2002/12/23 Caterpillar

Load Haul Dump:

R1700G (S/N: 8XZ)

Systems Operation Testing and Adjusting, RENR4668 (9EP5398), "R1700G LHD Hydraulic System", "Ride Control Accumulator - Test and Charge". This module is part of Service Manual, RENR4656 (9EP5386) Volume 2.

Reference: Service Magazine, SEPD0659, 09 December 2002, "A New Switch is Used for the Ride Control System".

Because the ride control switch has been changed the testing and charging procedure for the ride control accumulator contains incorrect information. The following information replaces the former information.

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Personal injury or death can result if two persons are not used in the following procedure.

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Personal injury or death can result from machine movement. Place blocks in front of and behind the wheels to make sure the machine does not move while the parking brakes are disengaged.

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Personal injury can result from hydraulic oil pressure and hot oil. Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system. Make sure all of the work tools have been lowered to the ground, and the oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand.

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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).

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NOTICE
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide" for tools and supplies suitable to collect and contain fluids on Caterpillar products. Dispose of all fluids according to local regulations and mandates.

Shutdown Procedure

1. Start the engine and move the machine to a hard, level surface.

2. Move the transmission control lever to the NEUTRAL position. Engage the primary steering/transmission lock lever (STIC steering) or the transmission neutral lock (wheel steering).

3. Engage the parking brake. Stop the engine.

4. Place blocks in front of the wheels and behind the wheels.

5. Install the steering frame lock.

6. Start the engine.

7. Disengage the parking brake.

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Illustration 1	g00918869
Location of the ride control switch

8. Move the ride control switch to the SERVICE position.

9. Lower the bucket to the ground.

10. Move the joystick control lever to the FLOAT position. This will release all of the hydraulic pressure in the accumulator.

    Reference: For more information about releasing the hydraulic pressure in the system, refer to Systems Operation, Testing and Adjusting, "System Pressure - Release".

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

Discharging the Accumulator

Table 1

Required Tools
Part Number	Description	Qty
7S-5437	Nitrogen Charging Group	1

If the accumulator must be replaced, first perform the "Shutdown Procedure". Then, perform the following steps:

Illustration 2	g00941402
Location of the ride control accumulator

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Illustration 3	g00638750
Ride control accumulator (1) Guard (2) Nitrogen charging valve

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
Accumulator charging kit (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) Chuck (16) Hose assembly (17) Tee

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

4. Turn valve handle (14) on nitrogen charging chuck (15) all the way in the counterclockwise direction

   Note: This will ensure that nitrogen charging valve (2) will not be opened when nitrogen charging chuck (15) is attached to nitrogen charging valve (2) .

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

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

7. 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 nitrogen from the accumulator through hose assembly (16) .

Nitrogen Charging Procedure

Table 2

Required Tools
Part Number	Description	Qty
7S-5437	Nitrogen Charging Group	1

1. Start the engine and move the machine to a hard, level surface.

2. Move the transmission control lever to the NEUTRAL position. Engage the primary steering/transmission lock lever (STIC steering) or the transmission neutral lock (wheel steering).

3. Engage the parking brake. Stop the engine.

4. Place blocks in front of the wheels and behind the wheels.

5. Install the steering frame lock.

6. Start the engine. Disengage the parking brake. Keep the engine running during the following steps. This will ensure that pilot oil flow is available in order to shift the diverter valve spool against the spring when the ride control switch is moved to the SERVICE position.

7. Move the joystick control lever to the FLOAT position.

8. Have an assistant press and hold the ride control switch in the SERVICE position.

   Note: The ride control switch will need to be held in the SERVICE position from Step 8 through to Step 23.

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

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

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Illustration 5	g00282185
Accumulator charging kit (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) Chuck (16) Hose assembly (17) Tee

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

12. 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 0 to 16000 kPa (0 to 2300 psi).

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

14. 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.

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

16. Raise the lift arms to the maximum height. Hold the joystick control lever in the RAISE position for five seconds in order to relieve the nitrogen pressure charge from the ride control accumulator.

17. Close needle valve (9) .

18. Lower the bucket to the ground. Move the joystick control lever to the FLOAT position.

19. Attach the open end of hose assembly (6) to regulator assembly (11). Install a 8T-0859 Pressure Gauge in the port that is directly above the regulator. This pressure gauge is rated at 0 to 25000 kPa (0 to 3600 psi).

    Install a 8T-0856 Pressure Gauge in the remaining port next to regulator assembly (11). This pressure gauge is rated at 0 to 6000 kPa (0 to 870 psi).

20. Install regulator assembly (11) on the nitrogen cylinder valve with the chuck for the nitrogen cylinder valve (13). Turn the valve on the top of the nitrogen cylinder counterclockwise for the flow of nitrogen. 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 accumulator charge valve end 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 Table 3 are recommended for machines with a typical bucket. For machines with a heavy bucket, the nitrogen pressure may need to be increased in order to keep the accumulator piston from striking the stop during normal roading while the ride control system is activated. Raising the nitrogen pressure will result in a stiffer ride.

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    Table 3

    Charging Pressure and Temperature Relationship for the Accumulator (Ride Control Pressure Chart)
    Temperature	Pressure (1)
    -7°C (20°F)	1790 kPa (259 psi)
    -1°C (30°F)	1835 kPa (266 psi)
    4°C (40°F)	1875 kPa (271 psi)
    10°C (50°F)	1915 kPa (277 psi)
    16°C (60°F)	1955 kPa (283 psi)
    21°C (70°F)	2070 kPa (300 psi)
    27°C (80°F)	2110 kPa (306 psi)
    32°C (90°F)	2150 kPa (311 psi)
    38°C (100°F)	2200 kPa (319 psi)
    43°C (110°F)	2250 kPa (326 psi)
    49°C (120°F)	2300 kPa (333 psi)

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    ( 1 )

    Nominal allowable tolerance equals ± 35 kPa (± 10 psi).

21. Open needle valve (9). The nitrogen pressure should show on the 8T-0858 Pressure Gauge within 20 seconds.

    Note: If the nitrogen pressure shows on the pressure gauge in less than 10 seconds, close 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 8 through 21.

22. If the ride control accumulator is properly charged, then turn tee handle (14) on nitrogen charging chuck (15) all the way in the counterclockwise direction. Close needle valve (9) .

23. Release the ride control switch. The ride control switch will return to the OFF position.

24. Turn the valve on the nitrogen cylinder clockwise in order to shut off the flow of nitrogen. Turn screw (12) on regulator assembly (11) counterclockwise, until the pressure on gauge (5) goes back to zero.

25. Slowly disconnect hose (16) from needle valve (9) .

26. Open needle valve (9) before you remove nitrogen charging chuck (15) from nitrogen charging valve (2) on the accumulator.

27. Remove nitrogen charging chuck (15) from the ride control accumulator.

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

Charging Procedure for a New or Rebuilt Accumulator

Prior to installing the ride control accumulator, it is necessary to remove all the air from the nitrogen chamber of the accumulator. When the accumulator is new or rebuilt, put approximately 1.9 L (2.01 qt) of SAE 10W hydraulic oil in the nitrogen end of the accumulator. This oil will be used to help remove the air out of the nitrogen chamber of the ride control accumulator and also to put lubricant at the top seal of the accumulator piston.

1. Discharge the ride control accumulator. Refer to "Discharging the Accumulator".

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Illustration 6	g00638750
Ride control accumulator (1) Guard (2) Nitrogen charging valve

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

3. Remove nitrogen charging valve (2) .

4. With the accumulator in the vertical position put approximately 1.9 L (2.01 qt) of SAE 10W hydraulic oil in the nitrogen end of the accumulator.

5. Move the accumulator piston fully to the nitrogen charging valve end of the accumulator. As the accumulator piston moves to the nitrogen charging valve end of the accumulator, the air and then the oil will be pushed out. When the flow of oil stops the accumulator will be free of air and the top seal of the accumulator piston will be lubricated.

6. Install nitrogen charging valve (2) .

7. Install guard (1) .

8. Install the ride control accumulator. Refer to Machine Systems, Disassembly and Assembly, "Ride Control Accumulator - Remove and Install" for the machine that is being serviced.

9. Charge the ride control accumulator. Refer to "Nitrogen Charging Procedure".

Testing the Ride Control Diverter Valve

The following procedure is used to determine whether the diverter valve is operating correctly. Perform this test after the accumulator is charged.

1. Move the ride control switch to the OFF position.

2. Apply the service brakes and disengage the parking brake.

3. Place the bucket in the full DUMP position. Lift the front wheels off the ground by moving the joystick control lever to the LOWER position.

4. Move the ride control switch to the SERVICE position. The front wheels should lower to the ground.

   If the wheels do not lower to the ground, the diverter spool has not shifted to the ON position. The following conditions are probable causes:

   • The ride control switch failed.

   • The solenoid coil on the diverter valve failed.

   • The spool valve in the diverter valve failed.

   • There is a blockage in the pilot circuit to the diverter valve.

Road Test

Note: The pressures in Table 3 are recommended for machines with a typical bucket. For machines with heavy buckets, the nitrogen pressure may need to be increased in order to keep the accumulator piston from striking the stop during normal roading while the ride control system is activated. Raising the nitrogen pressure will result in a stiffer ride.

1. Put a typical load in the bucket.

2. Move the ride control switch to the SERVICE position.

3. Drive the machine over a rough road surface.

   If the machine bounces too much or the accumulator piston is striking the stop, the nitrogen precharge pressure must be increased.

   Note: The ride control accumulators are rated up to 20700 kPa (3000 psi).

4. Refer to the "Nitrogen Charging Procedure". Increase the nitrogen precharge pressure by 345 kPa (50 psi) and perform the road test again.

   Note: Only add enough nitrogen in order to achieve a suitable ride for the machine's typical payload.