METHOD AND APPARATUS FOR SELECTIVE SUPPLEMENTARY HYDRAULIC DRIVING OF THE WHEELS OF A VEHICLE

摘要

The present invention relates to a method for selective hydraulic driving of the wheels of a vehicle, supplementary to the main driving wheels driven by an engine through a torque converter or a gearbox, by automated control of a closed hydraulic operating circuit, with wheel motors fed from a variable capacity pump, and a variable capacity pump and a control pump driven directly by the engine, the flow and pressure of the working fluid being controlled by the controllable control pump flow, and, in superimposition of the working fluid flow control, the working fluid pressure is controlled by the pattern of a predetermined function selectable in dependence upon the ratio between the output r.p.m. of the engine and the output r.p.m. of the converter stages or the gearbox.