DUAL PUMP DUAL PRESSURE HYDRAULIC CIRCUIT

摘要

A hydraulic system is provided for an engine driven vehicle. The hydraulic system includes a higher pressure engine driven pump for supplying pressuriz ed fluid to a higher pressure circuit via a first supply line. The system also includes a lower pressure engine driven pump for supplying lower pressure fluid to a lower pressure circuit via a second supply line. The system also includes a pressu re responsive relief valve. The relief valve has a sensing port connected to th e first supply line, an inlet connected to the first supply line, and an outlet connected to the second circuit via the second supply line. The relief valve opens when a demand of the higher pressure circuit is satisfied. A cut-off valve controls communication between the high pressure circuit and a reservoir, and a control unit contro ls the cut--off valve as a function of operation of the high pressure circuit.