GB790843A - Motion arrester - Google Patents

Abstract

790,843. Energy - absorbing elements. NATIONAL RESEARCH COUNCIL. May 8, 1956 [May 20, 1955], No. 14263/56. Class 103 (1). A device for producing a constant or otherwise controlled retarding force having no rebound characteristics after an article has been brought to rest consists of a sheet of material having a continuous smoothly curved groove 2 extending in regularly mutually spaced general coaxial convolutions, the depth of the groove in relation to the thickness and mechanical properties of the material being such that a continuous ribbon 5 may be torn from the sheet by a tensile force supportable by the ribbon; energy being dissipated in rupturing the material. Instead of the material comprising a disc 1, deeply scored with a spirally extending groove 2, set in the end of a cylindrical shockabsorber 3 of the type disclosed in Specification 790,844, as shown in Figs. 1 and 3, the invention may comprise a cylinder of metal provided with a helical groove such as illustrated in Fig. 4. In place of metal a synthetic material such as nylon or " Teflon " (Registered Trade Mark) may be used. The retarding force may be varied by making the groove progressively shallower or deeper in accordance with the desired characteristics. The arrester may be used as a safety device for retarding the motion of a falling body such that, combined with a harness, the device may be used for controlling the speed of descent of falling bodies.