Fig. 9. Typical flywheel with knives and paddles for cutting and blowing (John Deere)

The flywheel develops enough energy to force the knives through quite large slugs of forage. Hence a smaller engine can be used with a flywheel machine than with a cylinder-equipped machine of similar size.

The paddles on the wheel push the cut forage, and some air, up the discharge spout to the wagon or truck. Thus the flywheel cutter performs two tasks, cutting and blowing.

The knives on the flywheel can be taken off in pairs until only two remain, as with the cylinder type. And if a counterweight is substituted for one knife, you can run the machine with only one knife. This gives the longest possible cut without changing gears, sprockets, or pulleys.

One model that has four knives gives cuts of 1/4, 1/2, and 3/4 inches when a belt is shifted to each of three different-sized pulleys. When two knives are used, cuts of 3/4, 1, and 11/2 inches are obtained by shifting the belt. And with one knife, cuts of 11/2, 21/4, and 3 inches are secured. With this machine you can get nine different lengths of cut by changing the number of knives and feed roll and conveyor drive speeds. Feed roll drives on machines not using pulleys are varied by changing gears or sprockets.

The Feeding Mechanism. The feeding mechanism is considered a part of the basic unit, although on many machines part or all the feeding mechanism is on the pickup, row-crop, or cutter bar attachments. This mechanism consists of the conveyor apron, a hold-down apron or roll, and one or two other feed rolls.

The conveyor apron is a series of slats fastened to two or three chains. It carries the forage up to the cutting mechanism and is generally surrounded by sheet metal when an attachment such as the cutter bar is used.

The conveyor apron has many smooth or serrated slats. On a few machines a belt with rubber cross slats is used, often called a draper. It makes a tight apron, like those used on combines.

When the forage reaches the top of the conveyor apron, it must be held securely while the knives chop the stems, leaves, or stalks. Several differently shaped rolls are used for that purpose. Usually there is a bottom roll between the conveyor upper end and the shear plate. It may be smooth, ridged, or serrated.

A few manufacturers use a crawler-type upper roll. This is another conveyor apron running above the lower apron. The front of the crawler apron is held down by adjustable tension coil springs, but these permit it to rise over slugs and forces them to the cutter.

Many machines have large serrated rolls to hold the forage down and move it to the rear. Some use a drum with retracting steel fingers. Others have two upper feed rolls, with the rear one smaller than the front.

All the feed rolls are power-driven. The driving mechanisms are protected by slip clutches, overrunning clutches, or slipping V-belts. It is desirable to be able to reverse these feed rolls if the throat becomes clogged. The feed rolls and apron are both reversed at the same time, thus readily clearing the machine.

The throat is the space through which all forage must pass before being cut. The width of the throat gives some indication of capacity, but there are other factors to consider also, such as engine power and overall size.

The feed rolls are held down by adjustable springs but can move up and down to a certain extent. Self-aligning ball bearings are often used because of the twist that the upper rolls receive as they pass over uneven piles of forage.

Part V