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Stephenson steam train locomotive

Stephenson steam train locomotiveIn the early days of locomotive engines, Messrs. Sharp, Roberts & Co., Atlas Works, Manchester, built hundreds of engines the side frames of which were ash planks about 3 inches thick, secured between two iron flitch plates. For the comparatively small locomotives of the period these frames were most excellent. Fig. 2 is an elevation of a standard type of a steam locomotive engine constructed by Robert Stephenson & Co. It was closely followed in design by Sharp, Roberts & Co. The illustration is given here because the general features of the design were copied for many years.

A few steam engines are still running with them; indeed, at one period the ash side frame was in extensive use. Lateron, however, only the plate and the bar frame were used. This last was introduced by Mr. Bury, of the firm of Bury, Curtis & Kennedy, about the year 1833. As its name denotes, it is built up of a number of rectangular bars, either welded together or secured to each other with rivets, dovetails, and, in most cases, bolts. These last are turned dead true, and are made tight driving fits for the holes into which they are put.

In the early days the United States possessed no rolling-mills which could make plates fit for side frames. The average smith possessed skill enough to build up frames from bars forged under a water-driven tilt hammer. So the bar frame found favour, and although the United States could supply steel plates of any required dimensions later in time, the bar frame still retained. It was a very good frame, and possesses some advantages over the plate frame, but it is expensive to make and very costly to repair.

The plate frame was so simple that its essentials and its qualifications for the work it had to do can be understood in a moment. This is far from being the case with the bar frame, and an account of some of the modifications which it had undergone is introduced here because its history sets forth almost directly the nature of the stresses to which the framing of a locomotive, no matter how constructed, is exposed, and the way in which development proceeded.