950G Wheel Loader, 962G Wheel Loader and IT62G Integrated Toolcarrier Hydraulic System Caterpillar

Ride Control Accumulator - Test and Charge

Usage:

950G 3JW

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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 immediately 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 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 attachments have been lowered, 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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Sudden movement or accidental starting of the machine can cause personal injury or death to persons on or near the machine.
To prevent personal injury or death, perform the following:
Park the machine on a smooth, level surface.
Lower the work tool to the ground and engage the parking brake.
Stop the engine and remove the key.

Block the wheels and install the steering frame lock.

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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

Move the machine to a hard, level surface.

Engage the parking brake.

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Illustration 1	g00297434

Move ride control switch (1) to the ON position.

Lower all attachments to the ground.

Move the lift control lever to the FLOAT position. This will relieve all of the hydraulic pressure in the accumulator.

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

Disconnect the hydraulic lines for servicing, as needed.

Discharging the Accumulator

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

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Illustration 2	g00297435
Ride Control Accumulator

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Illustration 3	g00297440
(2) Nitrogen Charging Valve

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) Chuck (16) Hose assembly (17) Tee

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 . For a nitrogen charging valve with a .482 inch - 26 THD, use a 7S-5106 Nitrogen Charging Chuck .

Note: Do not attach hose assembly (16) to tee (17) when you are discharging the accumulator.

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

Turn valve handle (14) on chuck (15) all the way in the counterclockwise direction. This will ensure that nitrogen charging valve (2) will not open when chuck (15) is attached to nitrogen charging valve (2) .

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

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

Turn valve handle (14) on 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 ride control accumulator through hose assembly (16) . Now, the ride control accumulator can be removed from the machine.

Nitrogen Charging Procedure

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

Move the machine to level ground.

Move the transmission direction control lever to the NEUTRAL position. Move the transmission neutralizer lockout switch to the OFF position.

Engage the parking brake.

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

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

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Illustration 5	g00297440
(2) Nitrogen Charging Valve

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

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Illustration 6	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) Chuck (16) Hose assembly (17) Tee

Turn tee handle (14) on chuck (15) all the way in the counterclockwise direction. Attach appropriate 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 . For a nitrogen charging valve with a .482 inch - 26 THD, use a 7S-5106 Nitrogen Charging Chuck .

Attach hose assembly (16) between chuck (15) and tee (17) . Install needle valve (9) on one of the connecting points of the tee. Install 8T-0858 Pressure Gauge (10) in the remaining open port on the tee. The pressure gauge is rated at 0 to 16000 kPa (0 to 2300 psi).

Install coupling assembly (7) in the end of hose assembly (6) .

Install nipple (8) on needle valve (9) . Place the open end of hose assembly (6) away from the work area and away from other personnel.

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

Raise the bucket to the maximum height in order to relieve any additional nitrogen from the ride control accumulator.

Close needle valve (9) .

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

Install nipple (3) in the end of hose assembly (6) .

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 0 to 25000 kPa (0 to 3600 psi).

Install an 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).

Install regulator assembly (11) on the nitrogen tank valve. 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 Table are recommended for machines with typical buckets. For machines with heavy buckets, the nitrogen pressure may need to be increased in order to keep the accumulator piston from striking an internal stop during normal roading while the ride control system is activated. However, raising the nitrogen pressure will result in a stiffer ride.

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Table 2
950G Accumulator Precharge Pressure/Temperature Relationship for a Typical Ride Control Accumulator with a Precharge of 3270 kPa (475 psi)
Temperature	Pressure ⁽¹⁾
-7°C (20°F)	2994 kPa (435 psi)
-1°C (30°F)	3049 kPa (443 psi)
4°C (40°F)	3105 kPa (451 psi)
10°C (50°F)	3160 kPa (459 psi)
16°C (60°F)	3215 kPa (467 psi)
21°C (70°F)	3270 kPa (475 psi)
27°C (80°F)	3325 kPa (483 psi)
32°C (90°F)	3380 kPa (491 psi)
38°C (100°F)	3435 kPa (499 psi)
43°C (110°F)	2491 kPa (507 psi)
49°C (120°F)	2546 kPa (515 psi)

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^( 1 )

Nominal allowable tolerance equals ± 35 kPa (± 5 psi).

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Table 3
962G Accumulator Precharge Pressure/Temperature Relationship for a Typical Ride Control Accumulator with a Precharge of 3270 kPa (475 psi)
Temperature	Pressure ⁽¹⁾
-7°C (20°F)	2994 kPa (435 psi)
-1°C (30°F)	3049 kPa (443 psi)
4°C (40°F)	3105 kPa (451 psi)
10°C (50°F)	3160 kPa (459 psi)
16°C (60°F)	3215 kPa (467 psi)
21°C (70°F)	3270 kPa (475 psi)
27°C (80°F)	3325 kPa (483 psi)
32°C (90°F)	3380 kPa (491 psi)
38°C (100°F)	3435 kPa (499 psi)
43°C (110°F)	2491 kPa (507 psi)
49°C (120°F)	2546 kPa (515 psi)

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^( 1 )

Nominal allowable tolerance equals ± 35 kPa (± 5 psi).

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Table 4
IT62G Accumulator Precharge Pressure/Temperature Relationship for a Typical Ride Control Accumulator with a Precharge of 2760 kPa (300 psi)
Temperature	Pressure ⁽¹⁾
-7°C (20°F)	1793 kPa (260 psi)
-1°C (30°F)	1848 kPa (268 psi)
4°C (40°F)	1903 kPa (276 psi)
10°C (50°F)	1958 kPa (284 psi)
16°C (60°F)	2013 kPa (292 psi)
21°C (70°F)	2068 kPa (300 psi)
27°C (80°F)	2124 kPa (308 psi)
32°C (90°F)	2179 kPa (316 psi)
38°C (100°F)	2234 kPa (324 psi)
43°C (110°F)	2289 kPa (332 psi)
49°C (120°F)	2344 kPa (340 psi)

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^( 1 )

Nominal allowable tolerance equals ± 35 kPa (± 5 psi).

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 needle valve (9) . Disconnect hose assembly (6) from needle valve (9) . Repeat Steps through .

Turn tee handle (14) on chuck (15) all the way in the counterclockwise direction. Close regulator (11) and needle valve (9) . Slowly disconnect hose (6) from needle valve (9) . Open needle valve (9) . Remove chuck (15) from nitrogen charging valve (2) which is on the ride control accumulator.

Install the protective cap on the nitrogen charging valve (2) .

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 ride control accumulator is charged.

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Illustration 7	g00297434
(1) Ride Control Switch

Start the machine.

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

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

When the front wheels are off the ground, place the lift control lever in the HOLD position and move the ride control switch to the ON 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 is faulty.
- The solenoid coil on the diverter valve is faulty.
- The cartridge valve in the diverter valve is faulty.
- The diverter valve spool sticks.
- The pilot oil passage to the ride control diverter valve is blocked.

Road Test

Put a typical load in the bucket.

Move the ride control switch to the ON position.

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 20670 kPa (3000 psi).

Reference: For more information on the Nitrogen Charging Procedure, refer to Testing and Adjusting, "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.