HOUSING 9B3250 - Caterpillar

Main Relief Valve
Main Relief Valve
(1) Orifice. (2) Orifice or seat. (3) Pilot valve. (4) Spring. (5) Pressure passage. (6) Holes (six). (7) Dump spool. (8) Springs. (9) Adjustment screw.
Pressure Gauge Installed
(10) Valved coupling. (11) Connector. (12) Pressure gauge. (13) Hose.1. Use connector (11) to connect hose (13) to valved coupling (10).2. Connect the valved coupling to the fitting on the oil pump.3. Connect 50 000 kPa (7500 psi) pressure gauge (12) to the hose.4. Start the engine and raise the bucket to its maximum height.5. Increase the engine speed to HIGH IDLE rpm. Look at the test gauge and move the control lever to the RAISE position. The highest reading on the gauge is the pressure setting of the main relief valve. DO NOT keep the control lever in RAISE position (at the relief valve setting) more than 5 seconds. The correct pressure setting of the main relief valve is 21 400 700 kPa (3100 100 psi) at a flow of 121 3 liter/min (31 .8 U.S. gpm).6. If a pressure setting change is needed, lower the bucket to the ground and stop the engine. Remove the oil filter and oil filler tube from the hydraulic tank. Turn adjustment screw (9) clockwise for an increase or counterclockwise for a decrease in the pressure setting of the main relief valve. One-quarter turn of screw (9) changes the pressure setting approximately 1600 kPa (230 psi).7. When the pressure setting of the main relief valve is correct, remove the test equipment.Hydraulic Implement Tank Fill and Air Removal Procedure
Do this procedure any time the hydraulic system has been completely drained. This procedure is necessary to remove air from the hydraulic system. Damage to the hydraulic pump can be the result if this is not done.1. Fill the hydraulic tank to the top of the fill screen with clean SAE 10 oil.2. Use fittings from 6V4161 Pressure Gauge Kit to connect an air regulator and valve to the test fitting on the hydraulic tank. Connect a hose and needle valve from the kit to the test fitting on the hydraulic pump outlet line.
Do not use more than 105 kPa (15 psi) of air pressure in the hydraulic tank. Do not disconnect any of the quick disconnect fittings until all pressure in them is released.
3. Move the tilt control lever to the FULL TILT BACK position. Put 50 to 105 kPa (7 to 15 psi) of air pressure in the hydraulic tank. Open the needle valve to let oil drain out of the hose on the pump outlet line until it is free of air bubbles. Close the needle valve.4. Move the tilt control lever to the HOLD position.5. Close the valve on the air regulator. Loosen the filler cap on the hydraulic tank a small amount, to release all the pressure in the system. When all pressure is released, disconnect the hose from the test fitting on the pump outlet line and the air regulator from the test fitting