Load sensing system with increasing priority in series of control valves

摘要

A hydraulic system is provided for powering a steering unit, a trailer brake and an auxiliary power unit from a single pump. A control circuit ensures that the hydraulic trailer brake and/or the power steering unit on the vehicle will operate on a preferential basis over the auxiliary power unit. The hydraulic control circuit has two priority valves connected in series. The upstream priority valve has a priority position in which it makes the pump fluid available to a supply line for the common priority flow for the steering and braking apparatus and a non-priority position for powering the auxiliary power unit. The common priority flow is passed through the second or downstream priority valve for priority powering of the power steering circuit.