HYDRAULIC DEVICE FOR CAR

摘要

A vehicle hydraulic system wherein there is provided a primary pump coupled to a steering control valve through which steering of the vehicle is effected. A main priority valve is used to meter the flow of pressurized hydraulic fluid from the primary pump to either the steering control valve or an implement valve which is utilized to effect operation of auxiliary equipment, in accordance with the priority demands of the steering system. An auxiliary ground-drive pump provides a source of pressurized hydraulic fluid at all times the vehicle is in motion and is coupled to the steering control valve to provide a source of pressurized fluid when necessary or circulates the pressurized fluid to sump. The application of the output from the ground-drive pump is controlled by a secondary priority valve coupled to the output from the ground-drive pump to direct the output to the steering control valve or to sump. The main priority valve and secondary priority valve are both coupled to a common pressure source which applies a predetermined pressure differential to each of the valves for maintaining each of the respective valves in a desired position.