Abstract: A valve (1) comprises: a body (2); a bushing (3) slidably mounted on said body; a valve spool (4) slidably mounted on said bushing; said bushing and spool having respective control edges (5) that are adapted to cooperate with one another as a function of the relative position between said bushing and spool to vary the size of a control opening therebetween; a first drive (11) operatively arranged to controllably move one of said bushing and spool relative to said body; and a second drive (12) operatively arranged to controllably move the other of said bushing and spool relative to said body; whereby said first and second drives may be selectively operated to move said bushing and spool simultaneously in opposite directions to increase the dynamic response of said valve.

Abstract: A valve (1) comprises: a body (2); a bushing (3) slidably mounted on said body; a valve spool (4) slidably mounted on said bushing; said bushing and spool having respective control edges (5) that are adapted to cooperate with one another as a function of the relative position between said bushing and spool to vary the size of a control opening therebetween; a first drive (11) operatively arranged to controllably move one of said bushing and spool relative to said body; and a second drive (12) operatively arranged to controllably move the other of said bushing and spool relative to said body; whereby said first and second drives may be selectively operated to move said bushing and spool simultaneously in opposite directions to increase the dynamic response of said valve.

Abstract: Control arrangement for regulating the speed of movement of a hydrostatic energy consumer is provided in which the ratio between pressure supplied and power on the output side is constant, in particular, a piston capable of sliding in a cylinder connected to a pressure main line, characterized in that an initial hydrostatic displacement machine is connected between the pressure main line and the consumer and is coupled with a second hydrostatic displacement machine on the shaft side, the second hydrostatic displacement machine is adjustable with respect to its displacement volume per revolution and is connected on the one hand to the pressure main line and on the other hand to a chamber carrying a lower pressure, where the adjusting element of this second displacement machine is connected with an r.p.m.-regulating device.

Abstract: A control and regulating arrangement for an adjustable hydrostatic unit is provided in which the regulating device has an auxiliary control constant pump in the feed line of which there is a restrictor, in which case the pressure retained in front of the latter acts on a pressure chamber in which a regulating piston capable of sliding against the force of a spring and which influences the position of a regulating piston connected with the final control element of the hydrostatic unit and capable of sliding in a regulating cylinder is capable of sliding, characterized in that the unit is a hydrostatic motor and the auxiliary control pump is connected to its output shaft.

Abstract: A hydrostatic drive system is provided with an adjustable hydraulic motor operatively connected between a high pressure main line and a low pressure line and equipped with a control arrangement that influences the setting in an r.p.m.-dependent manner, the improvement comprising a safety means that limits the stream flowing through the hydraulic motor.