Patent GB-1072683-A (GB)
Title: Improvements relating to the propulsion of vehicles running along a track
Inventor: LAITHWAITE ERIC ROBERTS
IPC: H02K41/025
Filed: 1963-12-04
Abstract: 1,072,683. Electric railway systems. BRITISH RAILWAYS BOARD. Jan. 21, 1965 [Dec. 4, 1963], No. 47983/63. Heading B7L. [Also in Division H2] A railway or similar track vehicle is propelled by a linear induction motor comprised of a continuous plate 1, Figs. 1 and 2, secured to the track and a magnet structure 8 carried by the bogie frame 9 or body underframe, of the vehicle, through horizontally resilient spring hinges 10. The structure 8 has arms 11 which embrace the plate 1 with clearance and support laminated polepieces 12 which carry flat windings 13 connected to a three-phase alternating current supply. Rollers 14 at the ends of the structure engage the sides of the plate 1. The plate 1 has a greater area than the area swept by the magnetic field produced by the structure 8 and thus has a larger conducting capacity than would be afforded by a plate having only such swept area. The plate 1 may be made more conductive by the provision of an upper edge part of copper. The characteristics of the motor may be modified by the use of a plate comprised of a sandwich of different metals. In another embodiment the plate is disposed horizontally and the polepieces of the energizing structure are then vertical and the hinges 10 are disposed so as to be resilient in the vertical direction. According to a further embodiment supporting wheels for the vehicle are dispensed with and inclined polepieces of the energizing structure are provided at each side of the vehicle and connect with inclined and upwardly concave lateral plates as described with reference to Fig. 5 (not shown). In this case magnetic forces normally slightly in excess of the loaded vehicle act upwardly and the lifting is resisted by rollers engaging beneath the lateral plates. When a single plate 1 in the centre of the track or a plate 1 outside each track rail are utilized, turn-outs are provided with suitably cut-away sections of the plates hinged elastically to the remainder of the plate or plates, as described with reference to Figs. 6 and 7 (not shown), the cut-aways allowing the upper sections of the plates to pass over the track rails. When a horizontal plate is used turnouts are provided with a series of transversely movable parallelogram-shaped sections as described with reference to Fig. 8 (not shown). When the vehicle is supplied with three-phase current from two overhead conductors, the third phase being earthed through the track rails, the overhead turnouts are each provided with two intersecting insulated sections connected together and through a two-way switch to ensure continuity of supply, to either of the outer conductors beyond the turn-out, the switch being operated with the point mechanism controlling the running rails and plates, all as described with reference to Fig. 9 (not shown). The overhead conductors are supported by triangular droppers from an auxiliary catenary in turn suspended from a main catenary mid-way between masts which alternate along each side of the track. The masts have arms which serve to impose lateral restraint on the conductors. When running rails are dispensed with, pneumatically-tyred wheels may be used.