Fig. 813. Reciprocating curvilinear motion of the beam gives a continuous rotary motion to the crank and fly-wheel. The small standard at the right, to which is attached one end of the lever with which the beam is connected by the connecting rod has a horizontal reciprocating rectilinear movement.

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Fig. 814. Continuous rotary motion of the disc produces reciprocating rectilinear motion of the yoke-bar, by means of the wrist or crank-pin on the disc working in the groove of the yoke. The groove may be so shaped as to obtain a uniform reciprocating rectilinear motion.

Fig. 815. Steam-engine governor. The operation is as follows : - On engine starting, the spindle revolves and carries round the cross-head, to which fan3 are attached, and on which are also fitted two friction-rollers, which bear on two circular inclined planes attached securely to the centre shaft, the cross-head being loose on the shaft. The cross-head is made heavy or has a ball or other weight attached, and is driven by the circular inclined planes. As the speed of the centre shaft increases, the resistance of the air to the wings tends to retard the rotation of the cross-head; the friction-rollers, therefore, run up the inclined planes and raise the cross-head, to the upper part of which is connected a lever operating upon the regulating valve of the engine.

Fig. 816. Continuous circular motion of the spur-gears produces alternate circular motion of the crank attached to the larger gear.

Fig. 817. Uniform circular converted, by the cams acting upon the levers, into alternating rectilinear motions of the attached rods.

Fig. 818. A valve-motion for working steam expansively. The series of cams of varying throw are movable lengthwise of the shaft, so that either may be made to act upon the lever to which the valve-rod is connected. A greater or less movement of the valve is produced according as a cam of greater or less throw is opposite the lever.

Fig. 819. Circular motion into alternating rectilinear motion by the action of the studs on the rotary disc upon one end of the bell-crank, the other end of which has attached to it a weighted cord passing over a pulley.

Fig. 820. An ellipsograph. The traverse bar, shown in an oblique position, carries 2 studs, which slide in the grooves of the cross-piece. By turning the traverse bar an attached pencil is made to describe an ellipse by the rectilinear movement of the studs in the grooves.

Fig. 821. Circular motion into alternating rectilinear motion. The studs on the rotating disc strike the projection on the under side of the horizontal bar, moving it in one direction. The return motion is given by means of the bell-crank or elbow-lever, one arm of which is operated upon by the next stud, and the other strikes the stud on the front of the horizontal bar.

Fig. 822. Reciprocating rectilinear motion into intermittent circular motion, by means of the pawl attached to the elbow-lever, and operating in the toothed wheel. Motion is given to the wheel in either direction according to the side on which the pawl works. This is used in giving the feed-motion to planing machines and other tools.

Fig. 823. Circular motion into variable alternating rectilinear motion, by the wrist or crank-pin on the rotating disc working in the slot of the bell-crank or elbow-lever.

Fig. 824. A modification of the movement last described, a connecting rod being substituted for the slot in the bell-crank.

Fig. 825. Reciprocating curvilinear motion of the treadle gives a circular motion to the disc. A crank may be substituted for the disc.

Fig. 826. A modification of Fig. 825, a cord and pulley being substituted for the connecting rod.

Fig. 827. Alternating curvilinear motion into alternating circular. When the treadle has been depressed, the spring at the top elevates it for the nest stroke; the connecting band passes once round the pulley, to which it gives motion.

Fig. S2S. 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 farther from the centre, and so 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. 829. Water-wheel governor acting on the same principle as Fig. S28, 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 2 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.