2010/07/28 Caterpillar

Underground Articulated Truck:

AD55B (S/N: JNW182-UP)

The following additional information is applicable to machines AD55B JNW182-Up.

Refer to Testing and Adjusting, "Visual Inspection" before you service the suspension system.

The machine must be on level ground when you inspect the suspension charge. The body must be empty. Coast the machine to a gentle stop without using the brakes. Check the suspension cylinders dimensions compared to the last time that you performed the charging procedure. The suspension height will be different for each machine. The suspension accumulator is located on the left side of the front frame.

Suspension System Oil Purge Procedure

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Personal injury or death can result from escaping fluid under pressure. Escaping fluid under pressure, even a very small pin-hole size leak, can penetrate body tissue and cause serious injury and possible death. If fluid is injected into your skin, it must be treated by a doctor familiar with this type of injury. Always use a board or cardboard when checking for a leak.

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Personal injury or death can result from sudden suspension cylinder movement. Sudden movement, up or down, can cause the clearance above your head to change rapidly. Read all warning labels on the suspension cylinders before servicing. Do not check the oil in the suspension cylinder until all the nitrogen pressure has been released. Do not, under any condition, remove valves, cover or plugs from the cylinder unless the rod is fully retracted and all the nitrogen pressure is released. Do not stand under the machine when testing or adjusting the suspension cylinders.

1. Move the machine to a smooth, horizontal location. Move away from operating machines and move away from other personnel.

2. Move the transmission control to the NEUTRAL position.

3. Engage the parking brake.

4. Stop the engine.

5. Connect the steering frame lock. Refer to Disassembly and Assembly, "Steering Frame Lock - Separate and Connect"

6. Place wheel blocks in front of the wheels and place wheel blocks behind the wheels.

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Illustration 1	g01459059

7. Remove cover (1) .

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Illustration 2	g01528933

8. Remove cover (2) .

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Illustration 3	g01459060
(3) Oil charging valve (A) Nut

9. Remove the protective cap from oil charging valve (3) .

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Illustration 4	g01459949
9U-5617 Oil Refill Pump (4) Shutoff valve for the regulator (5) 1S-8938 Chuck (6) Shutoff valve (7) Charging hose

10. Disconnect charging hose (7) from the 9U-5617 Oil Refill Pump .

    Note: Only one charging hose (7) is used to purge the suspension system of oil.

11. Turn the handle of 1S-8938 Chuck (5) in the counterclockwise direction. Oil charging valve (3) will not be open during installation.

12. Attach 1S-8938 Chuck (5) with charging hose (7) to oil charging valve (3). Charging hose (7) will be used to drain the oil into an approved container.

13. Turn the handle of 1S-8938 Chuck (5) in the clockwise direction. The secondary seal will be open in oil charging valve (3) .

14. Turn nut (A) two and a half turns in the counterclockwise direction. The primary seal of oil charging valve (3) will be open.

15. Open shutoff valve (6) by turning in the counterclockwise direction. Oil will flow through oil charging valve (3) allowing the suspension cylinders to bottom out.

16. Leave shutoff valve (6) open for 5 minutes to ensure that the suspension cylinders have bottomed out completely.

17. After the suspension cylinders have fully bottomed out, turn the handle of 1S-8938 Chuck (5) in a counterclockwise direction. The oil charging valve (3) will be closed.

18. Remove the charging hose (7) from oil charging valve (3). Attach charging hose (7) to the 9U-5617 Oil Refill Pump. Place the end of charging hose (7) with 1S-8938 Chuck (5) into an approved container. Cycle some oil in order to ensure that charging hose (7) is full of clean oil.

Nitrogen Discharging Procedure for the Suspension Accumulator

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Personal injury or death can result from escaping fluid under pressure. Escaping fluid under pressure, even a very small pin-hole size leak, can penetrate body tissue and cause serious injury and possible death. If fluid is injected into your skin, it must be treated by a doctor familiar with this type of injury. Always use a board or cardboard when checking for a leak.

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Personal injury or death can result from sudden suspension cylinder movement. Sudden movement, up or down, can cause the clearance above your head to change rapidly. Read all warning labels on the suspension cylinders before servicing. Do not check the oil in the suspension cylinder until all the nitrogen pressure has been released. Do not, under any condition, remove valves, cover or plugs from the cylinder unless the rod is fully retracted and all the nitrogen pressure is released. Do not stand under the machine when testing or adjusting the suspension cylinders.

Note: If the accumulator must be replaced, first perform the "Suspension System Oil Purge Procedure". Then, perform the following steps:

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Illustration 5	g01510933
(8) Nitrogen charging valve

1. Remove the protective cap from nitrogen charging valve (8) .

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Illustration 6	g01525553
175-5507 Nitrogen Charging Group (9) Nipple (10) Coupling assembly (11) Pressure gauge (12) 162-4147 Hose As (13) Coupling assembly (14) Nipple (15) Valve (16) Pressure gauge (17) Regulator assembly (18) Pressure regulating screw (19) Chuck for the nitrogen cylinder valve (20) Valve handle (21) 1S-8938 Chuck (22) 1S-8941 Hose As (23) Tee

2. Close valve (15) by turning in the clockwise direction.

3. Turn handle (20) on 1S-8938 Chuck (21) in the counterclockwise direction to ensure that nitrogen charging valve (8) will not be open during installation.

4. Attach 1S-8938 Chuck (21) with 1S-8941 Hose As (22) and 162-4147 Hose As (12) to nitrogen charging valve (8) .

5. Place the open end of hose assembly (12) away from the work area and away from other personnel.

6. Turn handle (20) on 1S-8938 Chuck (21) in the clockwise direction. The nitrogen charging valve (8) will be open.

7. Open valve (15) by turning in the counterclockwise direction. The nitrogen from the suspension accumulator will be released.

8. When the pressure reaches zero, close valve (15) by turning in the clockwise direction.

9. Turn handle (20) on 1S-8938 Chuck (21) in the counterclockwise direction. This nitrogen charging valve (8) will close.

10. Remove 1S-8938 Chuck (21) and the hose assembly from nitrogen charging valve (8) .

Setting Up for Measurement

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Illustration 7	g01459951
(24) Reference line for the correct nitrogen charge (25) Reference line for the correct oil charge (26) Reference line on the front frame (27) Reference line

1. Position a steel ruler or a thin strip of sheet metal (as shown).

2. Create reference line (27) on the steel ruler. Reference line (27) should line up with reference line (26) on the front frame.

3. Create reference line (25) in order to indicate the guideline for the oil charging procedure. Reference line (25) should be 30.9 mm (1.21 inch) above reference line (27) .

4. Measure the difference between the outside ambient temperature and the temperature of the service shop. If this temperature difference is less than 11°C (20°F), use Table 2 to create guidelines for the nitrogen charging procedure. Table 2 shows the distance between reference line (27) and reference line (24).
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   Table 2

   Reference line (24)

   108 mm (4.25 inch)

5. Measure the difference between the outside ambient temperature and the temperature of the service shop. If this temperature difference is greater than 11°C (20°F), you will need to change the location of reference line (24). Add 3.09 mm (0.12 inch) of distance for each 5.5°C (10°F) of temperature difference.

   Refer to the examples that are listed below:

   Note: Estimate the temperature difference to the nearest 5.5°C (10°F).

   Temperature of the service shop ... 10°C (50°F)

   Outside ambient temperature ... −40°C (−40°F)

   Difference in temperatures

   10°C (50°F) − (−40°C (−40°F)) = 50°C (90°F)

   Additional length for temperature compensation

   50°C (90°F) × 3.09 mm (0.12 inch) ÷ 5.5°C (10°F) = 28.0 mm (1.10 inch)

   Corrected guidelines for the nitrogen charging procedure

   108 mm (4.25 inch) + 28.0 mm (1.10 inch) = 136 mm (5.35 inch)

Oil Charging Procedure

When the accumulator is new or rebuilt, put approximately 1.9 L (0.50 US gal) of SAE 5W oil with a service classification of CH in the nitrogen end of the accumulator. When the accumulator is installed on the machine, use the following procedure to charge the accumulator:

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Personal injury or death can result from sudden suspension cylinder movement. Sudden movement, up or down, can cause the clearance above your head to change rapidly. Read all warning labels on the suspension cylinders before servicing. Do not check the oil in the suspension cylinder until all the nitrogen pressure has been released. Do not, under any condition, remove valves, cover or plugs from the cylinder unless the rod is fully retracted and all the nitrogen pressure is released. Do not stand under the machine when testing or adjusting the suspension cylinders.

Note: Before charging the suspension system with oil, first perform the "Nitrogen Discharging Procedure for the Suspension Accumulator ".

Note: Ensure that the suspension accumulator piston is at the bottom of the accumulator before the system is charged with oil.

Note: Only one charging hose (7) is used to charge the suspension system with oil.

Note: Use SAE 5W oil with a service classification of CH for the oil charging procedure.

1. Close shutoff valve (4) by turning in the clockwise direction.

2. Ensure that oil charging valve (3) will not be open during installation by turning the handle of 1S-8938 Chuck (5) in the counterclockwise direction.

3. Attach 1S-8938 Chuck (5) with charging hose (7) to oil charging valve (3) .

4. Attach charging hose (7) to the 9U-5617 Oil Refill Pump.

5. Turn the handle of 1S-8938 Chuck (5) in the clockwise direction. Oil charging valve (3) will be open.

6. Attach 162-4147 Hose As (12) and 1S-8941 Hose As (22) with 1S-8938 Chuck (21) to nitrogen charging valve (8). Turn handle (20) on 1S-8938 Chuck (21) in the clockwise direction. Nitrogen charging valve (8) will be open .

   Note: During the oil charging procedure using a new or rebuilt suspension accumulator, oil will discharge from nitrogen charging valve (8). As hydraulic oil flows into the bottom of the suspension accumulator, the suspension accumulator piston will be pushed upward. The air and then the oil will be pushed out through the 1S-8938 Chuck (21). Place the end of the hose assembly into an approved container.

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Illustration 8	g02184653
(28) Cover

7. Remove cover (28) .

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Illustration 9	g02184654
(29) Left side suspension cylinder purge screw (30) Right side suspension cylinder purge screw

8. Connect one end of a transparent tube 6.4 mm (0.25 inch) in diameter to purge screw (29). Place the other end of the tube into a suitable container.

9. Repeat Step 8 for purge screw (30) .

10. Open purge screw (29) and purge screw (30) .

11. Open shutoff valve for the regulator (4). Adjust the air pressure on the regulator. The air pressure must not exceed 860 kPa (125 psi).

12. Open shutoff valve (6) by turning in the counterclockwise direction. Oil will flow through oil charging valve (3) .

13. Inject the oil into oil charging valve (3) until the oil flows free of air from purge screw (29) and purge screw (30). Close shutoff valve (6) by turning in the clockwise direction.

14. Tighten purge screw (29) and purge screw (30) .

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Illustration 10	g01459962
(24) Reference line for the correct nitrogen charge (25) Reference line for the correct oil charge (26) Reference line on the front frame (27) Reference line

15. Inject the oil into oil charging valve (3) until reference line (25) lines up with reference line (26) on the front frame. Close shutoff valve (6) by turning in the clockwise direction.

    Note: The initial charging procedure will take longer as the suspension accumulator piston will be moved to the top of the suspension accumulator.

16. Open purge screw (30) until the oil flows free of air. Allow the suspension cylinders to bottom out completely. Tighten purge screw (30) .

    Note: If necessary, repeat Step 15 through Step 16 at least three times to ensure that the oil is free of air.

17. Inject the oil into oil charging valve (3) until reference line (25) lines up with reference line (26) on the front frame. Close shutoff valve (6) by turning in the clockwise direction.

18. Close the shutoff valve for regulator (4). Turn off the air pressure at the regulator.

19. Turn handle (20) on 1S-8938 Chuck (21) in the counterclockwise direction. Secondary seal in oil charging valve (3) will be closed.

20. Tighten nut (A) in the clockwise direction. The primary seal of oil charging valve (3) will be closed.

21. After the pressure reading has returned to zero, remove charging hose (7) with 1S-8938 Chuck (5) from oil charging valve (3) .

22. Install the protective cap on oil charging valve (3). Torque the protective cap to 2.5 ± 0.5 N·m (22 ± 4 lb in).

23. Install cover (28) .

Nitrogen Charging Procedure

Note: Before you perform the nitrogen charging procedure, first perform the "Oil Charging Procedure". Then, perform the following steps:

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Dry nitrogen is the only gas approved for use in the suspension cylinders. Charging the suspension cylinders 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 cylinders and oxygen cylinders. 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).

1. Turn handle (20) on 1S-8938 Chuck (21) in the counterclockwise direction to ensure that nitrogen charging valve (8) will not be open during installation.

2. Attach 1S-8938 Chuck (21) with the 175-5507 Nitrogen Charging Group to nitrogen charging valve (8) .

3. On the nitrogen supply tank, open the valve and adjust the regulated pressure with pressure regulating screw (18) to 3450 kPa (500 psi).

4. Turn handle (20) on 1S-8938 Chuck (21) in the clockwise direction. Nitrogen charging valve (8) will open.

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Illustration 11	g01459959
(24) Reference line for the correct nitrogen charge (25) Reference line for the correct oil charge (26) Reference line on the front frame (27) Reference line

5. Allow the nitrogen to flow into the suspension accumulator until reference line (26) on the front frame lines up with reference line (24) .

6. After the correct suspension height is achieved, close shutoff valve (15) by turning in the clockwise direction. The flow of nitrogen will stop. Turn handle (20) on 1S-8938 Chuck (21) in the counterclockwise direction. Nitrogen charging valve (8) will be closed.

7. Turn off the nitrogen pressure at the supply tank. Remove the 175-5507 Nitrogen Charging Group with 1S-8938 Chuck (21). Install the protective cap on nitrogen charging valve (8). Torque the valve cap to 2.5 ± 0.5 N·m (22 ± 4 lb in).

8. Install covers (1) and (2) .

9. Remove wheel blocks from in front of the wheels and from behind the wheels.

10. Separate the steering frame lock. Refer to Disassembly and Assembly, "Steering Frame Lock - Separate and Connect".