NUT-SPECIAL 1784316 - Caterpillar

Introduction
The following procedure should be used in order to help determine if there is a problem with the steering pump. Pump performance should be checked if the machine has slow steering times.Specification
Table 1
Steering Time
3.7 . 3 seconds Machine Preparation
Move the machine to a smooth level surface. Move away from working machines and personnel. Lower the work tool 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 in order 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 work tool slightly off the ground.
Maintain the engine speed at high idle.
Record the steering time from stop to stop. The steering time should be 3.7 .3 seconds.
Lower the boom and place the work tool 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 backup relief valve is not within specifications.
The pump is not upstroking.
The pump may have excessive wear.
The margin pressure setting for the steering pump is not within specifications.The main relief pressure should be measured. If the main relief pressure is low, the cycle times should be retested after the main relief pressure has been corrected.Reference: For more information on Testing and Adjusting the main relief valve, refer to the Service Manual module Testing and Adjusting, "Relief Valve (Pump Backup) - Test and Adjust" for the machine that is being serviced.The margin pressure for the pump should be measured. If the margin pressure for the pump is low, the cycle times should be retested after the margin pressure for the pump has been corrected.Test the pressure of the steering pump in order to make sure that the pump is upstroking. Reference: For more information on Testing and Adjusting the steering pump, refer to the Service Manual module Testing and Adjusting, "Piston Pump (Steering) Margin - Test and Adjust" for the machine that is being serviced.If the cycle time is slow for only one of the steering circuits, 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 need to 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.