| 摘要 |
<p>A control mechanism 18 is provided for a turnstile 10 of the type comprising a plurality of arms 12 which meet at a central hub 14 and are rotatable on a rotational axis 16. The turnstile 10 is adapted to stop in a position with an arm 12 forming a barrier across a passageway and is operable to rotate through an arc defined by the angle between adjacent arms 12 when the control mechanism 18 is actuated to allow a person to pass through the passageway. The control mechanism 18 comprises a first gear wheel 20 adapted to be mounted to the turnstile to rotate therewith on the rotational axis 16 of the turnstile, and second gear wheel 22 adapted to be driven by the first gear wheel 20. A drive means 24 connects the first and second gear wheel 20, 22 together, and a release mechanism is adapted to coact with the second gear wheel 22 to releasably lock the second gear wheel 22 against rotation each time said turnstile 10 has rotated through the arc. An actuating mechanism is adapted to operate the release mechanism. Preferably the drive means 24 comprises an endless chain which passes around the two gear wheels 20, 22 keeping the two gear wheels in registry with each other. <IMAGE></p> |
