Low pressure oil is supplied to the pilot valve (oil manifold) by the pilot/brake pump. The pilot oil flows through the pilot valve (oil manifold) to pilot valve (2). The oil then flows to the main control valve in order to control the operation of the lift cylinders, tilt cylinder, and auxiliary cylinders.
Note: Illustration 1 shows a machine without an auxiliary control lever. Machines with an auxiliary function (logging fork, side dump bucket, multipurpose bucket, etc) have an auxiliary control lever to the right of lift control lever (4).
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| Illustration 1 | g00348752 |
Control Levers for the Pilot Hydraulic System (1) Ball valve (hydraulic lever lock) (UNLOCKED position). (2) Pilot valve. (3) Tilt control lever. (4) Lift control lever. | |
The following components are found on the right side of the operator seat: Ball valve (hydraulic lever lock) (1), pilot valve (2), tilt control lever (3) and lift control lever (4). Tilt control lever (3) and lift control lever (4) are attached to the pilot valve.
Pilot valve (2) has a separate valve for controlling the tilt function and the lift function. When a control lever is moved out of the HOLD position, the valve directs the flow of pilot oil to a valve spool in the main control valve.
When a valve spool in the main control valve moves, high pressure oil flows to the corresponding implement cylinder. This causes the implement cylinders to operate.
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| Illustration 2 | g00308451 |
View of the Right Side of the Cab (5) Ball valve (hydraulic lever lock) (LOCKED position). | |
In order to disable the implement hydraulic system, move the ball valve (hydraulic lever lock) (5) into the LOCKED position. When the ball valve (hydraulic lever lock) is in the LOCKED position, the flow of pilot oil to the pilot valve is blocked. The control levers can still move, but the implement cylinders will not operate.
The control levers cannot be placed in a DETENT position, when the ball valve (hydraulic lever lock) (5) is in the LOCKED position. An override switch that is in contact with the ball valve (hydraulic lever lock) opens. The flow of electricity to the pilot valve is stopped.
The override switch prevents the electromagnets in the pilot valve from becoming energized. The lack of electrical current keeps the control levers out of the DETENT position.
Reference: For more information on the operation of the control levers in the DETENT position, refer to the Service Manual module for Systems Operation, "Kickout System (Pilot Hydraulic System)" for the machine that is being serviced.