The Locomotive Of Today

The Engine : Piston Rods, Stuffing Boxes. 71 Many elaborate patterns of pistons and rings are in use in America, with springs to keep the rings tight in the cylin- ders, but the Ramsbottom rings above described are universal in Britain, for in addition to being equally efficacious they are very much simpler in construction and cheaper to maintain. ” The piston rods are made of Steel or wrought iron, and are from to 3| inches in diameter. One for engines with 17-in. cylinders and larger is shown at D. It has a taper shoulder and thread at one end, and a taper at the other on a portion of larger diameter than the rod, so that the cotter hole may not weaken it there. The joint at the front end, attaching it to the piston, has already been described, at the other end the crosshead embraces it, and the rod is ground in until it is within of an inch of being “home, the cotter being then driven in to do the rest. The taper at this end is about 1 in 16. Sometimes the end of the rod is swelled out to form the crosshead. On small engines the ends of the rod are simply turned down to the required taper, and no shoulder formed, but for larger engines the weaker portions are generally thickened up. The rods are passed through a stuffing box at the back end of the cylinders, and many means have been devised for allowing them to work through freely without permitting steam to pass. On the cylinder drawing, Fig. 13, a simple stuffing box is shown, having a solid neck ring and giand. This design could only be used for engines which have the piston rods with the crosshead end of the same or less diameter than the rod, as a large end could not pass through the holes in giand and neck ring. Fig. 13a shows a tail rod for the piston. At E, Fig. 14, anotlier pattern which has been largely adopted for rods with large ends is shown in section. . Ihe neck ring is split along the dotted line, and half put on either side of the rod, and the two pushed home, holes being frequently drilled and tapped in the front of each to receive the ends of a wire for use when it is necessary to draw them. The giand is bored out large enough to take a bush, also in halves, put on the rod as befbre, then pushed into the giand, and held by the set screw shown in the front view. Packing, consisting of hemp or some preparation of asbestos, is put in and compressed by the giand being fbrced home by nuts on the studs, lock nuts being used to prevent the first nuts from slacking back. The neck ring and giand bush are usually 01 gun metal, the giand, however, may be either of cast or wrought iron. This design of stuffing box has been until very recent years the general practice here, but now metallic packing is being largely adopted, the great advantages of