Chapter II: Jacquard Machines (2)

Fig. 35 shows how the raised hooks can be allowed to yield to the pressure of the needles. A, B, C, D are four hooks connected with two needles, 1 and 2. When the hook A is raised, if B, which raises the same warp--as will be seen by the connection of the tail cords with the harness at E--is not to be raised for the next shot, the needle 1 is pressed back by the card, and presses the hook B back from its knife as shown, the dotted line being its original position; the A hook, being connected with the same needle, must also be sprung back, but its head cannot get back, as it is held on the blade of the griffe, so that the wire would require to spring, if some escape were not made for it. The lower ends of the hooks are made V-shape in the grating, so that when raised, if pressed on by the needles, they can move forward as shown, the dotted line showing the original position of the hook A. When the hooks fall, they fill the slots in the grating, and are thus kept steady. G shows the tail cords as connected with the harness when both hooks are down; E shows them when one hook is up and the other down, and if the hook B was raised for the next shot, the tail cord on it would be tightening up as that on A would be falling, and the harness attached to them would be caught up a second time from the middle position, thus forming centre shedding with any portion of the harness that is raised several times in succession. With plain-texture cards the upper and lower portions of the shed would pass each other in the centre when the sheds are being reversed, all the even numbers of hooks being on one griffe, and all the odd numbers on the other.

The tail cord consists of two pieces of cotton cord, one fastened to each hook of a pair, then the two ends are together tied to the bunch of neck twines that are to hang from these hooks, as shown in Fig. 35, and at A, Fig. 36. When one hook is raised and the tail cord drawn up with it, the other portion of the tail cord, which is tied to the other hook, is slackened--as shown at A, Fig. 36--which causes a certain amount of friction on them. Also, when one hook of the pair is falling with the descending griffe, and the other hook rising, the pluck occasioned thereby on the cords, when the hooks are passing at the centre, has a tendency to wear and break them. Although this does not occur when the lingoes are of a moderate weight (18 to 25 per lb.), and when only a few neck twines are tied to each tail, yet when a large number of neck twines (say 20) are tied to each tail, with weighty lingoes, as may frequently be the case in weaving small patterns on woollen and worsted goods, the breakage of the tail cords is a common source of complaint, which not only gives the trouble of renewing them, but is liable to cause defects in the cloth, by the weaver not observing the breakage for some time, as one hook of the pair may be raising the neck twines--that is, in case of the tail cord to only one of the hooks breaking. To remedy this Messrs. Hancock, Rennie, and Hudson have this year (1890) introduced a patent link connection for joining the tail to the hooks, which only requires one cord, or double cord, to be used, instead of two as before. This is shown in Fig. 36 at B. When one hook is raised and the other down, the link is in the position shown at C. The old method is shown at A. When one hook is rising and the other falling, the partial turning of the link causes a loss of time equal to about a quarter of an inch of lift, and this eases the sudden pluck on the tail cord. When both hooks are down there is also a loss of a quarter of an inch in the lift when one hook begins to rise, caused by the turning of the link.

This patent works very well, but, except when heavy weights are on the hooks, is not likely to supersede the older methods. These links are fitted to machines by makers in Manchester and Bradford.

Before the form of griffe shown in Fig. 33 was adopted the hooks were made of two heights, as shown in Fig. 37, and one griffe wrought above the other, instead of the one set of blades or knives passing through each other; but this method was given up on account of the vibration of the long hooks, which made it uncertain whether they would remain on the knives or keep clear of them when required. Fig. 37 shows this arrangement of hooks for a double-cylinder machine; for a single-cylinder machine with two griffes the heights of the hooks would be similar, but the heads would all be turned in the same direction, and the knives sloped to suit this, as is done when the hooks are all of the one height; each needle would be connected to a short hook and a long one. The short hooks give much more certain work, and can have the cylinder set so as to press back the hooks only as much as is required, whereas with long and short hooks allowance had to be made for the uncertainty of the vibration and the difference in the length of the two sets of hooks.

Fig. 38 is a view of one of the best makes of double-lift jacquards with a single cylinder.

The machine is made by Devoge & Co., of Manchester, but is not here given as being specially recommended in preference to others; it is only given as an illustration. Those wanting to buy a machine had better see what are in the market, and select what they consider most suitable to their work and price. This applies to all the machinery given in these articles. There is rarely a best machine for all purposes.

These machines are much in use, and can be run at a high speed, say 160, or even 180, and by many are preferred to the double-cylinder machines, as there is no danger of one cylinder getting before the other, and the cards are all laced in one set; besides, it may be more convenient for working, as some arrange their machines so that the cards for one loom hang to the back, and those of the next to the front. When these machines are to work at a high speed, the slide-motion cylinder will probably be found the most satisfactory. Fig. 39 illustrates one of these machines with slide cylinder motion and the levers for driving it, the connections being as before given. The levers for raising the griffes are also shown, but here go to the back, whereas they are usually at the side.

The most perfect jacquard machine in the market is undoubtedly the

DOUBLE-ACTING JACQUARD WITH TWO CYLINDERS

The only drawback to this machine is, except what may be said against the method of shedding, the liability of one cylinder to be turned out of time, or get a shot or two before the other, so as to put the cards off their proper rotation; but this is only a difficulty in the hands of inexperienced weavers; nevertheless it exists. The effect will be to spoil the pattern on the cloth, giving the twill a mixed or broken-up appearance. There are motions in use for stopping the loom, unless the cards come in rotation, but many prefer to work without them. Fig. 40 is a view of a two-cylinder machine made by Messrs. Devoge & Co., with swing-motion cylinders, which are, perhaps, the best motions for these machines, as they do not require to travel quickly. A very good speed for the machines to work at is 160 to 180 or 200 picks per minute, and the cylinders would only travel at half this speed. The cylinders should be driven by an eccentric, same as given for the single-acting machines, but instead of being on the crank shaft, it should be on the tappet shaft, which runs at half the speed; and as the two cylinder frames are connected together, when the one is going out the other is coming in, so that one eccentric making a revolution for two beats of the slay will drive both cylinders. Sometimes the eccentric is on the tappet shaft, inside the framing of the loom, and is connected with the top lever, as shown in Fig. 34 (B). C is the eccentric, D the fulcrum of a short lever attached to it, and E the upright rod attached to an arm or lever on a horizontal shaft supported by the machine, or on the top of the loom. A lever from this shaft on each side of the machine drives the cylinders. The eccentric may be on the end of the tappet shaft, same as it is shown on the crank shaft in Fig. 18; but it might not always be convenient to have it here, and perhaps the most desirable way to have it at any time is to have a pinion on the crank shaft with, say, twenty teeth in it, and a stud wheel alongside with forty teeth gearing into it. On this stud the eccentric can be fixed, and will give a very steady and convenient method of driving. The griffes are raised in the same way as for the double-lift jacquard with one cylinder. (See Fig. 34 (A)).

Fig. 41 shows the arrangement of a row of hooks and needles for a double-cylinder machine. The top needle of the upper set and the bottom needle of the under set are attached to two adjoining hooks, which are connected together with the same tail cord. This arrangement is to enable the cards when working at both sides to act on the correct hooks, which will be better understood by referring to the description of lacing cards for these machines. In Fig. 41 it will be observed that all the hooks are vertical. Sometimes the hooks are slanted a little, as in Fig. 42, to give more space between the hooks at the top, without increasing the width of the machine, and there is a slight difference in the arrangement of the hooks and needles, as is shown. Both work very well.

Fig. 43 shows a two-cylinder machine, by Messrs. Devoge & Co., with a slide motion for the cylinders, which would be driven in the same way as the swing motion.

It has been said that the shedding of a single-acting jacquard is of the worst description for general weaving. That of the double-acting machine is by no means perfect either; some prefer the single-to the double-acting for making fine damask. Jacquard shedding cannot be regulated in the same way as tappets or the best shedding motions can. In tappets the dwell can be regulated to suit the cloth required, and the time of the shedding can be made early or late as desired. In jacquards this cannot be done to anything like the same extent. The shed must always be open in time for the pick, and the pick should begin when the cranks are about the bottom centre, a little earlier or later, as desired. The jacquard must have the shed open at this time, and must keep it open till the shuttle passes through.

It has been said that the usual method of raising the griffe or griffes is by a crank (or a stud in the wheel, which is practically a crank) on the crank shaft for a single-acting machine, and by a double crank on the tappet shaft for a double-acting machine. Now, a crank gives a continuous eccentric motion with a slight dwell when it is at both top and bottom centres. Sometimes a tappet is used to raise the griffes instead of a crank, and of course any required dwell can be made on a tappet; but then it must suit the jacquard, and the greater the dwell, the less time is occupied in the rising and falling of the harness. If the harness is plucked up or dropped down too quickly, the result is a dancing or unsteadiness of the cords, and in a double-lift machine there will be a considerable plucking when the hooks that are rising take up the cords that are falling. In order to keep the cords as steady and free from vibration as possible, if there is any swinging in the weights or lingoes, it is a common practice to put a frame round these, with wires run through it at whatever distance apart is thought desirable, so as to partition them off in bunches and keep them from swaying about.

The smoother and slower the harness can be raised and lowered, the better. Therefore, to get a high working speed, the time or the portion of a revolution of the crank shaft given to the rise and fall must be as great as possible, so that very little could be gained by using a tappet. If a tappet is to be used, a box tappet will be required, or is more satisfactory for a single-acting machine, in order to make the griffe in falling follow the tappet and avoid any plucking or jerking; sometimes a fork lever, with the tappet or wiper working between the prongs of the fork, is used for the same purpose. For a double-acting machine double wiper tappets, acting on levers or treadles, are sometimes used, the griffes falling of their own weight; the tappets are nearly round eccentrics, or like plain tappets with a very short dwell, not more than one-fourth of a revolution of the crank shaft. It may therefore be considered that the harness should always be moving either up or down, with a small pause when the griffes are at the top and bottom, to admit of an easy turn and to allow the shuttle time for its passage through the shed. With the crank drive the shed will require to be opened a little wider than if the dwell was as great as it should be, especially in wide looms, in order to let the shuttle get through freely; but it would be more desirable, and a saving of strain on the yarn, to have the dwell greater, and not open the shed any wider than is necessary to admit the shuttle.

Speaking generally, the usual rule for the time of shedding may be said to be to let the shed be closed when the cranks of the loom are at the top centre, or perhaps one-sixteenth of a revolution farther forward, and let the shed be full open when the cranks are about the bottom centre. It therefore follows that the single-acting jacquard must open the shed in a little less than half a revolution of the crank shaft, and close it in the same time; but the double-acting machine takes nearly a full revolution (three-quarters, or a little more, should do) to either rise or let fall one of the griffes. It will be evident that there is a considerable difference in the nature of the shedding. A single-acting machine requires the weft to be beaten up on a closed shed (the time of the crank in coming from the top to the front centre being taken up with rising the griffe from the bottom up to catch the hooks), whereas in a double-acting machine the case is different; though the shed is closed at the same place, or in the same position of the cranks, the griffes are in an entirely different position. The closed shed with the single-acting jacquard is when the griffe is down, but with the double-acting machine it is when the two griffes are on a level--that is, halfway up. Of course, more or less of the yarn may be at the bottom position, so that there may be no closed shed, or in no position of the griffes may the yarn be all on a level, unless none of the hooks are on either of the griffes, or if one griffe has all the hooks on it. When the single-acting machine begins to open the shed, the driving-crank of the griffe is upright or at the top centre, and in the position to give the slowest motion to the griffe; whereas for the double machine the lifting cranks are horizontal when the shed is closed, and in the position to give the griffes the quickest motion; therefore, when the lay gets to the fell of the cloth in a single-acting machine, the shed is still close, whereas with a double-acting machine it is fully half open. From this it follows that, to get a close covered cloth, the double-acting machine is the better, as the weft is beaten up in a crossed shed; but to get a clean-surfaced fabric, with the weft lying straight between the two portions of the warp, the single-acting jacquard is better. It is for this reason that the single-acting machine is preferred by many workmen for making fine damask, which does not require much covering to give it a good appearance, and there is less chance of having cut weft and of looping when striking on the open shed. Of course the weft may be cut in a hard fabric by the reed having to strike too heavily against it, and in this case striking on a crossed shed might prevent the cutting, by the weft going on easier.

In hand-loom linen damask the shot is struck up when the shed is about half closed; the warp is held so firm in the loom that there is no spring in it, and the weft does not rebound. A cleaner surface is thus made on the cloth than if the weft was struck up in a closed or cross shed.

In a single-acting machine the faults in the cloth are more readily seen than with a double-acting one, as, in case of a hook missing the knife, in a single machine it would show in a short time, whereas in a double-lift machine one hook of the pair might be missing the knife and the other taking it, so that it might be some time before it would be observed. One of the tail cords breaking might have a similar effect.

The foregoing gives a general description of working the jacquard; but no hard-and-fast lines can be laid down--a little variation may be necessary at any time, to suit circumstances and the class of work.

JACQUARD STOP MOTION

When working with two cylinders, one may happen to be turned at a time when it should not, and thus put the cards out of rotation. Many attempts have been made to overcome this difficulty by stopping the loom when the cards get out of the proper order, but none of the methods adopted have ever gained much favour. Recently a new motion has been patented, and is being applied to machines by Messrs. Devoge & Co., of Manchester. It is called the ‘Devoge jacquard stop motion.’

Fig. 44 shows how it may be applied to a machine. The hooks A and B and the needles E and F are those here used to work the motion. They may be at either side of the machine, but should be at the side of the belt handle. One hook must belong to the front cylinder needles, and the other to the back ones. The hook A requires a lingo attached to it to draw it down after being lifted. The hook B is attached to a lever connected to the side of the loom, so that when one end is raised a hammer on the other end pushes off the belt handle (a lever and bracket are supplied for the purpose). C C^1 is a wire bell-crank lever with a turn or loop on it at D to act as a spring. The fulcrum is at L, on a piece of iron bolted to the edge of the machine; the lower end of this lever passes through an eye in the hook A at C^1, and the upper end passes through an eye in the needle E. There is a spring on the point of the needle E, between the face-plate and the eye, which the lever goes through, and which holds the needle back as shown.

Each time the hook A is raised the lever presses forward the needle E, and with it the hook B, which would then be raised by the lower griffe, unless the card pressed the needle back again and pushed it off. Thus, by having a hole cut in the cards for the needle F, and none for the needle E, the hook B would never be raised; but if a hole is cut for E in a card following one in which a hole was cut for F, the hook B would be raised and the loom stopped. It is, therefore, only necessary to arrange the cutting of the cards to allow the loom to work when they are following each other in rotation; but as soon as one card gets out of order the loom should be stopped, though, perhaps, not till it has run for a few shots. Thus--

Number of cards--

1 3 5 7 9 11
-- -- -- -- -- --
O · · · O O

Cut the large dots for the needle E.

2 4 6 8 10 12
-- -- -- -- -- --
O O O · · ·

Cut the large dots for the needle F.

This gives a repeat of twelve cards; but any number to suit may be used. Thus--

Number of cards--

1 3 5 7 9 11 13 15
-- -- -- -- -- -- -- --
O · · · O O O O

Cut the large dots for the needle E.

Number of cards--

2 4 6 8 10 12 14 16
-- -- -- -- -- -- -- --
O O O · · · · ·

Cut the large dots for the needle F.

This gives a repeat of sixteen cards. The even numbers of cards go to the front or top cylinder, and the odd numbers to the low cylinder, and it may be seen that a hole in an even-numbered card following one in an odd-numbered card will not stop the loom; but a hole in an odd number following one in an even number will stop the loom, as it is the hook B rising after A that stops it; therefore any suitable rotation of cutting may be adopted, and the stoppage can take place either at short or long intervals, as desired, the principle being to raise the hook A two or three times, and push the hook B back again by having no hole cut for the needle E. Then leave A down for three or four shots, and cut holes for E, which have no effect unless the cards get out of rotation, and one of those with a hole cut to raise the hook A comes before one with a hole cut for the needle E, when B will be raised and the loom stopped. This is a good arrangement, and works very well.

Another motion for a similar purpose, invented by the writer, is shown in Fig. 45. It is based on the following principle: Suppose a cord is taken from any two hooks of the jacquard, and passed round a pulley on the ‘hound tail’ or long lever of the weft fork motion; if the cord is left slack, so that raising one of the hooks will just tighten it, then raising both hooks together will lift the lever, and can be made to stop the loom. The difficulty to be got over is that one of the hooks must belong to one griffe, and the other to the other one, in order to make the motion act with the two sets of cards. As the two griffes pass each other at the centre, or at the half-lift, this must be taken as the full lift, the cord must be stopped here, and not drawn any farther; for the remaining portion of the lift the hooks must draw a spring. This can be easily arranged by having loops on the cord passing round wires in the cumber board, or by having the two ends of the cord passing through a small hole board, and having knots or beads on them, beneath it. Other methods may also be adopted.

One of the most desirable arrangements is shown in the figure: A, A are the two hooks; B, B are two small springs by which the two levers, C, C are attached to the hooks with cords; D is the frame for holding the levers, and is fastened to the top rail of the loom, under the jacquard, or in any convenient place. It will be observed that the front bar of the frame passes above the levers, so that it will prevent them rising above the half-draw of the hooks, in which position they are shown. E, E are two cords connected with a jack or tumbler, F, on the end of a bell-crank lever, G H L, having its fulcrum at H, which may be on the same stud as the weft fork lever, or in any convenient place.

The weight of F and G keeps the cords in tension, and the point L of the lever is set behind the lever on the loom which carries the weft fork, at such a distance from it that when one of the cords E is drawn it does not act on it; but when both hooks are raised, drawing up the two cords, the point L of the lever presses against the weft fork lever, pushing off the belt handle and stopping the loom.

The lever G H L may act directly on the belt handle, if desired; in this case it would be fixed outside the loom framing. The cards are cut on the same principle as for the last motion, but the same holes will do in both sets of cards, as the two needles are acted upon by the same number of holes in both back and front sets; that is, for two hooks coming beside each other.

The following order of cutting will answer:--

Number of cards--

1 3 5 7 2 4 6 8
--- --- --- --- --- --- --- ---
O O · · · · O O

Cut the large dots on the number of cards given, and of course they must be cut to suit the needles connected with the hooks used.

The above gives a continuous working of the motion, but it would be sufficient for it to work at intervals having 8 or 10 shots between them, as--

Number of cards--

1 3 5 7 9 11 13 15 17 19 2 4 6 8 10 12 14 16 18 20
---------------------------------------------------------------------
O O · · · · · · · · · · O O · · · O O ·

This will not allow the loom to run for more than 20 shots after the cards get out of order.

Some other motions are in use, but these are simpler.

Before describing twilling machines or any special make of jacquards, it may perhaps be better to explain the mounting of ordinary machines, according to the usual methods adopted in some of the leading districts.