247B and 257B Multi Terrain Loaders Machine Systems Caterpillar

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 complete hydraulic system. Refer to the Testing and Adjusting, "Visual Inspection".

The following test is performed in order to determine if a line relief valve for the work tool is damaged or improperly set.

Machine Test (Pressure)

Table 1

REQUIRED TOOLS
Part Number	Description	Qty
6V-4143	Coupler Assemblies	2
177-7861	Hose	1
6V-3989	Unvalved Fitting	1
8T-0855	Gauge (0 to 40000 kPa)	1

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

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NOTICE
Do not adjust the main relief valve above the specified pressure. Adjustment of the main relief valve above the specified pressure may cause damage to the gear pump.

Stall Test (Boom Lower)

Perform the following test in order to determine if the main relief valve is set properly.

1. Perform the Testing and Adjusting, "Main Relief Valve - Test and Adjust".

2. Record the main relief valve pressure setting.
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   Table 2

   MAIN RELIEF PRESSURE
   Machine	Main Relief Pressure
   247B/ 257B	23000 ± 700 kPa (3336 ± 102 psi)

3. Do not disconnect the pressure gauge.

Stall Test (Boom Raise)

Perform the following test in order to determine if the line relief valve for the lift raise is set too low.

7. If the pressure gauge is not attached, attach the pressure gauge. Refer to Testing and Adjusting, "Main Relief Valve - Test and Adjust".

8. Sit in the operator's seat. Fasten the seat belt. Lower the armrest. Start the engine. Disengage the parking brake.

9. Run the engine at HIGH IDLE.

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NOTICE
Do not stall the hydraulic system for more than 10 seconds. If necessary, release the work tool from the stall condition and wait 30 seconds before you repeat the following step.

10. Press the pilot operated hydraulic control backward in order to raise the boom. Continue pressing the pilot operated hydraulic control backward in order to stall the boom.

11. Record the pressure on the pressure gauge.

12. Compare the test pressure to the main relief valve pressure setting that was recorded in table 2.
    • If the test pressure is less than the main relief valve pressure setting, then the line relief valve is set too low. Perform the "Bench Test and Adjust" in order to adjust the line relief valve pressure setting.

    • If the test pressure is equal to the main relief valve pressure setting, then the line relief valve pressure setting may be correct or the line relief valve pressure setting may be too high. Perform the "Bench Test and Adjust" in order to adjust the line relief valve pressure setting.

13. Repeat the "Stall Test (Boom Raise)" for the Tilt Forward, for the Tilt Back, and for the Auxiliary circuit.

Bench Test and Adjust

Perform the Bench Test and Adjust in order to adjust the line relief valve pressure setting.

Table 3

REQUIRED TOOLS
Tool	Part Number	Description	Qty
A	3S-6224	Electric Hydraulic Pump Gp	1
	3B-7722	Pipe Bushing	2
	7J-8611	Pipe Elbow	1
	8F-0024	Hose As	2
	1P-2375	Quick Connect Couplers	2
B	299-1731	Test Manifold Gp	1
	6V-3965	Fitting As	3
	6V-8398	O-Ring Seal	3
C	8T-0860	Pressure Gauge ( 40000 kPa (5802 psi))	1
	1P-2376	Quick Connect Coupler	2

Table 4

REQUIRED TOOLS
Part Number	Description	Quantity
1P-2377	Plug As	2
030-8370	Pipe Adapter	2

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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.

Show/hide table

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

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NOTICE
Do not adjust the main relief valve above the specified pressure. Adjustment of the main relief valve above the specified pressure may cause damage to the gear pump.

1. Lower the boom to the ground.

2. Engage the parking brake. Stop the engine.

3. Release the hydraulic system pressure. Refer to Testing and Adjusting, "Hydraulic System Pressure - Release" for the correct procedure.

4. Turn the key to the OFF position.

5. Raise the cab. Refer to Operation and Maintenance Manual, "Cab Support Operation" for the proper procedure.

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Illustration 1	g01138070
(1) Line relief valve for Lift Raise (2) Line relief valve for Tilt Forward (3) Line relief valve for Tilt Back (4) Line relief valve for Auxiliary

6. Remove the line relief valve that will be tested.

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Illustration 2	g01357866
(5) Line Relief Valve (A) Tooling (B) Tooling (C) Tooling

7. Assemble tooling (B) , as shown. Secure tooling (B) in a suitable holding device.

8. Install tooling (A) to tooling (B) .

9. Install tooling (C) to tooling (B) .

10. Install the line relief valve (5) that will be tested. Install relief valve (5) to tooling (B) .

11. Turn the electric hydraulic pump to the ON position. Check for leaks at the connection.

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NOTICE
The 3S-6224 Electric Hydraulic Pump only has a 7.6 L (2 US gal) reservoir. Pump damage may result if the pump is operated with an empty reservoir.

12. Slowly increase the pressure. Record the pressure, when the line relief valve opens. Compare this pressure to Table 5.

13. Stop the pump.
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    Table 5

    LINE RELIEF VALVE PRESSURES
    Position	247B/ 257B
    Lift Cylinder Head LIFT	27600 ± 700 kPa (4003 ± 102 psi)
    Tilt Cylinder Head TILT FORWARD	24500 ± 700 kPa (3554 ± 102 psi)
    Tilt Cylinder Rod TILT BACK	27600 ± 700 kPa (4003 ± 102 psi)
    Auxiliary Circuit	24500 ± 700 kPa (3554 ± 102 psi)

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Illustration 3	g01355331
(6) Adjustment screw (7) Cap (8) Locknut

14. If the line relief valve is within the specification, go to Step 16. If the line relief valve is not within the specification, then an adjustment is required.

    1. Remove cap (7) . Loosen locknut (8) and turn adjustment screw (6) clockwise in order to increase pressure. Turn adjustment screw (6) counterclockwise in order to decrease pressure.

    2. Check the oil level in 3S-6224 Electric Hydraulic Pump and refill the oil if it is necessary. Repeat Steps 11, 12, 13, and 14.

       Note: If you are unable to adjust the line relief valve to the correct specification, replace the old line relief valve with a new line relief valve.

15. Tighten locknut (8) to a torque of 24 ± 3 N·m (18± 2 lb ft). Install the cap (7) and tighten the cap to a torque of 24 ± 3 N·m (18± 2 lb ft).

16. Remove the line relief valve from the manifold.

17. Install a new seal on the relief valve.