GB1305519A - - Google Patents

Abstract

1305519 Electromagnetic brakes; non- frictional track-brakes on rail vehicle M BAERMANN 16 July 1971 [18 July 1970] 33536/71 Heading F2E An eddy current and hysteresis brake for rail vehicles comprises an iron core having a pluralty of pole legs joined by a yoke and coils arranged on the individual legs to produce, when energized, poles of alternating polarity in the pole legs; the protruding part of the each pole leg forms a pole head, and the thicknesses of the pole heads and pole legs and the inter-pole leg spacing in the direction of motion of the vehicle are specified, with limits; spacing means are provided to maintain a constant air gap between the pole surfaces and the parts in which eddy currents and hysteresis work are produced. Fig. 2 shows a casing 5 incorporating pole legs 21 (the energizing coils not being shown), supported on a spring-mounted part of the vehicle 2 by a bar 15, the assembly being displaced downwards into the operative position shown by a pneumatically-operated piston 18. Wheels 22 which roll on the track normally maintain constant the air gap 21, but at turnouts and similar places on the track where the wheels are unsupported, wear-resisting end skids 14, whose lower surfaces lie between the levels of the wheels 22 and the pole heads slide on the track, are provided. In Figs. 6 and 7 a large winding space is obtained by making the direction-of-motion dimension a of the wound part 27 of pole-leg 20 less than the equivalent dimension b of polehead 28. But to ensure that the magnetic flux crosssectional area of the wound part is at least equal to the cross-sectional area of the polehead, transverse dimension d, Fig. 7, is made greater than dimension e. A cooling body 30 with cooling ribs 31 is provided. The poleheads are preferably welded or soldered in a plate 29 made of non-magnetic alloy (composition exemplified in the Specification). Fig. 8 shows the application of the invention to a wheel instead of to the track, pole surfaces 11 of pole legs 20 of brakes 1 being spaced from lateral faces 34 by an air gap 21 on both sides of wheel rim 33. The yoke (25), (Fig. 9, not shown), is arcuate and covers one third of the rim. The pole surfaces may alternatively face the wheel treads. In the truck of Fig. 10 brakes 1 of the invention face the rails 10 somewhat as in Fig. 2, brakes 1a to 1h face the wheel rims as in Fig. 8, and the energizing current is provided by a generator 45 driven by an axle through gearing 46. As shown all the brakes are connected in series but they may be connected partly in series and partly in parallel. The stator configuration of the generator may be varied to adjust the energizing current by a compressedair actuator 47, 48. Disc brakes 51, 52 may be provided on the axles 40. The energizing current may be controlled (e.g. by centrifugally-controlled resistors), so that when driving speed is reduced the magnetic attraction does not exceed the allowable bearing load.