COUPLING 9Y6663 - Caterpillar

Illustration 3 g00755962
Main Control Valve for the 834H Wheel Dozer
(2) Manual lower valve
Remove rod end hose (1) from the main valve and place rod end hose (1) into a suitable container that has a capacity of at least 19 L (5 US gal). Allow oil that is in rod end hose (1) to drain into the container. In order to prevent oil leakage, install the following tools: A, B and C
Start the engine. Use the blade in order to raise the front wheels 300 mm (12 inch) off the ground. Use suitable cribbing under the blade in order to raise the wheels.
Shut off the engine.
Observe rod end hose (1) for ten minutes. If oil is draining from rod end hose (1) and the wheels are drifting toward the ground, the cylinder seals are leaking.
If oil is not draining from rod end hose (1) and the wheels are drifting toward the ground, the main control valve is leaking or manual lower valve (2) is not working.
Use manual lower valve (2) in order to place the wheels on the ground. Make sure that the hydraulic oil pressure is released from the hydraulic system by completing the procedure that is specified in the Service Manual module Testing and Adjusting, "System Pressure - Release" for the machine that is being serviced.
Remove the following Tools: A, B and C. Connect the hose assembly for the rod end of the cylinder.
Check the hydraulic tank for proper oil level.
Start the machine and check the machine for leaks.
Install the cover for the main control valve. 836H Landfill Compactor Lift Cylinder
Drift test
Connect the steering frame lock.
Start the engine. Operate the lift cylinder at least five cycles in order to heat the hydraulic oil to normal operating temperature.
Raise the blade approximately 300 mm (12 inch) off the ground. Place the lift control lever into the HOLD position. Apply the parking brake. Shut off the engine.
Measure the original extension length of the lift cylinder rod. Record this measurement. Measure the amount of additional extension of the cylinder rod over a set time. Refer to the following table for times. The values that are shown in the table below are for new machines.
Table 3
Lift Cylinder Drift
Oil Temperature 38 °C (100 °F) to 49 °C (120 °F) 49 °C (120 °F) to 66 °C (150 °F) Above 66 °C (150 °F)
Time Interval in Minutes 5 2.7 1.7
Maximum Permissible Drift 60 mm (2.35 inch) 60 mm (2.35 inch) 60 mm (2.35 inch) The following problems may cause excessive amounts of cylinder drift.
Hydraulic oil line connections may be loose. The hoses that are between the control valve and the rod end of the lift cylinder may be damaged.
The piston seals in the lift cylinder are leaking.
The control valve is leaking. This can be caused by a worn section of the valve. This can also be caused if the makeup valve is not seated.
If there are no damaged hoses or loose hose connections then proceed to the isolation test for