GUARD ASSEM. 8E9528 - Caterpillar

Charge Pump Pressure Becomes Low
The charge pump is a fixed displacement gear-type pump. The charge pressure relief valve must open in order to allow enough oil to flow in order to maintain charge pressure. Oil flow past the charge pressure relief valve will increase as engine RPM increases. However, if the charge pressure relief valve is stuck open too far, the steering charge pressure cannot be maintained.The charge pressure relief valve maintains (limits) the charge pressure to approximately 2850 kPa (413 psi) at 2000 engine RPM. Charge pressure oil is sent to the following:
drive loop
steering control valve
dual tilt valve (used as pilot oil)
pump actuator pistonTest and adjust the Charge Pressure Relief Valve. Refer to Specifications, System Operation, Testing and Adjusting, UENR4081, "Relief Valve (Charge) - Test and Adjust".Note: The Cold Oil Relief Valve can also cause similar symptoms. Ensure that the cold oil relief valve is operating properly prior to performing any test and adjust procedures on the charge pressure relief valve.Crossover Relief and Makeup Valves
Test and adjust the crossover relief and makeup valves. Refer to Specifications, System Operation, Testing and Adjusting, UENR4081, "Steering Hydraulic Circuit - Test and Adjust".Oil from the high-pressure side of the steering loop may leak across to the low-pressure side of the loop under one of the following conditions:
The relief function or the makeup function of one of the valves is stuck open
One of the valves springs is weak
One of the valves springs is broken
One of the valves springs is misadjustedIf one of the conditions listed above exists: the necessary high pressure may not be possible, or maintainable, in one or both sides of the steering loop.Test the mechanical neutral position for the steering pump control valve. Refer to Specifications, System Operation, Testing and Adjusting, UENR4081, "Neutral Adjustment (Steering Pump) - Test and Adjust". If the neutral position of the steering pump control valve is incorrect (off-center while in the NO STEER condition): the steering pump control valve will command the actuator piston to move off-center when there is no steering request. This condition may cause the machine to stray from straight-line travel in a NO STEER condition. This condition may also cause the machine to steer more sharply in one direction than the other.Charge Pump Flow Becomes Low
If the charge pump becomes too inefficient and cannot produce, the required oil flow then one or more of the following may occur:
steering will be slow to react
turns will not be as sharp
machine may not steer at allUse a flow meter in order to test the flow rate of the steering charge pump. The charge pump flow rate should be approximately 61.9 L/min (16.4 US gpm) at 1850 engine RPM.Piston Pump (Rotating Group) Flow Rate
If the piston pump becomes too inefficient and cannot produce the required oil flow: steering will be slow to react, turns will not be as sharp, or the machine may not steer at all.Use a flow meter to test flow rate of the steering pump (flow from the rotating group). The