SCREW 2868710 - 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, "Tools and Shop Products Guide" for tools and supplies suitable to collect and contain fluids on 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.To ensure that the nitrogen charge is correct, each brake accumulator piston must be at the bottom of the accumulator cylinder. Nitrogen gas pressure varies with the temperature. To obtain the most accurate nitrogen charge, the temperature of the accumulator must be identical to the air temperature around the accumulator.If the 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 repeatedly in order to prevent trapping oil in the accumulator. Oil in the accumulator will give an inaccurate precharge reading.However, the temperature of the accumulator could be higher than the air temperature around the accumulator. 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 21°C (70°F). Adjust the pressure for other ambient conditions, as required.
Table 2
Accumulator Precharge Pressure/Temperature Relationship for a Typical
6900 kPa (1000 psi) Brake Accumulator    
Temperature     Pressure    
-7°C (20°F)    
6250 kPa (907 psi)    
-1°C (30°F)    
6380 kPa (926 psi)    
4°C (40°F)    
6510 kPa (945 psi)    
10°C (50°F)    
6640 kPa (964 psi)    
16°C (60°F)    
6770 kPa (983 psi)    
21°C (70°F)    
6900 kPa (1000 psi)    
27°C (80°F)    
7030 kPa (1020 psi)    
32°C (90°F)    
7160 kPa (1039 psi)    
38°C (100°F)    
7290 kPa (1058 psi)    
43°C (110°F)    
7420 kPa (1077 psi)    
49°C (120°F)    
7550 kPa (1096 psi)    
Illustration 1 g00107133
Nitrogen Charging Group (1) Nipple. (2) Coupling assembly. (3) Pressure gauge. (4) Hose assembly. (5) Coupling assembly. (6) Nipple. (7) Valve. (8) Pressure gauge. (9) Regulator assembly. (10) Pressure regulating screw. (11) Chuck for the nitrogen cylinder valve. (12) Valve