Abstract

A mechanism is disclosed which produces linear motion from a rotating input while preventing the transmission of back forces in either direction. The mechanism includes a housing with an output shaft mounted for rotation within the housing. A rotatable input drive means is mounted coaxial with the shaft. The drive means includes a radially extending impelling portion. The output shaft extends axially on both sides of the impelling portion. A tubular hub is fixedly mounted on the housing and extends around the output shaft on each side of the impelling portion of the drive means. A pair of coil springs are wrapped around the output shaft with one spring on each side of the impelling portion of the drive means. Each spring has a release toe at one end which extends axially to the impelling portion and which is capable of being engaged by the impelling portion upon rotation of the drive means. The other end of each spring engages the shaft, so that the spring rotates with the shaft. A portion of each spring has a relaxed outer diameter larger than the inner diameter of the hub, so that the springs engage the hub when relaxed. Means are provided for producing linear motion from the rotation of the output shaft.