The Ball engine, as shown in [Fig. 42], is a typical horizontal single valve high-speed engine with a direct-connected dynamo. It is very rigid in design and especially compact for the power developed. The valve is of the double-ported type shown in [Fig. 2], having a cover plate for removing the steam pressure from the back of the valve. The piston is hollow with internal ribs similar to that shown in [Fig. 29], and is provided with spring packing rings carefully fitted in place. The governor is of the shaft type, having only one weight instead of two, as shown in [Fig. 37].
Fig. 43. The Sturtevant Vertical Engine
The Sturtevant engine shown in [Fig. 43] is a vertical high-speed engine of a form especially adapted to electrical work. Engines of this general design are made in a variety of sizes, and are often used on account of the small floor space required. In the matter of detail, such as valves, governors, etc., they do not differ materially from the high-speed horizontal engine.
Fig. 44. Moderate Speed Engine of the Four-valve Type
[Fig. 44] illustrates a moderate-speed engine of the four-valve type. These engines are built either with flat valves, or with positively driven rotary or Corliss valves, the latter being used in the engine shown. It will be noticed that the drop-lever and dash-pot arrangement is omitted, the valves being both opened and closed by means of the wrist-plate and its connecting rods. This arrangement is used on account of the higher speed at which the engine is run, the regular Corliss valve gear being limited to comparatively low speeds. All engines of this make are provided with an automatic system of lubrication. The oil is pumped through a filter to a central reservoir, seen above the center of the engine, and from here delivered to all bearings by gravity. The pump is attached to the rocker arm, and therefore easily accessible for repairs.