Patent GB-777335-A (GB)
Title: Improvements relating to electrical connectors between relatively rotating parts
Inventor: KENYON HAROLD FREDERICK
IPC: H01R39/64
Filed: 1954-01-26
Abstract: 777,335. Supplying current to rotating conductors. ASSOCIATED ELECTRICAL INDUSTRIES, Ltd. Jan. 13, 1955 [Jan. 26, 1954; Aug. 12, 1954], Nos. 2374/54 and 23458/54. Class 38 (1). Current is supplied to a rotating shaft 1 by a conducting liquid 5, e.g. mercury engaging a reduced endportion 4 of the shaft and contained in a housing 3 surrounding the end of the shaft. A bearing portion 2 on the shaft is a close running fit in the housing so as to seal the liquid coupling and is suitably lubricated. In a modification designed for uni-  directional rotation (Fig. 2, not shown), the housing is closed at the liquid end by a plug and the bearing portion has a helical thread filled with oil, the direction of rotation being such as to force the oil in the direction of the conducting liquid. Fig. 3 shows an arrangement for making two connections to the shaft, which in this case comprises concentric conductors 11, 14. The housing is built up of insulating sleeves 15, 16, 17, and copper sleeves 18, 19, the latter one forming a cap and sleeves 15, 16 forming bearings. The copper sleeves enclose mercury glands 20, 22, the former contacting conductor 14 and the latter an extension 21 of conductor 11. Oil is included with the mercury to lubricate the bearing surfaces. Alternatively, Fig. 4, the ends of concentric conductors 25, 26 on the shaft may engage concentric mercury glands 33, 30 in the end face of the housing. Both of the arrangements shown in Figs. 3 and 4 may be extended by the use of further sleeves and mercury glands to accommodate three connections (Figs. 5 and 6, not shown). In an arrangement for six connections, Fig. 7, conductors 18 contained in longitudinal grooves 19 in shaft 1<SP>1</SP> are connected to copper rings 21 carried by insulating sleeves 20. The stationary conductors are connected to copper rings 25 carried by insulating sleeves 26 in the housing 24. The sleeves 20, 26 are a close running fit, the clearance between them containing a film of lubricant, and the spaces between the rings 21, 25 are filled with mercury. Such an arrangement may be used intermediate the ends of a shaft by making the housing open at both ends for the shaft to pass through (Fig. 8, not shown). Fig. 9 shows such an arrangement except that instead of the stationary contacts being carried by a housing they are individually assembled to the rotating part. Copper sleeves 29 to which the stationary conductors are attached have tubes 30 fitting tightly in each end, these tubes being a running fit on the rotating insulating sleeves 20<SP>1</SP> and the central cavity formed between the tubes being filled with mercury. The stationary part or both parts may be made in halves to facilitate assembly to the shaft. The Fig. 9 arrangement may be modified to give additional safeguard against leakage of mercury by providing tongues on the rotating copper rings which project into grooves in the stationary parts 29 (Fig. 10, not shown), the mercury being held in these grooves by centrifugal force. Individually assembled stationary contacts may be used in an arrangement where the rotating conductors comprise three concentric sleeves (Fig. 11, not shown), one stationary contact being in the form of a cap over the end of the shaft. Lubricant is fed to the bearing surfaces from containers which communicate with the mercury compartments.