PLUNGER 9U8070 - Caterpillar

Machine Preparation
Move the machine to a smooth level surface. Move away from working machines and personnel. Lower the bucket to the ground.
Allow only one operator on the machine. Keep all personnel away from the machine or in the view of the operator.
Engage the parking brake.Performance Test
Steering Cycle Time
The steering time is affected by the amount of oil flow that is produced by the steering pump. Check the steering times to determine if there is a problem with the steering pump.
Perform the machine preparation for testing.
Warm the hydraulic oil to normal operating temperature. Raise the bucket slightly off the ground.
Maintain the engine speed at rated engine speed.
Record the steering time from stop to stop. The steering time should be 4.3 0.3 seconds.
Lower the lift arm and place the bucket flat on the ground.
Reduce engine speed to low idle.
Stop the engine.Compare the test results with the cycle times that are listed. The steering pump should be working properly if the cycle times match the cycle times that are listed.If the cycle times are not correct one of the following conditions may be present:
The pressure setting for the margin relief, pump margin, or crossover relief may not be within specification.
The pump is not upstroking.
The pump may have excessive wear.If the cycle time is slow for only one of the steering directions, the circuit with slow cycle time should be tested for one of the following conditions:
Low relief valve setting
Leak in the circuit
Control spool that is not shifting fullyFlow balance shims may be adjusted if the steering times are consistently slow in one direction.Reference: For more information on Testing and Adjusting the main relief valve, refer to the Service Manual module Testing and Adjusting, "Steering Time - Check and Adjust" for the machine that is being serviced.