BREATHER CAP 4645135 - Caterpillar

Install an 8T-0856 Pressure Gauge 4000 kPa (580 psi) on a 6V-3014 Hose Assembly that has quick disconnect fittings. Install the other end of the hose to the pressure tap for the pilot pressure in the pressure reducing valve.
Start the engine and run the engine at high idle. The pressure gauge will read 3100 172 kPa (450 25 psi).
Stop the engine. Turn the start switch to the ON position.
Moving the joystick uses the accumulator in order to will release the pressure in the pressure reducing valve.
Watch the pressure gauge as you move the joystick. The pressure will steadily decrease as you move the joystick.
When the pressure is approximately 860 kPa (125 psi) the pressure will suddenly drop to zero. This occurs because no oil is left in the accumulator. The final pressure prior to the sudden drop to zero is the approximate pressure of the accumulator charge.Discharging the Accumulator
Ensure that the oil in the hydraulic system is at normal operating temperature. Park the machine on a smooth, level surface.
Install the steering frame lock. Block the wheels. Stop the engine.
Turn the engine start switch to the ON position. Move the joystick, the third function lever, and the fourth function control through the full range of travel.Note: Moving the joystick and moving the levers will release the pressure in the pilot hydraulic system.
Illustration 3 g00627402
Raise the door on the right side of the machine in order to access the pilot accumulator.
Illustration 4 g00613371
Accumulator for the pilot valve
Illustration 5 g00282181
Remove guard (1) which protects nitrogen charging valve (2) .
Remove the protective cap on nitrogen charging valve (2) .
Illustration 6 g00282185
(3) Nipple. (4) Coupling assembly. (5) Pressure gauge. (6) Hose assembly. (7) Coupling assembly. (8) Nipple. (9) Valve. (10) Pressure gauge. (11) Regulator assembly. (12) Pressure regulating screw. (13) Chuck for the nitrogen cylinder valve. (14) Valve handle. (15) Nitrogen charging chuck. (16) Hose assembly. (17) Tee.
Identify the correct nitrogen charging chuck.Note: For a nitrogen charging valve with a .305 inch -32 THD, use a 1S-8938 Nitrogen Charging Chuck and a 1U-5551 Extension Assembly. For a nitrogen charging valve with a .482 inch -26 THD, use a 7S-5106 Nitrogen Charging Chuck and a 7S-5439 Extension Assembly .
Attach hose assembly (16) to nitrogen charging chuck (15) .
Turn the valve handle (14) on nitrogen charging chuck (15) all the way in the counterclockwise direction. This will ensure that nitrogen charging valve (2) will not be opened when nitrogen charging chuck (15) is attached to the nitrogen charging valve.
Attach nitrogen charging chuck (15) and hose assembly (16) to nitrogen charging valve (2) .
Place the open end of hose assembly (16) away from the work area and away from other personnel.
Turn valve handle (14) on nitrogen charging chuck (15) all the way in the clockwise direction in order to open nitrogen charging valve (2). This will release all of the compressed gas from the accumulator through hose assembly (16). Now, the accumulator can be removed from the machine.
Disconnect the hydraulic lines for servicing, as needed.Nitrogen Charging Procedure
Table 1
Required