- Boom hydraulic circuit
- Stick hydraulic circuit
- Swing hydraulic circuit
- Stabilizer hydraulic circuit
- Pilot hydraulic circuit
- Return hydraulic circuit
- Saw/Delimber hydraulic circuit
Release Of Hydraulic Pressure From the Hydraulic System
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Personal injury can result from contact with hot hydraulic oil and from contact with hydraulic oil that is under high pressure. Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. The hydraulic oil pressure must be released before any service on the hydraulic system is performed or serious personal injury could occur. Verify that all of the work tools have been completely lowered to the ground. Release the hydraulic oil pressure at the hydraulic tank through the breaker relief valve when the breaker relief valve is cool enough to touch with your bare hand. Verify that the hydraulic oil is cool before you begin to remove any hydraulic components or hydraulic lines. |
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Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Tools and Shop Products Guide" for tools and supplies suitable to collect and contain fluids. Dispose of all fluids according to local regulations and mandates. |
Perform the following steps in order to release the hydraulic pressure from multiple hydraulic circuits of the main hydraulic system.
- Position the machine on level ground.
- Lower the boom until the grapple is resting on the heel of the trailer.
- Shut off the engine.
- Turn the engine start switch to the ON position without starting the engine.
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Illustration 1 g03178276 Hydraulic lockout control in Locked position. Show/hide table
Illustration 2 g03189676 (1) Pilot enable button - Place the hydraulic lockout control in the UNLOCKED position by bringing down the left armrest. See Illustration 1.
Note: In order for the pilot system to operate, the left armrest must be in the Lowered position. The pilot enable button on the dash must be activated (green indicator light Off). See Illustration 2. When the lever is lowered and the pilot enable button is activated, the pilot shut-off solenoid valve is open, and the pilot system is pressurized.
- Move only the joysticks or the pedals of the hydraulic circuit that requires service to the FULL STROKE positions. This process will release the high pressure only in that hydraulic circuit. This process will also release any pressure that might be present in the pilot hydraulic circuit and the pilot accumulator.
Note: If the hydraulic circuit that requires service requires the activation of a switch for operation, activate the switches for the operation of the hydraulic circuit.
- Repeat Steps 4 through 6 for each additional hydraulic circuit that requires service.
- After releasing the hydraulic pressure in each of the desired hydraulic circuits, place the hydraulic lockout control in the LOCKED position.
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Illustration 3 g03177805 (2) Location of hydraulic tank relief valve button. - Turn the engine start switch to the OFF position.
- Depress hydraulic tank relief valve button (2) located directly behind the operator station on top of the hydraulic tank. See Illustration 3.
- The pressure in the multiple hydraulic circuits that require service is now released. Lines and components can be disconnected or removed from those hydraulic circuits.
