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| Illustration 1 | g00301803 |
Components of the priority valve (1) Inlet passage. (2) Body. (3) Spacers. (4) Outlet passage. (5) Spool assembly. (6) Poppet valve. (7) Slug. | |
The priority valve is fastened to the rear of the transmission selector and pressure control valve. Body (2) supports the bellcranks for the speed and direction spools. Also, the body is a manifold for the oil that flows in and out of the pressure control valve.
The priority valve makes sure that the oil pressure is available first for the steering and braking. After the steering and braking oil pressure has been provided, oil pressure is then provided for the hook winch control operation. Lastly, oil is provided for transmission operation.
The priority valve is set to open to the transmission controls at 2900 kPa (420 psi).
Oil from the transmission charging section of the power train oil pump flows through the transmission oil filter into inlet passage (1). The oil flows from the inlet passage through a hole in spool assembly (5) and into the chamber between poppet valve (6) and slug (3) .
The pressure oil can now move spool assembly (5) to the right against the force of the spring. When the pressure of the oil in the chamber becomes higher than the force of the spring, spool assembly (5) moves.
The movement of the spool allows oil flow to outlet passage (4). From outlet passage (4), the pressure oil flows to the transmission selector and pressure control valve.