Hydraulic circuit for motor vehicles

Claim 1

A hydraulic circuit for vehicles of the type provided with a chassis, at least one axle having ground wheels, a servo-steering system including an open center valve and a level-regulating device in which a single pump is employed for supplying pressure fluid to the system and unit, the improvement comprising a pressure line for said valve, a pressure line for the levelregulating device connected parallel to the pressure line for said valve, said level-regulating unit including a levelregulating valve operably connected to the axle and at least one adjusting cylinder piston unit located between the chassis and the axle, an unlockable check valve arranged in a line between the level-regulating valve and the adjusting cylinder piston unit, said check valve opening in the direction of the adjusting cylinder piston unit, a control line for the unlockable check valve connected, at least in the down regulating position of the level-regulating valve, with the pressure line for the levelregulating device, and an unlocking piston therefor being so dimensioned that if the pressure in the pressure line for the level-regulating device is lower than the pressure in the adjusting cylinder piston unit, there is no unlocking of the check valve.