24H Motor Grader Hydraulic and Steering System Caterpillar


Accumulator (Steering) - Test and Charge

Usage:

24H 7KK

------ WARNING! ------

Dry nitrogen is the only gas approved for use in the accumulator. Charging the accumulator with oxygen gas will cause an explosion. This danger will not happen if nitrogen cylinders with standard CGA (Compressed Gas Association, Inc.) Number 580 connections are used. When you order nitrogen gas, be sure that the cylinders are equipped with CGA No. 580 Connections. Do not use color codes or other methods of identification to tell the difference between nitrogen and oxygen cylinders.


Testing the Steering Accumulator

Note: Before you perform this test, refer to the General Information section.

Table 1
Required Tools 
Tool  Part Number  Description  Qty 
8T-0860  Pressure Gauge 
4C-4892  Hydraulic Test Fitting Gp 


Illustration 1g00563237
Top View of Combination Valve
(1) Steering supply port

Note: Do not test the accumulator charge pressure by installing a pressure gauge directly into the top of the steering accumulator. Excessive nitrogen leakage will result during the installation and during the removal of the pressure gauge.

  1. Stop the engine. Turn the steering wheel to the left and to the right several times to relieve the steering accumulator pressure.

  2. Remove the line from steering supply port (1) on the side of the combination valve. Install the tee from Tooling (B) into the steering supply port. Next, install the nipple from Tooling (B) into the Tee. Install the supply line to the tee. Connect Tool (A) onto the test port .

  3. Start the engine and operate the engine at high idle.

  4. Steer the front wheels left or steer the front wheels right against the stops. The pressure gauge should read 21500 ± 310 kPa (3130 ± 45 psi), which is maximum steering pressure.

    Note: If the steering system pressure in Step 4 was incorrect, refer to the Testing and Adjusting, "Steering System Maximum Pressure - Test and Adjust" section in this manual.

  5. Release the steering wheel and stop the engine.

  6. The oil pressure will slowly lower until the pressure reaches the precharge pressure of the steering accumulator. The nitrogen precharge for the accumulator is 6900 kPa (1000 psi). When oil pressure reaches this pressure, the gauge will suddenly drop off to zero. Make a note of the pressure just before the gauge suddenly drops, showing the accumulator precharge. At zero pressure, the steering accumulator has purged the stored oil. Purging the stored oil in the steering accumulator takes 10 minutes to 12 minutes.

    Note: To speed up the time of the purge, slowly turn the steering wheel to the left and right. Turning the wheel will cause the oil to discharge quickly. Reading the pre-charge pressure will be difficult, due to the speed of the oil pressure drop.

Charging the Steering Accumulator

Table 2
Required Tools 
Tool  Part Number  Description  Qty 
175-5507  Nitrogen Charging Group 
224-5152  Male-to-Male Adapter(1) 
222-2367  Male-to-Female Adapter(2) 
(1) For use with Female Fittings
(2) For use with a Male and a Female Fitting

Note: When you are connecting the nitrogen charging equipment, never use an adapter that can be used on any other gas cylinders. MAKE SURE THAT YOU ARE USING DRY NITROGEN.

The accumulator has a precharge of approximately 6900 kPa (1000 psi).

Use the following procedure to relieve the steering accumulator pressure:

  • Turn the engine to the off position. Slowly turn the steering wheel to the left and right to relieve the hydraulic pressure for the steering accumulator.

  1. Test the steering accumulator.

  2. Remove the dust cap from the top of the steering accumulator.


    Illustration 2g06186967
    Nitrogen charging group (Tool (A))
    (1) 162-4147 Hose As
    (2) 8S-4600 Fitting
    (3) 8S-1506 Coupling
    (4) 162-4146 Regulator
    (5) 1S-8938 Chuck
    (6) 7S-5106 Chuck
    (7) 8T-0859 Pressure Gauge
    (8) 8S-4599 Coupling
    (9) 2S-5244 Fitting
    (10) 1S-8937 Needle Valve
    (11) 2D-7325 Pipe Tee
    (12) 1S-8941 Hose As

  3. Make sure that valve (10) and the valve on chuck (5) are closed.

  4. Install Tool (D) or (E) on the valve of the steering accumulator. Attach chuck (5) to the adapter.

  5. Completely open the valve on chuck (5). To open the valves, turn the valve handles counterclockwise. Check the temperature of the air around the steering accumulator. The pressure on gauge (7) must be within the tolerances that are shown on the following Table 3.

    Table 3
    Charging Pressure and Temperature Relationship for the 6900 kPa (1000 psi) Accumulator 
    Temperature  Pressure(1) 
    -7°C (20°F)  6205 kPa (900 psi) 
    -1°C (30°F)  6340 kPa (920 psi) 
    4°C (40°F)  6480 kPa (940 psi) 
    10°C (50°F)  6620 kPa (960 psi) 
    16°C (60°F)  6755 kPa (980 psi) 
    21°C (70°F)  6900 kPa (1000 psi) 
    27°C (80°F)  7030 kPa (1020 psi) 
    32°C (90°F)  7170 kPa (1040 psi) 
    38°C (100°F)  7310 kPa (1060 psi) 
    43°C (110°F)  7450 kPa (1080 psi) 
    49°C (120°F)  7585 kPa (1100 psi) 
    (1) The allowable tolerance on nominal pressure is ± 70 kPa (± 10 psi).

  6. If the pressure reading on gauge (7) is too high, lower the pressure by slowly opening valve (10).

  7. If the pressure reading on the gauge is too low, then the steering accumulator must be charged.

  8. Connect coupling (8) on hose assembly (1) to valve (10). Attach regulator (4) to the nitrogen cylinder.

  9. Close valve (10) , open the valve on the nitrogen cylinder, and adjust the regulator (4). Adjust regulator (4) until the gauge is at the pressure that is needed to charge the steering accumulator. Use Table 3 as a reference for the correct charging pressure.

  10. Open valve (10) and charge the accumulator. Close valve (10). The steering accumulator is charged if the pressure on gauge (7) does not change. The steering accumulator is charged if the pressure on gauge (7) is equal to the pressure on the gauge on regulator (4). If there is a decrease in pressure on regulator (4), open valve (10) and allow more nitrogen to charge the steering accumulator. Repeat this procedure as many times as necessary until the pressure on gauge (7) is equal to the pressure on regulator (4). Also, the pressure on gauge (7) does not change when valve (10) is turned to the OFF position.

  11. Turn the steering wheel to the left and to the right to relieve the hydraulic pressure for the steering accumulator. Repeat the procedure several times. Check gauge (7).

  12. Repeat step 9 through step 11 if the nitrogen pressure is low.

  13. Close the valve that is on the nitrogen cylinder.

  14. Close valve (10). Close the valve that is on the nitrogen cylinder.

  15. Open chuck (5).

  16. Remove the test equipment.

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