ORIFICE-AIR 7G8271 - Caterpillar

Illustration 1 g02703598
Right main control valve
(1) Tilt cylinder line relief valve (rod end)
Illustration 2 g02703619
Left main control valve
(2) Tilt cylinder line relief valve (rod end) The line relief valve (dump) is located on the rear side of the right main control valve. The line relief valve (dump) relieves pressure in the rod end circuit of the tilt cylinders when the main control valve is in the HOLD position. The line relief valve protects components of the tilt circuit from high pressure. External loads on the bucket may cause these high pressures.A hydraulic test bench is the most accurate method for testing line relief valves. If a test bench is not practical to use, then use the following procedure on the machine.Reference: For the pressure and flow for bench testing this valve, refer to the Service Manual module Specifications, "Relief Valve (Line)" for the machine that is being serviced.
Connect Caterpillar ET to the machine. The ET connector is located on the control panel on the right side of the cab.
Turn the engine start switch to the ON position.
Open the ET software program.
When ET has started, start the engine. Run the engine at high idle. Warm the hydraulic oil to normal operating temperature.
Illustration 3 g02593416
Typical example
Select "Implement 994H". Press the "OK" button.
Illustration 4 g01447462
Typical example
Select "Diagnostic Tests" from the "Diagnostics" menu. Select "Cylinder End Line Relief Pressure Tests".
Illustration 5 g01447484
Typical example
When the dialog box appears on the screen, read the information in the dialog box. In order to continue with the test procedure, select the "OK" button.
Illustration 6 g02593636
Typical example
When the dialog box appears on the screen, four checked boxes appear. Leave the check mark in the box for each test that will be performed. Select the "Begin" button in order to start the procedure.
Illustration 7 g01447443
Typical example
Press the "Next" button in order to begin the procedure. Follow the instructions on the screen. A check mark will appear next to each step as each step is completed.
Make sure that the area around the machine is level and clear of obstacles. Keep all personnel away from the machine. Press the "Next" button.
Engage the parking brake.
Lower the work tool to the ground. Press the "Next" button.
Place the steering frame lock in the LOCKED position. Press the "Next" button.
Start the engine. Ensure that the parking brake is engaged.
Engage the transmission lockout.
Place the hydraulic lockout switch in the UNLOCKED position.
Warm the hydraulic oil to a temperature of 43 °C (109 °F) or higher. Press the "Next" button.
Illustration 8 g01447442
Typical example
Place the lift control lever in the RAISE position until the linkage is fully raised.
Place the tilt control lever in the DUMP position until the bucket is fully dumped.
Run the engine at low idle.
Ensure that the lift control lever and the tilt control lever are in the HOLD position. Press the "Next" button.
Place the tilt control lever in the DUMP position. Hold the lever in the DUMP position until the check mark appears on the screen.
Place the tilt control lever in the HOLD position. Press the "Next" button.
Lower the bucket until the bucket