330,330 L & 330 LN EXCAVATORS MACHINE SYSTEMS Caterpillar

NOTE: The proportional reducing valve is located behind the right rear access door.

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At operating temperature, the hydraulic oil tank is hot and under pressure. Hot oil can cause burns. To prevent possible personal injury, release the pressure in the implement hydraulic circuits (boom, stick and bucket) before any hydraulic lines or components are disconnected or removed.

1. Release the pressure in the hydraulic system as follows:

a. Fully retract the rod in the stick cylinder.

b. Adjust the position of the bucket so it will be flat on the ground when the boom is lowered.

c. Lower the boom until the bucket is flat on the ground.

d. Shut off the engine, and put the hydraulic activation control lever in the "Lock" position.

e. Move the control levers for the boom, bucket, stick and swing through their full travel strokes. This will relieve any pressure that may be present in the pilot system.

f. Slowly loosen the air breather cap on the hydraulic oil tank to release the pressure.

g. Tighten the air breather cap on the hydraulic oil tank.

h. The pressure in the hydraulic system has now been released. Lines and components can now be removed.

2. Disconnect wiring harness (4) from the clip. Disconnect wiring harness (4).

3. Disconnect hose assembly (1) from the proportional reducing valve.

4. Remove two socket head bolts (2) and proportional reducing valve (3) from the pilot manifold.

NOTE: Install the proportional reducing valve in the reverse order of removal.

5. Check the oil level in the hydraulic oil tank. Fill the hydraulic oil tank with oil to the correct level. See the Operation & Maintenance Manual for the correct filling procedure.

Disassemble & Assemble Proportional Reducing Valve

Start By:

a. remove proportional reducing valve

1. Be sure the outside of the proportional reducing valve is clean and free of dirt and debris prior to disassembly.

2. Remove O-ring seals (1) and (2) from the proportional reducing valve.

3. Remove two socket head bolts (3) and solenoid (4).

4. Remove fitting (6) from the valve body. Remove the O-ring seal from the fitting.

5. Remove O-ring seal (10), rod (9), spool (8) and spring (7) from the valve body (5).

NOTE: Assemble the solenoid valve in the reverse order of disassembly. Prior to assembling the solenoid valve, be sure all parts of the valve are clean and free of dirt and debris. Put clean hydraulic oil on the internal parts of the valve. Also, check the condition of the O-ring seals. If the seals are worn or damaged, use new parts for replacement.

End By:

a. install proportional reducing valve