Cotton Weaving and Designing / 6th Edition

by John T. Taylor

Double-lifts, owing to the counterpoise and the division of the work on to two knives, are undoubtedly steadier in working, and this is an argument decidedly in their favour. Single-lifts are still used in the manufacture of figured lenos, as no shaking motion has yet been successfully adapted to enable the crossing ends to cross with a double-lift machine.

FIG. 106.

A single-lift Jacquard for weaving a pattern which occupies 400 ends in a repeat consists of 400 hooks and 400 needles, with an extra row of eight hooks for selvedges, or other auxiliary use. The hooks are arranged in eight rows with 51 hooks in a row. A cross section of this Jacquard is shown at [Fig. 106], where the uprights are the hooks and the horizontal wires the “needles.” A is the “needle board,” and this is a perforated board through which the needles pass. The bottom needle B is twisted or looped round the back hook D, and the connection of the other needles and hooks is shown. At the back of each needle a small spring made of fine brass or steel wire is placed. These springs are held in position in the “spring-box” S. There are, therefore, 408 springs required for the 408 needles. The hooks rest on the grate G, but in some makes of machine the grate is not used and the hooks rest upon a “bottom board.” In this case the hooks are very liable to turn round, and thus cause annoyance. To prevent this, flat hooks have been used, and the needle loop was shaped so as not to permit the hook to turn within it. The eight knives form the griffe. These knives are all fastened together, and are moved up and down from the crank-shaft of the loom. The illustration shows the knives at the bottom of their stroke, and at this point, or immediately after the griffe begins to move upwards, the card on the perforated cylinder E is pressed against the needles, and if there is a hole in the card, the needle directly opposite the hole will pass through it and into the perforation in the cylinder, and the knife will take up the hook to which this needle is connected. If the card is blank opposite any needle it will press back the hook, and as the knife lifts, the hook is left down. Thus it is possible to lift any of the 408 hooks in the machine for any pick. When the cylinder is taken away from the needles the hooks are forced back into their original position by the small springs in the spring-box S.

It will be noticed that the knives are leaning a little, and the reason for this will be apparent, as if they were not leaning they would catch the tops of the hooks in coming down, and would break or bend them. The sloping position enables the knives in coming down to press back the tops of the hooks and so get under them, ready for the next card to be pressed against the needles. The knives should come down low enough to be quite clear of the hooks, and therefore in this machine there is a considerable dwell when the shed is closed.

The harness for a straight-over pattern is mounted as shown at [Fig. 107]. In order to prevent confusion the connection of the cords to the machine is not shown, but the numbers on the line A represent the hooks in the machine to which the cords are to be attached. The “comber-board” or “cumber-board” B is a frame into which perforated slips are fitted. These slips are perforated to different degrees of fineness, the fineness being regulated by the number of ends per inch required in the cloth to be woven. The lingoes, L, are metal weights, and serve the purpose of keeping the mails down. MM are the mails, through which the warp threads are drawn in the order shown by the numbers, beginning at the back left-hand corner. The draft in straight-over patterns is always taken in this way in Jacquard weaving, although it is not compulsory. The harness is built with linen thread, and the method of tieing the lingoes to the hooks will be understood from the diagram.

FIG. 107.

When one lingoe has been connected to each of (say) 400 hooks, the first pattern is complete. Supposing there are 100 ends per inch, the pattern will occupy 4 inches, and therefore if cloth is required 28 inches wide in the harness, there must be seven lingoes attached to each hook, making seven patterns, or seven repeats of the pattern, in the width of cloth. Thus when one lingoe has been tied to each hook, beginning with the first and ending with the 400th, another is connected to each hook, beginning again with the first; and when this is done other patterns are formed in the same manner until the required number is complete.