Abstract: A control for a hydrostatic unit is provided in which control mechanism is provided between the feed line of the hydrostatic unit and a servo piston controlling the drive unit whereby the pressure acting on the servo piston is dependent on the setting of the drive unit in addition to the feed pressure of the drive unit.

Abstract: A regulating device is provided for an aggregate of several pumps driven by a primary source at least one of which is adjustable and with a constant volume auxiliary control pressure pump driven by the same primary source in the delivery line of which a restrictor is located with the pressure gradient in front of and following the restrictor acting on the control pressures of an hydraulically regulated discharge valve in a drain line connected to the delivery line of the auxiliary pump, the drain line being connected in front of the restrictor, adjusting means connected to each adjustable pump and a control pressure line to which all adjusting means are connected, branching off from the drain line ahead of the discharge valve.

Abstract: A hydraulic system having at least two pumps including a variable-displacement pump and a constant-displacement pump, both driven from a common prime mover, includes a control-pressure pump operated by the shaft of the prime mover and operating with its input a valve which controls the pressure of a control piston acting upon a spring which bears upon the control member in a direction opposite to its setting piston. A cylinder of the setting piston is connected to the output of the adjustable-displacement pump.