The following procedure tests the oil pressure for raising the ladder.
The pressure setting for raising the ladder is controlled by a pressure reducing valve in the combination valve. The pressure setting of the pressure reducing valve is less than the standby pressure of the piston pump (implement). The standby pressure must be adjusted correctly before performing the procedure.
Reference: For more information on adjusting the standby pressure, refer to Testing and Adjusting, "Piston Pump (Implement) Standby Pressure - Test and Adjust" for the machine that is being serviced.
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Personal injury or death can result from escaping fluid under pressure. Escaping fluid under pressure, even a very small pin-hole size leak, can penetrate body tissue and cause serious injury and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury. Always use a board or cardboard when checking for a leak. |
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| NOTICE |
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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 machine. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "AVSpare Tools and Shop Products Guide", for tools and supplies suitable to collect and contain fluids in AVSpare machines. Dispose of all fluids according to local regulations and mandates. |
| Required Tools | ||
| Part Number | Description | Quantity |
| 198-4240 | Digital Pressure Indicator Group | 1 |
| 1U-7564 | Allen Wrench (5 mm) | 1 |
| 4C-6307 | Wrench | 1 |
- Park the machine on a level surface.
- Ensure that the hydraulic oil in the system is at normal operating temperature.
- Place the operating mode switch in the ROADING MODE position.
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| Illustration 1 | g00800981 |
- Move the parking brake switch to the ON position. The ladder will lower. Ensure that all personnel are clear of the ladder before you lower the ladder.
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| Illustration 2 | g00919915 |
Parking Brake Switch | |
- Stop the engine.
- Block the wheels.
- Install the steering frame lock.
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| Illustration 3 | g00913309 |
- Remove guard (1) from the right side of the machine in order to access the combination valve.
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| Illustration 4 | g00937482 |
Right Side of the Machine | |
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| Illustration 5 | g00916684 |
Location of the Combination Valve | |
- Connect the pressure gauge onto the pressure tap for the ladder, as shown.
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| Illustration 6 | g00918842 |
- Start the engine. Run the engine at low idle. Record the pressure setting. The pressure setting for the ladder should be 2800 kPa (405 psi). If the pressure setting is not correct perform Step 11.
- Loosen the locknut (4) on the valve section that is being tested. Turn the adjustment screw (3) until the correct pressure setting is reached. Tighten the locknut.
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| Illustration 7 | g00937480 |
Combination Valve (Differential Lock, Gate, Ladder, and Parking Brake) (2) Ladder valve. (3) Adjustment screw. (4) Locknut. | |
- When the valve section has been tested and adjusted, stop the engine.
- Remove the pressure gauge.
- Install the guard on the right side of the machine.