Before the high pressure screens for the hydraulic system can be removed, the pressure in the hydraulic system must be released. Refer to the following procedure in order to release the pressure in the hydraulic system and clean the high pressure screens.
- Fully retract the rod in the stick cylinder.
Hydraulic oil pressure can remain in the hydraulic oil system on this machine after the engine and pump have been stopped. Personal injury can be caused if this pressure is not released before any service is done on the hydraulic systems. To prevent personal injury, refer to the procedure in Testing and Adjusting Manual, "Release of Pressure in the Hydraulic System".
When possible, the bucket must always be lowered to the ground with the cutting edge rotated to the ground before service is started. When it is necessary for the boom to be in the raised position while tests or adjustments are done, be sure that the boom, stick and bucket have correct support.
Be sure the swing parking brakes and the travel parking brakes are on and the brake release lines are disconnected and plugged.
Always move the machine to a location away from the travel of other machines. Be sure that other personnel are not near the machine when the engine is running and tests or adjustments are being made.
Hot oil and hot components can cause personal injury. Do not allow hot oil or hot components to contact the skin.
- Adjust the position of the bucket as the boom is lowered. The bucket must rest flat on the ground.
- Lower the boom until the bucket is flat on the ground.
- Shut off the engine.
- Check the pilot pressure at the pressure tap (1) for the low pressure pilot circuit on the pilot manifold under the cab. If the pressure is below 3000 kPa (435 psi) connect an auxiliary pump unit to this port and pump the pilot pressure to 4000 kPa (580 psi).
(1) Pressure tap for low pressure pilot circuit
- Put the hydraulic activation control lever in the UNLOCK position. Turn the engine start key to the ON position. Do not start the engine.
- Move the control levers for the boom, the stick, the bucket and swing to each of the FULL STROKE positions. Actuate both the trigger switches for the front shovel bucket bottom dump controls. This should release any pressure that might be present in the main implement system. Disconnect the auxiliary pump unit (if used) and install the pressure gauge at the test port. Continue to move the control levers until the pilot system pressure is released. Use a pressure gauge to verify that the pilot system pressure is released.
- Press button (2) on the hydraulic tank breaker relief valve in order to release the hydraulic tank pressure. The hydraulic tank breaker relief valve is located on the hydraulic tank by the filler pipe.
Hydraulic tank breaker relief valve for 4CS1-147
Hydraulic tank breaker relief valve for 4CS148-UP
- The pressure in the system has been released and the high pressure screens can be removed and cleaned. Refer to Step 10 through Step 19 in order to clean all four high pressure screens for the hydraulic system.
- Open the access door for the hydraulic pump room on the first level of the operator's platform. For more information, refer to the Operation and Maintenance Manual, "Access Doors and Covers".
- Remove cartridge (3) that contains the high pressure screen.
- Remove the high pressure screen from cartridge (3) .
- Wash cartridge (3) and the high pressure screen in a nonflammable solvent. Dry the parts.
- Inspect the seals on the high pressure screen and on the cartridge. Replace any of the seals that are damaged.
- Lubricate the seals with a light coat of hydraulic oil.
- Carefully insert the high pressure screen into cartridge (3) .
- Tighten the cartridge.
- Repeat Step 11 through Step 17 for the other high pressure screens.
- Close the access door.