BEARING-ROLLER 1616566 - Caterpillar

Checks During Operation
Checks during operation can be used to find leakage in the system. They can also be used to find a valve or pump that is not working correctly. The speed of cylinder rod movement or the torque on a motor can be used to check the condition of the cylinders, motors and pumps.Raise or lower the boom. Move the stick in and out. Open and close the bucket. Swing the machine to the right and left. Do each of these operations several times and consider the following items.1. Pilot System: The pilot system controls the movement of the spools in the main control valve. It is important that the pressure and flow from the pilot pump be according to specifications. A problem in the pilot system will usually affect many or all of the machine functions. 2. Main Relief: The main relief valve controls the pressure setting for the boom, stick, and bucket functions. A main relief valve pressure setting that is low can result in increased cycle times, low operating forces and/or the noise associated with main relief valve opening. A main relief valve that is set to a pressure above specifications will cause decreased service life for hoses and other components.3. Line Relief Valve: A line relief valve problem will usually only affect the individual circuit in which the valve is installed. The symptoms of a line relief valve problem are similar to those of the main relief valve described above.4. Cycle Times: Check cycle times for each of the circuits (boom, bucket, stick and swing). Cycle times that are longer than those shown in the specifications (see Operational Tests in the specific service manual module for the machine being worked on) could be the result of insufficient pilot system pressure, leakage past cylinder seals, pump wear, low pump speed (rpm), faulty relief valve (main or line) or improper pump control adjustment.5. Circuit Drift: Check the drift rate for each of the circuits (see Operational Tests in Hydraulic System Testing and Adjusting in the specific service manual module for the machine being worked on). Circuit drift is caused by: leakage past cylinder pistons, O-ring seals in the control valve, check valves or makeup valves that do not seat correctly, or poor adjustment or fit of spools in the main control valve.6. Travel Circuit: Operate the machine in the FORWARD and REVERSE direction with the travel control levers/pedals shifted equally, and without operating any other hydraulic functions. If the machine does not travel in a straight line there could be a problem with the negative flow control signals to the pumps, pump or motor wear, or a line relief valve that is not operating correctly.Line Relief Pressure Setting In The Single Action Attachment Circuit
The line relief valve pressure setting in the single action attachment circuit is set to 17 700 490 kPa (2550 70 psi) at a flow rate of 150 L/min (40 gpm) from the factory.Specifications for pressure, flow rate and