ELEMENT-HEATING 2501081 - Caterpillar

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.
Table 1
REQUIRED TOOLS    
Part Number     Description     Quantity    
175-5507     Nitrogen Charging Group     1    Testing and Charging the Pilot System Accumulators
Stop the engine. Release the pressure from the pilot hydraulic system. Refer to Testing and Adjusting, "Hydraulic System Pressure - Release".Gas pressure is variable with temperature. Check the temperature of the air around the accumulator. In order to check the amount of charge in an accumulator, the accumulator must be at the same temperature as the surrounding air.Note: The temperature of the accumulator may change as the accumulator is being charged due to the expansion or compression of the nitrogen charge. It may be necessary to charge the accumulator in several steps in order to ensure a correct charge.
Table 2
Charge Pressures and Temperatures    
Temperature     Pressure    
-25°C (-13°F)    
761 kPa (110 psi)    
-20°C (-4°F)    
777 kPa (113 psi)    
-15°C (5°F)    
792 kPa (115 psi)    
-10°C (14°F)    
808 kPa (117 psi)    
-5°C (23°F)    
823 kPa (119 psi)    
0°C (32°F)    
838 kPa (121 psi)    
5°C (41°F)    
854 kPa (124 psi)    
10°C (50°F)    
869 kPa (126 psi)    
15°C (59°F)    
884 kPa (128 psi)    
20°C (68°F)    
900 kPa (130 psi)    
25°C (77°F)    
915 kPa (133 psi)    
30°C (86°F)    
931 kPa (135 psi)    
35°C (95°F)    
946 kPa (137 psi)    
40°C (104°F)    
961 kPa (139 psi)    
45°C (113°F)    
977 kPa (142 psi)    
50°C (122°F)    
992 kPa (144 psi)    If an accumulator has less than half of the required amount of precharge pressure, the accumulator should be charged. Oil in the accumulator will give an inaccurate precharge reading.
Illustration 1 g00995368
Accumulator (Typical Example) (1) Cap
Illustration 2 g00457381
175-5507 Nitrogen Charging Group (2) Pressure gauge (3) Connection to the nitrogen cylinder (4) Regulator (5) Valve (6) Pressure gauge (7) Pressure regulating screw (8) Valve handle (9) Chuck
Make sure that valve (5) is closed.
Remove cap (1) from the accumulator.
Rotate valve handle (8) on chuck (9) counterclockwise until the valve handle reaches the full out position. Install chuck (9) on the accumulator.
Turn valve handle (8) clockwise until the valve is completely open.
Check the pressure reading on pressure gauge (6). Refer to Table 2 for the correct charging pressure and temperature relationship for the accumulator.
If the pressure reading on the gauge is too high, use the following steps in order to purge the nitrogen from the accumulator.
Slowly open valve (5) .
Purge the nitrogen pressure until the pressure reading