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Buffer stop

Device to stop trains at end of track From Wikipedia, the free encyclopedia

Buffer stop
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A buffer stop, bumper, bumping post, bumper block or stopblock (US), is a device to prevent railway vehicles from going past the end of a physical section of track.

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This buffer stop at Milano Centrale in Italy is designed to move up to 7 metres (23 ft) to slow down an 850-tonne (840-long-ton; 940-short-ton) passenger train from 15 km/h (9.3 mph) without damaging the train or injuring passengers.

The design of the buffer stop is dependent, in part, on the kind of couplings that the railway uses, since the coupling gear is the first part of the vehicle that the buffer stop touches. The term "buffer stop" is of Italian origin, since railways in Italy principally use buffer-and-screw couplings between vehicles.

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Types

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Several different types of buffer stop have been developed. They differ depending on the type of coupler used and on the intended application.

  • Buffer stops with anticlimbers. These are particularly important for passenger railway applications, because the anticlimbers reduce the likelihood of telescoping of the railroad cars during a head-on impact.
  • Buffer stops for a knuckle coupler or an SA3 coupler (centrally positioned between the two rails)
  • Buffer stops with traditional "buffers" on either side
  • Hydraulic buffer stops
  • Friction buffer stops (bolted down to the rail)

If there is extra room behind the bumper block, there is usually a sand or ballast drag that is designed to further retard a runaway train. One such accident occurred in 1975 on the London Underground system, when a Northern City Line train powered past the bumper block at Moorgate station.

Energy-absorbing

Largely because of its mass, a train transfers an enormous amount of kinetic energy in a collision with a buffer stop. Rigid buffers can safely cope only with very low-speed impacts. (i.e., nearly stationary). To improve stopping performance, a way of dissipating this energy is needed, through compression or friction. Following a buffer stop accident at Frankfurt am Main in 1902, the Rawie company developed a large range of energy-absorbing buffer stops. Similar hydraulic buffer stops were developed by Ransomes & Rapier in the UK.[citation needed]

Examples

  • Raja Trains Depot in Tehran
    • Stopping speed: 20 km/h (12 mph)
    • Stopping distance: 20 m (66 ft).[1]

Wheel stop

Wheel stops or car stops are used to stop small numbers of light vehicles at the end of level storage tracks or to chock individual railroad cars on shallow grades.[2][3][4][5][6]

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Examples of accidents

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The aftermath of the Gare Montparnasse accident
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See also

References

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