Device for the power control of at least two hydrostatic variable displacement pumps

Device for the power control of at least two hydrostatic variable displacement pumps, driven by a common drive motor and delivering into respective operating lines, through the adjustment of their displacement in dependence upon the operating pressure in both operating lines by means in each case of an adjusting device which can be acted upon with an adjusting pressure and i.e. prestressed in the direction of maximum displacement,

• having in each case a power control valve associated with each adjusting device, which valve is acted upon by a first control pressure, corresponding with the operating pressure in the operating line of the variable displacement pump to be adjusted by the adjusting device, against a pressure difference in the direction of a control position, in which the power control valve controls the adjusting pressure acting upon the adjusting device in the direction tending to reduce the displacement of the variable displacement pump along a hyperbolic control curve,
• whereby the pressure difference results from a backpressure of a spring arrangement counteracting the first control pressure and from a second control pressure corresponding with the operating pressure in the operating line of the respective other variable displacement pump, and with increasing second control pressure drops from a specified maximum value to a specified minimum value,
• wherein the spring arrangement is divided into a first and a second pressure spring, in that the first pressure spring is set to a force corresponding with the minimum value (.DELTA.p.sub.min) of the pressure difference and the second pressure spring is set to a force corresponding with the difference (.DELTA.p.sub.max -.DELTA.p.sub.min) between the maximum value (.DELTA.p.sub.max) and the minimum value (.DELTA.p.sub.min) of the pressure difference, and in that the first pressure spring with its set force and the second pressure spring with a force decreasing with increasing second control pressure act upon the power control valve.