GB744973A - Means for protecting power supply conduits, or cables, connected to vehicles - Google Patents

Abstract

744.973. Retractive switches. MAVOR & COULSON. Ltd., and TOWLER. J. M. May 8. 1953 (Aug. 22, 1951], No. 19833/51. Class 38(5) [Also in Groups XXIX and XXX] In a vehicle having its traction power supplied through a trailing conduit 4, the power being electrical, pneumatic, or as shown hydraulic, means for disconnecting the power when the conduit is subjected to excessive tension comprises a member 12 movable to cut off the power against the action of a spring 14, and a pull-transmitter 7 between the member 12 and a part of the conduit 4. As shown the invention is applied to a coal-cutting machine 1 operated on a coal face F, the machine carrying hydraulic propulsion means of the ram motor type. The conduit 4 as shown comprises an internal high pressure pipe 3 and an external return pipe, the conduit being connected through a cut-off valve 8 to a main control valve 11 on the machine and the valve 8 housing the member 12. Secured by a clamp 5 to the conduit 4 is a lug 6 to which is pivoted the member 7 shown as a link. Excessive tension in a remote portion of the conduit causes the pipe 3 to be cut off from the valve 11. In modifications (1) the member 7 may be replaced by a chain or rope, (2) the link 7 may operate the valve spindle in the reverse direction through a flexible connection passing around a guide pulley or through a lever- and-link mechanism, and (3) the member 12 may connect the high pressure pipe 3 to the return pipe to by-pass the main valve. When the power supplied is electrical excessive tension in the conduit operates a switch.