Fig. 141.—Section of Cylinder
Fig. 143.—Piston Tongues
[Fig. 137] gives a side elevation of the engine, with the crank-shaft and sleeve shown in section. It will be seen that the sleeve butts to a shoulder, a slight undercut being given to the shaft when turning this portion to ensure a good joint. From this figure the inlet and exhaust principle will be manifest. It will be noticed that as each inlet pipe coincides with the right angular inlet in the shaft, so does it receive a charge of compressed air. The pressure on the piston revolves the engine, thus shutting off inlet to that particular cylinder and bringing the next cylinder in line with the inlet. As soon as the first cylinder nears the bottom of its stroke it begins to exhaust through the diametrically opposed exhaust port. Needless to say, the crank-shaft and sleeve must be turned a good running fit, otherwise there will be considerable waste of power. The best method to employ is to turn the shaft a push fit within the sleeve, and then to grind it in with rottenstone. When soldering the inlet pipes into the sleeve, care must be taken to ensure that they do not become “choked” with solder. The sleeve should afterwards be reamed out to remove all superfluous solder. When soldering the sleeve into the back plate care must also be exercised to ensure that it is truly at right angles to the plate.
It must be clearly understood that the engine revolves with the sleeve as a bearing. The five holes which are drilled round the sleeve to receive the inlet pipes must be equidistant, so that the periods of inlet are synchronous.
[Fig. 138] gives an enlarged view of the crank-shaft and sleeve, and is self-explanatory. Observe that the exhaust port is larger in diameter than the inlet.
Details of the pistons are shown by [Fig. 139]. The connecting-rods are soldered to tubular distance pieces, which rock on the ¹/₃₂-in. silver-steel gudgeon-pins, which pass through the pistons, being cut shorter than the outside diameter of the piston to avoid possible scoring of the bore of the cylinders. The gudgeon-pins are soldered into position, the superfluous solder being scraped from the piston walls. To ensure airtightness of the pistons and cylinders, cupped leather washers are fixed to the piston-heads by means of tin tongues soldered to them, and which are forced through the washer and bent over. The ordinary cycle-pump washer is admirably suited to the purpose, but the height of the washer when within the cylinder should not exceed ⅛ in.
Fig. 144.—Container