216B, 226B, 232B and 242B Skid Steer Loaders Machine Systems Caterpillar

Charge Pressure Test

The following test is performed in order to check the charge pressure of the pilot oil accumulator.

Accumulator That Is Not Rechargeable

Illustration 1	g01136249
Typical accumulator that is not rechargeable

Perform this test if the pilot accumulator is not rechargeable.

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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.

Before any tests are performed, visually inspect the complete hydraulic system for oil leaks and damaged parts. Refer to Testing and Adjusting, "Visual Inspection". Before any tests are performed, prepare the machine for troubleshooting. Refer to Testing and Adjusting, "Machine Preparation for Troubleshooting".

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

2. Lower the work tool to the ground. Stop the engine.

3. Engage the parking brake.

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

5. Turn the engine start switch key to the ON position.

6. Move the pilot valves to all positions in order to release the pressure in the hydraulic system.

7. Turn the engine start switch key to the OFF position.

8. Raise the cab. Refer to Operation and Maintenance Manual, "Cab Support Operation".

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Illustration 2	g01138678
Supply line for the pilot operated hydraulic control (work tool)

9. Install 7X-2444 Swivel Tee and 6V-5049 O-Ring Seal to the end of the supply line for the pilot operated hydraulic control (work tool). Install 6V-3965 Fitting and 3J-1907 O-Ring Seal to the tee.

10. Attach 6V-3989 Unvalved Fitting to 8T-0856 Pressure Gauge .

11. Attach two 6V-4143 Quick Connect Couplers to 177-7860 Hose .

12. Attach one 6V-4143 Quick Connect Coupler to the 6V-3965 Fitting. Attach the other 6V-4143 Quick Connect Coupler to the 6V-3989 Unvalved Fitting .

13. Lower the cab. Do not pinch the hose.

14. Sit in the seat. Fasten the seat belt and lower the armrest.

15. Start the engine. Disengage the parking brake.

16. Run the engine at specified RPM in 2. The pilot pressure should be within the specification in 2. If the pilot pressure is not correct, refer to Testing and Adjusting, "Hydrostatic System - Test and Adjust".
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    Table 2

    MODEL	ENGINE RPM	PILOT PRESSURE
    216BSCH1-2474	2500 ± 25 RPM	3225 ± 200 kPa (468 ± 29 psi)
    232B(S/N: SCH2475-Up)	2550 ± 50 RPM	3225 ± 200 kPa (468 ± 29 psi)
    226B/ 242B Group 1 (1)	2800 ± 10 RPM	3260 ± 200 kPa (473 ± 29 psi)
    226B/ 242B Group 2 (2)	2550 ± 25 RPM	3225 ± 200 kPa (468 ± 29 psi)

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    ( 1 )	GROUP 1: 226B MJH 1-7775, and 242B, BXM 1-3253
    ( 2 )	GROUP 2: 226B MJH 7776-UP, and 242B, BXM 3254-UP

    Note: For machines in Group 1, if the hystat pump is replaced with a new 289-6342 Piston Pump or remanufactured 10R-4356 Piston Pump, use the settings for Group 2.

17. Use the hydraulic implement control in order to move the lift arms to the full RAISE position. Stop the engine.

18. Turn the engine start switch key to the ON position.

19. Use the hydraulic implement control in order to move the lift arms to the full LOWER position. The lift arms will lower. The pressure will decrease in one of the following ways:
    • The pressure decreases slowly until the pressure reaches 900 ± 100 kPa (130 ± 15 psi). Then, the pressure decreases rapidly. If this happens, the accumulator is properly charged. Proceed to Step 20.

    • If the pressure decreases rapidly, the accumulator is not properly charged. Replace the accumulator with a rechargeable accumulator. Refer to Disassembly and Assembly, "Accumulator - Remove and Install". Proceed to the Accumulator Charge.

20. Remove the chocks.

Rechargeable Accumulator

Illustration 3	g01138634
Typical rechargeable accumulator

Perform this test if the pilot accumulator is rechargeable.

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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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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.

Before any tests are performed, visually inspect the complete hydraulic system for oil leaks and damaged parts. Refer to Testing and Adjusting, "Visual Inspection". Before any tests are performed, prepare the machine for troubleshooting. Refer to Testing and Adjusting, "Machine Preparation for Troubleshooting".

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

2. Lower the work tool to the ground. Stop the engine.

3. Engage the parking brake.

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

5. Turn the engine start switch key to the ON position.

6. Move the pilot valves to all positions in order to release the pressure in the hydraulic system.

7. Turn the engine start switch key to the OFF position.

8. Raise the cab. Refer to Operation and Maintenance Manual, "Cab Support Operation".

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Illustration 4	g01138645
Nitrogen Charging Group (1) Pressure gauge (2) Valve (3) Pressure gauge (4) Regulator assembly (5) Pressure regulating screw (6) Nipple assembly for the nitrogen cylinder valve (7) Valve handle (8) Chuck

9. Turn the valve (2) completely in the clockwise direction. Turn the valve handle (7) completely in the counterclockwise direction.

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Illustration 5	g01136222
Location of the Accumulator

10. Install the chuck (8) to the accumulator.

11. Turn the valve handle (7) completely in the clockwise direction. The reading on the pressure gauge (3) should be 900 ± 100 kPa (130 ± 15 psi).

12. If the reading on the pressure gauge is too high, repeat steps 5 through 7. This ensures that there is no hydraulic oil in the accumulator. If the pressure is still high, slowly open valve (2) in order to lower the pressure. If the pressure is too low, proceed to the Accumulator Charge.

13. Close valve (2). Close the valve on the nitrogen cylinder.

14. Turn the valve handle (7) completely in the counterclockwise direction.

15. Remove the chuck (8) from the accumulator.

16. Open the valve (2). This will release the pressure between the valve (2) and the valve on the nitrogen cylinder. Remove the nipple assembly (6) from the nitrogen cylinder.

17. Lower the cab.

18. Fasten the seat belt. Start the engine.

19. Move the work tool to the full RAISE position. Stop the engine.

20. Turn the engine start switch key to the ON position.

21. Move the work tool to the full LOWER position. If the work tool lowers to the ground, proceed to step 20. If the work tool does not lower to the ground, start the engine and lower the work tool to the ground. Repeat steps 5 through 19.

    Note: If the work tool does not lower to the ground after charging the accumulator two times, refer to Testing and Adjusting, "Hydraulic System Troubleshooting" for probable causes.

22. Remove the chocks.

Accumulator Charge

The following procedure is performed in order to charge the rechargeable accumulator (pilot) to the correct precharge pressure.

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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).

Show/hide table

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.

Before any tests are performed, visually inspect the complete hydraulic system for oil leaks and damaged parts. Refer to Testing and Adjusting, "Visual Inspection". Before any tests are performed, prepare the machine for troubleshooting. Refer to Testing and Adjusting, "Machine Preparation for Troubleshooting".

Show/hide table



Illustration 6	g01138645
Nitrogen Charging Group (1) Pressure gauge (2) Valve (3) Pressure gauge (4) Regulator assembly (5) Pressure regulating screw (6) Nipple assembly for the nitrogen cylinder valve (7) Valve handle (8) Chuck

1. Perform Steps 1 to 10 of Charge Pressure Test (Rechargeable Accumulator) in order to install the 175-5507 Nitrogen Charging Group .

2. Turn the valve handle (7) completely in the clockwise direction. The reading on the pressure gauge (3) should be 900 ± 100 kPa (130 ± 15 psi).

3. If the reading on the pressure gauge is too high, repeat steps 5 through 7. This ensures that there is no hydraulic oil in the accumulator. If the pressure is still high, slowly open valve (2) in order to lower the pressure. If the reading on the pressure gauge is too low, use the following procedure in order to charge the accumulator:

   1. Connect the nipple assembly (6) to the nitrogen cylinder.

   2. Open the valve on the nitrogen cylinder. Adjust screw (5) on the regulator assembly (4) until the reading on pressure gauge (1) is 900 ± 100 kPa (130 ± 15 psi).

   3. Open valve (2) and charge the accumulator. Then, close valve (2). If pressure gauge (3) and pressure gauge (1) show the same reading and the readings do not change, the accumulator has the correct charge.

      If the pressure reading on gauge (3) decreases, open valve (2) and allow more nitrogen to fill the accumulator.

      Perform this procedure until pressure gauge (3) and pressure gauge (1) show the same reading. Make sure that neither reading changes when valve (2) is closed.

4. Close valve (2). Close the valve on the nitrogen cylinder.

5. Turn the valve handle (7) completely in the counterclockwise direction.

6. Remove the chuck (8) from the accumulator.

7. Open the valve (2). This will release the pressure between the valve (2) and the valve on the nitrogen cylinder. Remove the nipple assembly (6) from the nitrogen cylinder.

8. Lower the cab.

9. Fasten the seat belt. Start the engine.

10. Move the work tool to the full RAISE position. Stop the engine.

11. Turn the engine start switch key to the ON position.

12. Move the work tool to the full LOWER position. If the work tool lowers to the ground, proceed to step 13. If the work tool does not lower to the ground, start the engine and lower the work tool to the ground. Repeat the Accumulator Charge.

    Note: If the work tool does not lower to the ground after charging the accumulator two times, refer to Testing and Adjusting, "Hydraulic System Troubleshooting" for probable causes.

13. Remove the chocks.