GB921821A - Improvements in or relating to slip couplings - Google Patents

Abstract

921,821. Hydraulic couplings. EDWARDS HIGH VACUUM Ltd. May 14, 1959, No. 17428/58. Class 69 (2). An hydraulic coupling comprises driving and driven members 1, 4, Figs. 1 and 2, arranged so that when the speed of the driving member exceeds the speed of the driven member a positive pumping action by the driving member causes liquid to be pumped around a closed path, a relief valve 16 in the path, normally blocking the flow of liquid, opening when the pressure difference across it reaches a predetermined limit, and means for inducing air into the liquid at a point where it can mix with the liquid to form an elastic and compressible medium. The driving member 1 has sliding vanes 8 which may be hydraulically or spring- urged into contact with an eccentric bore in the driven member 4 and draw liquid through an inlet 14 and pump it through an outlet 15, the inlet and outlet being connected to a reservoir 13 formed in a cover secured to the member 4 which may be connected by gears, bolts or a chain to a machine to be driven. The relief valve 16, which may be of the preset adjustablyloaded pressure-release type, normally closes the outlet but opens when the torque transmitted exceeds a predetermined value to permit slip to occur in the coupling. Out-of-balance forces in the coupling may be prevented by the provision of a pair of inlet ports and a pair of outlet ports, the ports of each pair being diametrically arranged. Noise when the coupling is slipping caused by the vanes passing the ports reduced by a pipe 43, Fig. 6, having holes 46 connecting an air space 45 formed within the reservoir by the centrifugal action of the fluid with the inlet ports 24, the air mixing with the liquid to form a compressible mixture. In other embodiments, the driving member may be in the form of a gear pump or have a camshape 34, Fig. 5, which co-operates with spring- urged blades 35 mounted in the driven member 36. The coupling may be cooled by fins formed on the reservoir cover or a fan on the driving shaft. Specification 680,001 is referred to.