Worm gear potentiometer ratchet system

Abstract

A lead screw type control for a miniature worm gear actuated potentiometer having a rotor with a main drive spur gear and a ratcheting drive rack gear. The invention contemplates rack gear teeth formed with a gentle ramp opposed to a more acute ramp such as to resemble a sawtooth configuration in profile. The main drive spur gear is formed on less than the total of the rotor circumference. The ratcheting rack gear is mounted on a portion of the rotor circumference that does not include the spur gear. The main drive spur gear teeth are functional in a plane perpendicular to the plane in which the ratcheting rack gears are effective. Ratcheting is accomplished when the driving lead screw has driven the main-drive spur gear to one of its limits in either a clockwise or counterclockwise direction. At this point, if the same direction of rotation is continued, the ratcheting rack gear is urged into engagement with the driving lead screw by the force of a contact spring. As long as the same direction rotation of the driving lead screw is maintained, the engagement continues so as to permit continued ratcheting and thus rotation of the worm gear without causing damage to the movable parts of the worm gear actuated potentiometer.

Dependencies are inferred from the claim text.