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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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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. |
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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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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. |
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| 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. |
Specifications
Note: The pressures in the following table are for an ambient air temperature of 21°C (70°F). Adjust the pressure for other ambient conditions, as required.
| Accumulator Precharge Pressure/Temperature Relationship for the 6200 kPa (900 psi) Service Brake Accumulators |
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| Temperature | Pressure |
-7°C (20°F) |
5620 kPa (815 psi) |
-1°C (30°F) |
5735 kPa (830 psi) |
4°C (40°F) |
5855 kPa (850 psi) |
10°C (50°F) |
5970 kPa (865 psi) |
16°C (60°F) |
6085 kPa (880 psi) |
21°C (70°F) |
6200 kPa (900 psi) |
27°C (80°F) |
6320 kPa (915 psi) |
32°C (90°F) |
6440 kPa (935 psi) |
38°C (100°F) |
6555 kPa (950 psi) |
43°C (110°F) |
6675 kPa (970 psi) |
49°C (120°F) |
6790 kPa (985 psi) |
Introduction
This information includes the following test:
- Brake Accumulator
This information includes the following charge procedure:
- Brake Accumulator
- Rebuilt Brake Accumulator
Test Preparation
Refer to Testing and Adjusting, "Machine Preparation for Troubleshooting".
Refer to Testing and Adjusting, "System Pressure Release".
Test Procedure
- Move steering frame lock to the LOCKED position.
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| Illustration 1 | g02181445 |
- Stop the engine. Engage the parking brake. Move the transmission direction selector to the NEUTRAL position.
- Turn the engine start switch to the ON position. The alert indicator (1) for the brake should come on if the braking system is not at normal operating pressure.
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| Illustration 2 | g03502389 |
- Start the engine. Run the engine at low idle speed until the engine is warm in order to increase the accumulator pressure. The alert indicator (1) should go off.
- At low idle engine speed, fully depress the brake pedal and release. Repeat this process until hearing the brake charging system recharge the accumulators. When charging, you will hear a slight dip in engine rpm.
- When charging is completed, stop the engine and turn the key to the ON position without starting the engine.
- Fully apply the brake pedal and fully release off the brake pedal at a rate of one second on and one second off. Count the number of cycles until the alert indicator (1) for brake oil pressure comes on. A minimum of three applications of the brake pedal are required.
- If the alert indicator (1) comes on before the required number of cycles, use the following procedure to check the accumulator pre-charge pressures and charge the accumulators if necessary. If brake accumulator charge is correct, then troubleshoot brake charging components and inspect service brakes for wear. Refer to Testing and Adjusting, "Service Brake Wear Indicator (Existing Brake Disc) - Check".
Charge Procedure
Refer to Special Instruction, REHS5464, "Accumulator Discharging and Charging Procedures" for the required tooling, and the testing and charging procedure.
Charge Procedure for Rebuilt Brake Accumulator
Refer to Special Instruction, REHS5464, "Accumulator Discharging and Charging Procedures" for the required tooling, and the testing and charging procedure.