The middle block is loosely dropped into a recess machined in the bottom block, and has a cup shaped depression at the top to suit the shape of the buffer head when finished. The top block is secured by wedges to the tup of the steam hammer. The two bottom blocks are made with a central hole to take the shank of the buffer. After the buffer head has been hammered to shape the “fin” of metal round it is cut off, after which the finished piece appears as shown at C. The middle block being loose can be rotated by the forgeman during the hammering, by placing a bar in the recess a shown in the side. All such blocks are machined and fitted together, and the exact shape of the forging is cut out in them.
Hydraulic Forging. A considerable amount of forging is now done by hydraulic press, instead of under a steam hammer. In this case the white hot pieces are welded by squeezing them together under pressure, the process being done in blocks or dies as in the case of hammer forgings. At one large railway works some of the casings in which the buffer heads work are made in this way, more especially for wagons. Formerly these used to be of cast iron, but they are now much stronger forgings. Such a finished buffer casing is shown in Fig. 13, and the three portions from which it is forged in Fig. 14. These consist of a flat steel plate C, in which a hole is punched, a conical cylinder B which is bent round a vertical roll and has an open seam a, and a ring A having
