Fly wheel governors are not uncommon, which are placed directly on the engine shaft, or placed within the fly wheel itself, the latter being a well known form for engines which move slowly.
Injectors.—The Injector is one of the anomalies in mechanism. It actually forces water into a boiler by the action of the steam itself, against its own pressure. It is through the agency of condensation that it is enabled to do this.
The illustration, [Fig. 69], which represents the original type of the device, comprises a shell A, within which is a pair of conically formed tubes, B, C, in line with each other, the small ends of the tubes being pointed towards each other, and slightly separated. The large end of the conical tube C, which points toward the pipe D, which leads to the water space of the boiler, has therein a check valve E.
The steam inlet pipe F, has a contracted nozzle G, to eject steam into the large end of the conical tube B, and surrounding the nozzle F is a chamber which has a pipe H leading out at one side, through which cold water is drawn into the injector.
Surrounding the conical pipes B, C, is a chamber I, which has a discharge pipe J. The action of the device is very simple. When steam is permitted to flow into the conical tube B, from the nozzle G, it passes out through the drain port J, and this produces a partial vacuum to form in the space surrounding the nozzle G.
As a result water is drawn up through the pipe H, and meeting with the steam condenses the latter, thereby causing a still greater vacuum, and this vacuum finally becomes so great that, with the inrushing steam, and the rapid movement through the conical tubes, past their separated ends, a full discharge through the drain J is prevented.
As it now has no other place to go the check valve E is unseated, and the cold water is forced into the boiler through the pipe D, and this action will continue as long as condensation takes place at the nozzle G.