PIN 1799270 - Caterpillar

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).
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.
Reference: Refer to Testing and Adjusting, "Machine Preparation for Troubleshooting" before you begin the test.Specifications
Table 1
Accumulator Precharge Pressure/Temperature Relationship for a Typical 4830 kPa (700 psi) Brake Accumulator
Temperature Pressure(1)
-10°C (14°F) 4319 kPa (626 psi)
-5°C (23°F) 4401 kPa (638 psi)
0°C (32°F) 4484 kPa (650 psi)
5°C (41°F) 4566 kPa (662 psi)
10°C (50°F) 4648 kPa (674 psi)
15°C (59°F) 4730 kPa (686 psi)
20°C (68°F) 4812 kPa (697 psi)
25°C (77°F) 4894 kPa (709 psi)
30°C (86°F) 4976 kPa (721 psi)
35°C (95°F) 5058 kPa (733 psi)
40°C (104°F) 5140 kPa (745 psi)
45°C (113°F) 5222 kPa (757 psi)
50°C (122°F) 5304 kPa (769 psi)
(1) The tolerance on the nominal pressure is 240 kPa (35 psi).Introduction
Blade cushion accumulators are mounted on the frame in front of the blade lift cylinders. The accumulators cushion the head end of the cylinder from sudden rises in pressure.The following procedure will determine if the accumulator is charged to the appropriate pressure.Lowering the Piston in 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 a minimum of 110 applications have been completed. Do not assume that the pressure is removed from the circuit if the brake pedal has no resistance. In order 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 in order to determine the correct charging pressure for the brake accumulator.Accumulator Charge Procedure
Refer to Special Instruction, REHS5464, "Accumulator Discharging and Charging Procedures". Accumulator Charge Procedure for a Rebuilt Accumulator
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