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Personal injury or death can result from improper accumulator charging. Dry nitrogen is the only gas approved for use in the accumulator. Charging the accumulator with oxygen gas will cause an explosion. This danger will not happen if nitrogen cylinders with standard CGA Compressed Gas Association, Inc.Number 580 connections are used. When ordering nitrogen gas, be sure that the cylinders are equipped with CGA Number 580 Connections. Do not use color codes or other methods of identification to tell the difference between nitrogen and oxygen cylinders. 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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Sudden movement of the machine or release of oil under pressure can cause serious injury to persons on or near the machine. To prevent possible injury, perform the procedure that follows before testing and adjusting the hydraulic system. |
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Cold ambient temperatures could result in the loss of secondary braking capability due to inadequate hydraulic accumulator nitrogen pre-charge. The loss of the secondary braking system as well as the main hydraulic pressure will result in little or no braking capability and a potential for injury or death. It is recommended to perform a brake accumulator check anytime the machine has been idle for longer than two hours below |
| Accumulator Precharge Pressure/Temperature Relationship for a Typical |
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| (1) | The tolerance on the nominal pressure is ± |
The brake accumulators are mounted ahead of the right front wheel well. The purpose of the accumulator is to store pressure. This stored pressure will allow the machine operator to bring the machine to a stop in the event of an interruption of pressure from the brake pump.
The following procedure will determine if the accumulator is charged to the appropriate pressure.
- Refer to Special Instruction, REHS5464, "Accumulator Discharging and Charging Procedures".
Lowering the Piston in Brake Accumulators
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Hydraulic accumulator contains gas and oil under high pressure. Improper removal or repair procedures could cause severe injury. To remove or repair, instructions in the service manual must be followed. Special equipment is required for testing and charging. |
Relieving the pressure in the brake circuit will not release the nitrogen precharge pressure in the brake accumulators.
- Remove the pressure from the brake system by pumping the service brake pedal at a rate of one second ON and one second OFF. Continue to pump the brakes until the pressure at the TF port on the fan/brake manifold is less than
140 kPa (20 psi) . Do not assume that the pressure is removed from the circuit if the brake pedal has no resistance.
To charge the accumulator, the piston in the brake accumulator must be on the bottom of the cylinder. The air temperature outside the accumulator is the ambient temperature. Before the dry nitrogen pressure in the accumulator can be accurately checked, the temperature of the accumulator must be equal to the ambient temperature. Before the accumulator may be correctly charged, the temperature of the accumulator must be equal to the ambient temperature.
Use Table 1 to determine the correct charging pressure for the front service brake 389-0369 Hydraulic Accumulator Gp, or the rear service brake 389-0373 Hydraulic Accumulator Gp.
Note: The 389-0367 Hydraulic Accumulator Gp and the 389-0371 Hydraulic Accumulator Gp are CE-compliant accumulators.
Accumulator Charge Procedure for a Rebuilt Accumulator
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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. |
When the accumulator has been rebuilt, the air must be removed from the upper chamber of the accumulator. After the accumulator is rebuilt, put approximately
Install the rebuilt accumulator on the machine. Refer to Special Instruction, REHS5464, "Accumulator Discharging and Charging Procedures" to charge the rebuilt accumulator.