INSULATION 1606476 - Caterpillar

Charging the Brake Accumulators
Table 2
REQUIRED TOOLS    
Part Number     Description     Quantity    
175-5507     Nitrogen Charging Group     1    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 each accumulator must be identical to the air temperature around the accumulators.
Table 3
Charging Pressure and Temperature Relationship for a Typical
3450 kPa (500 psi) Accumulator    
Temperature °C (°F)     Pressure kPa (psi)    
-7 °C (20 °F)    
3123 kPa (453 psi)    
-1 °C (30 °F)    
3185 kPa (462 psi)    
4 °C (40 °F)    
3254 kPa (472 psi)    
10 °C (50 °F)    
3323 kPa (482 psi)    
16 °C (60 °F)    
3385 kPa (491 psi)    
21 °C (70 °F)    
3448 kPa (500 psi)    
27 °C (80 °F)    
3509 kPa (509 psi)    
32 °C (90 °F)    
3578 kPa (519 psi)    
38 °C (100 °F)    
3640 kPa (528 psi)    
43 °C (110 °F)    
3709 kPa (538 psi)    
49 °C (120 °F)    
3771 kPa (547 psi)    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 repeatedly in order to prevent trapping oil in the accumulator. Oil in the accumulator will give an inaccurate precharge reading.
Illustration 1 g01087885
Nitrogen charging group (1) Pressure gauge (2) Regulator assembly (3) Pressure regulating screw (4) Hose assembly (5) Chuck (6) Valve handle (7) Valve (8) Pressure gaugeThe brake accumulators are located on the right side of the machine. The panel that is behind the cab must be removed in order to allow full access to the accumulators.
Illustration 2 g01084889
Location of the accumulators
Illustration 3 g01084892
Location of the accumulators without the panel
Illustration 4 g01087888
Accumulator (9) Cover (10) Cap
Remove cover (9) from the brake accumulator. Remove cap (10) from the nitrogen charging valve on the accumulator.
Use pressure gauge (7) in order to check the nitrogen charge in the brake accumulators.Note: The 198-4240 Digital Pressure Indicator can be used in place of the above tools.
Install chuck (5) onto the nitrogen charging valve on the brake accumulator.
Open valve (7) and charge line (4) to the correct precharge.
Turn valve handle (6) completely in the clockwise direction.
If the reading on the pressure gauge is too high, slowly open valve (7) in order to lower the pressure. If the reading on the pressure gauge is too low, use the following procedure to charge the brake accumulator:
Connect a hose from the nitrogen cylinder to valve (7) .
Close valve (7) and open the valve on the nitrogen cylinder. Adjust screw (3) on regulator assembly (2) until pressure gauge (1) is at the correct charging pressure.
Open valve (7) and charge the brake accumulator.