The class of slide-rods shown by Fig. 32 is forged of three pieces. One of the three constitutes the intermediate part of the rod, indicated in the Figure by B B ; the second piece is formed into the circular portion, denoted by C C; and the third piece becomes the friction portion and the screw part, represented by A.

The intermediate piece is first made, by punching a hole into and cutting open the end of a bar whose diameter is about 11/2 times the diameter of the intended sliding part. The two ends thus produced are carefully separated while at a bright yellow heat, and shaped into the form of a T. The length of the three arms of the T-piece are sufficient to allow the other two pieces to be conveniently welded to it. The proper length and thickness of the two smaller arms are attained by driving in a fuller at the two curved parts, B B, and afterwards reducing the remaining lumps to the dimensions desired; a thick portion being allowed to remain at the ends of the two thin arms, for being formed into a scarf. The larger arm is next reduced by a fuller to the forged diameter required; a lump remaining for a scarf, as for the two thin arms. By this mode, all upsetting of the T-piece is avoided.

After the T-piece is made, the length of bar necessary for the circular portion may be ascertained by subtracting the lengths of the two thin arms of the T-piece from the entire length of the ring's mid-circle circumference, and that which remains indicates the length of the ring-piece required, if the thickness of the bar previous to being welded is equal to the thickness of the ring after being finished to the forged dimension. It is always convenient to use a rather shorter length of bar than the symbols indicate ; and also to select bar which is rather thicker than the finished forged thickness, because the ring can be stretched or lengthened after being welded, but it cannot be upset or shortened without trouble.

Previous to joining the ring-piece to the T-piece, the two thin arms are curved to their proper form; and the bending or curving of the ring-piece is also partly effected previous to welding it to the T-piece.

After being scarfed while straight, the ring is formed across the anvil beak until nearly circular, to avoid contact with that arm of the T-piece which is not to become part of the joint first made; and after the first joint is made, the ring is properly curved to its circular form, and to fit the scarf of the other thin arm; and while in this relation, the second joint is made by welding; after which the ring is stretched, if necessary, while on a piece of large round iron which is placed upon the blocks having angular gaps. Another mode of lengthening is performed by aid of a long cast-iron conical filler, slightly tapered to suit rings of various diameters.

After the two ring-joints are effectually made by using a large supply of sand and a rapid hammering, the lump at the end of the thick arm of the T-piece is scarfed, and a piece of iron is prepared for the parallel portions of the slide-rod. The diameter of this piece is only equal to the forged diameter of the sliding or friction part of the rod ; and the length of the piece is sufficient for the sliding portions and the screw part.

A slide-rod which is indicated by Fig. 33 requires but little more forging than welding and closing the fibres of a bar of good iron or fibrous steel, and then cutting the rod to a proper length, and squaring or curving the extremities to facilitate the centring process, previous to turning. In that part of the rod's parallel portion which is to be outside the packing-gland, two flats are made for the convenience of rotating the rod while in its place. A spanner which fits the two flats is employed to rotate the rod, whereby the position of the slide-valve is altered at pleasure. These flats being very shallow, no attention need be given them by the smith, who makes the rod sufficiently solid throughout its whole length.

Fig. 34 represents a slide-rod whose small end is fixed in the slide-valve by nuts on each screw, the valve being between. An opening, which is four-sided instead of circular, contains the block and pin by which motion is given to the valve-rod. In the figure this opening is indicated by F; and when of small size, the whole of the rod may be forged of one piece which is large enough to produce the boss by being flattened and spread out by a steam-hammer, the four-sided opening being afterwards made by drilling and slotting.

A more convenient mode of making large rods of this character consists in using a shorter piece of iron, which is only sufficient to make the boss and two short steins. These steins are reduced from the lump by fullers and hammering, and produced to a convenient length for welding to two other pieces, which are to be formed into the friction parts, indicated by A and B. These two pieces are of a suitable diameter, to admit only a small amount of reducing and hammering to attain to the forged diameter, and to ensure sufficient solidity for the screws.'

Rods that are to have large frames in the middles, to fit the outsides of slide-valves, require a different method of forging. Instead of forging a solid boss and leaving it to be drilled and slotted, the square frame itself is forged upon the anvil. In such cases, six pieces are necessary to make one rod. Of these six, two are formed into T-pieces, whose thin arms constitute portions of the intended square frame, and whose thick arms are scarfed for welding to the two cylindrical friction parts of the intended rod. After the T-pieces are made, two thin bars are bent to the forms of crotchets or brackets, thus , and the thin arms of the two T-pieces are welded to the two crotchet-pieces. When the square or rectangular frame is thus complete, it is welded to the two cylindrical ends of the rod, by which the forging is finished.

In many cases the friction portions of the slide-rod are keyed or screwed into the bosses of the valve-frame; such a frame may be made of four pieces only, as indicated in Fig. 134.