Abstract: A hydraulic control system of a transport vehicle, wherein the flow of hydraulic fluid from the source of pressure is fed to the servomotor through a control hydraulic circuit which incorporates a fluid directional control device mechanically linked to a steering unit of a transport vehicle, a number of hydraulic lines and at least one throttle regulator, and through the actuating hydraulic circuit which incorporates a number of hydraulic lines, a throttle regulator and a discrete-type three-position fluid directional control device controlled by a pressure of the fluid flows admitted along the hydraulic lines communicated with the fluid directional control device of the control hydraulic circuit.

Abstract: The distributing device of a vehicle hydraulic control system comprises a distributor connected via hydraulic lines to a servomotor, a pump and a tank, the control member of the distributor being mechanically connected with the steering drive shaft, and further includes a hydraulic machine connected via hydraulic lines with the hydraulic distributor, the rotary member of this machine being adapted to vary the volume of the working chambers and being mechanically connected with the actuating member of the hydraulic distributor and with the steering drive shaft, the steering drive shaft being rotatable relative to the rotary member of the hydraulic machine within an angular play value providing for the preset displacement of the control member of the hydraulic distributor.