Priority Valve

1. The oil from the pump enters the priority valve through port P and, passing through the external passage of spool, it reaches port CF. From port CF, the oil flows through the internal passage of the spool and then through the following:

Orifice Cdy → Pressure chamber B → Orifice Cls → LS port of orbitrol→ tank.

2. The pressure difference produced when the oil passes through orifice Cdy (called “dynamic orifice”) causes spool to move toward spring until the oil pressure pushing the spool balances with the spring force. As a result, almost all the oil delivered from the pump is routed through port EF and available for use by the other actuator circuits.