In the case of hackling by machinery, the flax is first roughed and arranged in stricks, as above described under hand hackling. In the construction of hackling machines, the general principles of those now most commonly adopted are identical. The machines are known as vertical sheet hackling machines, their essential features being a set of endless leather bands or sheets revolving over a pair of rollers in a vertical direction. These sheets are crossed by iron bars, to which hackle stocks, furnished with teeth, are screwed. The hackle stocks on each separate sheet are of one size and gauge, but each successive sheet in the length of the ma chine is furnished with stocks of increasing fineness, so that the hackling tool at the end where the flax is entered is the coarsest, say about four pins per inch, whereas that to which the fibre is last submitted has the smallest and most closely set teeth. The finest tools may contain from 45 to 6o pins per inch. Thus the whole of the endless vertical revolving sheet presents continuous series of hackle teeth, and the machines are furnished with a double set of such sheets revolving face to face, so close together that the pins of one set of sheets intersect those on the opposite stocks. Overhead, and exactly centred between these revolving sheets, is the head or holder channel, from which the flax hangs down while it is undergoing the hackling process on both sides. The flax is fastened in a holder consisting of two heavy flat plates of iron, between which it is spread and tightly screwed up. The holder is 11in. in length, and the holder channel is fitted to con tain a line of six, eight or 12 such holders, according to the num ber of separate bands of hackling stocks in the machine. The head or holder channel has a falling and rising motion, by which it first presents the ends and gradually more and more of the length of the fibre to the hackle teeth, and, after dipping down the full length of the fibre exposed, it slowly rises and lifts the flax clear of the hackle stocks. By a reciprocal motion all the holders are then moved forward one length ; that at the last and finest set of stocks is thrown out, and place is made for filling in an addi tional holder at the beginning of the series. Thus with a six-tool hackle, or set of stocks, each holder full of flax from beginning to end descends into, and rises from, the hackle teeth six times in travelling from end to end of the machine. The root ends being thus first hackled, the holders are shot back along an inclined plane, the iron plates unclamped, the flax reversed, and the top ends are then submitted to the same hackling operation. The tow made during the hackling process is carried down by the pins of the sheet, and is stripped from them by means of a circular brush placed immediately under the bottom roller. The brush revolves in the same direction as, but quicker than the sheet, consequently the tow is withdrawn from the pins. The tow is then removed from the brush by a doffer roller, from which it is finally removed by a doffing knife. This material is then carded by a machine sim ilar to, but finer than, the one described under JUTE (q.v.). The hackled flax, however, is taken direct to the preparing department. In the machine just described the work is usually performed by four operatives, who feed in the holders, remove them at the oppo site end, and change the stricks of flax--end for end—in the holders. The automatic hackling machine does all this work except that of the first feed. The holders are removed, the nuts un screwed, the flax turned, the nuts screwed tight and the furnished folder replaced in the machine by ingenious mechanism. Further, in some machines, the hackled stricks are mechanically fed into the spread-board—a type of drawing frame.
hackling the now smooth, glossy and clean stricks are taken to the sorting room, where they are assorted into different qualities by the "line sorter," who judges by both eye and touch the quality and capabilities of the fibre. So sorted, the material is passed to the spreading and drawing frames, a series or system of machines all similar in construction and effect. The essential features of the spreading frame are : (s) the feeding cloth or creeping sheet, which delivers the flax to (2) a pair of "feed and jockey" rollers, which pass it on to (3) the gill frame or fallers. The gill frame consists of a series of narrow hackle bars, with short closely stud ded teeth, which travel between the feed or retaining rollers and the drawing or "boss and pressing" rollers to be immediately attended to. The fallers are moved forward, at a slightly greater speed than that of the retaining rollers, by means of spiral screws, and the flax fibres are drawn out or attenuated by the drawing rollers; meanwhile the fibres are straightened between the gill pins of the fallers. When the fallers successively approach within a short distance of the drawing rollers, they are pushed down wards into a lower plane to be carried backwards by a similar but coarser spiral screw to a point near the retaining roller, when they are pushed upwards to repeat the cycle. They thus form a field of pins or an endless moving level toothed platform for carrying away the flax from the feed rollers. This is the machine in which the fibres are, for the first time, formed into a continuous length termed a sliver. In order to form this continuous sliver, it is neces sary that the short lengths of flax should overlap each other on the spread sheet or creeping sheet. This sheet contains four or six divisions, so that four or six lots of overlapped flax are moving at the same time towards the first pair of rollers—the boss rollers or retaining rollers. The fibre passes between these rollers and is immediately caught by the rising gill pins which carry the fibre towards the drawing rollers. The pins of the gills should pass through the fibre so that they may have complete control over it. The fibre is thus carried forward to the drawing rollers, which have a surface speed of from ten to 3o times that of the retaining roll ers. The great difference between the speeds of the retaining and drawing rollers results in each sliver being drawn out to a corre sponding degree. Finally all the slivers are run into one and in this state are passed between the delivery rollers into the sliver cans. Each can should contain the same length of sliver, a common length being i,000yd. A bell is automatically rung by the machine to warn the attendant that the desired length has been deposited into the can. From the spreading frame the cans of sliver pass to the drawing frames, where from four to 12 slivers combined are passed through feed rollers over gills, and drawn out by drawing rollers to the thickness of one. A third and fourth similar doubling and drawing may be embraced in a preparing system, so that the number of doublings the flax undergoes, before it arrives at the roving frame, may amount to from i,000 to soo,000, according to the quality of yarn in progress. Thus, for example, the doublings on one preparing system may be 6 X 12 X 12 X 12 X 8 = The slivers delivered by the last drawing frame are taken to the roving frame, where they are passed singly through feed rollers and over gills, and, after drafting to sufficient tenuity, they are slightly twisted by flyers and wound on bobbins, in which condition the material—termed "rove" or "rovings"— is ready for the spinning frame.