797F Off-Highway Truck Steering System: Steering Accumulator - Test and Charge

Table 1

Tools Needed
Tool	Part Number	Part Description	Qty
A	175-5507	Nitrogen Charging Group	1
B	152-2023	Nitrogen Charging Fitting Gp	1
C	4L-7412	Adapter	1
D	227-1415	Adapter	1
E	227-9942	Hose As	1
F	8T-0857	Pressure Gauge (0 to 10,000 kPa (0 to 1450 psi))	1
	6V-7830	Pressure Gauge (Multiple Gauge)	1

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.

Table 2

Relationship Between the Charging Pressure and the Ambient Temperature
Ambient Temperature	Charging Pressure (1)
−7°C (20°F)	6735 kPa (977 psi)
−1°C (30°F)	6790 kPa (985 psi)
4°C (40°F)	6900 kPa (1000 psi)
10°C (50°F)	7010 kPa (1016 psi)
16°C (60°F)	7120 kPa (1032 psi)
21°C (70°F)	7230 kPa (1050 psi)
27°C (80°F)	7340 kPa (1064 psi)
32°C (90°F)	7450 kPa (1080 psi)
38°C (100°F)	7560 kPa (1096 psi)
43°C (110°F)	7670 kPa (1112 psi)
49°C (120°F)	7725 kPa (1120 psi)

( 1 )

The allowable tolerance on nominal pressure is ± 345 kPa (± 50 psi).

Do not use an adapter to connect the nitrogen charging equipment to a valve that can be used on oxygen cylinders or gas cylinders. Use dry nitrogen.

Check that the engine has not been running for at least five minutes. This will allow the oil level in the steering accumulators to decrease. The accumulator piston must be on the bottom of the cylinder. This will ensure that the pressure of the nitrogen charge is correct.

The steering accumulator must have a dry charge of 7230 ± 345 kPa (1050 ± 50 psi) at 21 °C (70 °F). Refer to Table 2 for the charge pressure at the ambient temperature that is different from 21 °C (70 °F).

Checking the Nitrogen Charge Pressure

Steering accumulators(1) Protective cap for gas valve



This is a typical view of the top of an accumulator. (G) Seal(H) Cap



(B) Fitting(F) Gauge



1. Remove cap (1) from the top of the accumulator.

2. Insert a 6 mm Allen wrench into the screw in the charging valve. Loosen the screw by 1/6 of a turn. Do not turn the screw more than is required in order to break the screw loose. Opening the screw will cause the nitrogen charge to escape.

3. Install Tool (F) to the nitrogen charging adapter from Tool (B). Install the tooling on the accumulator gas valve.

4. Turn the handle on the adapter clockwise in order to open the screw.

5. Use the pressure gauge on the adapter to check the nitrogen charge in the accumulator.

6. The pressure on the gauge must be within the tolerances that are listed in Table 2.

7. If the pressure reading on the gauge is too high, lower the pressure by slowly opening the purge valve on Tool (B) .

8. When the pressure reading for the accumulator is correct, close the purge valve and close the charging valve. Remove the adapter from the accumulator. Tighten the screw to a torque of 20 N·m (15 lb ft). Install cap (1) to the top of the accumulator.

9. If the pressure reading on the gauge is too low, charge the accumulator. Close the screw on the accumulator. Refer to "Increasing the Charge Pressure in the Accumulator".

Increasing the Charge Pressure in the Accumulator

Nitrogen charging group (Tool A) (2) 8T-0857 Pressure Gauge (3) Connection to nitrogen cylinder valve (4) Regulator assembly(5) Pressure regulating screw



1. Start with the setup of the accumulator from "Checking the Nitrogen Charge Pressure".

2. Connect the pressure regulator from Tool (A) to the nitrogen cylinder.

3. Install Tool (C) to the outlet port of the pressure regulator. Install Tool (D) into Tool (C) .

4. Turn screw (5) fully counterclockwise in order to set the regulated pressure to zero.

5. Connect Tool (E) between the check valve on Tool (B) and Tool (D) on the pressure regulator.

6. Turn the knob on the valve for the nitrogen cylinder clockwise in order to open the valve. The pressure gauge on the pressure regulator will show pressure in the nitrogen cylinder. Pressure gauge (3) should show zero.

7. Open the screw in the gas valve on the accumulator by turning the handle on the charging adapter clockwise. This will allow nitrogen to charge the accumulator.

8. Adjust pressure regulating screw (5) on the regulator assembly until the pressure reading on pressure gauge (2) indicates the pressure that will charge the accumulator to the correct precharge. Use Table 2 as a reference for the correct charging pressure.

9. When the pressure reading on Tool (A) and the pressure reading on pressure gauge (2) are identical, close the screw by turning the handle in the charging adapter counterclockwise.

10. Allow a waiting period of five minutes for the temperature of the nitrogen inside the accumulator to stabilize.

11. If there is a decrease in the pressure on Tool (A), open the screw by turning the handle on the charging adapter. This allows more nitrogen to enter the accumulator.

12. Repeat Steps 9, 10, and 11 until the following items occur:
    • Pressure readings of Tool (A) and pressure gauge are identical.
    • Pressure readings do not change.

13. Close the valve on the nitrogen cylinder.

14. Remove the adapter from the accumulator.

15. Tighten the screw to 20 N·m (15 lb ft).

16. Install protective cap (1) hand tight on the accumulator.

Charging a New Accumulator or a Rebuilt Accumulator

Before a new accumulator or a rebuilt accumulator is installed on a machine, use the following procedure to charge the accumulator to the correct precharge:

1. Remove protective cap (1) from the gas valve on the top of the accumulator.

2. Insert a 6 mm Allen wrench into the screw in the charging valve. Loosen the screw by 1/6 of a turn. Do not turn the screw more than is required in order to break the screw loose. Opening the screw will cause the nitrogen charge to escape.

3. Install Tool (F) to the charging adapter from Tool (B). Install the tooling on the accumulator gas valve.

4. Connect the pressure regulator from Tool (A) to the nitrogen cylinder.

5. Install Tool (C) to the outlet port of the pressure regulator. Install Tool (D) into Tool (C) .

6. Turn screw (4) fully counterclockwise in order to set the regulated pressure to zero.

7. Connect Tool (E) between the check valve on the Tool (B) and Tool (D) on the pressure regulator.

8. Turn the knob on the valve for the nitrogen cylinder clockwise in order to open the valve. The pressure gauge on the pressure regulator will show pressure in the nitrogen cylinder. Pressure gauge (1) should show 0 kPa (0 psi).

9. Turn pressure regulating screw (4) on the regulator assembly clockwise until the indicator needle in pressure gauge (1) moves from 0 kPa (0 psi) to 69 kPa (10 psi).

10. Open the charging valve screw.

11. Allow the bladder to expand slowly in order to begin the process of filling the inside of the accumulator cylinder.

12. When the pressure reading on the pressure gauge on the charging adapter and pressure gauge (1) are identical, close the charging valve.

13. Allow a waiting period of five minutes for the temperature of the nitrogen inside the accumulator to stabilize.

14. Turn screw (4) on the regulator assembly clockwise until the indicator needle on pressure gauge (1) moves to 170 kPa (25 psi).

15. Open the charging valve.

16. When the pressure reading on the pressure on the adapter and pressure gauge (1) are identical, close the screw.

17. Allow a waiting period of five minutes for the temperature of the nitrogen inside the accumulator to stabilize.

18. Repeat Steps 14, 15, 16, and 17 for 345 kPa (50 psi) and 790 kPa (100 psi).

19. Adjust pressure regulating screw (4) on the regulator assembly until the pressure reading on pressure gauge (1) indicates the pressure that will charge the accumulator to the correct precharge. Use Table 2 as a reference for the correct charging pressure.

20. Open the screw in the gas valve on the accumulator by turning the handle on the adapter. This will allow the nitrogen to charge the accumulator.

21. When the pressure reading on the pressure gauge for the charging adapter and the pressure reading on pressure gauge (1) are identical, close the screw.

22. Allow a waiting period of five minutes for the temperature of the nitrogen inside the accumulator to stabilize.

23. If there is a decrease in the pressure on the pressure gauge for the adapter, open the valve. This allows more nitrogen to enter the accumulator.

24. Repeat Steps 21, 22, and 23 until the following items occur:
    • Pressure readings of the gauge on the adapter and gauge (1) are identical.
    • Pressure readings do not change after the five minute stabilizing period.

25. Close the valve on the nitrogen cylinder.

26. Remove the adapter from the accumulator.

27. Tighten the screw to 20 N·m (15 lb ft).

28. Install protective cap (1) hand tight.

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797F Off-Highway Truck Steering System: Steering Accumulator - Test and Charge 2013-01-20T09:10:00-08:00 Rating: 4.5 Diposkan Oleh: Unknown