Jacquard Weaving and Designing

by T. F. Bell

Fig. 112

The front mounting of a damask hand loom is shown in [Fig. 112]. A, A are the shafts, four in number, but eight are generally used for an 8-leaf satin; B, B are the jacks; C the lams, which require to be one more in number than the leaves of heddles; D the treadles; E, E¹ the upper marches or jacks; F, F¹ two sets of coupers or levers, with their fulcrums at f, and loaded at the outer ends with the weights G. Under the ends of these levers is a bar N, to which the weights draw them, and keep the heddles up to their middle position. The cords I are not fastened to the heddles, but pass down through them to the lams C. The cords L connect the coupers with the heddle shafts. Each lam has two cords tied to it, except the two outer ones—i.e. the first and last one—which together act as one, to avoid crossing the cords. One of the cords I is tied to each lam, and also one from the jacks B; but the first and last lams have only one cord tied to each of them, one having the cord I, and the other that from B. Both these lams are connected with one treadle, and the others are each connected with a treadle. Of course, the cording is made in the usual way, agreeably to the pattern, two methods of twilling being shown in [Fig. 113]. When the weaver presses down a treadle, one leaf of heddles is raised by the cord I connected from one of the levers E, E¹ to one of the marches or lams C, and one leaf is at the same time sunk by the cord connected from one of the jacks B to the lam connected to the treadle. The other treadles act similarly when corded for a twill or satin.

Fig. 113

The cording generally used for an 8-shaft satin is shown at A, Fig. 113. Sometimes the twill is run in the reverse direction. In either case it will be observed that the twill on both ground and figure run in the same direction, which makes one a sateen, or coarse twill, and the other a satin, or fine twill. In order to have both twills alike they require to be run in the opposite direction on the cloth, as shown at B, which will give a fine twill on both ground and figure, on both sides of the cloth, with single yarn. This does not hold good with every twill. When weaving, the weaver presses down the treadle which is connected with the jacquard (another treadle being required for this purpose) with his left foot, then works over the twilling treadles with his right foot, holding down the machine treadle till he gives as many shots to the cards as are required. When the card is to be changed the weaver lets down the machine and draws another shed, striking up the weft again without throwing in a shot or taking his right foot off the treadle. This clears up the shed, and makes the yarn steady before he springs another shed with the presser leaves, giving a regularity and firmness to the work which it is impossible to get otherwise, but which has to be done without in the power loom. The weft is struck up on the open shot, or before the heddles have closed the shed. Sometimes a sort of dobby is used below the lams, which enables the weaver to work the heddles with one treadle. In power looms a similar principle of front mounting is sometimes adopted, substituting a wyper tappet for the weaver’s foot; but a better plan, as it avoids having the cords passing through the yarn and heddles, is to have a box tappet, on the Woodcroft style, made with solid plates, and struck to give the rising and falling motion. The connections from the tappet to the heddle shafts are made in the same way as the ordinary Woodcroft tappet. The jacquard may either be a single or double-lift one. Some prefer the one, some the other. The single-lift is more easily fitted up, especially if the number of shots to the card varies. When the shots on each card are alike, perhaps the steadiest method of lifting the machine is to have a box tappet struck one up and three down, or one up and two down, according to the number of shots on the card. This tappet acts on a bowl on a treadle, to which the rod for raising the machine is connected. For a double-acting machine there must be two treadles and tappets acting alternately. The cylinder can be driven from the rising and falling of the machine with a swan-neck or lever motion, or may be driven from an eccentric on the loom with a pinion on the crank shaft turning it one to three or four shots, as may be desired. When the shotting to the card is irregular there are several methods adopted for lifting the machine griffes, one of the best of which is shown in [Fig. 114] for a single-lift machine.

A is the treadle to which the connecting-rod from the machine is fastened by a bolt through the slot at H, or the slot may be in any desirable place. B is a rack in which the end of the lever works, which keeps the treadle bowl steady to the tappet. E is the tappet on the tappet shaft of the loom, and is made so as to act at every shot. D is the fulcrum of the lever, and C is the stand, which is bolted to the ground and fastened to the side of the loom. This portion of the motion working alone would raise the griffe for every shot, the same as would be required for a full-harness, single-acting jacquard; but when the griffe is raised by the tappet E, it can be held up as long as is desired by letting the bell-crank catch F fall in over it as shown. When the treadle A is in this position the tappet merely touches the bowl, depressing it about 1/8 in., so as to clear it off the catch; this is to allow the catch to be easily pushed off when it is required to let the treadle up, or to drop the griffe. The catch is moved by the cam or tappet G acting on the bell-crank F. This tappet can be driven by a pinion on the crank shaft or by a catch on the slay. It may be a tappet struck to suit, or a barrel with a set of lags or pins on it, so that the machine griffe may be raised and lowered in any order that is desired.