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Hydraulic oil pressure can remain in the hydraulic system on this machine after the engine and pump have been stopped. Serious injury can result if this pressure is not released before any service is done on the hydraulic system. In order to prevent possible injury, release the hydraulic system pressure before working on any fitting, hose, or hydraulic component. Lower all work tools to the ground before service is started. If the hydraulic system must be serviced, tested, or adjusted with the work tool in the raised position, the work tool and lift cylinders must be supported properly. Always move the machine to a location away from the travel of other machines. Be sure that other personnel are not near the machine when the engine is running and tests or adjustments are being made. |
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Personal injury can result from removing hoses or fittings in a system under pressure. Failure to relieve pressure can cause personal injury. Do not remove or disconnect hoses or fittings until all pressure in the hydraulic system has been relieved. |
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| NOTICE |
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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. |
ReferenceRefer to System Operation, "Machine Preparation for Troubleshooting" before you begin this procedure.
Introduction
The following test procedure will verify whether the pressure setting for the pilot pressure is within the specified limit. The following adjustment procedure will explain the procedure for adjusting the pilot pressure.
Required Tools
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| Illustration 1 | g02109937 |
Tooling (A) | |
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| Illustration 2 | g01623868 |
Tooling (B) | |
| Tool | Item | Part Number | Description | Qty |
|---|---|---|---|---|
| A | A1 | 8T-0855 | Pressure Gauge (0 to 4,000 kPa (0 to 580 psi)) | 1 |
| A1 | 8T-0857 | Pressure Gauge (0 to 10,000 kPa (0 to 1,450 psi)) | 1 | |
| A2 | 6V-3989 | Fitting | 1 | |
| A3 | 6V-4143 | Quick Connect Coupler | 2 | |
| A4 | 177-7861 | Hose As (4.3 m (14 ft)) | 1 | |
| B | 198-4240 | Digital Pressure Indicator Gp | ||
| B1 | 198-4234 | Digital Indicator | 1 | |
| B2 | 198-4239 | Pressure Sensor Gp (0 to 41,368 kPa (0 to 6000 psi)) | 1 | |
| B3 | 198-4236 | Adapter Cable As | 1 | |
Note: Tooling (A) or Tooling (B) may be used to perform these tests.
Machine Preparation
- Move the machine to a smooth horizontal location.
- Chock the wheels.
- Lower all of the implements.
- Remove the dust cap on test port (1) .
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| Illustration 3 | g03405507 |
(1) Pressure test port for pilot pressure (2) Adjustment screw for pressure reducing valve (pilot pressure) (3) Locknut (4) Pressure reducing valve | |
- Attach Tooling (A) to test port (1) . Pressure test port (1) will indicate the oil pressure in the pilot system for the implements. Pressure reducing valve (4) limits the pilot system for the implements. Pressure reducing valve (4) will close when the pilot system reaches the pilot pressure.
Test Procedure
- Start the engine.
- In order to test the pilot pressure, run this test with hydraulic oil at 60° ± 5°C (140° ± 9°F).
- Stall the blade tip cylinder.
- Operate the engine at high idle. Throttle to 2150 rpm
- Check that pump discharge pressure is 10,000 kPa (1450 psi) or higher.
- Record the pilot pressure at test port (1) . Pilot pressure should be 4000 ± 200 kPa (580 ± 29 psi).
- If the pressure at Tooling (A) is within the specified limit, the test is complete.
Adjustment Procedure
- In order to adjust the pilot pressure, run this test with hydraulic oil at 60° ± 5°C (140° ± 9°F).
- If the pressure reading is incorrect, loosen locknut (3) on adjustment screw (2) . Turn the adjustment screw clockwise in order to increase the setting. Turn the adjustment screw counterclockwise in order to decrease the setting.
- When you tighten locknut (3) hold adjustment screw (2) secure. Repeat this procedure until you obtain the correct pressure setting in Step 6.
- If the pressure at Tooling (A) is at the specified limit, the adjustment procedure is complete.
- If the pressure is not within the specified limit, repeat Step 2 and Step 3.
- Stop the engine.
- Remove Tooling (A) . Replace the dust cap on test port (1) .