PUMP GP-OIL 7L5553 - Caterpillar

Quick Release and Holding Valve
Start the tractor engine and allow the pressure to reach the cut out pressure.
Move the knob of the parking brake control in and out. This movement will cycle the system.
The brakes should actuate immediately when the control knob is moved. If the brakes do not actuate, there is a failure in one or both of the quick release and holding valves.Note: There are two quick release and holding valves. One is for the scraper and one is for the tractor. The brakes will not activate immediately, but the brakes must release immediately.Caterpillar Monitoring System Panel
Make sure that the battery disconnect switch is in the ON position.
Start the tractor engine.
Allow the pressure to reach approximately 690 kPa (100 psi).
The action alarm and the brake air pressure indicator light for low air pressure will operate until the pressure is approximately 517 34 kPa (75 5 psi).
If the action alarm and/or action light do not operate, stop the engine.
Check the following electrical connections: action alarm, action light and pressure switches. Check the bulb for the action light.
If the connections are good, connect a continuity light across the terminals of one of the pressure switches.Note: The air pressure must be less than the specifications of the pressure switches.
If the continuity light does not operate, install a new pressure switch.
Check the other pressure switch.
Start the tractor engine.
Allow the pressure to reach approximately 690 kPa (100 psi).
Slowly open the rear drain valve in order to purge pressure.
The action alarm and the action light must operate at 517 34 kPa (75 5 psi).
Stop the engine.
If the action alarm and/or action light do not operate at the correct pressure, check the electrical connections for the following components: the action alarm, the action light and the pressure switches. Check the bulb for the action light.
If the connections are good, install a new pressure switch or switches.
Remove the test equipment.
To prevent possible injury, make sure all of the air pressure is released from the air tank before you disconnect the test gauges and the hose assemblies.
Retarder Control Valve
Tractor
Table 2
Required Tools
Tool Part Number Part Description Quantity
C 9U-7400 Multitach Tool Gp 1
Illustration 1 g00420584
9U-7400 Multitach Tool Group
The 9U-7400 Multitach Tool Group can measure engine speed. This measurement uses either the photo pickup and reflective tape, or a magnetic pickup of tachometer generator.
Start the tractor engine and run the tractor engine. When the air pressure reaches the cut out pressure, make sure that the high idle engine speed and the set point are correct according to the Systems Operation/Testing and Adjusting manual.
With the transmission control lever in theNEUTRAL position run the tractor engine at high idle speed. Then move the retarder control lever to the FULLY ACTIVATED position.
Table 3
Sales Model Engine Speed
621G. 623G, 627G 1850 100 rpm
631G, 637G 1575 100 rpm
Be sure that the torque converter (transmission) oil does not get too hot.
The tractor engine speed must match the chart. If the engine speed is not correct, see Systems