outlet port and the burnt gas is forced out through the exhaust on the upward return stroke as in Fig. 32. This Knight type of motor is practically noiseless in operation, has little wear, and obviates all trouble with badly fitting or worn valves or weak springs. It also provides Fig. 29.-Knight Sleeve-valve Motor; General View an ample and uniformly sized opening for both intake and exhaust of gases, and tests appear to prove that it actually improves in efficiency with age and use. The sliding sleeves must of course create quite an appreciable amount of friction, although it is doubtful if this is much. greater than the combined friction on the various cams, push-rods, valve stems, springs, and other parts of the poppet-valve motor. Lubrication is very essential to this motor, for if allowed to run dry, or to overheat, the Fig. 30.-Knight Sleeve-valve Motor; Section to show Operation friction on the sleeves becomes enormous and severe cutting and extreme wear soon result. Rotary-valve motors are now being made which work excellently; and the Reynolds motor, illustrated in Fig. 33, has proven a most practical and reliable engine of this type. The illustration represents a view of the upper portion of the cylinders with the rotary valves A in place in cylinders II, III, and IV, and removed from Fig. 31.-Knight Sleeve-valve Motor; Section to show Operation cylinder I. The valves consist of circular disks A, A, revolving in recesses machined in the cylinder heads R, R, and are provided with openings B, which correspond in shape with openings in the cylinder heads, C, D. The stems of these disk valves are connected together on top of the cylinders by means of spiral or helical gears E, which are in turn operated by a geared vertical shaft F connected at its lower end with a gear on the engine Fig. 32.-Knight Sleeve-valve Motor; Section to show Operation shaft. On the suction stroke the valves are rotated through the action of the gears, and the opening B in a valve moves into line with the corresponding inlet port C, thus allowing a charge of gas to be drawn into the |