Hydraulic system and apparatus for use with vehicle accessory units

Abstract

This patent relates to a hydraulic system for a vehicle mounted, power operated plow blade. The power unit attached to the vehicle in the front bumper area includes a fluid reservoir, a pump in the reservoir and the lift cylinder for producing vertical movement of the blade. The hydraulic system includes four way, three way, and two way valves, all along with the necessary passages and ports provided in a unitary, manifold block attached directly to the side of the power unit. The four way valve controls flow to and from the reservoir relative to the three way valve and one of the angling cylinders for the blade. The three way controls flow to and from the four way valve relative to the other angling cylinder and the lift cylinder. The two way valve controls fluid flow to and from the lift cylinder relative to the three way valve. An adjustable restrictor valve is included in the hydraulic circuit between the lift cylinder and return flow from the lift cylinder to the reservoir to allow control over the lowering action of the blade. A cushion valve is positioned in the flow passages and between the two angling cylinders to allow fluid flow from the pressurized angling cylinder to the angling cylinder which would not ordinarily be pressurized; this is to accommodate the condition where the extended edge of the blade strikes an obstacle in that the non-pressurized cylinder will be pressurized through the cushion valve causing the blade to angle opposite to the set orientation and thereby prevent damage to the blade and/or system.