| 摘要 |
A turnstile comprises a shaft mounted for rotation about its own axis, at least one set of arms equi- angularly mounted there-on, ratchet means for constraining the shaft to rotate in one direction only, and means under operator or user control to permit intermittent rotation of the shaft to allow a single person to pass through the turnstile. The lastmentioned means includes an LED/photosensor pair to provide a halt signal each time the shaft has rotated through an admittance angle, brake means responsive to each halt signal to prevent further rotation of the shaft, and operator or user controlled means (for example a card, badge or ticket reader, or a foot pedal) to release the brake. |
