenoid valve (4) , these valves may be stuck open. If the cut-in pump pressure is reached and the cutout pump pressure is not reached, inspect the following components:
Diverter valve (3)
Solenoid valve (4)
Main relief valve
Solenoid valve (accumulator purge valve)
Pump pressure sensorNote: If no issues are found with the sensors or valves, inspect the brake pump. If the pump pressure exceeds cutout pressure, inspect the pump pressure sensor, the accumulator pressure sensor, diverter valve (3) , and solenoid valve (4) . The valves may be stuck in the closed position. Also, there may be a sensor that has failed.Leakage
When the pump is at the low idle setting, the pressure will cycle between the cut-in pressure and the cutout pressure. The cycle should occur in approximately 15 seconds. If this cycle occurs in less than 15 seconds, there is leakage in the system that must be corrected.
Start the engine. Allow the brake accumulators to charge fully.Note: Once the brake accumulators are fully charged, the cycle between the cut-in and cutout pressure will increase to 30 seconds.
To locate the cause of the excessive leakage, shut down the engine with the engine shutdown control or disconnect the electrical cable from the wiring harness. Do not shut down the engine with the ignition key. The engine shutdown switch is located on the right side of