Destroking start valve for variable displacement pump

A control for a variable displacement pump driven by a prime mover comprising a thrust plate, means for pivotally mounting the thrust plate such that it is movable between a position of minimum fluid displacement and a position of maximum fluid displacement, a fluid inlet and a fluid outlet, means for biasing the thrust plate towards the maximum fluid displacement position, a stroke control piston, means for guiding the stroke control piston to engage the thrust plate, first valve means alternatively movable between an open position in which pressure fluid from the fluid outlet is supplied to the stroke control piston to move the thrust plate towards the minimum fluid displacement position and a closed position in which the supply of outlet pressure fluid to the stroke control piston is interrupted, means in the first valve means for setting the maximum allowable pressure of the fluid in the outlet, wherein the first valve means is moved to the open position if the pressure of the fluid in the outlet exceeds the set maximum fluid pressure, second valve means alternatively movable between an open position in which pressure fluid from the fluid outlet is supplied to the stroke control piston to move the thrust plate towards the minimum fluid displacement position, and a closed position in which the supply of outlet pressure fluid to the stroke control piston is interrupted, means in the second valve means for setting a minimum fluid pressure in the fluid outlet to which the second valve means responds and means for moving the second valve means from the open position to the closed position to disable the second valve means when the pressure of the fluid in the fluid outlet reaches the set minimum, wherein the second valve means is in the open position when the prime mover is started to thereby reduce the load on the prime mover and is moved to the closed position after the prime mover has reached its rated operating speed.