950M and 962M Wheel Loaders Power Train, Steering, Braking, Hydraulic, and Machine Systems Caterpillar

Ride Control Accumulator - Test and Charge

Usage:

962M EJB

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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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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, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat^® products. Dispose of all fluids according to local regulations and mandates.

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Illustration 1	g03554576
Ride control switch

Specifications

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Illustration 2	g03730779
View of Ride Control Accumulators from Left Side of machine. (6) Ride Control Accumulator - High Pressure (7) Ride Control Accumulator - Low Pressure

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Table 1
Ride Control Accumulator Pressures at 21° C (70° F)
Item	Pressure
6⁽¹⁾	6000 kPa (870 psi)
7⁽¹⁾	2000 kPa (290 psi)

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⁽¹⁾	Refer to Illustration 2

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Table 2
Accumulator Precharge Pressure Temperature Relationship for a Typical Ride Control Accumulator
Temperature ° C (° F)	Pressure Correction kPa (psi)
−7° C (20° F)	−270 kPa (−39 psi)
−1° C (30° F)	−215 kPa (−31 psi)
4° C (40° F)	−160 kPa (−23 psi)
10° C (50° F)	−105 kPa (−15 psi)
16° C (60° F)	−50 kPa (−7 psi)
21° C (70° F)	0 kPa (0 psi)
27° C (80° F)	60 kPa (8 psi)
32° C (90° F)	115 kPa (16 psi)
38° C (100° F)	170 kPa (25 psi)
43° C (110° F)	225 kPa (32 psi)
49° C (120° F)	280 kPa (40 psi)

Machine Preparation

Prepare the machine for testing by completing the procedure that is specified in the Service Manual module Testing and Adjusting, "Machine Preparation for Troubleshooting" for the machine that is being serviced.

Discharging the Accumulator

Refer to Special Instruction, REHS5464, "Accumulator Discharging and Charging Procedures" for the required tooling, and the testing and charging procedure.

Testing Procedure for the Accumulator Precharge Pressure

Refer to Special Instruction, REHS5464, "Accumulator Discharging and Charging Procedures" for the required tooling, and the testing and charging procedure.

Charging Procedure

Refer to Special Instruction, REHS5464, "Accumulator Discharging and Charging Procedures" for the required tooling, and the testing and charging procedure.

Note: Each accumulator will need to be isolated prior to servicing.

Ride Control Activation

Note: The following steps are used to determine if the ride control valve is operating correctly. This test should be performed in order to verify that the ride control is being activated.

Lift the front wheels off the ground by moving the bucket to the full LOWER position. With the front wheels off the ground, place the lift control lever in the HOLD position.
Turn the ride control ON and place into "SERVICE" mode.
1. Set the parking brake.
2. Press and hold the ride control button for 2 seconds. The bottom two LEDs next to the button will illuminate to indicate that the ride control is in service mode. The Ride Control LED will turn green on the indication display while in the service mode.
  Note: The front wheels should lower to the ground. If the wheels do not lower to the ground, the ride control spool has not shifted to the ON position. The following causes could be the reason that the ride control spool does not move to the ON position:
  - A failure of the solenoid coil on the ride control valve
  - A failure of the cartridge valve in ride control valve
  - A failure of the spool valve in the ride control valve
  - A blockage in pilot circuit to the ride control valve

Road Test

Note: The pressure of 2000 kPa (290 psi) at 21 °C (70 °F) is the recommended low-pressure accumulator charge pressure for machines with an empty bucket of typical weight.

The pressure of 6000 kPa (870 psi) at 21 °C (70 °F) is the recommended high-pressure accumulator charge pressure for machines with normal payloads.

Note: Due to the presence of dual accumulators, the Road Test procedure requires testing with both empty and loaded payloads for proper adjustments.

Procedure for Empty Bucket Ride Road Test

Place the empty bucket in a typical carry position.
Place the ride control system in "AUTO" mode
1. Momentarily press the ride control button until only the middle LED is illuminated.
  Note: For more information refer to Operation and Maintenance Manual, "Operator Controls" for your machine.
Drive the machine over a fairly rough road surface.
Make sure that you achieve a speed above the ride control activation speed.
If the ride is too soft or a noise is heard from contact between the piston and the stop, the nitrogen charge pressure in the low-pressure accumulator (7) must be increased.
Increase the low-pressure accumulator (7) charge pressure by 345 kPa (50 psi).
Refer to Special Instruction, REHS5464, "Accumulator Discharging and Charging Procedures" for details.
Note: The ride control accumulators are rated up to 30000 kPa (4351 psi).
Repeat Steps 3 thru 5 as required until a suitable ride is achieved.

Procedure for Loaded Bucket Ride Road Test

Obtain a typical load in the bucket and place in a typical carry position.
Place the ride control system in "AUTO" mode
1. Momentarily press the ride control button until only the middle LED is illuminated.
  Note: For more information refer to Operation and Maintenance Manual, "Operator Controls" for your machine.
Drive the machine over a fairly rough road surface.
Make sure that you achieve a speed above the ride control activation speed.
If the ride is too soft or a noise is heard from contact between the piston and the stop, the nitrogen charge pressure in the high-pressure accumulator (6) must be increased.
Increase the high-pressure accumulator (6) charge pressure by 345 kPa (50 psi).
Refer to Special Instruction, REHS5464, "Accumulator Discharging and Charging Procedures" for details.
Note: The ride control accumulators are rated up to 30000 kPa (4351 psi).
Repeat Steps 3 thru 5 as required until a suitable ride is achieved.