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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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Personal injury or death can result from not engaging the parking brake. Transmission engagement alone will not prevent machine from rolling when the engine is stopped. |
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Tilting the cab while the cab is occupied could result in serious personal injury or death. Before the cab is tilted, remove all loose articles from the cab, and secure all the cab windows and the cab doors. Be sure that the cab is not occupied before the cab is tilted. The improper securing of a tilted cab can cause the cab to fall suddenly which could result in personal injury or death. Before you work under a tilted cab, be sure to install the lock pin in order to prevent the cab from falling. Refer to the Operation and Maintenance Manual for the correct procedure for tilting the cab. |
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If the proper torquing procedure is not used when reinstalling the ROPS structure, the ROPS structure may be weakened which could result in serious injury or death. Ensure that all contact surfaces are clean before reinstalling the ROPS structure. Ensure that the correct torquing procedure is followed when reinstalling the ROPS structure. |
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If the cab tilt cylinder is connected and a crane is used to tilt the cab instead of the cab tilt cylinder, serious damage to the machine and/or serious injury or death may occur. Ensure that the cab tilt cylinder is disconnected from the cab when using a crane as the lifting device to tilt the cab. |
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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. |
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The weight of the cab is approximately |
| Implement Pump Specifications | |||
| Type | Range | Actual | |
| Discharge Pressure | |
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| Load Sense Pressure | |
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| Margin Pressure | |
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Pump discharge pressures are known values that can be found under specific conditions. The first condition is a test of margin pressure during operation of the bucket. The second condition is the high-pressure stall.
The high-pressure stall test indicates if the load sensing relief valve or the pressure compensator needs to be adjusted. The margin pressure test indicates if the flow compensator needs to be adjusted.
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| Illustration 1 | g01089423 |
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Tooling (A) | |
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| Illustration 2 | g01623868 |
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Tooling (B) | |
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| Illustration 3 | g01879273 |
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Tooling (D) | |
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| Illustration 4 | g01871217 |
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Tooling (F) | |
| Required Tools | ||||
|---|---|---|---|---|
| Tool | Item | Part Number | Part Description | Qty |
| A | A1 | 8T-0860 | Pressure Gauge ( |
2 |
| A2 | 6V-3989 | Fitting | 2 | |
| A3 | 6V-4143 | Quick Connect Coupler | 4 | |
| A4 | 177-7861 | Hose As | 2 | |
| B | 198-4240 | Digital Pressure Indicator Gp | ||
| B1 | 198-4234 | Digital Indicator (PRESSURE) | 1 | |
| B2 | 198-4239 | Pressure Sensor Gp ( |
2 | |
| B3 | 198-4236 | Adapter Cable As (DIGITAL PRESSURE INDICATOR) | 2 | |
| D | 1U-5796 | Pressure Differential Tool Gp | ||
| D1 | 177-7861 | Hose As | 2 | |
| D2 | 6V-4143 | Quick Connect Coupler | 4 | |
| D3 | 6V-3965 | Fitting | 3 | |
| D4 | 6V-4144 | Quick Connect Coupler | 1 | |
| D5 | 8T-0861 | Pressure Gauge ( |
1 | |
| D6 | 8C-8431 | Tee | 1 | |
| D7 | 1U-5796 | Oil Filter Pressure Differential Gauge Gp | 1 | |
| D8 | 6V-0484 | O-Ring Adapter | 1 | |
| F | F1 | 6V-3965 | Quick Disconnect Coupler | 1 |
| F2 | 3J-1907 | O-Ring Seal | 1 | |
| F3 | 164-0193 | Adapter | 1 | |
| F4 | 6V-8397 | O-Ring Seal | 1 | |
| G | 6V-9807 | Union | 1 | |
Note: If Tooling (A) is used, then one set of Tooling (D) will also be required to perform the following tests. Otherwise, Tooling (B) can be used to perform all of the following tests.
Reference: Refer to Tool Operating Manual, NEHS0818, "Using the 198-4240 Digital Pressure Indicator Group" for more information on using Tooling (B).
Reference: Refer to Special Instruction, SEHS8979, "Component Identification and Calibration of the 1U5796 Differential Pressure Gauge Group" for more information on using Tooling (D).
Test Preparation - Discharge Pressure
Note: Ensure that pilot pressure is set before proceeding.
- Ensure that the steering lock is engaged.
- Ensure that the oil temperature is at least
60° C (140° F) . - Ensure that ride control is set to OFF.
Show/hide table
Illustration 5 g03663644 (18) Implement discharge pressure port - Attach a pressure gauge to the implement discharge pressure port (18)
Testing Procedure - Implement Discharge Pressure
- Start the engine and set to high idle.
- With the engine in high idle, raise the linkage and allow the linkage to stall in the raise position. Refer to Table 1 for specifications.
- If pressure is correct, lower linkage and stop engine. Properly purge the system and disconnect the gauge. If the pressure is not within specifications, refer to the "Adjustment Procedure - Implement Discharge Pressure" section.
Adjustment Procedure - Implement Discharge Pressure
- Locate the load sense relief valve (J) on the main implement valve (H). Best practice is to access the valve from the right side of the machine in the hitch.
- Use a hex wrench to loosen the lock-nut and an internal hex to adjust the implement load sense pressure. Turn inwards to increase the pressure or outwards to decrease the pressure.
Note: The final pressure adjustment must be inward to increase pressure. If the setting is too high, adjust the pressure down below the target pressure. Then, increase the pressure to reach the final setting.
- Tighten the lock-nut and retest the implement discharge pressure to verify setting.
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| Illustration 6 | g03664394 |
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(18) Implement discharge pressure port
(19) Implement pilot pressure tap (20) Implement load sense pressure tap | |
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| Illustration 7 | g03664396 |
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(H) Main implement valve
(J) Load sense relief valve | |
Test Preparation - Implement Load Sense Pressure
Load sense pressure can be checked in the same way as implement discharge pressure. Checking the load sense pressure will provide an accurate reading of the pressure signal that is being sent to the implement pump.
Ensure that pilot pressures are set before proceeding.
- Ensure that the steering lock is engaged.
- Ensure that the oil temperature is at least
60° C (140° F) - Ensure that ride control is set to OFF.
- Attach a pressure gauge to the implement load sense gauge port (20). Refer to Illustration 8.
Test Procedure - Implement Load Sense Pressure
- Start the engine and set to high idle.
- With the engine in high idle, raise the linkage and allow the linkage to stall in the raise position. Check gauge reading. Refer to Table 1 for specifications.
- If pressure is correct, lower linkage and stop engine. Properly purge the system and disconnect the gauge. If the pressure is not within specifications, refer to the "Adjustment Procedure - Implement Load Sense Pressure" section.
Adjustment Procedure - Implement Load Sense Pressure
- Locate the load sense relief valve (J) on the main implement valve (H). Best practice is to access the valve from the right side of the machine in the hitch.
- Use a hex wrench to loosen the lock-nut and an internal hex to adjust the implement load sense pressure. Turn inwards to increase the pressure or outwards to decrease the pressure.
Note: The final pressure adjustment must be inward to increase pressure. If the setting is too high, adjust the pressure down below the target pressure. Then, increase the pressure to reach the final setting.
- Tighten the lock-nut and retest the implement load sense pressure to verify setting.
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| Illustration 8 | g03664394 |
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(19) Implement pilot pressure tap
(20) Implement load sense pressure tap | |
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| Illustration 9 | g03664396 |
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(H) Main implement valve
(J) Load sense relief valve | |
Test Preparation - Implement Pump Margin Pressure
Margin pressure can be checked to troubleshoot hydraulic issues. The implement pump margin pressure is the difference between the implement pump load sense pressure and the implement pump discharge pressure. When a load sense signal is sent to the pump, the controller adds some margin pressure on top of the signal.
- Two high-pressure gauges or a differential gauge is required to check the margin pressure.
- Take note that the margin pressure may be inaccurate when measuring on the machine level.
- With the machine off and the pressure bled out of the hydraulics, attach a pressure gauge to the implement discharge gauge port (18). Connect another gauge on the implement load sense gauge port (20). Use a pressure gauge that can sustain 5000 psi (34,500 kPa) pressure for both ports.
The second option is to use a differential pressure gauge. Connect the high-pressure side to the discharge test port and the low-pressure side to load sense test port.
- Start the engine and warm up the machine if needed.
- Ensure that the hydraulic oil temperature is at least
60° C (140° F) . - Set engine to high-idle when the required hydraulic oil temperature is reached.
Test Procedure - Implement Pump Margin Pressure
- Start the engine and go to high idle.
- With the linkage on the ground give a 50% raise command while remaining at high idle. While the linkage is raising, observe the margin pressure. When using 2 gauges, subtract the load sense pressure from the discharge pressure to determine the margin pressure. When using a differential gauge, the margin pressure is given on the gauge.
- Refer to Table 1 for specifications. Note the gauge reading may be inaccurate.
- If pressure is correct, lower linkage and stop engine. Properly purge the system and disconnect the gauge. If the pressure is not within specifications, refer to the "Adjustment Procedure - Implement Pump Margin Pressure" section.
Adjustment Procedure - Implement Pump Margin Pressure
Margin pressure is often checked to help troubleshoot hydraulic issues. Adjusting the margin pressure is not recommended on the machine. If margin pressure is set incorrectly, replacing the implement pump is often necessary. Margin pressure is set and tested by the supplier. Incorrect margin setting could be caused by contaminants in the pump controller.
Making adjustments on the machine is possible if, the margin pressure is not within the specified range.
- With the engine off, locate the margin pressure adjustment (K). The margin pressure is the only adjustment on the implement pump controller. The pump (L) can be located inside the frame on the left side of the machine. The adjustment can be accessed through the platform by the cab.
- Use a hex wrench to loosen the lock nut on the adjustment and an internal hex to adjust the pressure. Turn inwards to increase the pressure and outwards to decrease the pressure.
Note: The final pressure adjustment must be inward to increase pressure. Adjust the pressure down below the target pressure. Then, increase the pressure to reach the final setting.
- Tighten the lock-nut and retest the implement margin pressure to verify setting.
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| Illustration 10 | g03565419 |
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(K) Margin pressure adjustment
(L) Implement pump | |