TAKING-UP OR COILING MOTIONS.

There are two distinct classes of taking-up motions—the positive, and the negative or drag motion. In the former the cloth is taken up a small but regular distance each pick, and the number of picks per inch can be regulated to a fraction. [Fig. 71] is the common form of positive take-up motion. A ratchet wheel or “rack wheel,” A, is moved forward one tooth every pick by a click or catch, M, operated by a projection, G, on the slay sword. As the slay moves forward the rack wheel is moved one tooth, and the holding catch or detent N prevents it from going back. There are five wheels in the train, and the names usually given to them are as follows: A, rack wheel; B, change wheel; C, stud wheel; D, stud pinion; E, beam wheel. The emery taking-up roller is marked F. The cloth, as it is woven, is drawn forward by the emery roller and is wound upon the cloth roller, which is pressed against the emery roller by weighted levers, and is turned by friction.

FIG. 71.

The speed at which the emery beam roller is turned regulates the number of picks per inch, and as changes are constantly required in most weaving mills, the wheel B is usually taken as a change wheel. As this wheel is a driver, a smaller wheel will make the emery roller move slower, and therefore more picks will be put in the cloth, and a larger wheel will drive the emery roller quicker, and as a consequence a smaller number of picks will be put in. If the rack wheel has 50 teeth, the stud wheel 120 teeth, the stud pinion 15 teeth, and the beam-roller wheel 75 teeth, the beam roller being 15 inches in circumference, and if the change wheel used has 25 teeth, the number of picks per quarter-inch will be 20.

This may be proved by multiplying the drivers together and by the circumference of the emery beam roller in quarter-inches for a divisor, and multiplying the drivens together for a dividend: the quotient will be the number of picks per quarter-inch.

DRIVERS.

125

375

quarter-inches in beam

22500

DRIVEN.

120

6000

22500)

450000

(20 picks per quarter-inch

45000

When the cloth is taken out of the loom, rather more than this number of picks will be counted, as there is not the same tension as when the cloth is being woven. It is usual to allow about 1½ per cent. for this shrinkage.

For the purpose of easy calculation the dividend of the loom is obtained; that is, the change wheel required to give one pick per quarter-inch. By using this as a dividend and dividing by the number of picks required in a quarter-inch, the quotient will be the change wheel required; and, vice versâ, by dividing by the change wheel, the number of picks given by that wheel can be obtained.

To find the dividend of a loom—

Multiply the rack, stud, and beam wheel together for a dividend, and the stud pinion and the number of quarter-inches in a circumference of the emery beam for a divisor, and the quotient will be the mathematical dividend. Add 1½ per cent. to this for the practical dividend.

With the wheels given in [Fig. 71] the dividend will be as follows:—

15	stud pinion
60	quarter-inches in circumference of beam
900
	50	rack wheel
	120	stud wheel
	6000
	75	beam wheel
900)	450000	(500 mathematical dividend
	4500
	00
		500
		7 = 1½ per cent. for shrinkage
		507 practical dividend.

Having the dividend, it is only necessary to divide by the picks to obtain the change wheel required, or to divide by the teeth in the change wheel to obtain the picks which it will give, thus—

picks	507	= 39 change wheel change wheel	507	= 25⅓ picks.
	13		20

The following are the wheels used by various loom makers:

Rack wheel.

Stud wheel.

Stud pinion.

Beam wheel.

Circumference
of beam in
inches.

Dividend.

120

507

120

609

146

794

100

528

100

634

Example.—Find the dividend of a loom with a rack wheel 60 teeth, stud wheel 100 teeth, stud pinion 12 teeth, beam wheel 75 teeth, beam 15 inches circumference.

rack stud beam wheel

60 × 100 × 75
12 × 60
stud quarter-inches
pinion in beam

= 625 mathematical dividend
9 = 1½ per cent.
634 practical dividend.

It is not possible by changing one wheel only to obtain any number of picks or fraction of a pick, as will be seen from the following examples:—

picks 50740 = 12·67

picks 50741 = 12·12

picks 50742 = 12·07

For the lower number of picks the motion does fairly well, but for the higher numbers of picks the changes cannot be made with sufficient exactitude by changing a single wheel. Even in the lower picks it is now required to make the smallest fractional changes.

An improved arrangement of wheels is now largely adopted. This is Pickles’ motion. [Fig. 72] shows the train of wheels. The change wheel B is in this case a driven wheel, and therefore if a larger wheel is used it will give a larger number of picks in the cloth, and if a smaller wheel is used it will give a smaller number of picks; so that if the wheels are so proportioned that the change wheel B has the same number of teeth that there are picks per quarter-inch, it will always remain so, whatever size the wheel is. If a 20 driven wheel gives 20 picks, a 30 will give 30 picks, and so on.

The wheel A is also changed, and this is usually called the “standard” wheel. This is a driver wheel, and therefore a smaller wheel gives more picks, and vice versâ. The wheels are so proportioned that if A, the standard wheel, has nine teeth, each tooth in B, the change wheel, represents one pick, and therefore, this wheel being a driven, the number of teeth in it will also represent the number of picks per quarter-inch. If an 18 standard wheel is used, it is obvious that the emery beam will be driven twice as fast, therefore each tooth in the change wheel B will then represent half a pick per quarter-inch. With a 27 standard each tooth in the change wheel B will represent one-third of a pick. With a 36 standard each tooth in B will represent a quarter of a pick per inch.

FIG. 72.

The wheels mostly used are those in the diagram, and supposing we have a 36 standard and a 45 change wheel, and taking the emery beam as 15·05 inches in circumference, we get—

B
24 × 45 × 89 × 90	= 11·088
36 × 24 × 15 × 60·20	= 11·088
A	·166 = 1½ per cent. for shrinkage
	11·254 picks per quarter-inch.

Thus with a 36 standard a 45 change wheel, B, gives 11¼ picks per quarter-inch, or each tooth in the change wheel gives a quarter of a pick per quarter-inch.

By changing these two wheels any fraction of a pick can be obtained. Thus if 13½ picks per quarter-inch are required, the wheels used would be an 18 standard and a 27 change wheel. For 13⅔ picks a 27 standard and a 41 change wheel would be used, and so on.

The following examples will fully illustrate the principle of this motion:—

Picks per quarter-inch.

Standard wheel.

Change wheel.

15½

14⅓

14⅔

13¼

13¾

12⅕

It is not always customary to change the wheels in the above manner, as a different value is often given to each tooth in the change wheel by altering the standard wheel, otherwise than by multiples of nine.

Any number may be made the basis of a train of wheels of this kind; there is no reason why it should be nine more than any other number, and in adapting looms from the ordinary five-wheel motion to this principle, it is not necessary to get all new wheels, as sow of the old ones may be made to form part of the train.

There are several kinds of negative or drag take-up motions. One of the older forms is that given in [Fig. 73]. A lever, AB, centred at C is weighted on the arm B. A small cam, D, on the crank-shaft presses down A every pick and lifts the catch E, which operates the ratchet wheel F. As the weights drop they act as a drag upon the ratchet wheel. A small pinion on the same centre as the ratchet wheel drives the wheel G on the cloth beam. The cloth in a negative motion is wound directly on to the cloth beam, and thus there is no risk of damaging the finer fabrics, as is the case when an emery beam is used, as in a positive motion. The number of picks put in the cloth is regulated by the weights on the lever B; the greater the weight the less the number of picks, and vice versâ.

FIG. 73.

The action of a negative motion is as follows:—As the slay beats up, the cloth between the cloth beam and the reed is slackened a little, and the weights on the lever at that moment act as a drag upon the ratchet wheel F. The holding catch is usually a double one, and will hold the ratchet wheel when taken forward the space of half a tooth.

By increasing the drag upon the ratchet wheel, a slighter blow from the slay will enable the weights to act, and thus less weft is put into the cloth. If a loom is regulated so as to put a certain number of picks per inch into the cloth of a given count of weft, and weft of a finer count is then used, it is obvious that the number of picks per inch would be increased. If the weft varies in thickness the negative motion compensates for this somewhat, by putting more picks in where it is thinner, and thus a more even thickness of cloth is produced than where a positive motion is used.

As the cloth is wound on the beam the circumference of the latter gradually increases, and consequently there would be a gradual alteration in the amount of weft put into the cloth, owing to the difference in leverage. It is necessary, therefore, to count the cloth and adjust the weights at intervals in order to keep the number of picks regular.

FIG. 74.

FIG. 75.

Another kind of negative take-up motion is shown at Figs. [74] and [75]. This is now more generally used than the other kind. The cloth beam A is driven by a screw, S. The ratchet wheel B is fastened to the screw-shaft, and the method of operating the ratchet wheel will be seen from [Fig. 75], which is another view of the mechanism. A short lever, E, is attached to the rocking shaft K, and as the slay moves backwards from the cloth the weights W are lifted a little, and when the slay moves forward, the weights, acting through the catch M, will take the ratchet wheel forward a tooth, or half a tooth, as the case may be. There is usually a double-holding catch N, which will hold the wheel if taken forward half a tooth. When the ratchet wheel has made one revolution, the wheel on the cloth beam will only have been moved one tooth by the screw, so that the required slow movement of the cloth beam is obtained by very simple means. There is a hand wheel, P, for unwinding the cloth readily. The negative motion is used principally in weaving the heavier classes of cotton fabrics and those in which there is a large number of picks per inch, such as velvets, and similar fabrics. Its advantages are that the cloth is wound directly on to the cloth beam, and cannot therefore be injured by an emery beam, and that it makes the cloth of a more even thickness, as it compensates for any variation in the thickness of the weft; and its disadvantages as compared with a positive motion are that it requires frequently adjusting (less frequent, of course, when a very large number of picks are put in, as in velvets), and that it does not put a perfectly regular number of picks in the cloth, as a positive motion does. This latter is the chief objection to it, as even in the lighter makes of common velvets a positive motion is preferred on account of its giving a more evenly picked cloth. In silk looms, where it is absolutely necessary to dispense with an emery beam, a very large cloth beam is used, and the cloth is wound directly on to the cloth beam although the take-up is positive. The cloth beam is sometimes over a yard in circumference, so that it will hold a fair length of cloth without making much difference in the number of picks. The cloth is taken off the beam frequently, or the gradual change in the thickness of the cloth beam would cause the piece to get too thin. This would, of course, not do for cotton goods.

Another ready method of obtaining any required pick in a positive motion is used in the East Lancashire districts. Seven wheels are used, as in Pickles’ arrangement, but the ordinary wheels of a 507 dividend (or other dividend) are used, and in addition the two wheels B and C, as in Pickles’ ([Fig. 72]), are introduced. The wheel B, the driven wheel, is called the standard in this arrangement; and suppose it is required to put 15 picks per quarter-inch in the cloth with the rack wheel 50 teeth, stud wheel 120, stud pinion 15, beam wheel 75, beam 15 inches circumference. The standard used is a 24—this, it must be borne in mind, is in this case a driven wheel. Then by multiplying the dividend of the five-wheel motion, viz. 507·5, by 24, the teeth in the standard, and dividing by the picks per quarter-inch required, we get the product of the two drivers, A and C, thus—

507·5 × 24 standard B15 picks

= 812

This 812, then, is the product of the two drivers, and any two convenient wheels which, multiplied together, give this number can be used—thus 81228 = 29. Therefore the two drivers may have 28 and 29 teeth respectively. The two wheels are found by experiment. If the dividend of the five wheels is 609 a 20 standard wheel is used, and the same drivers as in the preceding case will do. If it is required to change only one wheel, and to have the arrangement such as to give an exact number of picks, or half-picks, or quarter-picks, in the quarter-inch of cloth, by taking the two drivers A and C of such numbers that their product amounts to 507, the number of teeth in the driven wheel B will always equal the number of picks per quarter-inch exactly. Thus 507/13 = 39. Therefore if the drivers A and C have respectively 13 and 39 teeth, every tooth in the driven wheel B will represent one pick per quarter-inch.

Suppose half-picks are required exactly, the method of obtaining the wheels is as follows:—Multiply the 507·5 by 2, which equals 1015, then find two convenient wheels which, multiplied together, produce this number; 35 × 29 = 1015, and the two drivers A and C may be 35 and 29. This will cause every tooth in the driven wheel B to represent half a pick exactly.

Thus with a 35 wheel A, and a 29 wheel C, a 31 wheel B will give 15½ picks per quarter-inch, the other wheels being the same as in an ordinary 507 dividend motion.

The following examples will prove this:—

50 rack × 31 B × 120 stud × 75 beam wheel35 A × 29 C × 15 pinion × 60 quarter-inches

= 15·27

and

15·27

0·23

= 1½ per cent. shrinkage

15·50

picks.

When quarter-picks are required exactly, by changing one wheel only—multiply 507·5 by 4, and the product of the two drivers A and C must equal this. Then every tooth in the driven wheel B will represent a quarter-pick per quarter-inch.

There are many methods of letting off the warp positively, but none are likely to succeed in displacing the older and quite satisfactory method of levers, ropes, and weights. The very fact of making the let-off positive, causes too great a rigidity in the hold of the warp, which is detrimental to the yarn. The frictional let-off is not likely to be replaced in cotton goods weaving unless it be in some of the heavier kinds of fabrics. Where it is a question of putting in as much weft as possible, the positive let-off has an advantage.

CHAPTER III
DROP-BOX LOOMS

WHERE more than one kind or colour of weft is used in a fabric, it is, of course, necessary to change the shuttles automatically. Sometimes two or more different counts of weft of the same colour are used, and sometimes different colours of weft. Checks of all kinds, extra weft spots, and others are the chief classes of fabrics which require change boxes.

FIG. 76.

The oldest and commonest form is the Diggle’s chain motion illustrated at [Fig. 76]. The number of boxes used in this motion is either 2, 3, or 4. It would be possible to use more, but it is not usually done with this arrangement for operating them. A lever, AC, is centred at C ([Fig. 76]), and the friction bowl B on this lever is moved upwards by a chain, composed of links fastened together on pins, which work round a barrel, D. These links are of different sizes, according to the number of boxes used. The smallest link leaves the top box in a line with the shuttle-race, and the other links are of such a size as to raise either the second, third, or fourth boxes (assuming that there are four) into this position. The general method is to raise the boxes one at a time, and drop them all together, but this is not compulsory. It will be seen that the motion of the boxes is not positive downwards—that is, the boxes drop by their own weight, and are not mechanically forced down, as in Wright Shaw’s or Whitesmith’s motions—and it will be well understood that there will thus be a limit to the speed at which the loom can be run. The method of turning the barrel D which carries the chain is as follows. A wheel, E, on the crank-shaft drives a larger wheel, F, above it. On the face of this wheel, F, is a rim and two projections, PP, or, it may be, only one projection. These projections or pins gear into the star wheel G, which is fastened to the barrel carrying the chain, and therefore when the star wheel is turned one tooth, or one-eighth of a revolution, it will move the chain a space of one link. The wheel E on the crank-shaft often has one-fourth the number of teeth contained in the wheel F; therefore, if there are two pins or projections, PP, in the circumference, the star wheel will be moved one tooth every two picks, and the boxes may be changed so often by making the chain accordingly. The lever M, which is centred at R, has the boxes attached to one end, and the other end may be pressed down by the foot when it is required to lift the boxes for any purpose when the loom is stopped. Supposing the wheel E to have 15 teeth and F 60 teeth, if there are two projections, PP, on the face of F, the shuttle may be changed every two picks, but if there is only one projection or pin, there may be a change every four, or a multiple of four picks.

The chief disadvantage of this motion in the form given at [Fig. 76] is that the chain becomes very cumbersome if a long pattern is required. To obviate this, the projections PP are, in an improved motion, made so that they can be withdrawn from gear with the star wheel. This is effected by a clutch motion which is subsequently described in connection with the “pick-and-pick loom.” With this improvement, each link in the chain may be made to represent any number of picks, the number being regulated by a small chain of metal cards, and thus larger patterns may be made without the long heavy chains which are required in the ordinary “Diggle.”

The Diggle’s chain principle, although suitable for some types of looms, is not an ideal motion, as the downward movement of the boxes is negative. The boxes have nothing to force them down but their own weight and the weight of the levers connected with them, and this necessitates the loom being run at a slower speed than is the case with some of the positive drop-box motions. Of this latter kind Wright Shaw’s motion is one of a great variety of different types, and has been in use for a long time.

TAKING-UP OR COILING MOTIONS.

CHAPTER IIIDROP-BOX LOOMS

CHAPTER III
DROP-BOX LOOMS