TH580B Telehandler Hydraulic System Caterpillar

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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).

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.

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	g01283483
Accumulator (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

1. Make sure that valve (5) is closed.

2. Remove the cap from the accumulator (1) .

3. Rotate valve handle (8) on chuck (9) counterclockwise until the valve handle reaches the full out position. Install chuck (9) on the accumulator.

4. Turn valve handle (8) clockwise until the valve is completely open.

5. Check the pressure reading on pressure gauge (6). Refer to Table 2 for the correct charging pressure and temperature relationship for the accumulator.

6. If the pressure reading on the gauge is too high, use the following steps in order to purge the nitrogen from the accumulator.

   1. Slowly open valve (5) .

   2. Purge the nitrogen pressure until the pressure reading is within the specification.

   3. Close valve (5) .

   4. Turn valve handle (8) on chuck (9) counterclockwise until the valve is completely closed.

   5. Remove the test equipment. Replace cap (1) .

7. If the pressure is too low, use the following procedure to charge the accumulator:

   1. Turn valve handle (8) on chuck (9) counterclockwise until the valve is completely closed.

   2. Connect the 175-5507 Nitrogen Charging Group to the nitrogen cylinder with connection (3) .

   3. Connect the other end of the hose to valve (5) .

   4. Open the valve on the nitrogen cylinder. Make an adjustment to screw (7) on the regulator assembly until gauge (2) indicates the proper precharge pressure for the accumulator. Refer to Table 2.

   5. Open valve (5). Loosen chuck (9) slightly. Allow the nitrogen to purge the air from the hose. Tighten chuck (9) .

   6. Open valve (8) in order to charge the accumulator.

   7. Close valve (5) .

   8. The accumulator has the correct charge if the pressure on gauge (6) and the pressure on gauge (2) are equal and the gauge readings do not change. If there is a decrease in pressure on gauge (6), open valve (5) and allow more nitrogen to go into the accumulator.

   9. Repeat steps 7.d through 7.g until the following items occur:
      • The pressure on gauge (6) is equal to the pressure on gauge (2) .

      • There is no pressure change when valve (5) is closed.

   10. Close valve (5). Close the valve on the nitrogen cylinder.

   11. Turn valve handle (8) on chuck (9) counterclockwise until the valve is completely closed.

   12. Remove the test equipment. Replace cap (1) .