Axle motor

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Bogie of the RA 30 and 32 of the Veltlinbahn with axle motors
Direct drive of the first Baltimore and Ohio Railroad electric locomotive from 1896, which was in service in the Baltimore City Tunnel , with axle motors

The axle motor was a type of electric motor in electrically driven vehicles, in which the traction motor was arranged in various designs concentrically on the wheel shaft of the drive axle. Vehicles equipped with these engines were among the first to be electrically powered. This design is no longer used today.

history

The first application of axle motors is known from the year 1869, when in London the rotor of the axle motor was firmly keyed to the shaft of the drive wheel and the stator of the motor was also mounted on the wheel axle. As a counterpart against the rotary movement, it had to have an abutment against fixed parts of the vehicle. This design was unfavorable and could not prevail because the weight of the drive motor was unsprung on the drive axle. Strong impacts from the axles to the rails and vice versa were not cushioned and could damage the rotor and the rails.

This drive was later modified so that the rotor was not shrunk directly onto the axle, but onto a hollow shaft surrounding the axle. The motor frame was fixed in the bogie or locomotive frame and the transmission to the drive wheels was done via spring cups as with the hollow shaft drive . Among other things, the three-phase motor cars of the study society for electrical rapid transit systems and the RA 30 and 32 of the Veltlinbahn were equipped with this drive . The weight of the stator only partially loaded the drive wheels and the shocks were minimized. Some locomotives of the New York, New Haven and Hartford Railroad were equipped with axle motors and achieved outputs of up to 550 hp.

A third design was made in 1903 by the General Electric company . This version was only suitable for DC machines. The rotor was shrunk directly onto the drive axle. The magnetic field, which only consisted of two horizontally lying pole pieces , was screwed to the frame and could be closed magnetically by the iron mass of the same. This enabled the rotor, which oscillates with the drive wheel, to compensate for a certain height difference. The design required a larger air gap than with the drives with hollow shaft and could not be used with every motor. This arrangement was built in large numbers in the United States through 1918 and was known on the Baltimore and Ohio Railroad .

The advantage of the axis motors was their use at high speeds, where practically no reduction had to be accepted and a gearbox could be saved. This shows their application in the express railcars of the study society for electric express trains. This faced a number of difficulties. The performance was limited by the wheel diameter and the track width. The engine arrangement required a low center of gravity, which was not favorable for vehicle running. Likewise, due to the deep arrangement of the motors, there was a high risk of contamination of the electrical machine. Motors with a reduction were able to transmit a significantly higher torque. For this reason, the use of axle motors was limited primarily to underground railways and applications in which everyday use was not to be expected. Today they are no longer used in rail vehicle construction.

See also

literature

  • Richard Bäcker: About drives and types of electric locomotives. In: Electric rail vehicles in Glaser's annals 1909–1929. Transpress Reprint, Berlin 1990, ISBN 3-925952-11-X .
  • Walter Kummer: The machine theory of electrical train conveyance . Springer-Verlag, Berlin / Heidelberg, ISBN 978-3-662-42861-0 (first edition: 1915).

Individual evidence

  1. ↑ a b Richard Bäcker: About drives and types of electric locomotives. In: Electric rail vehicles in Glaser's annals 1909–1929. Transpress Reprint, Berlin 1990, ISBN 3-925952-11-X , p. 108.
  2. ^ A b Walter Kummer: The machine theory of electric train conveyance . Springer-Verlag, Berlin / Heidelberg, ISBN 978-3-662-42861-0 , p. 61 (first edition: 1915).
  3. ^ EE Seefehlner, HH Peter: Electric train conveyance. Manual for the theory and application of electric traction on railways . 2nd Edition. Springer-Verlag, Berlin / Heidelberg, ISBN 978-3-642-50943-8 (first edition: 1922).