- Locomotive frame
A locomotive frame is the structure that forms the backbone of the
railway locomotive , giving it strength and supporting the superstructure elements such as a cab, boiler or bodywork. The vast majority of locomotives have had a frame structure of some kind. The frame may in turn be supported by axles directly attached to it, or it may be mounted onbogies (UK) / trucks (US), or a combination of the two. The bogies in turn will have frames of their own.Types of frame
Three main types of frame on steam locomotives may be distinguished [Ransome-Wallis Encyclopedia, p 255.] :
* Plate frames, used in Britain and continental Europe, which use steel plates about 1-2" thick
* Bar frames, likewise used in Britain and Europe, which are usually 4-7" thick
* Cast steel beds, imported to Britain from the USAArticulated locomotives
An
articulated locomotive with no fixed wheels (i.e. excluding theMallet locomotive but including other articulatedsteam locomotive s, as well as most diesel andelectric locomotive s) may have a separate frame beneath the superstructure, or the bodywork's internal structure may be load-bearing. Rarely is a truemonocoque structure used.Diesel and electric locomotives with a traditional, full-width body, known as
cab unit s inNorth America , tend to have their strength in an internal structure. This style of construction is still popular elsewhere, but North American locomotives nowadays are overwhelminglyhood unit s—with a strong frame beneath the superstructure that carries all the load, and bodywork made of removable panels for easy maintenance. Fully enclosed locomotives are used in some limited applications, mostly forpassenger train s. These tend to becowl unit s, in which the body is not load-bearing.References
ee also
*
Steam locomotive components
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