Fluid supply system for vehicles

Claim 1

In a vehicle having a hydrostatic transmission which is operable to vary travelling speed of the vehicle in a non-stepwise manner, a fluid-operated clutch which is disposed in a power transmission path, and at least one hydraulic actuator which is actuated by high pressure fluid, a fluid supply system comprising: a single hydraulic pump (6) for supplementing fluid to said hydrostatic transmission (1) and for supplying fluid respectively to said fluid-operated clutch (2) and to said hydraulic actuator (3, 4, 5), said hydraulic pump flowing out its discharge flow into a discharge path (7); a pressure-reducing valve (8) operable to reduce its inlet pressure to a predetermined outlet pressure with flowing out a part of its inlet flow into a fluid drain path (9), said discharge path (7) being connected to said hydrostatic transmission (1) through said pressure-reducing valve so as to supplement fluid of said outlet pressure to said hydrostatic transmission, said fluid drain path being fashioned to a fluid supply path for supplying fluid to said fluid-operated clutch (2); a high pressure relief valve (10) for establishing a high fluid pressure to be applied to said hydraulic actuator (3, 4, 5), said relief valve being connected to said discharge path (7); a second fluid supply path (11) connected to said discharge path (7) for supplying fluid from said discharge path to said hydraulic actuator (3, 4, 5); and a flow-restricting means (12, 12A) incorporated in said second fluid supply path (11) for maintaining fluid pressure in said discharge path (7) higher than said outlet pressure of said pressure-reducing valve (8) but substantially lower than said high fluid pressure determined by said high pressure relief valve (10).