| 摘要 |
<p>A speed responsive engagement device comprises: a wheel arranged for rotation about a first axis and having a plurality of outwardly projecting spaced apart teeth with each pair of adjacent teeth being separated by a circumferential surface with a constant radius; a pawl arranged for pivotal movement about a second axis between a first unengaged position and a second engaged position in which the pawl engages one of said teeth and contacts a circumferential surface; and a resilient means arranged to urge said pawl towards the first position when the pawl is not in contact with a circumferential surface. When the wheel rotates in a first direction each tooth contacts the pawl, generating an oscillating movement of the pawl from the first position towards the second position with an amplitude dependent on the speed of the rotation. When the speed of rotation reaches a predetermined value the oscillating movement brings the pawl into the engaged position, preventing further rotation of the wheel in said first direction.</p> |
