Art collection under art collection 924 in which a nut and bolt are interlocked by a pawl and rachet mechanism which automatically locks the nut or bolt from movement in one direction but permits free movement in the other and further wherein a washer is secured to the bolt and carries a pawl which interlocks with a special made ratchet surface of the nut.
(1) Note. The corner of the ordinary nut are not regarded as forming a ratchet surface.
