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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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To prevent personal injury when checks are made while the machine is in operation, make sure only approved personnel are on the machine. Keep other personnel off the machine and in view of the operator. Make sure checks are done in an open area. |
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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. |
When you are analyzing a system for poor performance, remember that correct oil flow and correct oil pressure are necessary for correct operation. Oil flow increases with increased pump output. A restriction to the flow of oil increases the oil pressure.
Before any tests are performed, visually inspect the complete system for oil leaks and for damaged parts. Also, visually inspect the wiring connectors and wiring harnesses for damage, corrosion, and contact.
- Make sure that the machine is resting on a smooth, level surface. The machine should be moved away from other operating machines and away from personnel.
- Permit only one operator on the machine. Keep other personnel away from the machine or in the sight of the operator.
- Fully extend the stick cylinder rod.
- Lower the boom until the felling head is resting on the ground.
Note: If the machine is equipped with a harvester head, place the harvester head in the HORIZONTAL position before you lower the head to the ground.
- Shut off the engine.
- Turn the start switch to the ON position without starting the engine.
- Place the hydraulic lockout control in the UNLOCKED position.
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| Illustration 1 | g01162811 |
Hydraulic lockout control | |
- Cycle all control levers through the full range of motion. This action will release any pressure that might be present in the hydraulic system.
Note: If the hydraulic circuit requires the activation of a switch for operation, activate the necessary switches for the hydraulic circuit.
- Open the hood for the engine compartment.
Note: The switch is located on the right-hand console.
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| Illustration 2 | g01162235 |
Layout of the cab for 511, 521, 522, 532, 541, 551, and 552 | |
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| Illustration 3 | g02741085 |
Layout of the cab for 521B, 522B, 541 Series II, and 552 Series II | |
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| Illustration 4 | g01074453 |
Zero tail swing machines | |
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| Illustration 5 | g01069398 |
Full tail swing machines | |
- Turn the start switch to the OFF position.
- Move the hydraulic lockout control to the LOCKED position.
Note: When the hydraulic lockout control is in the LOCKED position, no implements will function.
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| Illustration 6 | g01162814 |
Hydraulic lockout control | |
- Push down on the hydraulic tank breaker relief valve until all pressure is released.
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| Illustration 7 | g01224020 |
511, 521, 522, and 532 machines | |
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| Illustration 8 | g02741096 |
521B and 522B machines | |
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| Illustration 9 | g01229081 |
Full tail swing machines | |