Rotary to linear servo mechanisms

Claim 1

A rotary to linear servo mechanism for converting low force mechanical rotary motion into hydraulically assisted linear motion, comprising a source of fluid under pressure, a housing, an elongate bore in said housing, first passage means in said housing connecting said bore with the source of fluid under pressure, a fluid reservoir spaced from the housing, second passage means in said housing connecting said bore with said reservoir, a piston movable axially in one end of said bore, said piston having a hollow axial bore therethrough, rotatable valve means extending through said axial bore of the piston, said valve means having a tapered end passage means controlling the flow of fluid from said first passage means by rotation within the bore of said piston whereby in one rotated position of the valve means said bore is blocked and fluid acts on one side of the piston urging it axially of the bore in the housing in one direction to a preselected position, said value means including by pass means in said piston communicating with said axial bore whereby fluid from the inlet passes around the end of said valve means in said axial bore to the opposite side of the piston to stop movement of said piston in said one direction and in a second rotated position of said value means fluid is delivered through said axial bore in the piston and tapered end passage means from a point intermediate the valve end to the opposite side of the piston and resilient means in said bore normally biasing said piston in said opposite direction urging it axially of the bore in the opposite direction, wherein said valve means is a rod, said rod having handle means at one end externally of said housing for rotating said rod and the other end being cut away at an angle defining said tapered end passage means, and connection means on said piston extending externally of the bore in the housing.