PULVERIZERS AND HARROWS. The " pulverizers" constitute connecting-links between the plow and the harrow, and are, indeed, loosely termed harrows ; hut the action of those with obliquely revolving disks cuts and turns the earth after the manner of the ordinary plow, rather than by raking and scratching it like the harrow proper. The ten dency of the revolving-disk " barrow " to encroach on the province of the common breast plow is illustrated by Clark's cutaway disk machine, Fig. 1, which cuts a furrow 40 in. wide and may be run as much as 7 in. deep. It lifts the soil, inverts it, and effectually aerates it. Each of the revolving members is a 24-in. notched disk, dished, and sharpened at the edges, and behind each is suspended a spring-steel moldboard to turn each furrow or cut. Stationary cleaning-knives are added, to scrape any adhering dirt from the disks. A sharp revolving disk land-side precedes each of the notched disks which act as shares. The land-sides do also the work of coulters. A long beam is used, supported at its front end by a 16-in. easter. The plow-heads are supported and by two carrier-wheels on a hinged axle governed by a hand lever at the right. The depth of cut of the land-sides is governed by a hand lever on the beam. The lever at the left adjusts the moldboards. The original disk-harrow was furnished simply with a gang of revolving circular dished disks.
The change of the form of the disks, in the implement under consideration, by cutting away portions at regular intervals so as to leave merely the five or six spade-like blades on each rolling member. has given this class of machine a new impulse of usefulness. Thus made, the blades "scour" better than before in all soils, but are comparatively free from the fault of trailing the soil into ridges, and leaving a dead-furrow or piney at the center line of travel or the two outer edges, according as the disks are set on an inward or outward gather. The implement is suitable for stubble-plowing and all free working soils, also hard adobe and clay, but not for stiff sod or very sticky soils. It does not need the heavy weighting required by the solid disk machines, especially on sod lands, fields that have been plowed some months previously, or corn, wheat, or other grain-stubble lands. Four horses are advan
tageously used. Where this class of machine is used on such land the tilth is better than that of the ordinary plow, and consumes far less time. The cutting edge of a round disk of the customary size is some 50 in., and some 50 ft. of crating edge must therefore be pressed into the earth at each revolution ; while the " cutaway "penetrates the earth with only some 22 ft. of cutting edge, and, therefore, with considerably greater ease. In working say 4 in.
deep, each circular disk must have an incisory bearing of some 15 in. per revolution, making 15 ft. of incisory bearing for a twelve-disk machine ; but the " cutaway " machine, with the same number of disks and depth of work, has less than 8 ft. of ineisory bearing ; this diminishes the draft, and yet the disks, by their troweling action, chop the soil into finer frag ments. In the Clark cutaway pulverizer, six shovel-blades enter the earth at each revolu tion of each member, making nearly a quarter turn to stir the earth laterally four inches, crumbling it quite finely. Clark's disk is shown separately in Fig. 2.
All harrows of the rotating-disk class are subject to a considerable amount of side pres sure on each disk, which accumulates at the rearward hanger, causing a severe friction there. For this hanger, the Keystone Manufacturing Co., of Sterling. Ill., make for their machine of the same class the ball bearing exhibited in Fig. 3 (shown with side-plate removed), which diminishes the wear and eases the draft.
The " Acme " harrow (Fig. 4,) includes the functions of clod-crushing and pulverizing plowed ground. The front cutters are deflected to one side. and the rear cutters to the other, to neutralize tendency to ridge the soil. The angle of the cutters is adjustable, and they are reversible, doubling their service. Bradley's steel lever-harrow (Fig. 5) will serve to illus trate the improvement by which the entire harrow-frame, connected throughout by a series of pivoted rods, is manipulated by levers to incline the pitch of the teeth backward, thus chang ing the implement from a stirring to a smoothing harrow, or causing the removal of any gathered trash from the teeth.