GB713318A - Improvements in and relating to hydraulic buffers - Google Patents

Abstract

713,318. Hydro-pneumatic shock-absorbers; railway-vehicle buffers. FITZJOHN, A. P., TURTON, PLATTS & CO., Ltd., G. Nov. 1, 1950 [Nov. 4. 1949], No. 16260/53. Divided out of 713.242. Classes 103(5) and. 108(3) The invention relates to hydraulic buffers, of the kind having an impact-receiving member 44, Fig. 1, operable in the buffer casing 14 in association with piston and; cylinder units in which hydraulic fluid ismaintained under load by air pressure. According to the invention, the piston 12 is orificed and co-operates with a member- 31 for affording progressively-increasing resistance to the displacement of fluid' through the orifice on relative inward movement of the member 44, whereby a resistance is set up in the fluid which is greater than the air pressure acting on the fluid, while on the recoil stroke the plunger is subjected to less than the full force of the air pressure. An air chamber 20 is connected by a pipe 21 with a bore 29 of the. piston 12. The member 31 has tapered grooves 32. In a modification of the chamber 20, Fig. 4 (not shown), the pipe 21 opens into the chamber 20 through a plurality of orifices. In a further modification, Fig. 5 (not shown), the tapered grooves 32 on the member 31, are dispensed with and the bore 28 is tapered. In operation, compressive load on the buffer head 44 drives liquid from the cylinder 10 into the bore 28 and against air pressure in the chamber 20. The grooves 32 progressively increase the damping action. In an alternative construction, Fig. 2, the piston 12 is rigid with the buffer head 44 and the cylinder 10 is rigid with the casing 14. On compression, liquid is dsplaced from the cylinder 10 into a bore 45 of the piston and thence to a space 48 within the buffer plunger 11. Compressed air is contained in the plunger 11 above the space 48 at 50.