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Personal injury can result from hydraulic oil pressure and hot oil. Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system. Make sure all of the work tools have been lowered to the ground, and the oil is cool before removing any components or lines. Remove the 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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| NOTICE |
|---|
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. |
| Needed Tools | ||
|---|---|---|
| Part Number | Part Description | Qty |
| 177-7860 | Hose Assembly | 2 |
| 6V-4144 | Coupler | 2 |
| 6V-4142 | Unvalved Nipple | 2 |
| 8T-0859 | Pressure Gauge 25000 kPa (3600 psi) |
2 |
| 3J-7354 | O-Ring Seal | 1 |
| 5P-2937 | O-Ring Adapter | 1 |
| 6V-3966 | Fitting As | 1 |
Note: The margin pressure test should be used as a reference only. Performing the steering pump margin pressure test is difficult. In order to obtain more accurate pressure readings, perform the Service Manual Module, RENR6427, "Piston Pump (Steering and Pilot) Low Pressure Standby - Test and Adjust".
- Lower the work tool to the ground.
- Stop the engine.
- Engage the parking brake.
- To release any steering system pressure, turn the steering wheel to the left and to the right .
- Remove panel (1) from the right side of the machine.
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| Illustration 1 | g00634079 |
924G and 924Gz | |
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| Illustration 2 | g00906214 |
928G and IT28G | |
- Attach one 6V-4142 Unvalved Nipple to the second end of the 6V-2076 Hose Assembly .
- For the 924G and 924Gz, the pressure reducing valve is behind panel (1) . For the 928G and IT28G, the pressure reducing valve is below panel (1) . Remove the cap from pressure tap (2) .
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| Illustration 3 | g00634049 |
924G and 924Gz (Test port for the steering system pressure) | |
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| Illustration 4 | g00906217 |
928G and IT28G (Test port for the steering system pressure) | |
- Attach the 6V-4144 Coupler on the hose to pressure tap (2) on the pressure reducing valve.
- Remove panel (3) from the left side of the machine.
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| Illustration 5 | g00634358 |
- Attach one 6V-4142 Unvalved Nipple to the other end of the hose.
- The steering piston pump is behind panel (3) . The pressure compensator valve (4) is attached to the top of the steering piston pump. On the 924G and 924Gz, remove the cap from pressure tap (5) . On the 928G and IT28G, remove plug (6) from the port in the pressure and flow compensator valve. Install one 3J-7354 O-Ring Seal onto a 5P-2937 O-Ring Adapter . Install the 5P-2937 O-Ring Adapter into the port. Install one 6V-3966 Fitting As into the O-ring adapter. The 3J-7354 O-Ring Seal , 5P-2937 O-Ring Adapter , and the 6V-3966 Fitting As are part of the 8T-5320 Hydraulic Test Group .
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| Illustration 6 | g00634408 |
924G and 924Gz (4) Steering and pilot compensator valve | |
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| Illustration 7 | g00634409 |
924G and 924Gz (5) Test port for steering signal pressure | |
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| Illustration 8 | g00906221 |
928G and IT28G (4) Steering and pilot compensator valve | |
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| Illustration 9 | g01001374 |
928G and IT28G | |
- Attach the 6V-4144 Coupler on the hose to the test port on the pressure and flow compensator valve.
- Position both gauges so you can easily read both gauges.
- Start the engine.
- Run the engine at LOW idle. Check for hydraulic oil leaks.
- Run the engine at HIGH idle.
- Slowly turn the steering wheel to the left or to the right.
- Record the readings on both gauges as you turn the steering wheel.
- Stop the engine.
- The margin pressure is the difference between the discharge pressure of the steering piston pump and the signal pressure to the steering metering pump. The margin pressure should be 3600 ± 100 kPa (522 ± 15 psi).
Note: If the margin pressure is not correct, perform the Service Manual Module, RENR6427, "Piston Pump (Steering and Pilot) Low Pressure Standby - Test and Adjust" and the Service Manual Module, RENR6427, "Piston Pump (Steering and Pilot) High Pressure Stall - Test and Adjust" before adjusting the pump controller.
- Remove the hoses and gauges.
- Replace panels (1) and (3) .