SICHERHEITSVORRICHTUNG.

摘要

A normally helically interacting shaft (12, 32) and nut (11, 33) assembly having a common longitudinal axis (A, 40) along which the nut (11, 33) is normally displaced linearly by rotation of the shaft (12, 32) is provided with a wedging passage (13, C, 38, 45), located by or in the nut (11, 33), inclined at an angle to the longitudinal axis (A, 40) and facing into an aperture in the nut (11, 33) normally partially occupied by a threaded portion of the shaft (12, 32); and a detent (14, 41), such as a ball, in the passage (13, C, 38, 45). In the event of failure of the normal engagement between nut (11, 33) and shaft (12, 32) (such as can occur with the threads on the nut (11, 33) wearing) free relative linear motion of the nut (11, 33) relative to the threaded shaft (12, 32) causes the wedging passage (C, 45) to displace the detent (14, 41) towards, and into engagement with, the threaded shaft (12, 32) and thereafter maintain the detent (14, 41) in such engagement so as to inhibit further free linear motion by the nut (11, 33) relative to the shaft (12, 32). At least a part (34) of the nut (33) engaging with the shaft (32) can be of a self lubricating material such as a graphite loaded plastics material.