SHAFT 6L7479 - Caterpillar

Probable Cause
Insufficient system pressure
Brake components have failed.
Steering clutch and brake control valve
Proportional solenoid valveRecommended Actions
If the brakes are applied and the machine does not slow down or if the machine does not stop, follow this procedure.The brakes are engaged with spring force. Hydraulic pressure is required to disengage the brakes. If hydraulic pressure is lost, the brakes fully engage due to the action of the spring force.Initially, a check of the brake pressure guides the diagnosis of the symptom to the brakes or to the steering clutch and brake control valve.If the brake pressure is correct, then the steering clutch and brake control valve is eliminated as the probable cause of the symptom. Thus, the brakes are the probable cause.If the brake pressure is not correct, then the steering clutch and brake control valve is the probable cause of the symptom. If the brake pressure is corrected and the symptom still exists, then the brakes could be the second contributor of the symptom.Insufficient Pressure Oil To The Brakes
Check the brake pressure.The brakes are engaged by spring force. The brakes are released by pressure oil which is sent from the steering clutch and brake control valve to the brakes. Therefore, insufficient oil pressure to the brakes is a probable cause of the symptom.Reference: Refer to (D8R and D8)