TUBE AS 8W9620 - Caterpillar

Personal injury or death can result from sudden machine movement.Sudden movement of the machine can cause injury to persons on or near the machine.To prevent injury or death, make sure that the area around the machine is clear of personnel and obstructions before operating the machine.
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, and the 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 machine. 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 in Caterpillar machines.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 work smoothly with no jerky motion.
Check for noise from the pump and drive motors.
Check for the sound of the relief valves that are opening. The opening pressures of the relief valves are given in Relief Valve (Piston Pump) - Test and Adjust and Relief Valve (Charge) - Test and Adjust of this module.
After selecting the travel speed of the compactor, the forward and reverse motion should be identical.Probable Causes of Problems in the Propel System
ProblemThe machine starts to move very slowly when the propel lever is moved out of neutral in either forward or reverse.Probable Cause
Low charge pressure.
The control orifices in the piston pumps are plugged.
The oil is too viscous and/or the oil is too cold.
The hydraulic oil level is low.
The control valve is malfunctioning.
The automatic speed control is set to a low settingProblemThe propel system engages very suddenly when the operator moves the propel control lever.Probable Cause
The control valve spool in one or both of the propel pumps is sticking.
The initial current is set too high on the pumps and needs to be recalibratedProblemThe propel system operates in one direction only.Probable Cause
The pump servo piston has failed.
One of the combination valves is faulty.
The control valve in one of the propel piston pumps is faulty.
There is contamination in one of the ports of the control valve
One of the propel