To place the fibres into their proper positions, a method may be adopted by which the two levers may be separately made, the axle and crank-pin also separately made, and the four pieces welded together.

All the pieces may be separately forged at different fires, as for other large forgings, each component being trimmed to shape and cut to length while adapting them to each other. The two parts for the levers are made by reducing them of one straight bar of sufficient length for both levers; or of two shorter bars, each of sufficient length for one lever. When both levers are drawn down until their thickness and width are about equal to the required forged thickness and width, the ends are cut open by first punching a hole, and next cutting a slit, as described for other work. The gaps thus made are further enlarged and shaped to fit the two ends of the crank-pin, and also to fit the axle-piece ; so that each lever has one of its forked parts shaped to fit one end of the crank-pin, and the other forked part shaped to fit some part of the axle. The length of this axle-piece may, therefore, be about three times the width of the crank between the two axle junctions. For short axles, the length of the axle-piece may be equal to the entire forged length, to avoid lengthening by welding pieces to it. The length of the crank-pin piece is only a few inches longer than the finished length, to allow the crank-pin ends to be riveted with upsetting, if considered necessary, during the welding of the pin to the levers. The four components appear in Fig. 193.

The joints first made are those of the levers with the axle. By referring to the Figure, it may be observed that the ends of the levers are of sufficient length to project beyond the axle, and allow them to be closed towards each other previous to welding, by which the components are retained in position until welding is effected.

The hammering for welding commences by first placing the work with the axle upwards; the axle is then driven down with a narrow hammer to thoroughly weld the bottoms of the lever-gaps ; after which, the work is put down with one side next the anvil-face, and the lever ends closed towards each other. After this the welding is completed at one or two other heatings, with additional upsetting and welding of the lever sides, if necessary.

If it is intended to weld both levers to the axle at one welding, the thickness of the two levers together should equal the total width of the crank, which is the distance between the two axle junctions. The levers may then be put close together on the axle, having the lever ends closed together sufficiently to maintain them in proper position until welded. By thus welding the levers close together, the crank is made as if solid, although a slit remains which is the centre of the gap intended; and the same amount of boring and slotting will result as if the crank were a single solid piece. But when it is necessary to avoid this boring, each of the levers may be forged nearer to its desired dimensions, and welded to the axle, so that the distance between the two levers shall be equal to the forged width of the required gap. This arrangement is denoted in Fig. 196.

After the levers are united to the axle, the opposite forked ends are adapted to contain the crank-pin; and the joint parts of the pin are trimmed or thinned at one side to fit the gaps in the levers. The pin is next put in and tightened sufficiently to allow the work to be carried about, and, after heating, the welding is performed in a manner similar to that for the axle. The crank is afterwards completed by cutting off the superfluous metal at the projecting fork ends, and joining other axle-pieces to the primary one, if not already of sufficient length.

Crank forging by means of forked levers is specially applicable to all crank-axles intended to have levers of comparatively great length, or whose levers are long when compared with the axles. For short levers the next mentioned methods are more suitable.