A gate for closing a corridor is provided, the gate having driving means and means to terminate its motion if an opposing force is applied while the gate is being closed. The gate is mounted on a fixed axis and the apparatus rotates about a fixed hub. The driving force to close the gate is applied to a rotatable member which rotates about the axis of the hub and which is coupled to a second rotating member through a lost motion coupling and a spring, which spring transmits the driving force. The second rotating member carries and rotates the gate. If a force is applied to the gate in a direction which would oppose the closing motion, and which is of sufficient magnitude, the spring extends and the lost motion coupling permits relative movement between the first and second members. A plurality of fingers carried by the first member are then moved an amount sufficient to permit a locking apparatus to engage the hub and the second member, preventing further rotary motion between these members until the force is removed and the spring recovers the motion in the lost motion coupling. The locking device disclosed includes a plurality of surfaces formed on the second member, which surfaces slope toward the hub and form, with corresponding surface portions on the hub, converging channels. A plurality of rollers are disposed in the large ends of these channels, the rollers being urged toward the small ends of the converging channels by springs. During normal rotation, a plurality of fingers carried by the first member keep the rollers out of contact with the hub, but when the spring in the lost motion coupling is extended and the first member moves relative to the second, the fingers move away from the rollers, allowing their respective springs to urge them into contact with the walls of the converging channls, thereby locking the hub and second member together.