Crank moulds are used principally for what are termed solid cranks, which are forged without, gaps. If necessary, crank moulds may be made to shape the largest cranks that are made, and are useful to thoroughly .condense the metal in any solid crank, whether it is made by piling up the cranks of small pieces, whether the levers are forged and welded to the axles, or whether the crank is a solid piece, which is made by drawing down the two axle-ends, and thus forming the crank between.

Crank moulds for large work must be very strong, because, to shape a solid crank properly, a superabundance of metal must be provided, which is cut off during the forging. All such moulds may be used as bottom tools without any top shaper, except ordinary hammers and top-rounding tools ; but to make a number of cranks of one size, it is proper to make a top shaper to shape the half of the axle and the short part of the crank that projects above the mould.

One great advantage in using these moulds, and others of similar character, consists in the facility and speed with which the desired contour of any forging is indicated by the shapers. Although the entire shape may not be obtained at one or two hammerings, through too much metal being in the mass to be shaped, the desired form is attained at all parts except between the faces of the two shapers. This space is named the fin-way; and into this place all the superabundant metal is squeezed. This portion is the fin, and in large work it may be a projecting ridge of fifty or sixty pounds, and another 6n may be formed at the opposite side of the axle; if so, the work is well and equally condensed, but if only one fin is formed, it signifies that the mass was not properly piled up previous to being driven down. This piling consists in laying the crank, or whatever is being forged, upon its side, and hammering it to make it taper, and of a sufficient length to stand up above the remainder of the crank when it is put into the mould. By thus making a taper pile or projection which is exactly in the middle of the upper side of the crank or other lump to be shaped, the projecting portion will be battered into the middle of the mould, instead of being spread out into one side of the fin-way and not into the other.

During the forging of cranks that are being made of square iron or of round iron, shaping-moulds, whether with top shapers or without them, will greatly facilitate the work; consequently, crank moulds are much used. A few crank moulds are represented by Figs. 253, 254, and 255.

Fig. 253 represents a mould for shaping a crank intended to have the circular axle-ends, the arms, and the crank-pin all of one thickness. Fig. 254 indicates a mould for producing cranks with square axle-ends. The mould denoted by Fig. 255 is shaped to forge a large and ordinary class of cranks whose levers or arms are to extend from the axles in four directions. While looking at a crank which is in its mould being shaped, these four directions are upwards, downwards, to the right, and to the left.