down to shape. After one end of the axle has been finished, the other is treated similarly. As the axle has to be machined, about ¼ in. of metal is left all round for turning, and the proper length is tried over with a template.
This method of swaging or forming the shape in dies is characteristic of nearly all locomotive forgings, when any quantity has to be made. Naturally it does not pay to make expensive dies when only one or two similar forgings are required. In such cases the forgeman has to work out the shapes with such ordinary swages and tools as are usually to be found in a forge.
The most difficult forging, and the one requiring the greatest care is that for the crank axle.[1] The ingot is heated in a large furnace, having at the same time a “porter” bar or staff welded to one end at p (Fig. 11a). The “porter” is a long taper bar, which serves for the handling of the work by the forgeman, and is supported by a crane chain. Frequently it is welded to the ingot whilst the latter is being made. The ingot is first hammered down under a heavy steam hammer to a rectangular shape with chamfered edges as shown in Fig. 11a. This slab will be about 24 or 25 ins. deep × 12 ins. wide, and nearly 6 ft. long, and weighs about 2¾ tons without the “porter.” Whilst still hot it is taken to a hot saw, close at hand, and four saw cuts are made as shown at a, which extend
- ↑ An illustration of a crank axle is given in the primer on The Steam Railway Locomotive.
