_JACQUARD MACHINES_
The jacquard machine was introduced into England about 1818 and came
into general use from 1824 to 1832. It was introduced into Scotland
about 1824. Fig. 16 is a representation of the early form of jacquard,
and of course intended for hand-loom work. Although the present
machines for power-loom work are very different in make, nearly all
the working parts as here used are to be found in different machines
at present working, or still being made, though the best machine
makers have adopted newer and better principles for fast working and
withstanding wear and tear. Fig. 16A is a view of the interior of the
machine. The working of the machine will be explained further on;
only those parts that will not be given in the new machines will now
be noticed. The griffe or frame for raising the hooks is lifted by
the straps A, A, Fig. 16, which are attached to the pulleys B, B, and
a cord C over a pulley on the same shaft as B, B, is attached to a
treadle beneath the loom. As the weaver presses down this treadle the
griffe is raised, and when the treadle is released the griffe falls
of its own weight. The cylinder is moved out and in by the pulley E,
fastened on the bent iron bar, attached to the frame which carries the
cylinder, when the griffe rises and falls. D, D is a frame which lies
in the turned-up portion of the hooks; only a few hooks are shown, and
the outer bars of the frame. There should be a bar in the frame for
each row of hooks. This frame rises up and down with the hooks, the
turn on the ends of which must be of such length that when the frame
is raised by the hooks lifted by the griffe, it will not be raised
out of the turns on those that are left down. This frame is for the
purpose of preventing the hooks from turning round, so that the turns
on the upper end of them, as shown at A, A, Fig. 16A, cannot get out
of position to be caught by the blades or crossbars of the griffe. The
lower ends of the hooks rest on a perforated board as shown in Fig.
16A, and tail cords are looped on them and pass through the perforated
board as shown. To these cords is fastened the neck of the harness.
Machines with these perforated boards and frames to keep the hooks in
position are still (1890) being made in Yorkshire. In Fig. 16A is shown
a section through the spring box B. This box contains a spiral spring
for each of the horizontal needles, the ends of which press against the
springs, which allow them to yield or move back as the cards press on
their points; but recover them again when the card is moved away by the
cylinder. Similar spring-boxes are now used.
[Illustration: Fig. 16]
It might be interesting to describe the various changes and attempted
improvements that have been made on the original jacquard, but it
would take up too much space, and many of them are of more historical
than practical importance; some of them will be mentioned that may be
interesting from a mechanical point of view, in connection with the
descriptions of the machines, even though they have only been partially
successful. Though a very different machine from what it originally
was, the principle of the jacquard remains the same, and is not likely
to be altered or superseded till a revolution takes place in the
process of weaving.
[Illustration: Fig. 16A]
A jacquard machine is simply a shedding motion by which a great variety
of sheds can be formed; the larger the machine, or the greater the
number of hooks it contains, the greater is the variety of shedding
that can be produced by it.
If a jacquard is made small, with, say, from 16 to 48 hooks, it is
called a dobby or shedding motion, and is used for working shaft
mountings; but the ordinary jacquard machines have from 200 to 600
hooks, which have long cords, called the harness, connected to them, no
shafts being required, as each hook has only a few cords tied to it,
which can be raised independently of the others. The fewer the cords
that are tied to each hook, the greater is the variety of shedding that
can be made on the same number of warp threads, till, when there is but
one cord to the hook, any thread or any number of threads can be raised
independently of any of the others.
Jacquards may be divided into four classes--viz. single-acting,
double-acting lift, double acting with double cylinders, and twilling
jacquards; and besides these there are several other varieties made
for special purposes. The single-acting is the real jacquard, and much
the simplest machine. It has the disadvantage which all single-acting
shedding motions have--viz. that one shed must be closed before the
following one begins to open. This is on account of the same lifter
having to open each shed; it must bring down the set of hooks that are
raised, and then raise the next set.
This constitutes the true jacquard lift; and while it makes a clear
shed, and is desirable for some purposes, it is generally considered
the most imperfect form of shedding--that is, so far as the making
of a good cloth is concerned. It is not suitable for making a heavy,
well-covered cloth, nor for working at a high speed, 120 to 140 picks
per minute being a very good speed to drive it.
A single-acting jacquard is a very simple machine, and when properly
made should give very little trouble in working, particularly if the
motions are properly set in relation to each other, and if such methods
of working are adopted as will cause the least wear and tear on it.
In whatever way jacquards are made, the principle of working is much
the same. There are a number of upright hooks set in a frame; attached
to each hook is a horizontal wire or needle, one end of which is
pressed upon by a spring, which keeps both it and the hook steady and
in position, while the other end, or point, passes through a perforated
plate, beyond which it projects about half an inch (see Fig. 16A). To
lift the hooks there is a set of bars or knives arranged in a frame,
just below the heads of the hooks; this frame is called the ‘griffe’
or ‘brander,’ and if raised would draw all the hooks up with it. What
hooks will be lifted for each shed is regulated by perforated cards
being pressed against the points of the needles. A perforation in the
card allows the point of a needle to pass through and the hook to be
raised; but where there is no perforation the card comes against the
point of the needle, pressing it back, and holding the head of the hook
clear of the blade of the griffe, so that the griffe will pass without
raising the hook. It will thus be seen that any variety of shedding
can be made by punching the cards to suit it. Fig. 17 shows one of
the best makes of single-acting jacquards. One of the best methods
of driving is shown in this and the following figure. The griffe is
raised by means of the lever G, which is sometimes supported on a beam
fastened to the roof or pillars of the shed, or it may be supported by
an upright fastened on the frame of the loom. A portion of this upright
is shown in Fig. 17, and as well as being fastened to the loom frame,
it should be stayed to the top of the machine. One end of the lever
is fastened by a link connection to the centre of the bar across the
griffe frame, care being taken that the connection is so made as to
draw up the griffe vertically, and not have any strain on the slide
rods or spindles that are used for keeping the griffe horizontal when
rising.
[Illustration: Fig. 17]
The other end of the lever is connected to a crank on the crank-shaft
of the loom by a rod, E (Fig. 17); also shown at A (Fig. 18), where the
crank is also given.
[Illustration: Fig. 18]
In hand-loom machines the griffe is frequently pushed up from below
instead of being drawn up from the top as is shown in Fig. 17. The
method of doing this is similar to that given for lifting the griffes
of twilling jacquards.
F (Fig. 17) is called the cylinder or barrel, evidently taking its name
from the round cylinders or barrels used in the old machines, but is
in reality a square prism. It is made of wood, and perforated on each
side with a set of holes--a hole for each needle in the machine; its
use is to draw round the chain of cards and press each one against the
needles, or horizontal wires, in the machine. In order to keep the
cards firmly on the cylinder, flat steel springs are sometimes used, as
shown, attached to the top rail of the frame which holds the cylinder;
and there are also steel wires which pass down in front of the cylinder
over the ends of the cards. These springs are useful when only a small
number of cards is used and the machine driven quickly; with a large
set of cards, where there is plenty of drag on them from their own
weight, they are not necessary, and but seldom used; but they are in
common use in the Yorkshire districts.
It will be seen from the illustrations (Figs. 17 and 18) that the
cylinder hangs in a frame suspended from the top of the machine;
this is called the swing or batten motion, to distinguish it from
the horizontal or sliding motion which is shown at Fig. 20 (No. 1)
and in Fig. 27. The swing motion is the simpler of the two, and is
cleaner, requiring less oil; but the sliding motion is steadier, and
does not swing the cards so much, consequently is more suitable when
the cylinder has to travel quickly. The swing motion also requires the
machine to be higher; with a slide motion the frame is usually cut off
a little above the griffe.
The cylinder has to travel out and in when the machine is working, so
that it may be turned round and bring a fresh card against the needles
for each shot. There are many methods of accomplishing this, which may
be divided into two classes--viz. independent motions, or those which
are driven from the loom independently of the machine; and self acting
motions, or those which drive the cylinder out and in through the
rising and falling of the griffe. The latter are the simpler, but the
former are much better, causing less wear and tear on both the cards
and machine, as will be explained further on.
It will be seen in Fig. 18 that as the cylinder travels out it will be
caught by the hook K^1, and turned round; the head or lantern of the
cylinder is made of iron, as shown, so that the hook, or shears, will
take a firm catch on it. To prevent the cylinder from turning more than
one card at once, and to keep it steady so that it will always come in
fair against the needles, it is held firm by a hammer pressed on it by
a spring. This pressure is applied in different ways, one of which may
be clearly seen in Fig. 17, and another in Fig. 27. When taking out
the cylinder, or wanting to run it round quickly to draw over a number
of cards, the hammers can be held up by a hook or sliding catch, which
should be fitted to the machine for the purpose.
One of the best independent motions for driving the cylinder is shown
in Fig. 17; and that shown in Fig. 18 is also a very good one for small
machines, perhaps the most convenient that is made; but the former
is much stronger. In Fig. 17 a connecting-arm from the frame of the
cylinder is attached to the lever B. The connecting-arm should have a
slotted joint, so that it can be made shorter or longer, if required,
for the purpose of regulating the pressure of the cylinder on the
needles.
The lever B is on a horizontal shaft, bracketed to the frame of the
loom, or to the beams on which the machine rests; or some machines
have bearings attached to their framing for it. There is, of course, a
lever, as B, and a connecting-arm at each side of the machine. There
is another lever on the end of the shaft, at right angles to B, which
is connected with an eccentric on the crank-shaft of the loom by a
rod, C, in the same way as the rod C is connected with the eccentric
in Fig. 18. The eccentric can be set to bring the cylinder against
the needles at any required time, independent of the lifting motion
of the machine, which cannot be done when the self-acting motions are
used. The larger the eccentric, the greater dwell the cylinder will
have against needles. The method of working the cylinder in Fig. 18
is somewhat similar, and can easily be seen; but it will be observed
that a good deal of pressure will be put upon the studs on which the
cylinder frame, or batten, hangs, particularly when the cylinder is
being pressed in, as this is effected by drawing down the lever L;
however, in a light machine this does not matter much.
[Illustration: Fig. 19]
The principal feature in this motion is the escapement apparatus for
the purpose of disengaging the cylinder from its connection with the
driving eccentric when it is required to turn some of the cards back.
Fig. 19 (Nos. 1 and 2) shows this arrangement. The motion is not quite
the same as that given in Fig. 18, but is on the same principle, and
one may be easily understood from the other. In Fig. 18 the latch G
comes out of the notch in the quadrant F, when the handle E is pressed
close; the handle is on the lever D, having its fulcrum on the shaft N,
and the quadrant F is connected to the eccentric rod C. The quadrant
is loose on the shaft, and the lever is fast on it. Fig. 19 is a more
convenient motion. The two halves of the handle A are held apart by
the spring H, and this, through the hook B on the inner end of the
handle, presses the latch or catch on the slide D into the notch on
the quadrant C. The quadrant and handle are one piece, and are fast on
the shaft E, and a lever F on this shaft is connected to the batten of
the machine, in the same manner as shown by D and B in Fig. 18. When
there are two or more machines, one of these levers would be required
for each. The lever K is loose on the shaft E, and the rod G connects
it with the eccentric, same as is shown by the rod C in Fig. 18. In
No. 2, Fig. 19, the quadrant is left out to show clearly how the hook
B acts on the slide D, and also to show the lever K on the shaft. The
two halves of the handle, being pressed out by the spring, keep D in
position, firmly pressed inwards; but when the handle is pressed the
hook B presses the slide D outwards, leaving the quadrant free to pass
up or down; and by pulling down the cord H (Fig. 18), which raises
the shears K and K^1, the cards can easily be turned back by working
the handle up and down, as the under shears will catch the cylinder
and turn it the reverse way. The weaver must be careful not to jerk
the motion and throw the cards off the cylinder or damage them; but a
very little practice will enable anyone to turn them back quite easily
and quickly. This motion answers very well for one, or perhaps two,
small machines; for a 400 or 600 machine, or any smaller size working
spottings, &c., it is very convenient, but when large mountings are
required, as in 800 to 2400 machines, it is quite too weak for the
work; even if made strong enough it would not be satisfactory, as the
strength of spring that would be required to bear the strain and keep
the catch in the notch would make it a very difficult matter to use the
motion for reversing the cylinder. For heavy machinery the method of
working the cylinder shown in Fig. 17 is far preferable, and separate
motions for turning back the cards can be fixed on the machine. These
will be explained further on.
Instead of the eccentric and crank for driving the cylinder and raising
the griffe being as they are shown in Fig. 18, though a plan frequently
in use, it is neater, and perhaps better, to have the eccentric at the
back of the fly-wheel, and the fly-wheel either cast with one half
solid, or have a plate fastened across two or more of the spokes, to
which the connecting-rod can be attached with a bolt fastened in a
slot. The amount of lift can be increased or diminished, either by
shifting the top of the connecting-rod along the lever G (Fig. 17), or
by increasing or reducing the throw of the crank at the fly-wheel.
[Illustration: Fig. 19A]
Self-acting motions actuate the cylinder through the rising and falling
of the griffe without requiring any special connection from the
loom. One of the most convenient of these is that frequently used on
hand-loom machines, and known as the S iron or swan-neck motion. It is
shown in Fig. 19A (No. 1), and another form of it on a swing cylinder
motion is shown in Fig 16. D is the swan-neck or S iron. In the groove
in it a roller stud on the griffe frame travels, sliding in and out the
cylinder A as the griffe falls and rises. E is the slide bar, which may
be flat or round; if round, there must be some means of keeping it from
turning in its bearings, which is generally accomplished by having a
crossbar bolted across the two slide bars behind the machine.
No. 2, Fig. 19A, is a motion for the same purpose, but consists of a
series of levers; and No. 3 is an arrangement of a similar nature. B is
the fulcrum of the levers, or fast pin by which they are connected to
the machine. C shows the attachment of the levers to the slide rod of
the machine. A is the connection with the cylinder frame. As the griffe
rises or falls it will easily be seen that the cylinder will be driven
out or in.
The connecting-bar H is in two parts, slotted and bolted together at H
to admit of regulating the position of the cylinder.
No. 4 is a motion on a different principle; it is a French motion. It
will readily be seen that the cylinder is driven out and in by the
toothed wheel, which is wrought by a rack on the slide rod E. This
slide rod works outside the framing of the machine, as is common in the
French machines. One point must be observed about these motions--viz.
that they must have a certain amount of dwell at the bottom of the
stroke, or when the cylinder is in. The reason of this dwell will be
explained further on, but the method of obtaining it may be given
here. In the swan-neck motion (No. 1), any desired dwell can easily be
obtained at either top or bottom by the length of the slot that is in
a vertical direction, as when the stud is passing through this portion
of the slot no motion is given to the cylinder. In the lever motions
Nos. 2 and 3, as well as in No. 4, the dwell is got by the levers or
arms passing the centres; in Nos. 2 and 4 it is by the lever or arm H
passing the back centre, which may be considered as a crank; and in No.
3 it is the short lever C passing the centre that gives the dwell.
[Illustration: Fig. 20]
[Illustration: Fig. 21]
[Illustration: Fig. 22]
Fig. 20 is a view of the interior of a single-acting jacquard machine
with the framework removed; only one row of hooks and needles are
given, to avoid confusion. The blades or knives of the griffe, with
a support running across their centres, are shown at B. A is the
face-plate or needle board, sometimes made of iron, but better to
be of hard wood. C is the spring-box, the detail of which is given
in Fig. 24. E, E^1 are the hooks, and F, F^1 the needles. D is the
grating through which the hooks pass, and are supported by it. It will
be seen that the hooks and needles are arranged in rows of eight: a
400 machine would have 50 or 51 of these rows in it; 500 machines
are usually arranged in rows of 10, and 600 machines in rows of 12.
The hooks should be set perfectly upright or vertical, and should
be close up against the knives, but not pressing against them. There
should be a provision made for shifting both the grating and the
knives, so as to admit of both them and the hooks being properly set
in relation to each other; but if set correctly by the maker, which
they should be, no alteration is necessary. A (Fig. 21) is a side view
of four hooks and needles, with the ends of the knives of the griffe
shown at _a_, _a_, _a_, _a_. When the machine is working the needles
are acted upon by perforated cards cut from the pattern. Suppose we
take plain cloth--that is, a pattern in which each half of the warp,
or every alternate thread, is raised and sunk alternately; then, if
the first card acts on all the odd numbers of the needles, and the
second card on all the even numbers, this repeated would make plain
cloth. Whenever a hook of the jacquard is to be raised a hole is cut
in the card for the needle connected with that hook, and a card with
all the even numbers of holes cut in it will cause the griffe to
raise all the even-numbered hooks. Refer to _b_ (Fig. 21), where the
second and fourth holes are cut in the card. If the card is pressed
against the needles, as at _c_, the first and third needles will be
pressed back, and will push the first and third hooks back from their
position--shown by the dotted lines--to the position in which they are
shown in B (Fig. 21); but the second and fourth hooks are not moved,
as their needles pass through the holes in the card. If the griffe
is now raised, the blades or knives will pass the first and third
hooks, but will lift the second and fourth; and if the odd numbers
of holes are cut on the next card, the first and third hooks will be
lifted when it is pressed against the needles, as shown at C (Fig.
21), thus making the cross-shed; and this explains the principle of
working any pattern by the jacquard without taking into consideration
the intricacies of mounting, &c. In C (Fig. 21), it will be seen that
if the knives _d_, _d_ were upright instead of slanting, they would
come down on the heads of the hooks that are under them, but, being
slanted, their lower edges pass the heads of the hooks, and press them
away as the griffe descends. Sometimes, even with slanting knives, if
there is much vibration in the hooks, or if the loom ‘bangs off,’ some
of the hooks are liable to get under the knives and be ‘crowned,’ or
bent down. To avoid this deep blades are often used, principally in
double-acting machines, so that the lower edges of the blades will
not pass the bottom hook, as shown at D (Fig. 21). This prevents any
danger of crowning, but it darkens the machine a little--that is, makes
it more difficult to see down into it if any of the wires require to
be examined; it also requires the heads of the hooks to be somewhat
higher above the heads of the needles than is necessary with the narrow
blades. Another principle has been tried--viz. that of making the
heads of the hooks as shown in Fig. 22, and using narrow blades. This
effects its object well, but there is too much friction of the knives
against the hooks, and the latter are liable to wear out too quickly.
A good machine with firmly set hooks should work very well without
these protections if it is steadily placed above the loom, and it is
better not to be resting on the loom framing, if convenient to have
it so. It will be seen from the foregoing explanation that the proper
time, or, rather, the necessary time, for the cylinder to press against
the needles is just after the griffe begins to rise. When the griffe
is down the top edges of the knives should be 3/16in. or 1/4in. lower
than the turned points of the hooks, and before this edge rises up
to the hooks those that are not to be lifted should be full back, or
the cylinder should be close in, having the front of the head of the
hooks 3/16in. or 1/4in. behind the blades. The cylinder should have
a short dwell in this position; and if it has a longer dwell it may
assist to reduce the friction of the heads of the hooks against the
knives; but if it has too great a dwell it may have to travel out and
in too quickly to make up for the lost time, which will probably not
be compensated for by the advantage of the increase in the dwell. Now,
when the cylinder is driven with an independent motion, as in Figs. 17
and 18, it is easy to set the eccentric so that it can be brought in at
any required time; but when a self-acting motion is used, it is plain
that if the cylinder must press against the needles when the blades of
the griffe are passing the heads of the hooks in rising, it must also
press against them in the same position when the griffe is falling,
unless some special escapement motion could be devised to avoid it, and
this is where the dwell is required, and where the evil effect of the
motion takes place; and it is worse in a double-lift machine with one
cylinder, as the heads of the hooks in it are larger, or have a longer
turn on them. A little consideration will suffice to show that when the
brander or griffe is falling, say, with one-half of the hooks hanging
on its knives, and the cylinder is brought in against the needles
before the hooks are quite down, as it must be, it will either cause
the hooks to be shot off the knives, or will put a considerable strain
on them, as well as upon the needles and cards. It is for this reason
that these motions are objectionable, particularly in power-loom work,
where the speed is high and the hooks are strong. In hand-loom work
it is not so objectionable, as there is more spring in the wires, and
the heads of the hooks need not be too large, and, besides, the speed
is less and the wear and tear not so great; but, even with this, if a
hand-loom machine that has been in use for some time be examined, it
will be seen that the points of the hooks are considerably worn, and
that the edges of the knives are hollowed out like a coarse saw by the
friction of the hooks on them. This latter will partly arise from the
lifting of the hooks.
[Illustration: Fig. 23]
In the old Jacquard, given in Figs. 15 and 16, the hooks are shown
resting on a perforated board, and it was mentioned that in order to
prevent them from turning round a frame lay in the turned-up portion
of the hooks. The grating in Fig. 20, through which the turned-up
bottoms of the hooks pass, readily accomplishes this object. Sometimes
flattened hooks are used, as in C (Fig. 23), with the needles twisted
once or twice round the hooks; this makes a firm arrangement, but if
anything goes wrong with a hook it is not easy to get it clear of the
needle. When the needles were made with a full twist or loop on them,
as at B, the same was the case; they are now usually made as at A,
and if arranged in the machine as in Fig. 20, there is no danger of
the hooks sliding out of the recess in the needle, and if a hook gets
bent or broken, it can be taken out and replaced by a new one without
disturbing the needles.
Fig. 16 shows how the needles press against the springs in the
spring-box, which is much the same as that at present in use. Fig. 24
is the present arrangement. No. 1 gives a plan of the end of a needle,
B. C C is the horizontal wire which supports it as shown in section at
C C in No. 2. D (No. 1) is a section of the vertical wire shown at D
D (No. 2), which passes through the loops or eyes on the ends of the
needles, and keeps the springs from shooting them too far forward. A
(No. 2) is a wire which passes down at the outside of the box over the
ends of a row of springs, so that by drawing out this wire any of the
springs can be drawn out without taking off the spring-box, as the
springs pass through the box. The springs should be strong enough to
keep the hooks and needles steady, but if unnecessarily strong they
give the card and cylinder unnecessary work.
[Illustration: Fig. 24]
In some machines there is no spring-box. The hooks are made double, as
shown in Fig. 25, and rods, as _a_, _a_, run along between the rows
of hooks; the spring of the double wire keeps the hooks steady. There
is a clap-board used, similar to that in the French draw loom, (Fig.
13), which is pressed against the needles with springs; this board is
connected with the face-plate by a bar at each end, forming a frame.
The needles do not project much through the face-plate, but when the
cylinder is pressed against it, it slides back on the needles, and
presses the clap-board back, which also allows those needles to go
back which the card presses against. The needles are not looped on the
hooks, but have a turned catch in front of them as shown. The bottom of
the hook rests on a hole board, C, through which the tail cords pass;
and through the hooks at D are wires fixed in a frame which rises and
falls when the hooks are raised, and keeps them from turning round,
same as explained in Fig. 15. Machines of this description are at
present being made in France, and work with a rising and falling shed,
which will be hereafter explained (see Fig. 30).
[Illustration: Fig. 25]
[Illustration: Fig. 26]
[Illustration: Fig. 27]
In working, the card cylinder must be so set that it will come forward
fair on the needles--that is, that when it comes forward the points of
the needles will enter fair into the centres of the holes in it. For
the purpose of setting it there must be provision made in the fittings
so that it can be moved laterally or vertically. In the swing motion
the frame can be moved laterally by means of the two screw studs on
which it hangs. C, Fig. 27, shows the bearing on which the stud of the
cylinder revolves. This bearing can be raised up or down in the frame
R--a side view of which is given at S--by slackening the bolt B with
the wing nut A, and adjusting the bearing with the set screw D or E.
A method commonly adopted by tacklers or tuners to see that the needles
are perfectly fair in the centres of the holes in the cylinder, is to
rub their fingers on some dirty oil, and touch over the points of the
needles with it. They then bring in the cylinder against the needles
with a card on it, in which about half of the holes are cut. The points
of the needles mark the card where there are no holes, and it can
easily be seen whether the mark is in the centre of where a hole should
be, or not.
One of the best bearings and attachments for a cylinder with a
horizontal slide motion is given in Fig. 26. D is the bearing for the
cylinder E, and C the bolts for setting it. F F is the bracket which
holds the hammer and bearings, which can be set in position on the
slide bar B by the bolt A. I is the hammer held down by the spring H
attached to the rod G.
The cards are kept in position on the cylinder by pegs or studs,
originally made of wood, and driven into the cylinder. Now they are
made of brass, and set in a slotted bracket, so that they can be
shifted in order to have the holes in the cards corresponding exactly
with those in the cylinder. The pegs should also be set on springs, so
that if a card gets off them, and between them and the needle plate,
they will yield or sink into the cylinder, and not break the card. In
all good machines they are made in this way.
When the motion for driving the cylinder is not fitted with an
escapement for the purpose of turning back the cards, it is necessary
for the convenience of the weaver to have a motion on the machine for
the purpose.
[Illustration: Fig. 28]
Figs. 28 and 29 show two varieties of these motions. A is the cylinder
head; C, the catch for reversing the cylinder; F, the spring for
returning the catch to its position; E, a cord which hangs down, with a
knob on the end of it, in a convenient position for the weaver to catch
and work the motion. In Fig. 28 the motion is on the opposite side of
the machine to the shears, but might be on either side, and the weaver
has to raise the shears to turn the cylinder, which she can easily do
by catching the knob for raising the shears in one hand, and working
the reversing motion with the other. The cylinder must be full out for
this motion to turn it properly, and this prevents the weaver from
tearing the cards on the needles, as she might easily do by trying to
turn the cylinder when it is too close in. In Fig. 29, B is the shears
for turning the cylinder, and both it and the pushing catch, C, pass
through a keeper or bracket, D, on the side of the machine. There is a
rise on C a little back from the point, and when the cord E is pulled
down C is shot forward by the lever, which has its fulcrum at G, and in
going forward the rise on it comes into contact with the bend in the
shears, and raises them up so that it can turn the cylinder when it
catches on the head of it. Both these are good and convenient motions.
For the latter the cylinder should be about half-way out when the cards
are being turned back.
[Illustration: Fig. 29]
Sometimes the cylinder may not be completely turned by the shears when
the machine is working, by reason of the cards catching, or if the
shears are too long, or it may arise from other causes. In this case
the cylinder would come in with one corner against the needles, and
be pressed heavily against the needle plate. Some of the levers would
probably be broken, or the cylinder might be shot out of its bearings
and fall, breaking the yarn, or perhaps injuring the weaver. To avoid
this, small snecks, as at H, Figs. 28 and 29, are set so that when the
cylinder is square it will pass over them; but if turned angularly
its lower edge will catch on the point of the sneck, as the cylinder
is coming in, and turn it square. The sneck is held up with a spring
so as to allow the cylinder in turning to depress it. Sometimes the
sneck, as at H, is liable to cause broken shots; for if the weaver
turns back the loom, and the cylinder moves out sufficiently far to be
turned to its angular position, and remains there, it will, in coming
in, be turned square by the sneck, and thus a card would be passed
over without a pick being put in for it. This is sometimes remedied by
putting the sneck above the cylinder, instead of below it, which would
turn it the reverse way; but this might come wrong at other times. The
better plan is to keep it below, and let the weaver get to understand
what she is doing, as it is not very difficult to learn.
The setting of a jacquard machine for working consists in adjusting the
cylinder motion so as to bring in the cylinder at the proper time, and
press it sufficiently close against the face-plate to keep the hooks
clear of the knives of the griffe, without pressing it too close; and
regulating the lifting of the griffe to suit the time for shedding,
and to give the size of shed required. The shed must be open for the
shuttle to pass through; the time for picking is when the cranks of
the crank-shaft of the loom are at the bottom centre, therefore the
shed should be almost fully open at this time. The lifting of the
griffe can be made a little earlier or later to suit circumstances,
but very little alteration can be made, as it takes a full revolution
of the crank to raise and lower the griffe. Further consideration will
be given to jacquard shedding after double-acting machines have been
explained.
The motion for working the cylinder, if an independent one, should be
rigid and strong; for if there is any spring in it, though the cylinder
may be brought in sufficiently close when there is much cutting on the
card, if a blank card or one with very little cutting on it comes on,
the extra pressure on the needles, especially with a large machine,
may prevent it from getting in sufficiently close to clear the hooks
from the griffe. With self-acting motions there may sometimes be some
trouble in this way, as the weight of the griffe may not be sufficient
to press in the cylinder. In this case the griffe may be weighted, or
may be allowed to drop quicker, or the lifting rod and lever may be
made to assist in pressing it down somewhat.
Before starting the machine the needles should be examined to see
that they are all free, and that they will spring out easily after
being pressed back. The griffe should be perfectly horizontal and all
the knives properly set; the holes in the cards and cylinder should
exactly correspond, and when the cylinder comes in the needles should
be fair in the centre of the holes; if not, the cylinder must be set as
described (see description of Figs. 26 and 27).
The driving of heavy single-acting jacquards will be further considered
under Twilling Jacquards.
When any of the hooks or needles in a jacquard get bent or broken, they
can easily be straightened, or taken out and replaced by others. By
putting a thin blade of iron or wood down through the needles alongside
of the hook to be replaced, and springing open the passage, the old
hook may be drawn out and a new one put into its place. The tail cord
must, of course, be cut off the bottom of the hook, and a new one tied
on. For changing a needle take off the spring-box and draw up the pin
which fastens the row of needles at the back; then the needles in this
row may be taken out till the defective one is reached, and the row
made up again; or, the old one may be renewed without taking any of the
others out. A flat blade is used to slide through the hooks and keep
clear the place for the needle to be put in.
_Card Frames._--The cards for jacquard work are usually hung on a
frame as O, Fig. 18, wires sufficiently long to catch on both sides
of the frame being tied to the lacing of the cards. The number of
cards between each wire may vary to suit the space and the quantity
of cards. Sixteen to twenty suit very well, the former for small and
the latter for larger sets, and for very small sets twelve or fourteen
might be more convenient. The frame may be made of round iron rod, or
of flat or bar iron, and should be of the shape shown in the sketch,
and not semicircular, as is usually the case, which presses the cards
together in the centre; almost flat at the bottom, with just enough
of a slope to make the cards slide back, is much the best. Of course,
for a few cards it does not matter much what shape it is. P (Fig.
18) is the frame for the rollers over which the cards travel to the
cylinder. They should be so sloped as to make the cards travel up
nicely with sufficient drag on them, and not too much; on this depends
a good deal the proper working of the cards, particularly when the
machine is running at a high speed, and when springs are not used to
steady them on the cylinder. It is usual to have a roller below the
cylinder, attached to the frame which holds the cylinder, and the
falling cards pass over it. Sometimes the cards, when falling, are
shaken, so that some of the wires may not catch on the frame, but pass
through it, or the ends of some of the wires may be bent and cause
the same result; if the weaver neglects to put these up on the frame
before the cards work round to those that have fallen, the wire may
catch on it and prevent the cylinder from turning, or, perhaps, pull it
out. Sometimes a crank or bend is made in the frame at the outer end,
so that the wires can pass up through it without catching. The frame
should just be sufficiently wide to enable the cards to pass freely
through it with, say, one-eighth of an inch clearance at each side;
then, if three or four inches at the outer end is cranked, or set out
so as to be a little wider between the two bars than the length of
the wires, they will pass up through without catching. Frames of the
shape described are, of course, only suitable when the cards are to be
wrought forwards--that is, with the cards falling between the cylinder
and the machine; but if they require to be wrought both backwards and
forwards, as is sometimes the case, the card frame must be made more
of a semicircular shape, and the rollers must be set so as to give a
sufficient fall to the cards, and keep them firm on the cylinder.
As has already been said, the nature of the shedding of a single-acting
jacquard is objectionable for speed in working, for ease on the yarn,
and for heavy work, or for well-covered work. The jacquard harness
is levelled so that the yarn is all sunk, and the shed is entirely a
rising one; it can easily be understood that when the griffe rises to
open one shed, it must again fall before it can begin to rise to form
the next shed. Now, mostly all tappet motions, and a great many dobbies
or shedding motions, either have the yarn springing up and down from
the centre, or have one portion rising and the other portion falling
at the same time, so that in them the second shed could be open at the
same time that the griffe in the single-acting jacquard had fallen to
begin to rise the second shed; but as this would be much too soon,
they can take a greater time to accomplish the work, and thus have a
much slower and steadier motion.
It has been attempted to work the single-acting jacquard on the
centre-shedding principle, and machines are at present being made in
France of this class. It is only necessary to let the board on which
the upright hooks rest fall at the same time that the griffe is rising
in order to accomplish what is required, and the method of working is
good, and would suit well in dobbies where the heddles can be taken
firmly down. But in the jacquard the drawback is in the harness: the
constant rising and falling causes a vibration in it, and does not
admit of nearly so firm work as when the rising shed alone is used.
[Illustration: Fig. 30]
One of these machines is shown in Fig. 30; they are a very compact and
neatly made machine, and contain a much greater number of hooks than
one of the English machines. Fig. 26 gives one of the hooks in this
machine, and the way in which it acts is there explained. It will be
seen that the frame for the cylinder is inverted; F is the face-plate
or needle board as it rests when the cylinder is not pressing against
it, being held in this position by the spring H pressing on a stud on
the bar I, which extends from the face-plate to the clap-board G. The
cylinder frame is driven by a rod, C, connected with a lever. E, E^1
are two racks on the ends of the hole board on which the hooks rest,
and D, D are two levers with quadrant racks on each end, which work
into the racks E and E^1, and also into the racks on the slide bar
_a^1_. This slide bar is fastened to the griffe A A, which is raised by
a connecting-rod from a horizontal lever to the stud _a_. As the griffe
is raised one end of the racked levers, D, is also raised, and the
other end sinks, taking down the hole board by pressing on the racks E
and E^1. The hole board is fixed so that it will easily slide up and
down. If the griffe is raised two inches, the hole board falls rather
more than one inch.
This is a very good motion, perhaps could not be surpassed for the
purpose, but, as I said before, has the objection which all similar
contrivances for the purpose must have--viz., causing too much
vibration in the harness. All the cords constantly dancing up and down
causes an unsteadiness and swinging that is not to be found in the
ordinary jacquard harness. These machines have sixteen rows of needles
in them, which are much closer set together than those in this country,
and give a large number of hooks in a small-sized machine, which is a
great advantage when extensive patterns are required. In this machine
the half-card contains 440 holes, or 880 holes to the full or double
card. The pitch is shown at A, Fig. 31, which represents the end of
one of these cards, and a piece of one of the usual 8-row cards as
here used is shown at B for contrast, the black dots in both cases
representing holes.
These machines have not been adopted here, nor is it likely that they
will be, although they are said to work well in France. They have
been tried here, and the difficulty lay in setting the cards properly
so as to act correctly on the needles, and keeping them so for any
length of time. The least contraction or expansion of the paper, or any
irregularity in the cutting, any bend in the points of the needles, or,
in fact, anything but perfect exactness, interferes with the working:
there is too great compactness in the machine, and in the ordinary
wear and tear of work a little allowance is necessary for success.
Considering that these are working, it would appear that the pitch
and size of the holes in our cards are unnecessarily large, except
where small machines answer and saving of space is no consideration;
in that case the extra paper required for the cards might be more than
compensated for by the strength of the machine, and the saving of
trouble in attending to it.
[Illustration: Fig. 31]
The method already mentioned of getting over the disadvantage of the
single-acting jacquard is not likely to gain general favour, and is
not required, as it is surpassed by the double-acting jacquard, or
that in which there are two griffes, one rising when the other is
falling, forming a counterpoise as well, making the shed more after
the principle of ordinary tappet shedding. In a loom fitted with a
single-acting jacquard, if there is much weight to be lifted, it will
turn round the loom so that it will rest in no position but with the
griffe down, and this is frequently of so much annoyance to the weaver
as to necessitate a counterpoise being applied to balance it. Sometimes
weights are used, and sometimes springs. With the double-acting lift
nothing is required, and this was first used in Cross’s counterpoise
harness (about 1816).
[Illustration: Fig. 32]
[Illustration: Fig. 33]
In the double-lift machine there are double the number of hooks that
there would be in a single-lift machine of the same size, but the same
number of needles; each needle is connected with two hooks, as shown in
Fig. 32, which gives one row of hooks and needles for an 8-row or 400
machine. There are two griffes, one working above the other, as shown
at A and B, Fig. 33. E, E is the top griffe in both; C, C is the bottom
griffe, shown complete at A, but at B the side-bar of the frame is
omitted, leaving only the knives to show how they fall in between those
of the bottom griffe; D, D^1 are the two slide rods or spindles which
keep the griffes steady in their traverse. There must be a sufficient
space between the frame C of the lower griffe and that of the upper
griffe, E, to allow of the required draw being given to form the sheds
without them coming into contact. In these machines, although there
are 16 hooks in the row, they only act as eight, so far as forming the
pattern is concerned, as two hooks are governed by one needle; the
additional hooks are solely for the purpose of obtaining a rising and
falling shed. Each pair of hooks is connected together at the bottom
by a piece of strong cotton cord, called the tail cord or tug cord, as
shown in Fig. 35. The griffes are raised by two levers arranged side
by side, and similar to the one shown in Fig. 17. These levers are
wrought by rods connecting them to a double crank, or sometimes to a
tappet, on the tappet shaft of the loom. The common form of crank is
shown at A, Fig. 34. B is the tappet shaft, and on the end of it is
fastened a disc. A second disc, which carries the double crank, G, is
bolted against this one, and can be shifted to whatever position is
required to give the tread at the correct time. The cylinder is driven
from an eccentric on the crank-shaft as before described. One of the
griffes rises for each shot, the other falling at the same time; but
the cylinder must come in for every shot, and it is here that the
principal fault in this machine lies. Not only has the cylinder to
travel at a high speed, but when one griffe is at its highest position,
it has to press against the needles, so as to clear away those hooks
that are not to be lifted by the lower griffe, which should now be
beginning to rise; and in consequence of the needles being attached
to two hooks, one belonging to the upper griffe, and the other to
the lower one, it follows that those needles that are pressed in by
the cards have to spring back the hooks connected with them that are
raised by the upper griffe, which is a severe strain on both needles
and cards. To prevent the hooks being pushed off the upper griffe, they
must have larger turns on them than would otherwise be necessary.
[Illustration: Fig. 34]
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.
[Illustration: Fig. 35]
[Illustration: Fig. 36]
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.
[Illustration: Fig. 37]
[Illustration: Fig. 38]
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.
[Illustration: Fig. 39]
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
[Illustration: Fig. 40]
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)).
[Illustration: Fig. 41]
[Illustration: Fig. 42]
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.
[Illustration: Fig. 43]
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.’
[Illustration: Fig. 44]
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.
[Illustration: Fig. 45]
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.