Chapter VI: Special Jacquards and Harnesses (2)

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, E^1 the upper marches or jacks; F, F^1 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, E^1 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.

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.

An ingenious method of working the heddles of a pressure harness by the jacquard was invented in Bethnal Green shortly after the introduction of the original machine. It was used for weaving the richest silk damask, which had 400 threads of warp per inch and about one-fifth that number of weft shots, so that five threads of warp might be drawn into each mail without making the pattern appear any coarser in the warp than in the weft. A sketch of this mounting is given in Fig 115. A shows the hooks for working the heddles, and B those for working the harness. Eight hooks are given for working four leaves of heddles. It will be seen that a cord from two hooks passes round one of the pulleys C, and each of the heddle shafts is attached to one of these pulleys. These hooks may be raised by the griffe of the jacquard, which would require to rise and fall for every shot, or the griffe may be held up for the number of shots to the card, and the hooks for working the shafts may be wrought by a small dobby. When one of each pair of the hooks A is raised, the heddle shaft connected with it is raised to the middle position, as shown by the pulleys 1 and 2, and the leaves connected with them. If neither of the hooks is raised for any shaft, it will remain sunk, as shown in No. 3; and if both the hooks are raised, the leaf will be raised to its top position, as No. 4. The leaves are drawn down by weights or springs.

TWILLING JACQUARDS

As has been stated before, one of the drawbacks to a pressure harness is the strain which the warp has to undergo when forming the shed. This necessitates having a good warp, which adds to the cost of the cloth, and in low-class goods this consideration may hinder the sale. Many methods have been adopted for working the ground of the cloth without using a pressure mounting. Some of these are explained under ‘half harness’ and ‘split harness,’ but none of these methods would produce cloth like the pressure harness. A twilling jacquard to act similar to the pressure harness, but without using the front mounting, or by dispensing with the leaves of heddles, was patented by Mr. Shields, of Perth, in 1859. This machine underwent several improvements, and now there are two varieties of it in use, one known as the Irish or Bessbrook machine, being patented by Mr. Barcroft, of the Bessbrook Spinning Company Limited, county Armagh; the other as the Scotch machine, the improvements being made by Mr. Shields and others. The principal difference between the two machines is that the blades or knives of the griffe have a horizontal or sliding motion in the Scotch machine to enable them to get clear of the heads of the hooks, whereas in the Bessbrook machine they turn out of the way or partly revolve. A full description of the Bessbrook machine is here given. Fig. 116 is a view of the framing of the machine. K is the cylinder, which may be wrought by the swan-neck motion, as shown, but it is better to be wrought by a separate motion from the loom. D is a cord attached to the handle of the shears for reversing the cylinder; E is a brass bushing through which a shaft passes for raising the griffe. The shedding of this machine is exactly the same as that of an ordinary single-acting jacquard. The griffe rises and falls for every shot; the cylinder travels out and in, but does not turn till two or three or whatever number of impressions required are given by each card. To prevent the cylinder turning it is only necessary to raise the shears so that they will not catch it. This is done by means of the tappet A, shown in Figs. 116 and 117. The roller H on the shears rests on the tappet, which is turned by means of the rack wheel, which is fast on it, and the lever L, which is loose on the stud. This lever is pushed backwards and drawn forwards by the rod I, which is connected to an arm, either on the shaft for raising the griffe, or on one for working the cylinder, and the catch on the lever takes a tooth of the ratchet wheel at each draw, so that with four divisions on the tappet, and 12 teeth in the ratchet, three shots would be given to each card. If it is required to work the cylinder the reverse way, it is only necessary to tie the cord D on the end of the shears to a spiral spring made fast to any convenient part of the loom, then the roller C will be acted upon by the underside of the tappet, and the under hook of the shears will turn the cylinder when required. B is a spring acting as a pawl to keep the ratchet from moving backwards, and there is also a spring shown over the catch which moves it forward; both these springs serve to keep the tappet steady. There are two sets of hooks and needles in this machine--the ordinary set for working the harness, as shown at A (Fig. 118), and a set of twilling hooks, one row at each side of the machine, which are much stronger than the others. The ends of the twilling hooks are hooked round bars, which pass through the loops at the lower ends of the ordinary hooks, as shown at C (Fig. 118). These bars are kept in their places by a grid D, which is between the ordinary hooks and the twilling hooks. Each of the needles of the jacquard is connected with two or more of the ordinary hooks, as shown at A. The twilling hooks have also needles on them, but they are only for the purpose of keeping them in their places, and are not acted upon by the cards. The springs of these needles are on the ends next the cards, or at the back of the faceplate or needle, as shown at E. The centre support for the knives of the griffe is shown at F, with an end view of two knives G G. The ends of the knives enter the griffe frame at each side, so as to allow them to oscillate or partly revolve. This motion is given to them by a set of bars or flat needles, as shown at A (Fig. 119). A single needle is given at A^1. These needles have each the notch in them over the top edge of two or more of the knives, and are acted upon by a barrel C with studs in it, set to the twill. This barrel rises and falls with the griffe, and is turned from one row of pegs or studs to the next one each time the griffe falls by the head or lantern on it coming down on a finger, as shown at A (Fig 120). B in the same figure is a strong spring to keep the barrel steady and make it turn the correct distance.

The number of knives in the griffe must be regulated to suit the twill to be put on the cloth; they must be a multiple of the twill, and this to some extent regulates the number of needles that must be in each upright row. For example, an 8-leaf twill may have 16 or 24 knives, which would be twice or three times over the twill. If there are 8 rows of needles to 16 knives, or 16 rows of hooks, that would be 2 hooks to each needle, or if there are 24 rows of hooks there must be 3 hooks to the needle; but if only 2 hooks to the needle are required, there must be 12 rows of needles to 24 rows of hooks. The same principle holds good for a 5-leaf, or any twill. Eight or 12 rows of needles would not be suitable for a 5-leaf twill, neither would 10 rows of needles be suitable for an 8-leaf twill, if the same number of hooks have to be connected with each needle; but 10 rows of needles with 20 rows of hooks or 20 knives will answer for a 5-leaf twill with 2 hooks to the needle, or would answer for an 8-leaf twill with 24 rows of hooks, 4 of the needles to have 3 hooks to each, and 6 of them to have 2 hooks to each.

Each of the twilling needles, A, Fig. 119, must be connected with as many of the knives as there are repeats of the twill; thus, for 24 with an 8-leaf twill, the 1st, 9th, and 17th knives would be acted upon by the one needle, and so on with the others.

Now as to the action of the machine. When the pattern card presses upon the needles the griffe begins to rise, and when rising it must lift all the hooks required for the pattern except 1/8th part of them which must be left down (in an 8-leaf twill) to form the binding or texture of the cloth. In addition to this, 1/8th part of the ground warp must be raised for the weft to pass under it and form the ground texture. This is all accomplished by the one rising of the griffe. When the griffe is down, one of the twilling needles, A, Fig. 119, is pressed back by a peg or stud in the barrel, which causes the knives connected with this needle to turn out of the way of the heads of the hooks, so that when the griffe is rising these knives will pass clear of them, leaving every eighth row of hooks down to form the binding of the raised or pattern warp. In the Scotch machines the knives slide back instead of revolving. As shown at H, Fig. 118, there are projecting pieces of brass fastened on the knives between the twilling hooks. These hooks stand clear of the knives, but when the latter revolve the projections on them push the hooks forward to the next knife, which lifts them when the griffe is rising. The hooks draw up the bars to which their lower ends are looped, and raise the rows of ordinary hooks through which the bars pass, thus forming the twill on the ground in the same way, but in the reverse direction, that the knives passing clear of the adjoining rows of hooks form the twill on the figure.

The working of the texture requires the griffe to fall for every shot, which would be otherwise unnecessary, and the card must come in against the needles each time to push off the hooks that are not to be raised. This causes wear and tear, which cannot be avoided with this machine, but they work very well, though they are not by any means perfect. There is a good deal of friction on the needles, which causes them to wear quickly; but being so much easier on the warp than the pressure harness, and more easily managed, they are extensively used for large patterns in the fine linen damask trade. They will not make so firm a cloth as the pressure harness, and have the objection that all twills formed with the harness have when there is a gathered tie--viz. that a portion of the cloth will have the twill running in one direction and a portion in the reverse direction.

Like all single-acting jacquards, these machines have no counterpoise in themselves, and being very heavy require one added to assist the loom to raise them. Sometimes this is accomplished by means of a carriage spring placed on a beam or on the top rail of the loom frame; and an arm from the shaft, which raises the griffe resting on the spring, will form a sufficient counterpoise, the spring being made as strong as is required for the purpose. Unless the springs, which are made similar to those used for carriages, are nicely tempered, and the different pieces made so as to slide freely on each other, they are liable to snap when the loom is running quickly. The griffe is generally driven from the fly-wheel on the crankshaft in the same manner as for ordinary single-acting jacquards. It is, however, a better plan to drive it from a crank on a stud wheel gearing into the tappet-shaft wheel. This does away with the necessity for a counterpoise unless the machinery is very heavy, in which case a few strong spiral springs will suffice. The horizontal shaft for raising the griffe, or griffes if two or more machines are used, must be very strong, so as not to twist with the tortuous strain, which is very great. Three of these machines, with 500 or 600 needles to each, are required for tablecloth mountings when tied up for centred patterns--one machine to work the border, one the centre, and one the portion between the border and the centre; or two machines to work the double portion, and one the single portion. Fig. 121 gives a view of a mounting tied up in this way, Nos. 1 and 2 machines being double mounting and No. 3 single.

_The Karl Wein Jacquard._--This machine is a twilling jacquard on the same principle as that last described, but performs its work in a more scientific manner. It was patented by Messrs. J. Tschörner and K. Wein, Kesmark, Hungary, and was first introduced into this country at the Glasgow Exhibition of 1888.

The following is a description of the machine exhibited there: The principal feature of this machine is perhaps that each knife acts independently in a grid, and is wrought by a tappet at the side of the loom, so that any row of hooks can be raised or lowered at pleasure, and this without any change of card. Fig. 122 gives an end view of the framing, showing the upper and lower grids in which the knives or lifters slide. An end view of four of the lifters is given at A, 1 and 3 belonging to the top set, which work in the upper grid, and 2 and 4 to the bottom set, which work in the lower grid.

A perspective view of eight of these lifters is given at B C, Fig. 123, with upright slide bars D attached to them, which slide in the rack or frame E. These bars are for the purpose of making the lifters rise steadily and horizontally, as (which may be seen) they are not all lifted at their centre. Only one connection is fair in the centre, which would no doubt be an objection with a heavy harness to lift; but this arrangement is made to suit for the machine sitting across the loom, for a London tie, and some method of making vertical connections from the levers to the lifters is necessary. The above does very well for a narrow harness if light.

If the machine was fixed on the loom for a Norwich tie, or with the cards to hang over the back, then the connections from the levers might all be at the centres of the lifters and the bars D would only be required to steady them. The levers for raising the lifters are shown at F, with their fulcrum at I. G is a spring, one of which is attached to each lever to keep it down, as the tappet has not a positive rising and sinking motion, only raising the levers and allowing their own weight and the draw of the springs to recover them. One of the connecting rods from the lever to the tappet is shown at I. Fig. 124 gives the principle of this tappet. A is the lever or treadle with its fulcrum at A; the connecting rod B connects the point of it to one of the top levers F (Fig. 123), and C is a bowl at the other end of it which travels on the tappet plate D. The tappet is made up of 17 plates struck to suit; 16 of these are for working the lifters and 1 for the cylinder; it sits at the side of the loom like a Woodcroft tappet. For an 8-end satin twill 16 levers are required, 8 for the bottom set of lifters and 8 for the top set. Fig. 123A shows two lifters B^1 and C^1 with hooks and needles. A hook and a needle on a larger scale are shown in Fig. 125. The hooks are flat pieces of iron cut to the shape shown, with small projecting pieces, as _a_, riveted to them, by which they can rest on the bottom lifting knives, as at C^1 (Fig. 123A), so that when any of these knives are lifted a row of hooks will be raised by them. As before explained in reference to the Bessbrook machine, it is necessary when the pattern card presses on the needles for all the knives except one to act, and also for one of the bottom lifters to rise to form the texture of the cloth; the same must be in this machine, and can easily be regulated by the tappet, which should hold up the warp required for the pattern and work the ground texture as well. This is done in the following manner: Suppose there are 16 lifters, 8 top and 8 bottom ones. When the card presses on the needles, 7 of the top and 1 of the bottom lifters should be raised by the tappet, and the top lifter, which is left down, should be raised so far as to catch the heads of those hooks in the row belonging to it that are not pushed back by the card. For the next shot this lifter is raised and another one let down, but it is not let down far enough for the hooks to get off it, stopping at the same height that the first one was raised to, which is easily regulated by the tappet. If there are 3 shots to the card, another similar change takes place; then for the fourth shot all the lifters are dropped, the cylinder presses in, and all but one of the top lifters and one of the lower ones are again raised, and the twill proceeded with as before. It will thus be seen that the shedding for the twill acts as in a double-acting jacquard, but the lift at the change of card is similar to that of a single-acting jacquard. Of course the tappet must be struck to change the lifters according to the twill required on the cloth. In the Bessbrook machine there could be 16, 24, or 32 rows of hooks to 8 rows of needles by having 2, 3, or 4 hooks to each needle, or the number of hooks to each needle might vary and any number of needles might be used. There must be a knife for each row of hooks, but all the knives belong to the one griffe. In the Karl Wein machine there must be 2 lifters for each row of hooks, and 16 of them are enough to have for convenience. In the machine exhibited, 16 hooks, or 2 rows of 8, were attached to 6 needles, 4 needles having 3 hooks to each and 2 needles 2 hooks to each, as shown at B (Fig. 125), the thick vertical lines representing 1 row of hooks, and the thin lines the next row. There were 6 rows of needles in the needle board, and the point of each needle was cranked as shown at C; each row of holes for the needles in the needle board, or face-plate, stood between 2 rows of hooks: the first 3 needles were connected with 1 row of hooks and the second 3 with the next row, the cranks of the first and second set of needles being turned in the opposite direction so as to enable them to fall in with the rows of hooks. Of course there might as well have been 8 rows of needles with 2 hooks to each, or 4 needles to each row of hooks.

If necessary to use more than one machine, some arrangement would require to be made for lifting them. It might be done by using a double set of levers with connecting rods similar to those used for twilling looms.

The twilling of the ground might be wrought by a griffe and hooks as in the Bessbrook machine, thus doing away with seven treadles and seven tappet plates, but this would make the twilling a single-acting shedding motion.

Since this was written the machine has been altered so as to make it more suitable to the requirements of the work in this country, but does not appear to gain favour, and this class of weaving is not very extensively used.