CYL GP-BASIC 4779170 - Caterpillar

Performance Checks
Note: If the performance checks indicate that air pressure is not available at the supply passage(s) of the control valves, loosen the connection at the supply passage and use soapy water in order to check for air pressure.If the performance checks give an indication of leakage through a control valve, disconnect the delivery hose at the end opposite the delivery passage. Put the end of the hose in a pan of water to check for leakage.Problem
The service brakes do not engage correctly.Probable Cause
There is no air pressure at the inlet passage of the brake control valve.
Wear or damage to the brake control valve permits little air pressure or no air pressure at the outlet passages.
Wear or damage to the components between the brake control valve and the tractor brake actuators is preventing the flow of air.
Wear or damage to the scraper relay valve permits little air pressure or no air pressure at the delivery passages to the brake actuators.
The brake actuators have wear or damage.
The rod travel or the brake actuators is out of adjustment.
The brakes have wear or damage.Problem
The service brakes do not release correctly.Probable Cause
Mud or dirt under the pedal does not allow the brake control valve to release fully.
Wear or damage to the brake control valve restricts the release of air pressure to the tractor relay valve on the brake actuators and/or the scraper relay valve.
Wear or damage to the scraper relay valve restricts the release of air pressure from the scraper brake actuator.
The components between the brake control valve and the tractor brake actuators have wear or damage.
The brake actuators have wear or damage.
Wear or damage to the parking and secondary brake control valve releases the air pressure to the parking and secondary brake chambers in the brake actuators.
The quick release and holding valves and/or the double check valve have wear or damage.Problem
The parking and secondary brakes do not engage correctly.Probable Cause
Wear or damage to the parking and secondary brake control valve restricts the release of air pressure.
The quick release and holding valves and/or the double check valve have wear or damage.
The rod travel of the brake actuators is out of adjustment.
The brakes have wear or damage.
The brake actuators have wear or damage.Problem
The parking and secondary brakes do not release correctly.Probable Cause
Wear or damage to the parking and secondary brake control valve releases the air pressure to the parking and secondary brake chambers.
The quick release and holding valves have wear or damage.
The brake actuators have wear or damage.Problem
The tractor retarder does not engage correctly or the scraper retarder does not engage correctly.Probable Cause
There is no air pressure at the supply passage of the control valve.
Wear, damage or incorrect adjustment to the control valve permits little air pressure or no air pressure at the delivery passage.
The regulator valve has wear, damage or incorrect adjustment.
The hydraulic valve for the retarder has wear, damage or incorrect adjustment.
The retarder has wear, damage or incorrect adjustment.Problem
The tractor retarder does not release correctly or the scraper retarder does not