VALVE GP-RELIEF 1331666 - Caterpillar

Sudden movement of the machine or release of oil under pressure can cause injury to persons on or near the machine.To prevent possible injury, perform the procedure that follows before testing and adjusting the power train.
Personal injury can result from hydraulic oil pressure and hot oil.Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system.Make sure all of the attachments have been lowered, oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand.
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.
Operational Checks
Note: The checks during operation can be used to find leakage in the system. These checks can also be used to find a bad valve, a bad pump, or a bad motor. Travel speed can be used to check the condition of the propel motors and the pump.Operate the machine in each direction and in all speeds.
Watch the drum and the wheels.
Starting and stopping operations should be progressive.
The drum and the wheel rotation should be normal at all times.
Check for noise from the pump and from the drive motors.
Check for the sound of the relief valves that are opening. The opening pressures of the relief valves are given in Propel Pump Relief Valve - Test and Adjust and Charge Relief Valve - Test and Adjust of this module.
After you select the travel speed of the compactor, the forward and reverse motion should be identical.Probable Causes of Problems in the Propel System
Problem The propel system engages very slowly when the operator is attempting to shift. Probable Cause
Low charge pressure.
The orifices in the propel pumps are plugged.
The oil is too viscous and/or the oil is too cold.
The charge filter is plugged.
The hydraulic oil level is low.
The control valve is malfunctioning.ProblemThe propel system engages very suddenly when the operator is making a shift. Probable Cause
The shuttle valve spool that is inside the flushing valve is sticking.
The servo valve spool is sticking. ProblemThe propel system operates in one direction only.Probable Cause
The pump servo valve has failed .
The pump servo piston has failed.
The rocker arm section of the pump