Span bolster

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Span bolsters can be seen at both ends of this diagram of the 14"/50 caliber railway gun. 14 inch 50 caliber railway gun Mk I right elevation diagram.jpeg
Span bolsters can be seen at both ends of this diagram of the 14"/50 caliber railway gun.

A span bolster, in rail terminology, is a beam or frame used to link two trucks (US) or bogies (UK) so that they can be articulated together and be joined to the locomotive or railroad car at one rotating mounting point. In effect, they make one "super-truck" out of the two, while permitting each truck to move relative to the other. [1]

Bogie wheeled wagon or trolley

A bogie is a chassis or framework that carries a wheelset, attached to a vehicle—a modular subassembly of wheels and axles. Bogies take various forms in various modes of transport. A bogie may remain normally attached or be quickly detachable ; it may contain a suspension within it, or be solid and in turn be suspended ; it may be mounted on a swivel, as traditionally on a railway carriage or locomotive, additionally jointed and sprung, or held in place by other means.

British English is the standard dialect of English language as spoken and written in the United Kingdom. Variations exist in formal, written English in the United Kingdom. For example, the adjective wee is almost exclusively used in parts of Scotland and Ireland, and occasionally Yorkshire, whereas little is predominant elsewhere. Nevertheless, there is a meaningful degree of uniformity in written English within the United Kingdom, and this could be described by the term British English. The forms of spoken English, however, vary considerably more than in most other areas of the world where English is spoken, so a uniform concept of British English is more difficult to apply to the spoken language. According to Tom McArthur in the Oxford Guide to World English, British English shares "all the ambiguities and tensions in the word 'British' and as a result can be used and interpreted in two ways, more broadly or more narrowly, within a range of blurring and ambiguity".

Locomotive railway vehicle that provides the motive power for a train

A locomotive or engine is a rail transport vehicle that provides the motive power for a train. If a locomotive is capable of carrying a payload, it is usually rather referred to as multiple units, motor coaches, railcars or power cars; the use of these self-propelled vehicles is increasingly common for passenger trains, but rare for freight.

Contents

Use

Locomotives

The most common use on locomotives is to give a more flexible alternative to a four-axle truck; two two-axle trucks linked by a span bolster allows the wheels to follow a curve better, without excessive side forces or the need for lateral motion of the axles in the truck. The use of a span bolster is normally signified in the AAR wheel arrangement notation by a + sign; thus a locomotive with two span bolsters, each with two two-axle trucks (the most common arrangement) is a B+B-B+B.

A lateral motion device is a mechanism used in some railroad locomotives which permits the axles to move sideways relative to the frame. The device facilitates cornering.

The AAR wheel arrangement system is a method of classifying locomotive wheel arrangements that was developed by the Association of American Railroads. It is essentially a simplification of the European UIC classification, and it is widely used in North America to describe diesel and electric locomotives. It is not used for steam locomotives which use the Whyte notation instead.

Freight cars

Span bolsters have been used for some high-capacity freight cars. The most common use is for large flatcars to haul large, heavy loads. These cars need many axles to distribute the weight. Specialized Schnabel cars with up to 72 wheels have been built for carrying large heavy items. Often the span bolsters connecting the trucks are connected by additional span bolsters to the car. The use of span-bolster-connected trucks is essential to allow the load to be transported through curves.

Flatcar

A flatcar (US) is a piece of railroad (US) or railway (non-US) rolling stock that consists of an open, flat deck mounted on a pair of trucks (US) or bogies (UK), one at each end containing four or six wheels. Occasionally, flat cars designed to carry extra heavy or extra large loads are mounted on a pair of bogies under each end. The deck of the car can be wood or steel, and the sides of the deck can include pockets for stakes or tie-down points to secure loads. Flatcars designed for carrying machinery have sliding chain assemblies recessed in the deck.

Schnabel car

A Schnabel car or Schnabel wagon is a specialized type of railroad freight car. It is designed to carry heavy and oversized loads in such a way that the load makes up part of the car. The load is suspended between the two ends of the cars by lifting arms; the lifting arms are connected to an assembly of span bolsters that distribute the weight of the load and the lifting arm over a large number of wheels.

See also

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References

  1. Dukkipati, Rao (2000). Vehicle dynamics. Boca Raton, Fla. New Delhi: CRC Press Narosa Pub. House. p. 317. ISBN   084930976X.