GB988041A - Improvements in and relating to buffers and draw-gear for railway, tramway and like vehicles - Google Patents

Abstract

988,041. Hydro-pneumatic shock absorbers. OPEE Ltd. June 28, 1961 [June 28, 1960], No. 22630/60. Heading F2S. [Also in Division B7] A hydro-pneumatic buffer or draw gear comprises an annular plate 6, Figs. 1, 2, which may float radially in a recess 7 in a plate 8 screwed to the base 4 of the plunger, so that as full closure of the buffer is approached the plate 6 slides and centres over the pin and reduces the aperture area to substantially zero. In order to permit this movement of the plate the pressure on both of its faces is equalized by the provision of an annular groove or grooves 12, Fig. 4, which communicate through holes 11 with the pressure chamber. The plate 6 may be retained substantially concentric with the housing 8 by a corrugated peripheral leaf spring, Figs. 7 and 8 (not shown). In a modification the rear face of the plate 6 or the base 4 against which the plate abuts may be chamfered to reduce the pressure difference. The small axial movement permitted to the plate allows it to act as a one-way valve during recoil and permit fluid to return to the pressure chamber via ducts 8a, the plate being acted upon by an annular end spring. In another modification the end spring is provided with radial and bent fingers which retain the plate both radially and axially. Specifications 703,855, 721,222 and 808,931 are referred to.