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Sudden movement of the machine or release of oil under pressure can cause injury to persons on or near the machine. To prevent possible injury, perform the procedure that follows before testing and adjusting the hydraulic system. |
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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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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. |
The line relief valves, except for boom and stick head end, are not adjustable. If the circuit is below system pressure, replace the line relief valve for that circuit. The line relief valves, with the right service tool test block can be tested to verify proper cracking pressure.
| Line Relief Valve Pressure Settings | Actual | ||
|---|---|---|---|
| Hydraulic Circuit | Pressure Setting | Actual Recorded Pressure | |
| Rod End for BOX BLADE DOWN | |
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| REQUIRED TOOLS | ||
| Part Number | Description | Quantity |
| 8T-0860 | Gauge 0 kPa to 40000 kPa | 1 |
| 3S-6224 | Electric Hydraulic Pump | 1 |
| 8F-0024 | Hose Assembly | 2 |
| 1P-2376 | Coupler Assembly | 2 |
| 1P-2375 | Coupler Assembly | 2 |
| 1P-2377 | Plug | 2 |
| 7J-8611 | Elbow | 1 |
| 3B-7722 | Bushing | 2 |
| 030-8370 | Adapter | 2 |
- Move the machine to a smooth, horizontal location that is away from operating machines and away from personnel.
- Engage the parking brake.
- Lower the Loader bucket and box blade to the ground.
- Release the hydraulic pressure.
Note: Refer to the Service Manual "Testing and Adjusting", System Pressure Release for information needed to release hydraulic pressure.
- Use the following Steps to test or check the appropriate relief valve setting:
- Remove the line relief valve to be tested and fit to the appropriate service tool line relief valve test block.
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Illustration 1 g01296672 Example - Secure the appropriate test block in a suitable holding device.
- Install two 030-8370 Adapters (G) and two 1P-2375 Couplers (H) in 288-6823 Manifold (E).
- Attach two 1P-2376 Adapters (J) to two 8F-0024 Hose Assemblies (K).
- Install line relief valve (F) in 288-6823 Manifold (E).
- Connect two 8F-0024 Hose Assemblies (K), two 3B-7722 Bushings, and 7J-8611 Elbow to 3S-6224 Electric Hydraulic Pump.
- Connect 8T-0860 Gauge to 3S-6224 Electric Hydraulic Pump.
- Turn the 3S-6224 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. - Slowly increase the pressure. Record the pressure, when the line relief valve opens. Compare this pressure to Table 1.
- Stop the pump.
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Illustration 2 g01296607 Line Relief Valve
(A) Cap
(B) Screw for Adjusting
(C) Locknut - If the line relief valve is within the specification, then go to Step 14. If the line relief valve is not within the specification, then an adjustment or replacement is required.
- Remove cap (A). Loosen locknut (C) and turn adjusting screw (B) clockwise to increase pressure. Turn adjusting screw (B) counterclockwise to decrease pressure.
- Check the oil level in the 3S-6224 Electric Hydraulic Pump and refill the oil if necessary. Repeat Steps 9,10,11, and 12.
- Tighten locknut (C) to a torque of
20 N·m (15 lb ft) . - Remove the line relief valve .
- Install a new O-ring on the line relief valve .
- Install the line relief valve to a torque of
70 N·m (50 lb ft) .
