Limit Switch


limit switch

[′lim·ət ‚swich] (electricity) A switch designed to cut off power automatically at or near the limit of travel of a moving object controlled by electrical means.

Limit Switch

 

(or end switch), an electrical device used in switching control circuits of electrical machine drives or their elements at certain points of their motion.

Limit switches are actuated by the motion of the mechanism itself, usually at the end of its travel or at a predetermined point on the path of its motion. For example, in hoisting machinery a limit switch disconnects the motor and applies the brake upon approaching the end point, thus protecting the mechanism from damage. Limit switches may be of the contact or contactless type. According to their design they are classified as pressure (push-button), lever, shaft, and rotary switches.

limit switch

An electric switch, operated by a power-driven machine or by the movement of the car which it drives, which alters or controls the electric circuit associated with the machine, e.g., a switch which slows down and stops an elevator car or dumbwaiter car automatically at or near the top or bottom terminal landing; operates independently of the device which normally controls movement of the car.