FIGS. 6 AND 7. DRIVING GEAR OF NEW "CHAMPION" MOWER, ILLUSTRATING CLASS V, SUB-CLASS b. Fig. 6, showing bent lever, crank-pin wheel, and short pitman; the toothed wheels being boxed. Fig. 7, showing toothed wheels, and "universal joint." CLASS V. The system of transmitting power directly from the drive wheels or their axle to the crank pin by the interposition of an endless or tangent screw differs entirely from all others, and may well be made the basis of a separate class. The tangent screw is operated directly by a worm wheel attached to the main axle. Both wheel and screw are cast of red metal, the latter is made two-threaded, is fitted to the frame of the ma chine, and is actuated by the lower margin of the rotating worm wheel. The axle of the tangent screw extends forward, and carries the crank pin, which drives the pitman. The driving gear consists of: 1, worm wheel; 2, tangent screw; 3, crank pin; 4, pitman; hence machines of this class can be at once identified. The fifth or tangent screw class finds its sole representative in the "screw" machine. The extreme simplicity of the driving gear renders illustration unnecessary. CLASS VI. In the above classes are comprised the machines most frequently found in the American market, but in foreign markets, and, to some extent, in ours, methods of converting the rotary motion of the drive wheels and their axles into reciprocating motion by means of cams are occasionally seen. This reciprocating motion has been obtained by constructing the drive wheel with a rib, running round inside the rim, its scalloped edge projecting towards the hub, more or less slightly at regular intervals, so as to give it a sinuous outline. To a nearly horizontal sliding bar, a grooved roller is attached, its groove bearing against and partly embracing the sinuous projecting edge, the bar receiving therefrom. a reciprocating motion as the machine is drawn forward. This construction finds no favor here, but a modification of it was to be seen in the Russian department of the Centennial Exhibition, having a spur wheel on the main axle. This operated a pinion, carrying on its axle a cam wheel, with the cams projecting from its convex surface. These gave reciprocating motion to a sliding bar, in a manner similar to that just described, and thence to the pitman. CLASS VII.—An exceedingly ingenious application of the cam movement to mowers has been made in this country by casting the projections upon the face of a small wheel, in the form of radial ribs. Rapid motion is given to this ribbed wheel by putting it upon the axis of a pinion driven by a spur-wheel on the main axle. A similarly ribbed wheel, the ridges of which fit exactly into the furrows of its mate, is so fitted as, when in that position, not to rotate with it, but to slide to and from it at right angles, with the plane of rotation. Thus by the sliding of the ribs on the face of one wheel, up and down the sides of the ribs on the face of its opposing mate, reciprocating motion across the machine is obtained and imparted to the pitman. Class VII is represented by Goodwin's machine. To group the above classes under a few heads, to arrange them in the form of a schedule on a single sheet, is simply to imitate the convenient methods pursued in the study of natural history. The following schedule has been prepared with this view. Taking as its basis that movement common to mowers and reapers, whereby rotary motion is converted into reciprocating, it groups them under two divisions, and the divisions are characterized, one by the crank-pin, the other by the cam. Machines of the former division are further classified according to the means used to obtain transverse motion, whether by bevel gearing, bent lever, or tangent screw. Those of the latter division according to the position of the cams, whether on the edge of the cam-wheel or on its face. 1. Spur wheel; 2, spur pinion; 1, convex toothed wheel; 2, con- "SCREW." No. of CAM,. The cams on the internal or external edge of cam wheel operating a grooved roller, revolving in head of pitman, The cams on the face of cam wheel operating its mate, which is connected with pitman, |