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Hot hydraulic oil under high pressure can remain in the components of the hydraulic system or the power train system after the engine has been stopped. The uncontrolled release of the hydraulic oil can cause sudden machine movement and can also result in the following conditions:
If hydraulic oil penetrates body tissue, the injury must be treated immediately by a doctor who is familiar with this type of injury. Use a board or a piece of cardboard to check for a hydraulic oil leak. Make sure that all of the attachments have been lowered to the ground and that all trapped pressure has been released from the hydraulic system and the power train system. Also, make sure that the hydraulic oil is cool before the removal of any components or lines. Remove the hydraulic oil filler cap only when the engine is stopped and the filler cap is cool enough to touch with your bare hand. |
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Sudden movement or accidental starting of the machine can cause personal injury or death to persons on or near the machine. To prevent personal injury or death, perform the following: Park the machine on a smooth, level surface. Lower the work tool to the ground and engage the parking brake. Stop the engine and remove the key. Block the wheels and install the steering frame lock. |
| 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 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, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat® products. Dispose of all fluids according to local regulations and mandates. |
| Test Specifications | ||||
| Test Condition | Engine speed set at High Idle
(2010 RPM ± 25 RPM) |
Operating Temperature Range
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| Cutoff Pressure | Actual | |||
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The following adjustment procedure outlines the steps required to set the high-pressure cutoff setting of the fan pump. This adjustment procedure allows the technician to rule out the high-pressure cutoff setting of the fan pump as a problem source.
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| Illustration 1 | g02571852 |
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Tooling (A) 198-4240 Digital Pressure Indicator Gp | |
| Required Tools | ||||
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| Tool | Item | Qty | Part No | Description |
| A | 198-4240 | Digital Pressure Indicator Gp | ||
| A1 | 1 | 198-4234 | Digital Indicator | |
| A2 | 1 | 198-4239 | Pressure Sensor Gp
(0 to 41,368 kPa (0 to 6,000 psi)) |
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| A3 | 1 | 198-4236 | Adapter Cable As | |
- Move the machine to a smooth, horizontal location that is away from operating machines and away from personnel.
- Place the transmission direction in the NEUTRAL position.
- Engage the parking brake.
- Lower the work tool to the ground.
- Stop the engine.
- Relieve the pressure in the hydraulic system.
Reference: For more information about relieving the hydraulic pressure, refer to the Service Manual module Testing and Adjusting, "System Pressure - Release" for the machine that is being serviced.
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Illustration 2 g03676672 - Install the steering frame lock.
- Install tooling (A) to test port (T3).
- Remove the wiring harness connector plug from the solenoid on the fan pump compensator valve.
- Start the engine.
- Increase and lock the engine speed at high idle, (2010 RPM ± 25 RPM).
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Illustration 4 g03676146 (2) Lock nut
(3) Adjustment screw - Loosen lock nut (2) on the pump compensator valve.
- With the engine at high idle, turn the high-pressure cutoff adjustment screw (3) the proper direction until the discharge pressure is
12700 kPa (1842 psi) . - Lower the engine speed to low idle.
- Stop the engine.
- Turn the adjustment screw (3) Clockwise one turn.
- Turn the adjustment screw (3) past target an additional 1/8 to 1/4 turn and then back to target.
- Tighten the lock nut (2).
Note: Each full turn Clockwise of the adjustment screw is equal to a
15000 kPa (2175 psi) increase in pressure. The additional turn Clockwise of the adjustment screw in Step 9 will result in a high-pressure cutoff setting of27700 ± 500 kPa (4017.6 ± 73 psi) .
- Reconnect the wiring harness connector plug to the solenoid on the pump compensator valve.
- Remove tooling (A).
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| Illustration 3 | g03676139 |
| (T3) Fan pump discharge pressure tap | |
Adjustment procedure complete.