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Personal injury or death can result if two persons are not used in the following procedure. |
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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. |
| 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. |
| Steering Pump Margin Pressure | |
|---|---|
| Pump Margin Pressure | Setting |
| Margin Pressure (High Idle) | |
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| Illustration 1 | g06275281 |
This information includes the following test:
- Margin Pressure
This information includes the following adjustment procedure:
- Adjustment Procedure (Margin Pressure)
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| Illustration 2 | g01879273 |
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Tooling (D) | |
| Item | Part Number | Description |
|---|---|---|
| D | 1U-5796 | Pressure Differential Tool Gp |
| D2 | 6V-4143 | Quick Connect Coupler |
| D3 | 6V-3965 | Fitting |
| D4 | 6V-4144 | Quick Connect Coupler |
| D5 | 8T-0859 | Pressure Gauge
(0 to 25,000 kPa (0 to 3,600 psi)) |
| D5 | 8T-0861 | Pressure Gauge
(0 to 60,000 kPa (0 to 8,700 psi)) |
| D6 | 8C-8431 | Tee |
| D7 | 1U-5793 | Oil Filter Pressure Differential Gauge Gp |
| D8 | 6V-0484 | O-Ring Adapter |
Reference: Refer to Special Instruction, SEHS8979, "Component Identification and Calibration of the 1U5796 Differential Pressure Gauge Group" for more information on using Tooling (D).
Refer to Testing and Adjusting, "Machine Preparation for Troubleshooting".
Refer to Testing and Adjusting, "System Pressure Release".
- Move steering frame lock to the LOCKED position.
- Engage the parking brake. Move the transmission direction selector to the NEUTRAL position.
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| Illustration 3 | g03335539 |
- Attach a
0 to 60000 kPa (0 to 8700 psi) pressure gauge (D5) to the tee on pressure differential gauge group (D7).Show/hide table
Illustration 4 g06275289 Location of the diagnostic lines group
(G5) Steering pump discharge pressure tap - Connect one end of hydraulic line (D1) to pressure tap (G5). Pressure tap (G5) is located on the panel for the remote pressure taps that is on the left side of the machine. Connect the other end of hydraulic line (D1) to the tee on pressure differential gauge group (D7).
Show/hide table
Illustration 5 g06275375 (29) Steering metering pump
(G6) Pressure tap - Connect hydraulic line (D1) between signal pressure tap (G6) and the single pressure port on pressure differential gauge group (D7). Signal pressure tap (G6) is located below the front of the cab, next to the metering pump (29).
Note: Position pressure differential gauge group (D7) and hydraulic lines (D1) in order to prevent damage from any machine movement. Position the test equipment in order to allow a second technician to observe and record the pressure readings safely.
- Start the engine. Operate the engine at high idle. Continuously stall the RACK BACK function while simultaneously raising the lift arms at full speed. When the lift arms are almost raised, cycle the tilt cylinder almost to the FULL DUMP position. Then move the tilt cylinders to the full RACK BACK position. Continuously stall the RACK BACK function and simultaneously lower the lift arms back to the ground level position. Without stalling the RACK BACK function, cycle the lift function to raise the lift arms fully. Then lower the lift arms in order to allow the pump to operate at low-pressure briefly and circulate oil through the system. Repeat this process in order to increase the temperature of the oil to normal operating temperature.
- After the oil has reached normal operating temperature, lower the bucket to the ground. Stop the engine.
- Move steering frame lock to the STORED position.
- Start the engine. Raise the bucket until the bucket is slightly off the ground. Run the engine at high idle.
Note: During the following steps, do not continue to engage the STIC steering once the machine ceases to articulate. Once the machine ceases to articulate in one direction, immediately move the STIC control in the opposite direction. Make sure that you move the STIC control a constant rate. The pressure that is indicated on pressure gauge (D7) will vary with the speed of rotation. Slower rotation will cause a lower pressure reading. Faster rotation will cause a higher pressure reading.
- Articulate the machine all the way to the left or all the way to the right. After the machine ceases to articulate in one direction, immediately move the STIC control in the opposite direction. Make sure that you move the STIC control a constant rate. A second technician should look at pressure gauge (D7).
- Record the pressure reading on pressure gauge (D7). The reading that is on pressure gauge (D7) is the margin pressure. Margin pressure is the difference between steering pump pressure and the signal pressure. The margin pressure should be
2400 kPa (348 psi) .Note: The pressure reading on pressure gauge (D5) is the steering pump pressure.
- Adjust the flow compensator valve if the margin pressure is not correct.
- Run the machine at low idle. Lower the bucket and any attachment to the ground. Stop the engine.
- Relieve the hydraulic pressure. Refer to Testing and Adjusting, "System Pressure Release".
- Remove the hydraulic lines and the pressure gauge from the pressure tap.
Note: If you adjust the flow compensator spool in the steering pump pressure and flow compensator valve, repeat steps 7 through 9 of the test procedure to verify that the pressures after the adjustment procedure are correct.
Adjustment Procedure (Margin Pressure)
- Remove the cover from adjustment screw (11). Loosen locknut. Turn adjustment screw clockwise in order to increase the margin pressure. Turn adjustment screw counterclockwise in order to decrease the margin pressure. One turn of adjustment screw changes margin pressure by approximately
1415 kPa (205 psi) . - After you turn adjustment screw (11), tighten locknut to a torque of
21 N·m (16 lb ft) . - Repeat steps 7 through 9 of the test procedure to verify pressures after the adjustment procedure.
- Replace the cover on adjustment screw (11).
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| Illustration 6 | g06275281 |
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(3) Pressure and flow compensator valve
(4) Adjustment screw for the pressure compensator (7) Locknut (10) Locknut (11) Adjustment screw for the flow compensator (margin pressure) | |
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| Illustration 7 | g03344999 |
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(3) Pressure and flow compensator valve
(4) Adjustment screw for the pressure compensator (5) Pressure compensator spool (6) Spring (7) Locknut (8) Flow compensator spool (9) Spring (10) Locknut (11) Adjustment screw for the flow compensator (margin pressure) | |