A Course of Instruction in Machine Drawing & Design for Technical Schools and Engineer Students (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1896 Excerpt: ...the parts are made of cast-iron except the bush of the piston rod. The slide valve itself is sometimes of brass, but more usually of cast-iron. The motion of the piston inside the cylinder is communicated by the piston rod to the crosshead, and thence through the connecting rod to the crank. The opening in the cylinder end, through which the piston rod passes, is made steam tight by means of a stuffing box, that is, a hollow box for holding packing. The packing, which consists of soft twisted hemp and tallow, or other substitute, is pressed tightly round the rod by means of the gland, or stuffing box cover, which may be screwed up to any required degree of tightness by bolts. A similar arrangement will be noticed for the slide valve rods (Plate XXIV.) and for the pump plunger (Plate XXX.) A more elaborate form of gland and stuffing box, as fitted for the piston rods of marine engines with inverted cylinders, is illustrated in Fig. 54. The chief feature about this example is the arrangement for tightening up all the nuts of the main gland at once, by merely tightening up one nut. Each nut is cast solid, with a small toothed pinion. The pinions all gear with a toothed ring of brass, which fits round the neck of the gland. By tightening any one of the nuts the toothed ring turns all the other pinions in gear with it in the same direction, and thereby tightens all the nuts at once. This ensures that the gland shall be tightened up evenly, and its axis kept true with the axis of the rod, and thus preventing the possibility of friction between the piston rod and gland, which might otherwise occur. To Determine The Proportions Of A Steam Engine Cylinder.--Having given the indicated horse-power required, we can obtain the area of the piston from the following formu...