| 摘要 |
<p>A screw fastening device is described for use on an electrical box or other structure to which a component is to be fastened by at least one screw. The device includes a support adapted to be mounted on a flat surface portion of the device. The support includes a base having a flat inner surface and two spaced side walls which extend outwardly from the base and support the base with its flat inner surface parallel to the flat surface portion of the box when the device is fastened to the box. The side walls have convergent inner surfaces. The device also includes a pair of wedge-shaped screw-engaging members which can slide on the flat inner surface of the base and on the flat surface portion of the box. The members have grooved recesses which together define a thread complimentary to that of a screw to be received in the device. Spring means bias the screw-engaging members in the direction of convergence of the side wall surfaces so that, when a screw is inserted between the members, they will slide back and forth along said convergent surfaces as the threads on the screw ride over the corresponding thread defined by the recesses. The screw will then be held in its inserted position by the screw-engaging members but at the same time can be axially displaced by turning.</p> |
