ACCUMULATOR GP-STEERING 4368630 - Caterpillar

Illustration 2 g00295992
Pilot accumulator (1) Cap for valve assemblyStop the engine. Release the pressure from the hydraulic system. Refer to Testing and Adjusting, "General Information". 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.Use table 1 to determine the correct amount of gas pressure to use.
Table 1
Charge Pressures and Temperatures for 7Y-8421 Accumulator    
Temperature     Pressure    
-23°C (-10°F)    
1495 kPa (217 psi)    
-21°C (-5°F)    
1516 kPa (220 psi)    
-18°C (0°F)    
1529 kPa (222 psi)    
-15°C (5°F)    
1550 kPa (225 psi)    
-12°C (10°F)    
1564 kPa (227 psi)    
-9°C (15°F)    
1577 kPa (229 psi)    
-7°C (20°F)    
1598 kPa (232 psi)    
-4°C (25°F)    
1612 kPa (234 psi)    
-1°C (30°F)    
1632 kPa (237 psi)    
2°C (35°F)    
1646 kPa (239 psi)    
4°C (40°F)    
1660 kPa (241 psi)    
7°C (45°F)    
1681 kPa (244 psi)    
10°C (50°F)    
1694 kPa (246 psi)    
13°C (55°F)    
1715 kPa (249 psi)    
16°C (60°F)    
1729 kPa (251 psi)    
18°C (65°F)    
1750 kPa (254 psi)    
21°C (70°F)    
1763 kPa (256 psi)    
24°C (75°F)    
1777 kPa (258 psi)    
27°C (80°F)    
1798 kPa (261 psi)    
29°C (85°F)    
1812 kPa (263 psi)    
32°C (90°F)    
1832 kPa (266 psi)    
35°C (95°F)    
1846 kPa (268 psi)    
38°C (100°F)    
1860 kPa (270 psi)    
41°C (105°F)    
1880 kPa (273 psi)    
43°C (110°F)    
1894 kPa (275 psi)    
46°C (115°F)    
1915 kPa (278 psi)    
49°C (120°F)    
1929 kPa (280 psi)    Use the 7S-5437 Nitrogen Charging Group in order to test and charge the pilot accumulator.
Illustration 3 g00457381
7S-5437 Nitrogen Charging Group (2) Pressure gauge (3) Connection to nitrogen cylinder valve (4) Regulator assembly (5) Valve (6) Pressure gauge (7) Pressure regulating screw (8) Valve handle (9) ChuckChecking the Nitrogen Charge of the Pilot Accumulator
Rotate valve handle (8) on chuck (9) counterclockwise until the valve handle reaches the full out position. Close valve (5) .
Remove cap (1) from the valve assembly on the accumulator.
Install chuck (9) on the valve assembly of the accumulator.
Rotate valve handle (8) on chuck (9) clockwise until the valve assembly is completely opened.
Use pressure gauge (6) to check the amount of nitrogen charge in the accumulator. Check the temperature of the air around the accumulator. The pressure on the gauge must be within the values that are shown in table 1.
If the pressure reading on the gauge is too high, lower the