Figs. 118, 119. Rectilinear motion
[Fig. 120]. Centrifugal governor for steam engines. The central spindle and attached arms and balls are driven from the engine by the bevel gears at the top, and the balls fly out from the centre by centrifugal force. If the speed of the engine increases, the balls fly out from the centre, raise the slide at the bottom, and thereby reduce the opening of the regulating valve, which is connected with the slide. A diminution of speed produces an opposite effect.
[Fig. 121]. Water-wheel governor acting on the same principle as [Fig. 120], but by different means. The governor is driven by the top horizontal shaft and bevel gears, and the lower gears control the rise and fall of the shuttle or gate over or through which the water flows to the wheel. The action is as follows: The two bevel gears on the lower part of the centre spindle, which are furnished with studs, are fitted loosely to the spindle, and remain at rest so long as the governor has a proper velocity; but immediately the velocity increases, the balls flying farther out, draw up the pin, which is attached to a loose sleeve which slides up and down the spindle, and this pin, coming in contact with the stud on the upper bevel gear, causes that gear to rotate with the spindle, and to give motion to the lower horizontal shaft in such a direction as to make it raise the shuttle or gate, and so reduce the quantity of water passing to the wheel. On the contrary, if the speed of the governor decreases below that required, the pin falls and gives motion to the lower bevel gear, which drives the horizontal shaft in the opposite direction, and produces a contrary effect.
[Fig. 122]. Another arrangement for a water-wheel governor. In this the governor controls the shuttle or gate by means of the cranked lever, which acts on the strap or belt in the following manner: The belt runs on one of three pulleys, the middle one of which is loose on the governor spindle, and the upper and lower ones fast. When the governor is running at the proper speed the belt is on the loose pulley, as shown; but when the speed increases, the belt is thrown on the lower pulley, and thereby caused to act upon suitable gearing for raising the gate or shuttle and decreasing the supply of water. A reduction of the speed of the governor brings the belt on the upper pulley, which acts upon the gearing for producing an opposite effect on the shuttle or gate.
[Fig. 123]. Another form of steam-engine governor. Instead of the arms being connected with a slide working on a spindle, they cross each other, are elongated upward beyond the top, and connected with the valve-rod by two short links.
[Figs. 124, 125]. Diagonal catch and hand-gear used in large blowing and pumping engines. In [Fig. 124] the lower steam valve and upper eduction valves are open, while the upper steam valve and lower eduction valve are shut; consequently the piston is ascending. In the ascent of the piston rod the lower handle will be struck by the projecting tappet, and being raised will become engaged by the catch, so as to shut the upper eduction and lower steam valves; at the same time the upper handle will be disengaged from the catch, the back weight will pull the handle up and open the upper steam and lower eduction valves, when the piston will consequently descend. [Fig. 125] represents the position of the catches and handles when the piston is at the top of the cylinder. In going down, the tappet of the piston rod strikes the upper handle, and throws the catches and handles to the position shown in [Fig. 124].
Figs. 120, 121, 122, 123. Governors for steam-engines
[Fig. 126]. A mode of driving a pair of feed rolls, the opposite surface of which require to move in the same direction. The two wheels are precisely similar, and both gear into the endless screw, which is arranged between them. The teeth of one wheel only are visible, those of the other being on the back or side which is concealed from view.