HARVESTING MACHINERY. The three principal types of crop for the harvesting of which machinery is employed are (a) grass, (b) cereals and (c) roots. Mechanical methods are to some extent applied in the harvesting of other crops, e.g., flax : but the principal food crops are those which chiefly lend themselves to me chanical treatment. In many parts of the methods are still, however, employed, and a very substantial part of the world's harvest is cut with the sickle and threshed out with a flail or by means of a sledge drawn round and round by oxen on a cir cular threshing floor. Whether machinery is to be employed or not depends chiefly upon land tenure : in a country of peasant holdings, few individuals can employ machinery economically and the common organization of labour which might permit the in troduction of a machine is difficult. Weather, too, plays a large part in determining to what extent machinery may be used. The scythe, for example, is still employed habitually in certain hilly districts even in Great Britain, for mowing grass and the hand rake for turning it. Again, crops of cereals may be so badly laid that they cannot be cut mechanically and resort must be had to the scythe. Increasing attention is being paid to methods of dry ing crops artificially, and these are described elsewhere (see CROP DRYING).
Various machines are available for turning the grass in order to assist natural drying. The hay-turner or tedder which was one of thc first machines used for this purpose has a series of tines or teeth attached to a skeleton cylinder fixed on the axle of the ma chine and driven by gearing from the wheels. A metal shield is placed over the forward and upper part of the cylinder while the back is uncovered. When the tines rotate in a forward direction they pick up the grass and carry it round in the machine and throw it out backwards, spreading it evenly over the ground. When the tines rotate in the reverse direction the grass is merely knocked out backwards and stands exposed to the air. Modern practice favours the use of combined swath-turners, side-delivery-rakes and tedders which may be quickly adapted for each operation. Swath turners are used for turning over the swaths without dispersing the grass. This operation is performed by means of spring tines which revolve across the swath as the machine proceeds. When the machine is used as a tedder, the tines revolve at double the speed in the reverse direction. It should be noted that swath-turners must follow in the track of the mower, while the hay-turner can be used across the field. Side-delivery-rakes are employed for raking the partially made hay into windrows. The machine is carried on two main wheels and a small trailing wheel. The com monest type has four horizontal rake bars fitted with spring mounted, vertical steel tines. These bars are mounted at each end on revolving disks set at an angle to the frame behind the driver's seat, and are driven by gearing from the main shaft. The tines are mounted on each rake bar in three sections, the middle one of which is readily detachable. If the middle section is removed the swaths are merely turned over. If all three sections are used the hay is swept to one side and left in a windrow. The horse rake is being displaced by the side-delivery-rake for gathering purposes but is still used for cleaning fields afterwards. It consists of a number of curved steel tines, extending the whole width of the machine, carried on a light frame with two wheels. The teeth are often adjustable, both for pressure and pitch, so that the ground may be either closely or lightly raked. A ratchet-gear fitted to the wheels provides the means for depositing the load which the rake has collected. The use of hay sweeps or hay loaders is steadily displacing hand forking. Which method is adopted depends largely on the farm and the prevailing weather. In large fields and where the ricks are built in the fields, hay sweeps are usually employed. In smaller fields and where it is necessary to cart the hay some dis tance to the homestead, loaders are more useful. The hay sweep consists of a frame carried on two widely-spaced travelling wheels, and a large number of long wooden teeth or a wooden platform projecting forward from the frame. The hay is swept up as the im plement moves forward, drawn, as a rule, by two horses hitched to each side of the sweep. When the sweep is full the teeth or plat form is raised slightly from the ground and the machine is driven to the rick and unloaded. Hay loaders are of two distinct types: the apron and the reciprocating fork. The former consists of a gathering drum fitted with spring teeth mounted on a main axle and an endless apron or web. The hay is picked up by the gather ing drum and delivered to the travelling web, which elevates it to the waggon or cart. In the reciprocating-fork machine, hay is worked up the loader by means of shaker rods and tines operated by crank shafts, driven by chains from the travelling wheels. Loaders usually pick up hay from the windrows. The loader is mounted on a frame carried on four travelling wheels, and is drawn behind a waggon or lorry. Where the land is laid in ridge and fur row hay-loaders are at a disadvantage.
Grain Harvesting and Threshing Machinery.—Although in certain parts of the world cereal crops are harvested only for their grain, both in intensively farmed countries and in primitive countries great importance is attached to the straw. In intensively farmed countries straw is used for food and litter for the cattle and is converted into manure : in primitive countries where fodder is scarce the straw is bruised and fed to the farm animals. These several conditions mainly determine the type of machinery re quired : other factors are land tenure—since a small-holder does not as a rule use an expensive or complicated machine—and climate. Reapers are the simplest machines used for harvesting grain crops. There are two types of reapers, namely, the manual delivery and the self-delivery or sail-reaper. The former type is very similar to the mower (see above) but has a light wooden frame-work at tached to the cutter bar for collecting the cut corn which is raked off by hand and dropped in heaps for making sheaves. These heaps must be cleared away before the machine can cut another strip and it is usual to cut the crop across the field, the reaper running idle on the return journey. Often combined mowers and reapers are used. The self-delivery or sail-reaper is mounted on one main driving wheel having a fixed cutter-bar carried on travelling wheels at either end which may be adjusted for height of cut.
Behind the cutter-bar is a platform on to which the corn falls and from which it is swept to one side by four rakes working on arms attached to a capstan on the main frame and driven from the land wheel. This machine leaves a clear path for cutting the next strip and the machine is able to travel round and round the field.
Self-binders, which deliver the corn bound in sheaves, often known simply as binders, are really modifications of sail-reapers with the addition of elevating and tying mechanism. Binders are usually hauled by three horses or by tractors. Certain modifica tions have been introduced to enable higher travelling and cutting speeds to be used when the binders are drawn by tractors, and in some machines the cutting and binding mechanism is driven from the engine of the tractor. The sheaves are either thrown to the ground at the side of the machine or collected by a sheaf carrier and dropped in heaps to facilitate stooking or shocking. Com bined harvester-threshers were devised for harvesting in the dry climates of North and South America, Australia and South Africa.
Threshing machines are sometimes fitted with mechanical or self-feeders and conveyers are used for carrying the sheaves from the rick to the thresher. In America the thresher is usually of larger capacity than the English machine. The straw cavings and chaff are all blown through piping to a distance and deposited in heaps. In this way the straw is much broken, contrary to English practice, where straw is expected to be delivered in an unbroken condition.
Corn [Maize] Harvesting and Threshing Machinery.— The extensive cultivation of maize in America and elsewhere has led to the development of special machines for harvesting and threshing this crop, which may be cut and bound into sheaves or merely headed. The corn binder like the grain binder has cutting, elevating and tying devices and is carried on a framework with one large wheel (which drives the mechanism) and two or three smaller wheels. The stalks are cut between a fixed knife and mov able knives attached to two endless chains which rotate as the machine traverses the row. There is also a device to grip the stalks and to convey them to the binding platform from which they are either dropped on the ground for shocking or elevated to a waggon drawn alongside the binder. The corn header or picker takes the ears or cobs from the standing stalks, removes the husks and then elevates the cleaned ears into a waggon drawn alongside the machine. The stalks are left standing and the husks are dropped on the ground. The corn sheller removes the kernels from the ears, cleans the shelled corn and separates it from the cobs and other foreign matter. There is also a device to separate any loose kernels from the shredded material. The ears are afterwards put through a sheller for extracting the kernels.
The simplest form of beet-lifter consists of a special share attached to an ordinary plough beam. There are many different kinds of digging shares, but only two main types, those which exert a pressure on both sides of the beet, leaving it loose but still standing upright in the ground, and those which exert pres sure on one side only and tend to push the beet to one side. With all these machines the beet is afterwards pulled by hand and the tops cut off with a knife, the beet being subsequently loaded by hand into carts. Many machines have been invented for topping beet mechanically, either before or after the roots are lifted. The cutting implement is usually either a revolving disc or a hoe blade generally fixed diagonally across the row. These machines are built either simply as toppers, or in combination with lifters. It cannot, however, be said that an entirely satisfactory topping and lifting machine has yet been produced, though some will do useful work under favourable conditions. See also AGRICULTURAL MACHINERY. See F. N. G. Kranich, Farm Equipment for Me chanical Power. (B. J. O.; H. G. R.) Among the many devices invented for large-scale farming in the United States a few are of sufficient importance to call for full description here.
Previously the combine could be used successfully only where the grain ripened evenly and was free from weeds and other green material. Now with the development of a new machine, the windrow harvester, the farmer can begin cutting his grain at the same time he would go into his field with an ordinary binder, which is usually a week to ten days earlier than the combine can be started. The windrow machine, or windrow-harvester, as it is called, is virtually a right-hand header with facilities for delivering the cut grain in a windrow on the stubble. It is important that the stubble be cut high enough so that it will hold the cut grain and allow air to circulate underneath and cure it quickly. The grain is laid in the windrow with the heads overlapping the butts similar to that in which shingles are laid on a roof. After two or three days of good drying weather, a harvester-thresher equipped with a pick-up device is brought into the field and run in the same direction as the windrow harvester; the grain is picked up just as a man would raise shingles from a roof and goes into the com bine to be threshed and handled from there on just as if it were being cut from the stubble in the usual manner. The windrow method has been developed to supplement the combine method of harvesting; its use is especially advantageous where grain is weedy or ripens unevenly or weather hazards are prevalent at the time of harvesting. Frequently a farmer begins his harvest by windrowing his grain and later when conditions are right he re moves the pick-up device from the harvester-thresher and finishes the harvest by the straight combine method.
There are several types of combines now in use. The large machine developed for use in the Great Plains is now equipped with an auxiliary engine and may be pulled by horses or tractor. It is made in sizes that cut from 9 to 24 ft. swaths. Machines of this type cutting from 9 to 1 2 ft. swaths are used somewhat in the Corn Belt and require from 6 to 8 horses, or tractors of 12 to 15 drawbar horse-power. On the hilly farms in the Pacific North-west as many as 3o horses are sometimes used.
Another type of combine introduced in 1926 cuts a 9 or io ft. swath and is drawn by a tractor with a direct power drive from the tractor to operate the cutting and threshing machinery. This type can be operated by one man and has the further advantage of being less expensive than the large combines with auxiliary motors.
The smallest type of combine now on the market, also intro duced in 1926, is one mounted on the tractor from which it ob tains its power. It cuts an 8-ft. swath, the cutter bar being directly in front of the tractor. It also differs radically from all others in that an auger is used instead of canvases on the cutting platform. This small power machine is used mostly on farms which have small acreages of grain.
Combines can be equipped with grain tanks to store the grain until it can be run into a motor truck for hauling to the farm or market. Where wagons are used for hauling the grain away from the combine the grain is usually run directly into a trailing wagon. When one wagon is full, another is substituted to catch the grain while the loaded one is hauled away. The straw is spread behind the machine uniformly over the land by means of special equip ment for the purpose. It can then be plowed under without diffi culty. Without the straw-spreader equipment the straw is left in a narrow strip and must be raked into piles for burning or hauling.
Two main types of sleds, the finger type and the slot type, are now in general use. The sleds are commonly drawn by two horses and operated by one or two men. The finger type is adapted to small cotton of the kind grown in the Staked Plains area, and the slot type for use in the bottom lands of the plains area where cotton grows more vigorously and taller. The finger type is char acterized by toothed arrangements, not unlike mower guards, attached to the front of the sled where they strip all bolls from the stalks as one strips leaves from a tree branch by drawing it through the fingers of the hand. The harvested cotton falls or is raked back into a box for holding until the end of the row is reached.
The slot type differs from the finger type in that the stripping action is done by narrow slots running through the centre of the sled from front to rear. The slots become narrow and slope upward toward the rear of the sled so that the cotton is stripped from the stalks as they pass into the slots. Well-con structed sleds often gather as much as 95% of the cotton from the plants.
Recently manufacturers of farm machinery have made marked progress in developing an improved harvester of the sled type. The slot idea is retained but the cotton is stripped from the plants by revolving rollers, or by lugs attached to endless chains. The snapping rolls are either twisted, perforated, or spiked to provide a rough surface for removing the cotton from the plants. The stripped cotton is either raked or conveyed from beneath the snapping rolls to a box in the rear, provision being made in some cases to screen out some of the dirt and trash. The endless chain type, however, has no separate conveyor as the stripper fingers convey the cotton to the box.
The newest mechanical cotton pickers are known as the spindle type and have been built to operate with horses or tractor. While these machines are still regarded as in the experimental stage, they have made satisfactory field tests during the past season. The cotton row passes between two revolving cylinders set up right. The cylinders are filled with numerous spindles covered with barbs that catch the cotton and wind it around the spindles. A sleeve arrangement over each spindle automatically slips the cotton off and it is blown into sacks at the rear of the machine. With the development of these machines, as well as improved sled harvesters, a good start has been made toward placing the harvesting of the cotton crop on a mechanical basis.
Hay Stacking Machinery.—In western United States where hay is largely stacked in the field instead of being stored in the barn, stacking machinery is used to eliminate much of the hand labour. Stackers can be used to advantage on many farms in other parts of the country as well as in the West, especially when farm labour is scarce. They enable the farmer to handle hay more rapidly than by other methods and usually a smaller number of men will be required. Boys often replace men in some operations when stackers are employed. Loading the hay on wagons by hand and unloading it with a stacker eliminates half of the hand labour. If push rakes or hay loaders are used to move the hay to the stack, pitching by hand is avoided entirely.
There are two principal types of stackers in common use. One type handles the hay by means of the single or double harpoon fork, grapple fork, or sling, and the other type has long wooden teeth similar to those of the push rake on which the hay is placed for elevating to the top of the stack.
Stackers of the first type are usually home-made affairs and are represented by the cable stacker, the pole or derrick stacker, and the tripod stacker. With the cable stacker hay is brought to the stack on wagons or by push rakes. The load is elevated by forks or slings to a carrier which runs on the cable and deposits the load at any desired point on the top of the stack between the poles. The height and length of the stack is limited only by the height of the poles and the length of the cable used. The pole or derrick stacker consists of a single pole set upright and of suffi cient length to make a stack of the desired height. A shorter pole (or boom) is fastened at right angles near the top of the upright pole. By means of ropes and pulleys one or two horses elevate the fork or sling load of hay to the outer end of the boom pole which is then swung over the stack where the load is dropped. The upright pole is anchored by means of guy wires. The tripod stacker has 3 poles about 3o ft. long, bolted together at the top and spread out at the bottom far enough to permit a stack to be built under the tripod. The equipment for this outfit consists of three pulleys, a hay rope, a trip rope, and a horse fork.
The second type of stacker is represented by the "overshot," the "swing around," and the "combination." Each of these has long wooden teeth, like those of the push rake, on which hay brought from the windrow by push rakes is deposited for eleva tion to the top of the stack. The overshot stacker is so called because the hay is carried up and over the stacker frame and dropped on the stack. On some forms the stacker head merely slides up an inclined plane and dumps its load on the stack, while on others the stacker head is attached to a frame-work which vaults it up and over. These stackers are mounted on wheels or sled-like frames to facilitate their movement from place to place in the field. The swing around stacker is similar to the overshot except that the stacker head is attached to an arm balanced like an old-fashioned well sweep over the top of a high upright pole. A weight at the far end of the arm counterbalances the load of hay and helps to lift it. This stacker has the advantage of being able to deliver the hay at any desired point on the top of the stack. The combination stacker does the work of both the stacker and the push rake. Stacks a little more than 20 f t. high can be made with the combination stacker. It is most commonly used around the stack to pick up the loads brought in by push rakes, depositing them on the stack from either side or end. In all types of stackers one or two horses furnish the power to elevate the loads of hay to the top of the stack. (L. S. R.)