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Personal injury or death can result from sudden machine movement. Sudden movement of the machine can cause injury to persons on or near the machine. To prevent injury or death, make sure that the area around the machine is clear of personnel and obstructions before operating the machine. |
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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. |
Operational Checks
Operational checks of the leveling blade can be used for a diagnosis of poor performance. The operational checks can also be used to find leakage in the hydraulic system.
Probable Causes of Problems in the Leveling Blade System
Problem
The gear pump makes noise and the blade cylinder rod does not move smoothly.
Probable Cause
- There is air in the hydraulic circuit.
- The gear pump is worn.
- There is a loose oil line connection on the inlet side of the gear pump.
- The hydraulic oil level is low.
- Viscosity of the hydraulic oil is not correct.
- Malfunctioning flow priority valve in steer pump.
Problem
The blade does not move smoothly or the blade does not move at all.
Probable Cause
- Internal leakage in the blade cylinder
- The engine is not at high idle.
- The linkage for the blade control valve has malfunctioned.
- The blade control valve has malfunctioned.
- There is binding in the blade pivot points.
- Malfunctioning flow priority valve in steer pump.
Problem
Temperature of oil is too hot.
Probable Cause
- The hydraulic oil level is low.
- Viscosity of the hydraulic oil is not correct.
- Air is mixed with the oil.
- The relief valve is damaged or the adjustment of the relief valve is not correct.
- A hydraulic line or one of the components is restricted.
Problem
The position of the blade drifts when the control lever is in HOLD position.
Probable Cause
- The control valve body and the spool are worn.
- The centering spring in the control valve is damaged.
- Seal leakage in the cylinder.