Band brake

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Outer band brake
External band brake
Laurin & Klement type 1 (1899)
Outer band brake on the bike

A band brake is a mechanical friction brake in which, in contrast to the shoe brake, a band is looped around or in a drum. The braking effect is created by the friction between the drum and the belt. A distinction is made between the

  • External band brake - the brake band is wrapped around the outside of the brake drum - and the
  • Inner band brake , in which the brake band is pressed from the inside onto the brake drum.

history

The development of the band brake is closely linked to the history of the automobile . The Benz Patent Motor Car Number 1 of 1886 had a drum around which a brake band was tied to the countershaft - the first band brake when automobile. Daimler's steel wheeled car with an external band brake followed in 1889. While outer band brakes were hardly installed in cars in Europe until World War I and these were replaced by inner shoe brakes , outer band brakes remained the predominant braking principle in the USA until 1927. However, the parking brake continued to work as a band brake on the cardan shaft until World War II. B. in all Opel cars.

The first outer band brakes on motorcycles appeared in 1899 at Laurin & Klement Type 1 on the front wheel, in 1901 NSU Motorenwerke delivered the first series model with an outer band brake. With spring-loaded front wheel suspensions , the band brake on the steering axle disappeared (at NSU Motorenwerke 1906), while the outer band brake was installed on the rear wheel by various manufacturers until the 1920s. The cardan shaft was seldom braked using a band brake. B. on the BMW R 39 .

Structure and effect of the outer band brake

The band can be a steel, textile or leather band, but also a rope or a profiled band similar to a V-belt . One end is attached to a fixed point and the other end is loaded by a weight, a spring or a cable operated by muscle power. This allows the braking effect to be set precisely. In contrast to shoe brakes, the braking effect depends on the direction of rotation. The band brake is almost self-locking in one direction , which can lead to great loads. With knowledge of the tensile forces on the belt, the braking torque can be determined using the Euler-Eytelwein formula (also: rope friction formula ).

Today's use of the outer band brake

Bogie of a Matterhorn-Gotthard-Bahn cogwheel locomotive with gear box, cogwheel and two band brakes (from left to right)

It is still used today for low braking performance, for example in textile machine construction, but also in crane construction. The cardan brake, which was previously only used as a parking brake in vehicle construction, is also based on this principle. Earlier automatic transmissions had band brakes to brake the ring gears, today multi-disc brakes (function like multi-disc clutches ) are used for this. In sea and inland shipping, anchor winches are equipped with band brakes.

When used as a brake dynamometer , the brake is used to measure the power of rotating shafts. A brake applied to the shaft acts for this, and the power can be calculated from the measured torque and speed. The most common is the Prony brake bridle . In rack rail locomotives , the band brake serves as a reserve brake system which, as a speed-monitored compressed air brake, brings the train to a standstill if the service brake fails. Even children impellers are with band brakes as acting on the rear wheel brake equipped.

Application example outer band brake on the flywheel of a steam engine

  • Fixed point of the leather strap

  • flywheel to be braked

  • Pull point of the leather strap with threaded rod to adjust the strap length

  • Lever with pedal to operate the band brake

Web links

Individual evidence

  1. ↑ Olaf von Fersen (ed.): A century of automobile technology. Passenger cars. VDI Verlag 1986, ISBN 3-18-400620-4 , p. 398.
  2. ↑ Konrad Reif: Brakes and Brake Control Systems. Vieweg & Teubner Verlag, 2010, ISBN 978-3-8348-9714-5 , p. 40.
  3. ↑ Olaf von Fersen (ed.): A century of automobile technology. Passenger cars. VDI Verlag 1986, ISBN 3-18-400620-4 , p. 400.
  4. ^ Christian Bartsch (ed.): A century of motorcycle technology. VDI Verlag 1987, ISBN 3-18-400757-X , p. 220.
  5. ^ Peter Schneider: NSU in the picture - motorcycles since 1900. 1st edition. Motorbuch Verlag, Stuttgart 2000, ISBN 3-613-02063-7 , p. 14.