IT28G Integrated Toolcarrier and 928G Wheel Loader Hydraulic System Ride Control Accumulator - Test and Charge Caterpillar

Shutdown Procedure

1. Move the machine to a hard, level surface.

2. Move the transmission control lever to the NEUTRAL position.

3. Engage the parking brake.

4. Turn the ride control switch to the ON position.

5. Lower all work tools to the ground.

6. Move the lift control lever to the FLOAT position.

7. Stop the engine.

8. Turn the engine start switch to the OFF position and remove the key.

Discharging the Accumulator

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Illustration 1	g00282170
The ride control switch is shown in the OFF position.

1. While the engine is running, turn the ride control switch to the ON position.

2. Lower the work tool to the ground. Then, move the lift control lever to the FLOAT position. This will relieve all of the hydraulic pressure in the accumulator.

3. Stop the engine. Disconnect the hydraulic lines for servicing, as needed.

   Note: If the accumulator must be replaced, perform Steps 1 through 3. Then, use the following procedure:

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   Illustration 2	g00911692

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   Illustration 3	g00282181

   1. Remove guard (1) which protects nitrogen charging valve (2) .

   2. Remove the protective cap on nitrogen charging valve (2) .
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   Illustration 4	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.

   3. 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 .

   4. Attach hose assembly (16) to nitrogen charging chuck (15) .

   5. 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.

   6. Attach nitrogen charging chuck (15) and hose assembly (16) to nitrogen charging valve (2) .

   7. Place the open end of hose assembly (16) away from the work area and away from other personnel.

   8. 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.

Nitrogen Charging Procedure

1. Move the machine to level ground.

2. Move the transmission control lever to the NEUTRAL position. Move the transmission neutral lock to the LOCKED position.

3. Engage the parking brake.

4. Start the engine. Keep the engine running during the following steps. This will ensure that the pilot flow is available in order to shift the diverter valve spool against the spring when the ride control switch is turned to the ON position.

5. Move the lift control lever to the FLOAT position. Turn the ride control switch to the ON position.

6. Remove guard (1) which protects nitrogen charging valve (2) .

7. Remove the protective cap on nitrogen charging valve (2) .

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Illustration 5	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.

8. Turn valve handle (14) on nitrogen charging chuck (15) all the way in the counterclockwise direction. Attach the appropriate nitrogen charging chuck (15) to nitrogen charging valve (2) .

   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 .

9. Attach hose assembly (16) between nitrogen charging chuck (15) and tee (17). Install needle valve (9) on one of the connecting points of the tee. Install an 8T-0858 Pressure Gauge in the remaining open port on the tee. The pressure gauge is rated at 16000 kPa (2300 psi).

10. Install coupling assembly (7) in the open port of needle valve (9) .

11. Install nipple (8) on one end of hose assembly (6). Place the open end of the hose assembly away from the work area and away from other personnel.

12. Open needle valve (9) and turn valve handle (14) on nitrogen charging chuck (15) all the way in the clockwise direction.

13. Raise the lift arms all the way in order to momentarily relieve the nitrogen pressure charge.

14. Close needle valve (9) .

15. Lower the bucket to the ground. Move the lift control lever to the FLOAT position.

16. Attach the open end of hose assembly (6) to regulator assembly (11). Install an 8T-0859 Pressure Gauge in the port that is directly above the regulator. This pressure gauge is rated at 25000 kPa (3600 psi).

    Install an 8T-0856 Pressure Gauge in the remaining port next to regulator assembly (11). This pressure gauge is rated at 6000 kPa (870 psi).

17. Install regulator assembly (11) on nitrogen tank valve (2). Adjust screw (12) on regulator (11) in order to set the pressure on the 8T-0856 Pressure Gauge to the appropriate charge pressure.

    Note: To ensure that the accumulator nitrogen charge is correct, the accumulator piston must be at the bottom of the accumulator cylinder. Nitrogen pressure varies with the temperature. To obtain the most accurate nitrogen charge, the temperature of the accumulator should equal the outside air temperature. However, the temperature of the accumulator could be higher than the outside air temperature in some cases. If this is the case, the temperature of the accumulator should be used instead of the outside air temperature.

    Note: The pressures in the following table are recommended for machines with typical buckets (work tools) and with average payloads. For machines with heavy buckets, work tools, or large payloads, the nitrogen pressure may need to be increased in order to keep the piston from contacting the stop during normal roading while the ride control system is on. Raising the nitrogen pressure will result in a stiffer ride.

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    Table 2

    Accumulator Precharge Pressure/Temperature Relationship for a Typical 3000 kPa (435 psi) Accumulator
    Temperature	Pressure (1)
    -7°C (20°F)	2707 kPa (393 psi)
    -1°C (30°F)	2766 kPa (401 psi)
    4°C (40°F)	2824 kPa (410 psi)
    10°C (50°F)	2883 kPa (418 psi)
    16°C (60°F)	2941 kPa (427 psi)
    21°C (70°F)	3000 kPa (435 psi)
    27°C (80°F)	3059 kPa (443 psi)
    32°C (90°F)	3117 kPa (452 psi)
    38°C (100°F)	3176 kPa (460 psi)
    43°C (110°F)	3234 kPa (469 psi)
    49°C (120°F)	3293 kPa (477 psi)

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    ( 1 )

    The nominal tolerance is ± 35 kPa (± 5 psi).

18. Open the needle valve (9). The nitrogen pressure should appear on the 8T-0858 Pressure Gauge in 10 to 20 seconds.

    Note: If the nitrogen pressure appears on the pressure gauge in less time, close pressure regulating screw (12) on regulator assembly (11) and disconnect hose assembly (6) at coupling assembly (4). Close needle valve (9) and remove coupling assembly (4). Repeat Steps 5 through 18.

19. Turn valve handle (14) on nitrogen charging chuck (15) all the way in the counterclockwise direction. Close regulator (11) and needle valve (9). Slowly disconnect hose (16) from needle valve (9). Open needle valve (9) before you remove nitrogen charging chuck (15) from nitrogen charging valve (2) on the accumulator.

20. Install the protective cap on nitrogen charging valve (2). Install guard (1) over nitrogen charging valve (2) .