| 摘要 |
The security post, for use in car parks, town centres etc., comprises a tubular post 1 accommodated in a close fitting sleeve 2 for movement between a first extended position and a second retracted position, where it is located within the sleeve which itself is located below ground level. The sleeve is fixed to a base plate 3 to which a flanged tube 4 is also secured and to which, in turn, a nut element 6 is secured. A leadscrew 5 extends vertically through the nut and is rotatably secured to the post via a bearing assembly. The leadscrew is formed from a twisted bar with a cornered cross-section and the leadscrew and nut mechanism is designed so that it is non-self-sustaining, with the margin by which the mating threads exceed the minimum criteria for being self-sustaining being at least 50%. The post may be locked in the raised position by a lock pin that engages an end plate fixed to the end of the leadscrew, with the release of the lock pin allowing the post to fall to its retracted position under the effect of gravity. |
