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Sudden movement or accidental starting of the machine can cause personal injury or death to persons on or near the machine. To prevent personal injury or death, perform the following: Park the machine on a smooth, level surface. Lower the work tool to the ground and engage the parking brake. Stop the engine and remove the key. Block the wheels and install the steering frame lock. |
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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 work tools have been lowered to the ground, and the 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. |
| Required Tools | ||
| Part Number | Description | Qty |
| 6V-3965 | Fitting Assembly | 1 |
| 3J-1907 | O-Ring Seal | 1 |
| 8T-8902 | Tee | 1 |
| 6V-8397 | O-Ring Seal | 1 |
| 8T-0850 | Pressure Gauge | 1 |
The pilot control actuator is an electrohydraulic valve that controls the pilot oil pressure to each end of the main control valve spools. When the solenoid for the pilot control actuator is activated, pilot oil is drained to the hydraulic tank. The main control valve spool moves toward the activated pilot control actuator. When the implement control levers are in the HOLD position, there is full pilot oil pressure in the pilot control actuators at both ends of the main control valve spool.
This procedure measures the oil pressure in the pilot control actuators. This procedure will allow you to verify if the pilot control actuators are functioning properly.
For most tests, a pressure gauge should be connected to the pilot control actuator at each end of the valve spool. This procedure will allow pilot pressure to be measured on each end at the same time.
- Connect the steering frame lock link.
- Release the hydraulic system pressure. Refer to Testing and Adjusting, "System Pressure - Release" for the machine that is being serviced.
- Attach a 8T-0850 Gauge (
4000 kPa (580 psi) ) to the nipple 6V-3965 Quick Disconnect Coupler that is the supply for each actuator. - Engage the parking brake.
- Shift the transmission to neutral.
- Start the engine and warm the hydraulic oil to a normal operating temperature of approximately
49 to 65°C (120 to 150°F) . - With the engine at low idle, record the gauge reading.
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| Illustration 1 | g01448144 |
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Front of Implement Main Control Valve Location of the pressure taps for the solenoid valves (1) Tilt back (left) (2) Lower (left) (3) Lower (right) (4) Tilt back(right) (5) Main hydraulic valve (right) (6) Main hydraulic valve (left) | |
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| Illustration 2 | g01448193 |
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Rear of Implement Main Control Valve Location of pressure taps for the solenoid valves (5) Main hydraulic valve (right) (6) Main hydraulic valve (left) (7) Dump (right) (8) Raise (left) (9) Raise (right) (10) Dump (left) | |
With the control levers in the HOLD position, there must not be more than
When the control levers are in the HOLD position, the pressure for the pilot system should be approximately
The pressure for the pilot control actuator should be equal to the hydraulic tank pressure when the pilot control valve is fully actuated.