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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 attachments have been lowered, 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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Dry nitrogen is the only gas approved for use in the accumulators. The charging of oxygen gas in an accumulator will cause an explosion. An explosion can be eliminated by using nitrogen gas cylinders with standard CGA (Compressed Gas Association, Inc.) No. 580 connectors. When nitrogen gas is ordered, make sure to order the cylinders with CGA No. 580 connectors. Do not rely on color codes or other methods of identification to tell the difference between nitrogen and oxygen cylinders. In any application, never use an adapter to connect your nitrogen charging group to a valve outlet used on both nitrogen, oxygen, or other gas cylinders. BE SURE YOU USE DRY NITROGEN (99.8% purity). |
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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, PERJ1017, "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. |
| NOTICE |
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The following information applies only to service replacement accumulators. The factory accumulator does not have a nitrogen charge port and cannot be checked. |
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| Illustration 1 | g06243211 |
The steering/brake pilot oil accumulator is mounted to the right side of the rear frame below the left side of the hydraulic tank.
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| Illustration 2 | g06243223 |
The implement pilot oil accumulator is in the front frame mounted to the main control valve.
| Pilot Oil Accumulator Pre Charge Pressure |
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The implement system pilot pressure is generated by a pressure reducing valve that is the brake accumulator charging valve
- The primary steering pilot system supplies pilot pressure to the steering system
- The implement steering pilot system supplies pilot pressure to the implement system and the steering system if the primary steering system fails
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| Illustration 3 | g06243210 |
| Required Tools | ||||
|---|---|---|---|---|
| Tool | Item | Qty | Part No | Description |
| D | 175-5507 | Nitrogen Charging Group | ||
| D | D1 | 1 | 8S-4600 | Fitting |
| D2 | 1 | 8S-1506 | Coupling As | |
| D3 | 1 | 162-4147 | Hose As | |
| D4 | 1 | 8S-4599 | Coupling As | |
| D5 | 1 | 2S-5244 | Fitting | |
| D6 | 1 | 1S-8937 | Needle Valve | |
| D7 | 1 | 8T-0859 | Pressure Gauge
(0 to 25,000 kPa (0 to 3,600 psi)) |
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| D8 | 1 | 162-4146 | Regulator | |
| F | 349-4200 | Thermometer | ||
| H | 9U-6740 | Accumulator Charging Gp | ||
| 152-2023 | Nitrogen Charging Fitting Gp(1) | |||
| J | 334-1071 | Adapter | ||
| K | 9U-6741 | Adapter | ||
| (1) | Recommended for Type 4 Valves |
- 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.
Refer to Special Instruction, REHS5464, "Accumulator Discharging and Charging Procedures" for the required tooling, and the testing and charging procedure.
Testing Procedure for the Accumulator Precharge Pressure
Refer to Special Instruction, REHS5464, "Accumulator Discharging and Charging Procedures" for the required tooling, and the testing and charging procedure.
Refer to Special Instruction, REHS5464, "Accumulator Discharging and Charging Procedures" for the required tooling, and the testing and charging procedure.