Control system for positioning implements

Claim 1

A control system for positioning an implement, comprising: a source of pressurized fluid; a power steering unit including a rotary valve having a sleeve and a rotary spool rotatably received in the sleeve and metering means operatively associated with the rotary valve for metering pressurized fluid from said source in response to an angular displacement of the rotary spool relative to the sleeve; an implement pivotally mounted on a body; cylinder means connected with said power steering unit for angularly displacing said implement; first angular position detector means for detecting an angular displacement of said implement relative to said body; an operating lever means pivotally mounted on said body for operating said implement; second angular position detector means for detecting an angular displacement of said operating lever means relative to said body; a feed back circuit detecting the position of an actuator whereby to avoid displacement of a neutral position of said rotary valve; comparator means connected with said first and second angular position detector means for comparing signals therefrom and generating an output signal; amplifier means for receiving the output signal from said comparator means and generating an output signal therefrom; DC motor means connected with said amplifier means and said rotary spool of said rotary valve for rotating said rotary spool in response to the output signal from said amplifier means; and gear reduction means disposed between said DC motor means and said rotary spool.