Fig. 3.
Fig. 4.
Fig. 5.
A section of the cylinder is shown in [Fig. 3]; the piston and its rod are absent, to prevent confusion of the parts. The cylinder with the covers on is 2 inches long and 13⁄8 inches diameter across the flanges. The bore is 3⁄4 inch and 15⁄8 inches (full) long. The face of the cylinder where the valve works is level with the diameter of the flanges. This face is shown at [Fig. 4], where the size and position of each porthole may be seen. The rectangle represents the steam-chest itself, and the four small circles are the screw-holes in the valve-face for attaching the steam-chest.
Returning to [Fig. 3], the steam-ways are shown at A A. These are drilled from the ends to meet the inlet ports B and C, which are closed by the slide-valve (see [Fig. 5]). The exhaust way is at D, and the port-hole communicating with it needs no special mention. The steam inlet is E; the threaded exterior is for attaching the steam-pipe from the boiler. The glands and stuffing-boxes, for keeping the piston and valve-rod steam-tight, are shown in section. G G are the glands screwed into the castings; the parts bored out to receive the packings are marked H H. It will not be necessary to make special reference to the body of the cylinder, the covers, &c., as the reader will have become acquainted with these in the previous chapters.
By reference to [Fig. 3] the passage of the steam may be traced. It enters at E, filling the steam chest, and as the valve is shown it could find no outlet. The valve on being moved would uncover one port, say B, and allow the steam to enter by the steam-way A, through the slot filed in the edge. When in the cylinder it would force the piston towards the bottom, the action of the eccentric meanwhile pushing the valve along and further opening B. When the piston had made half its stroke the valve would commence to close again, and by the time the end was reached the valve would be again in the position shown. The momentum of the fly-wheel would carry round the eccentric, and with it the valve would move so as to open the way from B to D, thus allowing the steam in the cylinder to escape. The port-hole C would also be opened to the live steam, which would then exert its pressure on the lower side of the piston. By the motion of the valve the steam is let into B and C alternately, and thus the reciprocating motion of the piston is maintained.
