247B and 257B Multi Terrain Loaders Machine Systems Caterpillar

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

The pilot system pressure test determines the pressure to the joystick controls. The charge pump section of the gear pump supplies the pilot oil.

1. Engage the parking brake. Stop the engine.

2. Block the tracks of the machine.

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

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Illustration 1	g01355400
(1) Charge pressure tap

4. Install a 6V-4143 Quick Connect Coupler to each end of 177-7861 Hose. Install the 6V-3989 Fitting to the 8T-0856 Pressure Gauge. Connect the pressure gauge to the charge pressure tap (1) by using the hose and coupler assembly.

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Illustration 2	g01364317
(2) Supply line for the work tool joystick control

5. Install a 6V-3965 Fitting As to the end of supply line (2) by using the 7X-2444 Tee. Use a 6V-5049 O-Ring Seal when you install the tee. Use a 3J-1907 O-Ring Seal when you connect the fitting assembly to the tee. The supply line is for the pilot operated hydraulic control ( work tool).

6. Install a 6V-4143 Quick Connect Coupler to each end of the 177-7861 Hose As. Install the 6V-3989 Fitting to the 8T-0856 Pressure Gauge. Connect the pressure gauge to the pressure tap (2) on the pilot operated hydraulic control (work tool). Use the hose and coupler assembly.

7. Secure the three hydraulic lines so that the pressure gauges can be viewed by the operator during the test. The hoses should not be pinched when the cab is lowered.

8. Lower the cab.

9. Sit in the operator's seat. Fasten the seat belt and lower the armrest.

10. Start the engine. Disengage the parking brake.

11. Run the engine at LOW IDLE. Record the charge pressure and pilot pressure.
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    Table 2

    247B/ 257B	Low Idle
    Charge Pressure	3100 ± 200 kPa (450 ± 29 psi)
    Pilot Pressure	3100 ± 200 kPa (450 ± 29 psi)

12. Set the engine RPM for all machines to the specification in Table 3.
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    Table 3

    Model	Engine RPM
    247B/ 257B	2550 ± 25 RPM

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    Table 4

    247B/ 257B	Idle at 2550 ± 25 RPM
    Charge Pressure	3225 ± 200 kPa (468 ± 29 psi)
    Pilot Pressure	3225 ± 200 kPa (468 ± 29 psi)

13. Reduce the engine to LOW IDLE. Stop the engine.

14. Raise the cab. Remove the test equipment.

15. Lower the cab. Refer to the Operation and Maintenance Manual, "Cab Support Operation". Remove the blocks.

Brake Test

This test will determine if the brakes are functioning correctly. This test will check the solenoid valve ( brake) and the piston motor.

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

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Illustration 3	g00790186

2. Disconnect electrical connection (1) for brake solenoid (2) .

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Illustration 4	g00790283

3. Install a 7X-2444 Tee (3) and a 6V-3965 Valved Nipple Assembly (4) in the hydraulic line that runs from the brake solenoid to the piston motors.

4. Install a 8T-0855 Pressure Gauge to the valved nipple with a 177-7861 Hose .

5. Lower the cab. Make sure that the hydraulic line is not pinched.

6. Sit in the operator's seat and fasten the seat belt. Lower the armrest.

7. Start the machine. The pressure gauge should read less than 300 kPa (44 psi). If the gauge does not read less than 300 kPa (44 psi), inspect the brake solenoid.

8. Stop the machine. Raise the cab and reconnect the brake solenoid.

9. Lower the cab. Sit in the operator's seat and fasten the seat belt. Lower the armrest and start the machine. Set the governor at LOW IDLE.

10. Disengage the parking brake by pressing the parking brake switch. The pressure on the gauge should be 3100 ± 200 kPa (450 ± 29 psi).

11. If the pressure is not correct, inspect the following items: the brake solenoid, the voltage for the brake solenoid and the brake seal inside the piston motor.

12. If the brake solenoid is not functioning correctly, replace the solenoid.

13. When the test is completed, raise the cab and disconnect all gauges and hoses. Lower the cab and bolt the cab in place. Refer to Operation and Maintenance Manual, "Cab Support Operation".