TUBE AS 3005402 - Caterpillar

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).
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, "Caterpillar Tools and Shop Products Guide" for tools and supplies suitable to collect and contain fluids on Caterpillar products.Dispose of all fluids according to local regulations and mandates.
Stop the engine. Depress the brake pedal repeatedly until there is no brake pressure.Nitrogen gas pressure varies with the temperature. To obtain the most accurate nitrogen charge, the temperature of each accumulator must be identical to the air temperature around the accumulators.If an accumulator has less than half of the required amount of precharge pressure, the accumulator should be charged. Then charge the accumulator again after you apply the service brakes approximately 30 times in order to prevent trapping oil in the accumulator. Oil in the accumulator will give an inaccurate precharge reading.However, the temperature of the accumulators could be higher than the air temperature around the accumulators. In this case, the temperature of the accumulator should be used instead of the surrounding air temperature.Note: The pressures in the following table are for an ambient air temperature of 20°C (68°F). Adjust the pressure for other ambient conditions, as required.
Table 2
Accumulator Precharge Pressure/Temperature Relationship for a Typical
4200 kPa (600 psi) Brake Accumulator    
Temperature     Pressure    
-10°C (14°F)    
3770 kPa (550 psi)    
-5°C (23°F)    
3841 kPa (560 psi)    
0°C (32°F)    
3914 kPa (570 psi)    
5°C (41°F)    
3986 kPa (580 psi)    
10°C (50°F)    
4057 kPa (590 psi)    
15°C (59°F)    
4129 kPa (600 psi)    
20°C (68°F)    
4200 kPa (610 psi)    
25°C (77°F)    
4271 kPa (620 psi)    
30°C (86°F)    
4343 kPa (630 psi)    
35°C (95°F)    
4415 kPa (640 psi)    
40°C (104°F)    
4487 kPa (650 psi)    
45°C (113°F)    
4558 kPa (660 psi)    
Illustration 1 g00923710
Location of the Brake Accumulators (underneath cab)
Illustration 2 g00535595
Brake Accumulator (1) Cap. (2) O-ring seal. (3) Screw. (4) Accumulator valve.
Illustration 3 g00535589
Nitrogen Charging Group (5) Charging hose fitting. (6) Pressure gauge. (7) Valve body. (8) Knob. (9) Accumulator purge valve. (10) Charging hose. (11) Adapter.Note: The brake accumulators are mounted underneath the