GB190521852A - Expansible Bolts. - Google Patents

Abstract

21,852. Farrington, H. Oct. 26. Bolts; screw sockets.-Bolts, such as eye bolts, lag bolts, or bolts used for lifting stone &c., are formed for use with spiral coils, which are placed in cylindrical holes and expanded to grip the sides by the forward motion of such bolts. The coils are cylindrical externally and tapered internally. As in Fig. 1, this formation may be obtained by cutting away an external portion of the coil, or the coil may be a spiral of tapering wire or a strip of other suitable material as in Fig. 5. The screw-thread 4 is formed on the expanding member, and gradually changes from an almost cylindrical form at the upper end to a thread acutely inclined to the axis at the lower end. By this means, the shoulder 5 is of a maximum height at the lower end and gradually decreases therefrom while the width of the sloping part 4 remains uniform. The thread 10 shown in Fig. 5 is applied to, or formed on, a tapering shank and consists of a tapering spiral wedge-faced strip or screw-thread. Other bolts, partly tapering and partly cylindrical, are described, for use with the above or plain cylindrical coils. With any such devices, enclosing casings comprising split cylinders 11 with flanges 12 may be used. Specifications No. 21,065, A.D. 1894, No. 9902, A.D. 1901, and No. 3407, A.D. 1903, are referred to.