_JACQUARD WEAVING_
The Jacquard machine was the invention of a Frenchman of that name, who
exhibited the machine about the year 1800. It was introduced into this
country about twenty years later. The chief advantage of the machine
is that a large number of warp threads can be operated separately, and
a larger figure be produced than with a shaft harness. The chief ideas
in the machine are that each mail is connected separately to its hook,
and the use of perforated cards to leave any hook over the griffe if
it is required to be lifted, or to push it away from it if the hook is
required to be left down in the shed.
The original Jacquard machine was a single-lift, and although many
minor improvements have been made in it, the main features are
practically the same to-day as in the earliest machines introduced
into this country. At the present day the single-lift is comparatively
little used in cotton manufacture owing to the increased speed at
which double-lifts can be worked, but it is still preferred in silk
manufacture for several reasons. One reason is that the character
of the shed when beating up in a double-lift machine is essentially
different to that produced by a hand-loom, where of course a
single-lift is always used, and as hand-loom fabrics have a finer
touch and appearance than power-loom fabrics, the object is to imitate
the hand-loom production as nearly as possible. The cause of this
difference in the character of the shed when beating up will be
explained later in this chapter. Another reason is that silk-looms
could never be run at any speed higher than that of which a single-lift
machine is capable, and therefore the advantage of increased speed of
the double-lift is of no use.
Double-lifts, owing to the counterpoise and the division of the work
on to two knives, are undoubtedly steadier in working, and this is
an argument decidedly in their favour. Single-lifts are still used
in the manufacture of figured lenos, as no shaking motion has yet
been successfully adapted to enable the crossing ends to cross with a
double-lift machine.
[Illustration: FIG. 106.]
A single-lift Jacquard for weaving a pattern which occupies 400 ends
in a repeat consists of 400 hooks and 400 needles, with an extra row
of eight hooks for selvedges, or other auxiliary use. The hooks are
arranged in eight rows with 51 hooks in a row. A cross section of this
Jacquard is shown at Fig. 106, where the uprights are the hooks and the
horizontal wires the “needles.” A is the “needle board,” and this is
a perforated board through which the needles pass. The bottom needle
B is twisted or looped round the back hook D, and the connection of
the other needles and hooks is shown. At the back of each needle a
small spring made of fine brass or steel wire is placed. These springs
are held in position in the “spring-box” S. There are, therefore, 408
springs required for the 408 needles. The hooks rest on the grate G,
but in some makes of machine the grate is not used and the hooks rest
upon a “bottom board.” In this case the hooks are very liable to turn
round, and thus cause annoyance. To prevent this, flat hooks have
been used, and the needle loop was shaped so as not to permit the hook
to turn within it. The eight knives form the griffe. These knives are
all fastened together, and are moved up and down from the crank-shaft
of the loom. The illustration shows the knives at the bottom of their
stroke, and at this point, or immediately after the griffe begins to
move upwards, the card on the perforated cylinder E is pressed against
the needles, and if there is a hole in the card, the needle directly
opposite the hole will pass through it and into the perforation in the
cylinder, and the knife will take up the hook to which this needle is
connected. If the card is blank opposite any needle it will press back
the hook, and as the knife lifts, the hook is left down. Thus it is
possible to lift any of the 408 hooks in the machine for any pick. When
the cylinder is taken away from the needles the hooks are forced back
into their original position by the small springs in the spring-box S.
It will be noticed that the knives are leaning a little, and the reason
for this will be apparent, as if they were not leaning they would catch
the tops of the hooks in coming down, and would break or bend them. The
sloping position enables the knives in coming down to press back the
tops of the hooks and so get under them, ready for the next card to be
pressed against the needles. The knives should come down low enough to
be quite clear of the hooks, and therefore in this machine there is a
considerable dwell when the shed is closed.
The harness for a straight-over pattern is mounted as shown at Fig.
107. In order to prevent confusion the connection of the cords to
the machine is not shown, but the numbers on the line A represent
the hooks in the machine to which the cords are to be attached. The
“comber-board” or “cumber-board” B is a frame into which perforated
slips are fitted. These slips are perforated to different degrees of
fineness, the fineness being regulated by the number of ends per
inch required in the cloth to be woven. The lingoes, L, are metal
weights, and serve the purpose of keeping the mails down. MM are the
mails, through which the warp threads are drawn in the order shown
by the numbers, beginning at the back left-hand corner. The draft in
straight-over patterns is always taken in this way in Jacquard weaving,
although it is not compulsory. The harness is built with linen thread,
and the method of tieing the lingoes to the hooks will be understood
from the diagram.
[Illustration: FIG. 107.]
When one lingoe has been connected to each of (say) 400 hooks, the
first pattern is complete. Supposing there are 100 ends per inch, the
pattern will occupy 4 inches, and therefore if cloth is required 28
inches wide in the harness, there must be seven lingoes attached to
each hook, making seven patterns, or seven repeats of the pattern,
in the width of cloth. Thus when one lingoe has been tied to each
hook, beginning with the first and ending with the 400th, another is
connected to each hook, beginning again with the first; and when this
is done other patterns are formed in the same manner until the required
number is complete.
[Illustration: FIG. 108.]
It is important to have a clear understanding as to which is the hook
which lifts the first end in the draft. This hook is the one connected
with the bottom needle in the last row on the 25-side of the machine.
As we stated previously, a 400s machine has 400 hooks arranged in 50
rows of 8, or 8 rows of 50 hooks, and in addition there is always a
spare row of hooks, making 51 rows in all. As it is necessary to lace
the cards in the middle as well as at the sides, a space has to be
allowed for the lace holes, and therefore the machine is divided into
two parts by a space between the 26th and 27th rows.
A plan of a card is given at Fig. 108. The length of the card between
the two peg holes A and B is nearly 14½ inches, and the distance
between the centre of the top needles and the bottom needles is 1⅞
inch exactly. This holds good for all English-made machines, but the
American index is different.
It will be seen that there are 26 rows on the _right_ of the machine
and 25 rows on the _left_, and one is called the “26-side” and the
other the “25-side.” The cards are always numbered at the “26-side,”
and the cutting is commenced at this end. It may be as well to explain
here the order in which the holes are cut from the design, as it will
assist in following the point paper design to the loom. The cutting is
usually done in a “piano” cutting machine, which will be explained more
fully later on. By this machine one row of eight holes can be cut by
operating eight punches and pressing down the right-foot treadle of the
machine.
The number end of the card is gripped by the machine, and at the first
stroke of the right foot, the lace holes EF and the peg hole A are cut,
then one stroke of the treadle is made without cutting, and the pointer
of the machine arrives at the 1st or spare row. If the selvedges are
worked from this row, holes are cut accordingly. Then the pointer
comes to the 2nd row, and in this row the cutting from the design is
commenced.
At Fig. 109 the design is made on point paper, as it is required
to appear in the cloth right side up, with the twill in the ground
running in the same direction as shown on the design. When cutting, the
design is usually turned round, as shown at Fig. 110, and the cutting
commences from the top right-hand corner A. To show the matter clearly,
the first row of holes cut are numbered, both in the design and the
card, in consecutive order.
[Illustration: FIG. 109.]
[Illustration: FIG. 110.]
The first hole cut in the card is operated with the little finger of
the right hand. Following this hole to the loom, we find it operates
the _last_ or _400th_ end in the draft, and that the hole cut last on
the card (numbered 400) operates the first end in the draft. This
is the hole which operates the bottom needle in the last row on the
“25-side” of the Jacquard machine, which, as was previously stated, is
the hook from which the draft begins.
Following out the operation of cutting the card. When the 26th row has
been cut, the lace holes MN (Fig. 108) are cut, and then the cutting
is again straight-forward to the 50th row. The piano machine is so
constructed that with the same stroke of the treadle which cuts the
51st row the peg hole D is also cut, and then follows a stroke without
cutting, after which the two lace holes T and Y are cut. This makes 56
strokes of the foot for each card.
It is usual, in order to economise space, for the Jacquards with
straight, or “Norwich,” harnesses to be placed on the loom, so that
on one loom the cards hang over the weaver’s head, and on the next
the cards are at the back of the loom. In both cases the harnesses
are built the same way, but in one case (cards over weaver’s head)
the thread operated by the bottom needle on the “25-side” will be
at the back of the comber-board, at the left hand; and in the other
case (cards behind loom) the same thread will be at the front of the
comber-board at the right-hand side.
As previously stated, the single-lift Jacquard for cotton weaving is
not often employed except for special purposes, such as figured leno
weaving. The advantage possessed by the double-lift Jacquard as regards
speed is so very considerable that its adoption for ordinary forms of
cotton weaving has become universal; and the advantage of speed is not
the only advantage it possesses, as will be pointed out shortly.
A double-lift machine with one cylinder for a 400 end pattern consists
of 800 hooks and 400 needles. Each needle is twisted or bent round two
hooks, as shown at Fig. 111. The hooks are connected together in twos
by neck cords, which are usually strong whipcord, as will be seen from
the illustration. It will be seen that the bottom needle is bent round
the back pair of hooks, the next needle round another pair, and so on.
Each needle has a spring behind it, as in a single-lift machine.
[Illustration: FIG. 111.]
There are two griffes, which work oppositely--that is, as one goes up
the other comes down. The griffes (or knives) are worked by a double
crank on the bottom shaft of the loom, so that each griffe moves from
the bottom to top of its stroke in one pick, and from top to bottom in
another pick.
The principle of the double-lift will be understood from Fig. 112. One
knife, A, is at the top, and the other knife, B, is down. One hook of
the pair is lifted, and therefore the ends in the mails connected to
the neck cord at C will be lifted. Suppose now it is required to lift
the same ends of warp for the next pick: a card is pressed against the
needles, and if there is a hole in the card opposite the needle E, it
will leave the needle and the hook N where they are, and as the knife
B is lifted, the hook N will be taken up as the hook M is coming down.
The hooks will cross at about the middle of their stroke, and the
weight of the ends and lingoes on the cord C will at that moment pass
from the hook M to the hook N. In the diagram the cord attached to the
hook N is slack, but when this hook is lifted the cord will gradually
tauten until it bears all the weight, when the cord from the hook M
becomes slack. We thus have the ends for the second pick lifted whilst
the ends which were up for the previous pick are coming down. This is
where the advantage of the double lift lies. In a single lift the knife
must lift the hooks up and then come down to the bottom before another
card can operate the needles, whereas in a double lift the card for
a second pick can be brought against the needles as soon as the ends
which were up for the previous pick are ready to come down.
[Illustration: FIG. 112.]
It is obvious that in the position shown in Fig. 112, when one knife
is up and the other down and the needle pressed back by the card, that
the hook M will also be pressed back, as shown by the dotted line.
The bend of the hook over the knife, therefore, must be sufficient to
prevent the hook being pushed off the knife, and it will be noticed
that the hooks in this class of machine are bent more than the hooks
in a single-lift machine. The hooks rest on the grate G, Fig. 111, and
the shape of the hook at this point acts as a spring to straighten
the lifted hooks after the pressure of the card has been taken off
the needles. A machine of this kind can be run at a speed of about
160 or 170 picks a minute, as compared with the 130 or 140 picks of a
single-lift.
A double-lift machine on another principle is illustrated at Fig. 113.
This is a two-cylinder machine, and to weave a pattern repeating on 400
ends this machine requires 800 hooks and 800 needles. The cylinders
work at opposite sides. The hooks are placed as shown in the diagram,
the hooked parts facing each other in pairs, and by following carefully
the manner in which the needles are twisted round the hooks it will be
seen that there are really two single-lift machines placed together,
alternate rows of hooks representing each machine. There are two
griffes, as in the double-lift single-cylinder machine, and the griffes
are worked in the same manner.
[Illustration: FIG. 113.]
The cylinders work alternately, the cards being laced in two sets,
all the odd numbers being together in one set and the even numbers
forming another set. Immediately one knife is at the top and the other
at the bottom, one cylinder is pressed against the needles, and it
will be noticed that the hooks which each cylinder operates have the
hooked parts in the direction of the cylinder. When the hooks operated
by one cylinder are at the top the other cylinder is pressed against
the needles, and thus the work done by one cylinder in Fig. 111 is
divided between two in this machine. The advantage of this machine is
in the lessened speed of the cylinders. The vibration caused by the
cylinder working at a high speed in a single-cylinder machine is so
great that the limit is reached at about 170 picks per minute, whereas
a double-cylinder machine can be run up to 200 or sometimes even more
picks per minute, though perhaps 180 is a more advantageous speed. The
top set of needles project a little further through the needle board
to compensate for the difference in leverage on the hooks.
Besides the advantage of speed, double-lifts have an advantage in the
counterpoise obtained by one set of hooks going up as the other comes
down. This causes a more even motion and steadier working. Another
advantage possessed by double-lifts is that the beating up of the weft
is effected in a crossed shed, thus enabling more weft to be put in
than in a single-lift, where the beat-up is done with a closed shed.
This beating up in a crossed shed also spreads the warp better, and
prevents the reed marks from showing, for the same reason as was given
when referring to the spreading of the warp in the tappet loom.
In silk weaving a single-lift machine has an advantage in imitating
more closely hand-woven goods, as hand-loom weavers usually beat up in
a closed shed. This causes the weft to be put in straighter--that is,
less wavy, which is very desirable in silk fabrics.
The cause of this difference in the shed when beating up in the two
kinds of looms will be understood by following the relative positions
of the griffes and the loom crank throughout its revolution.
In a single lift the time allowed for opening and closing the shed must
be used to the best advantage; that is, as much time as possible must
be given for this purpose. On this account it is necessary to pick the
moment the slay is sufficiently far back to allow the shuttle to enter
the shed--that is, when the slay is half-way back, or the crank at the
bottom centre. The griffe is worked by a crank on the top shaft of the
loom, and there is no actual dwell of the griffe or of the ends when
the shed is open; therefore the shed must be opened a little wider than
would otherwise be necessary for allowing the shuttle to pass through.
The shed must be sufficiently open to allow the shuttle to enter when
the loom crank is at the bottom centre. This regulates the timing of
the other parts. Fig. 114 will make this quite plain. The shed must be
nearly fully open when the crank is at the bottom centre to allow the
shuttle to enter; and when the loom crank is at A the griffe must be
nearly at the top. When the crank is at B the griffe will be at the
extreme top, and when the crank is at the top centre, or C, the griffe
will be as near the bottom as it was to the top when the loom crank
was at A. As was previously pointed out, the griffe must go further
down than the hooks to allow another card to operate the needles, and
therefore it is when the loom crank has arrived at C that the knife is
leaving the hooks resting on the grate, or bottom board. The griffe
will be at the extreme bottom when the loom crank is at D, and when the
griffe is up at the hooks again the crank is at the front centre, or E.
Thus the shed has the fraction of a revolution between B and C to close
in, and between E and B for opening. The shed remains closed for the
quarter of a revolution, C to E.
[Illustration: FIG. 114.]
[Illustration: FIG. 115.]
In a double-lift the warp is much more leniently dealt with. As we have
said, the shed must be open for the shuttle to enter when the loom
crank is at the bottom centre. Therefore the griffes should be in their
extreme position--one up and one down--when the crank is at the bottom
centre.
The timing of the parts in a double-lift will be seen at Fig. 115. The
cranks that work the griffes are on the bottom shaft, which of course
makes a revolution every two picks. These cranks will be perpendicular
when the shed is fully open; therefore when the loom cranks are at
the bottom centre the cranks which drive the griffes must be in the
position AB. If they are so set they will be in the position CD when
the loom crank reaches the back centre, and in the position EF, or
horizontal, when the loom crank arrives at the top centre, when the
shed will be closed. We have thus a closed shed when the crank is at
the top centre, as in a single-lift; but in this case when the shed
is closed the griffes are moving quickly, whereas we have a quarter
of a revolution dwell after the loom crank reaches the top centre in
a single-lift. This causes, as we shall see, a difference in the shed
when the slay beats-up, or is at the front centre. When the griffe
cranks are in the position GH, the loom crank will be at the front
centre, and thus the shed will be partly opened for the next pick when
the reed comes in contact with the cloth.
Jacquards are made in various sizes. 100s, 200s, 300s, 400s, and 600s,
are the most common. 100s are arranged in rows of four; 200s and 400s
are in rows of eight; 300s and 600s in rows of twelve.
There are two distinct kind of harness mounting, the London and Norwich
systems. In the former the Jacquard is placed with the narrow end
towards the front of the loom, thus causing the cards to fall at the
side. In the Norwich system, or “tie,” the machine is placed with the
broad side facing the front of the loom, thus causing the cards to
hang either over the weaver’s head or at the back of the loom. On this
system, as there are eight rows in a machine, by taking the comber
board eight rows deep the harness becomes what is called a straight
neck. With the London system, the end of the machine facing the weaver,
there must be a twist in each pattern in the harness. There is not much
to choose between the two systems. Some prefer the London tie, as they
say the twist in the harness causes the harness threads to support
each other, and so last longer. The Norwich system is the more common,
especially in the cotton trade.
[Illustration: FIG. 116.]
Fig. 116 shows the method of tying up the harness on the Norwich system
for a bordered fabric, such as handkerchiefs. In these goods it is
usually preferred that both borders should point inwards, as in the
sketches Figs. 116 and 117.
[Illustration: Fig. 117.]
The hooks to which the harness threads are attached are numbered on
the line A, and it will be seen that the draft begins in the left-hand
corner at the back of the comber-board, the lingoes being numbered in
the order of the draft. The cords are tied up just as for an ordinary
straight-over harness for the first 400, or one full pattern of the
machine, but then, instead of commencing with the first hook again,
the 201st lingoe is tied to the 201st hook, and the second half of the
pattern is repeated. This forms the middle of the handkerchief, and it
must be repeated over a sufficient number of times to give the required
width of cloth after allowing for the trimming and border. In Figs.
116 and 117 nothing but a border and middle are shown, but sometimes
a trimming of another small weave is required outside the border, and
this, which is usually on a small number of hooks, is repeated over
in the same way as the middle. In Fig. 118 only two repeats of the
middle are shown; but supposing that the harness had 100 ends per
inch, and that the handkerchief was required to be twenty-four inches
wide excluding the border, there would be twelve repeats of the middle
required. When the middle has been repeated over a sufficient number
of times, the other border must be tied up, and to obtain the reverse
position of the figure the draft must be reversed. By tying the next
lingoe to the 200th hook, and going backwards with the draft, it can
easily be seen that the same figure will be woven at this side of the
harness as at the opposite side; the only difference will be that the
figure will point to the left, as will also the twill in the ground,
if it is a twill. This system of tying up is compulsory in the Norwich
system, as it is usual to keep the harness straight--that is, the
harness threads from each of the eight rows in the Jacquard each form
a separate row in the comber-board. We have thus eight rows in the
machine and eight rows deep in the comber-board, and it would not do to
have a thread taken from the front of the comber-board at one border
and from the back of the comber-board at the other border to the same
hook.
[Illustration: FIG. 118.]
If the harness is a “London tie” it necessitates a half-turn in each
pattern, as the machine is at right angles to the comber-board.
Therefore the draft may be continuous, as shown at Fig. 117, where,
after the middle has been repeated a sufficient number of times,
finishing with a thread from the 400th hook at the front of the
comber-board, the next one is taken from the 200th hook through the
back of the comber-board, and the border will finish with a thread from
the first hook going through a hole at the front of the board--just the
reverse to the other side.
Bordered goods are often made with two borders at each side, and
sometimes the borders are repeated a few times. The number of hooks
taken for the border and middle respectively vary according to
requirements. Sometimes, in a 400 machine, 300 will be taken for the
border and 100 for the middle, and so on. The cross-border must of
course be designed, and the cards cut. The number of cards in a set in
these goods is often very large, as the middle must be repeated over
the required number of times, and there will be as many cards used in
the set as there are picks in the handkerchief.
In designing for the mounting given at Fig. 117, the design would
be made on 400 ends: 200 for the border and 200 for the middle, and
the cards would be cut just in the ordinary manner. The cross-border
would also be designed in such a manner as to harmonize with the side
borders. The portion to be designed is enclosed by the dotted lines.
Centre ties or point ties are another class of harness in regular use.
This is really the two borders of a bordered harness joined together.
Fig. 118 shows how the tying up is done for a pattern of this kind. The
first 400 threads are connected as usual, the draft being from back to
front. When the 400th has been reached, the draft is reversed until
No. 1 is arrived at again. The same effect is obtained as in a point
of V draft in a shaft harness. The pattern must be of such a character
that one half is the exact reverse of the other. This kind of harness
is used for weaving large damask figures, and it is obvious that the
effect produced is really that of a figure on 800 ends, or twice the
size of the machine. Designs of this character are of course rather
stiff, but are suitable for damasks, and similar fabrics.
CROSS-BORDER JACQUARDS.
[Illustration: FIG. 119.]
The object of a cross-border Jacquard is to save the expense of cards
in handkerchiefs and other bordered goods. As pointed out previously,
the portion of the handkerchief between the two cross-borders is
usually repeated over for a considerable number of times, often from
twelve to twenty times. This often means using a few thousand cards,
which might be saved if the border and middle cards could be laced
separately and changed automatically. On the hand-loom it is usual for
the weaver to change the cards by hand when required, substituting the
border for the middle cards and _vice versâ_, but in the power-loom
this is of course out of the question, and usually the total number of
picks in the handkerchief have each a separate card. The cross-border
machine illustrated at Figs. 119 and 120 is the invention of Messrs.
Crossley and Davenport. The machine is double-lift, as will be seen
from the connection of the neck-cords. The border cards are put on one
cylinder, B, and the middle cards on another, A. When the cylinder
A presses back a needle, say the top needle C, it will press back
the pair of hooks EF, as in an ordinary double-lift single-cylinder
machine, and as long as this cylinder is worked every pick the machine
is to all intents and purposes a double-lift single-cylinder machine.
When this cylinder is stopped and the cylinder B is worked every pick,
the cards on the cylinder B have exactly the same effect on the ends
as those on cylinder A; for when the top needle in this set of needles
is pressed back, it will force backward the pair of hooks EF, exactly
as operating needle C by the other cylinder did. Only one spring-box
is used, as the upright wires MM pass through loops, P, in the long
needles, and small iron bars, HH, act as fulcra for the wires MM. The
tops of these wires are fastened to the short needles N, as indicated
in the diagram, and thus when the needle N is pressed back it moves the
needle C in the opposite direction and operates the hooks EF.
[Illustration: FIG. 120.]
The cylinders can be changed by pulling the cord L in Fig. 120. When
the parts are in the position shown in this illustration, the cylinder
A will be pressed against the needles every pick. The cylinders are
driven from the crank shaft, the rod X goes to the crank shaft, and a
reciprocating motion is given to the ~L~ lever CD centred at E.
The rocking lever FG is centred at K, and the reciprocating motion is
transferred from CD to FG. It will be seen that one end of the lever FG
is in the diagram inside the bend in the slot on M, and the other end
of the lever FG is in a position to move about its centre, K, without
moving the cylinder B. Thus as the crank shaft of the loom revolves
it will give motion to the cylinder A, but not to B. By pulling the
cord L, however, the bend on the slot on N takes hold of the top of
the rocking lever G, and at the same time, through the lever SR, M is
lifted, and the end F of the rocking lever moves freely in the slot
without moving the cylinder A. The disadvantage of this motion is that
the change is not made from the cards automatically, certainly not an
impossible piece of mechanism to contrive. There are other cross-border
motions, but this is only given as an example.
DOUBLE-SHED JACQUARD.
Double-shed Jacquards are used chiefly in weaving heavy goods where a
very large and deep shuttle is required to hold a reasonable quantity
of weft. The principle of this machine will be easily understood from
Fig. 121. A is connected to the crank shaft of the loom and moves the
end of the lever BC up and down, the fulcrum of the lever being at E.
The bottom board or plate F is therefore moved up and down, and in
doing so the griffe G is made to move oppositely, the bottom plate
coming down as the griffe goes up, and _vice versâ_. This is effected
by the top levers PR and QS, which are centred at O. One end of the
griffe is connected to Q, the other end of the griffe is connected to
P. This gives firmness and strength to the machine. These Jacquards are
usually made very heavy, as they are chiefly for heavy work.
[Illustration: FIG. 121.]
Only a few hooks are shown as an example, but the machines can be made
any size. When all the hooks are resting on the bottom board, which
will be when the bottom plate is at the top of its stroke, the card is
pressed against the needles and selects the hooks to be lifted in the
usual manner, after which the griffe rises as the bottom board sinks.
Thus an extra deep shed is produced without the griffe having so far
to lift as would otherwise be the case. The shed produced is a centre
shed, all the ends coming to the centre every pick.
“OPEN-SHED” JACQUARD.
Several open-shed Jacquards have been patented. That of Wilkinson’s is
illustrated at Figs. 122 and 123. A and B are a pair of hooks, which
are connected by a cord passing round a pulley, W. This pulley works
on a pin at one end of the thin plate C, and at the other end of the
plate is another pulley, X. The neck cord E passes round this pulley
to the bar D, to which it is fastened. It is obvious that when one hook
of the pair is lifted, say, 4 inches, and the other is at the bottom,
the pulley W will be lifted 2 inches; and as the cord E is fast to D,
the harness threads will be lifted 4 inches, the same as the hook.
[Illustration: FIG. 122.]
[Illustration: FIG. 123.]
If one hook of the pair is lifted and it is required to keep the same
ends of warp up for the next picks, the hooks being connected round
the pulley W, one hook going up as the other comes down will keep
the harness cords stationary, and the hooks A and B can be lifted
alternately one up, one down, without moving the cord E, which will all
the time be keeping the warp ends up. The shed thus obtained is similar
to that in a Keighley dobby; the ends, when once they are lifted, stay
in that position until they are required to come down. The principle
can be applied to either double-lift single-cylinder or double-lift
double-cylinder machines.
Another view of the pulleys is shown at Fig. 123, where the pulleys and
other parts are lettered as in the previous figure. Each pair of hooks
in the machine has these pulleys attached, and therefore it will be
understood that the pulleys must be rather thin in order to enable them
to be placed in a space equal to the size of the Jacquard machine. The
advantage which a satisfactory machine on this principle would possess
lies in the fact that the jerk which occurs in ordinary double-lifts
when the weight is passing from one hook to another in each pair is
done away with. This jerk causes breakage of the neck cords, and many
efforts to overcome the annoyance have been made. This principle of
open shed may be applied to dobbies such as the Blackburn dobby.
THE SPLIT HARNESS.
[Illustration: FIG. 124.]
The split harness is an ingenious method of increasing the size of
pattern which can be woven on a given Jacquard. What is termed a
“double-scale” split harness consists of two adjacent lingoes being
connected to each hook in the machine. Thus with a 400s machine there
are 800 mails in a pattern. A few lingoes are shown at Fig. 124 tied up
in the manner of a double-scale harness. The connections to four hooks
are shown. Underneath the comber-board a loop is made in the harness
thread, and shafts SS, either wood or metal, are inserted through the
loops in each row in the harness. These shafts are worked by the spare
hooks in the machine, and in the places where the ends are left down by
the Jacquard, the shafts, being lifted to a given ground pattern, will
weave the ends singly. In Fig. 124 the shafts are shown lifted to weave
a plain or tabby ground, every alternate one being lifted. Hooks No. 1
and No. 2 are lifted by the Jacquard, and hooks 3 and 4 are left down,
and it will be seen that where the hooks are down, half the ends will
be lifted by the shafts. The ends, when lifted by the Jacquard, cannot
be woven separately with this harness, and therefore the bindings in
the figure will show in twos, which, unless the harness is a fine one,
has a tendency to make the cloth appear coarse. Satin or twill grounds
may be woven. In fact, the ends left down by the Jacquard may be woven
singly to any pattern which repeats on the number of shafts used, or
into the number of rows which the harness is deep in the comber-board.
Of course either the figure or the ground may be woven singly,
according to the way the pattern is designed, but not both.
In silk weaving, harnesses are built on this principle to a threefold
scale--that is, with three mails attached to each hook--and as in the
double-scale a figure repeating on 800 ends can be woven on a 400s
machine, so with a threefold scale a 1200 figure can be woven on a 400s
machine. In this case the bindings in the figure will be in threes, but
the ground ends may be woven quite singly by the shafts.
This principle is only adapted for very fine reeds in cotton goods, but
is often used in silk manufacture, where 300 or 400 threads per inch
are not uncommon.
THE PRESSURE HARNESS.
The pressure harness was invented with the object of enabling very
large figures to be woven on ordinary sized Jacquard machines. In very
fine silk damasks--say, with about 400 threads per inch--a very large
machine (or machines) is necessary to obtain a figure suitable for
damask on the ordinary principle. The pressure harness overcomes this
difficulty in a most ingenious manner.
[Illustration: FIG. 125.]
The method originally used consisted in drawing a number of ends in
each mail, and then drawing each end separately through a shaft in
front of the harness. These shafts had long eyes, as shown in Fig. 125;
in fact, the eyes are large enough to permit of the shed being opened
without their interfering with it. In Fig. 125 two of the Jacquard
lingoes are shown, A, representing those lifted by the Jacquard, and
B, those left down. There may be any number of ends in each mail, say
five. After being drawn through the Jacquard harness in fives, the ends
are drawn singly through the shaft harness in front. These shafts are
either worked by treadles or by a Jacquard. In the diagram they are
shown worked in the latter manner. A small pulley is placed between the
hooks and the shafts, and each shaft is connected to two hooks, a cord
from one hook passing round the pulley to the other hook. When both
hooks are lifted, the shaft will be lifted to the top, like the shaft
1; when only one hook of the pair is lifted, the shaft will be taken
up half way, like the shafts Nos. 2, 4, and 5; and when both hooks are
left down, the shaft is left at the bottom, like the shaft No. 3 in the
diagram. These shafts require to be worked by a machine with double
the lift of the Jacquard machine behind them, as from bottom to top
the lift is twice the size of the shed. They may also be worked on the
centre shed principle, one shaft going up and another one going down
from the centre each pick.
If one of these shafts is lifted to the top, like shaft No. 1, it is
obvious that it will take up one end out of every mail left down, and
by lifting the shafts in satin order the ends left down by the Jacquard
in fives would be woven singly five shaft satin. By leaving one shaft
down every pick, the ends lifted by the Jacquard will be split up in
the same manner. So that with one shaft at the top, one at the bottom,
and the other three lifted half way, a figure repeating on 2000 ends
can be woven on a 400s Jacquard, every end being woven singly in both
the ground and the figure. Of course only simple weaves can be used,
and the figure will move in steps round the edges. If it is required
to weave an eight shaft weft satin figure on an eight shaft warp satin
ground, eight shafts must be used instead of five. The ends may still
remain five in a mail, as it is not necessary that the number of ends
in each mail should be the same as the number of shafts used. These
shafts are called pressure healds; hence the name given to the harness.
In designing for this class of harness the figure is put on point paper
in simple colour, no binding dots being used, as the binding is all
done by the pressure healds. The method of putting down the plan for
lifting the healds, and of devising a variety of weaves for pressure
harness weaving, will be found fully explained in Chapter X.
[Illustration: FIG. 126.]
Another and better kind of pressure harness is illustrated at Fig. 126.
Instead of healds with long eyes, two sets without eyes are used, but
with a simple clasp in the middle. Fig. 126 shows the mounting for a
five end satin figure on a five end satin ground, and two lingoes only
of the Jacquard are shown, O representing the lifted hooks, and P the
hooks left down.
[Illustration: FIG. 127.]
There may be five, six, eight, or more ends in each mail, and they
are drawn singly into the pressure healds in front in the following
manner:--There are two sets of healds with clasps, as shown at Fig.
127. Each end is drawn singly _over_ a clasp in the set A, and _under_
a clasp in the set B. The clasps in the set A are fixed at the bottom
of the shed, and the clasps in B are fixed at the top of the shed. By
pulling one of the set B down and lifting one of the set A every pick
in satin order, the ends lifted in fives or sixes are woven singly in
warp satin, and the ends left down in fives or sixes are woven singly
in weft satin.
[Illustration: FIG. 128.]
The method of operating the pressure healds in a hand loom is shown
at Fig. 128. The shafts in set B are pulled down by lifting the end E
of the levers EF, and the same on the other side. The shafts in the
set A are lifted directly by the hooks. The shafts are lifted by a few
spare hooks in the Jacquard. Sometimes the Jacquards have three or
four rows of extra hooks for this purpose, and these hooks are placed
a little to one end of the machine, and a small separate cylinder is
used. The cards for lifting or pulling the pressure healds are put on
this cylinder, and the large cylinder carrying the figure cards is
only turned round once every few picks by arranging the catches to
do this. The same card is thus brought against the needles several
times in succession, and the smaller cylinder being turned every pick,
interweaves the threads in satin or the required order. This will form
steps at the edges of the figure in the weft way as well as warp way,
and is a considerable saving of cards. The weights M are to pull the
healds B up, and the weights N to keep the healds A down. Springs may
be used in their place, but weights are preferred in the hand loom.
The mails used in the Jacquard harness are made with a separate hole
for each end. Sometimes as many as twelve or sixteen ends are drawn in
each mail, thus giving in the latter case a 6400 end figure from a 400s
machine, so that with 300 ends per inch the figure would measure over
20 inches wide.
EDLESTON HARNESS.
A method of weaving an 800 figure on a 400 double-lift machine has
been patented by James Edleston, of Preston. This is a very useful and
ingenious idea, as a floated figure can be formed, and the machine
remains a double-lift, with all its advantages as regards speed.
Certain limits are placed upon the weaves, which can be employed for
the ground or for developing the figure, but sufficient scope is
afforded for all practical purposes to make the invention a success.
An illustration is given of this harness at Fig. 129. The inventor
gives no drawing in his specification, but presumably the illustration
(Fig. 129) will represent his method; at least, it will effect the
same object. One row of hooks of a 400s double-lift single-cylinder
machine are shown, and it will be noticed that the hooks are not joined
together by a neck cord as in the ordinary machine, but the harness
threads are taken singly from each hook as in a single-lift machine.
The knives work as in a double-lift, one up, one down. By cutting the
cards in a certain manner the whole of the 800 hooks may be operated
by the 400 needles so as to produce ordinary brocade or damask figures
with a repeat of 800 ends. The same end cannot be lifted for two
picks in succession, as the knives have to move up and down and work
oppositely; but an end can be _left down_ any _odd_ number of picks,
and a figure can thus be formed. At Fig. 130 the design for eight-end
satin ground is given. It must be remembered that for eight ends there
are only four needles, and therefore the lifting dots must be put on
four ends on the point paper. By carefully comparing this design with
the mounting of the harness, the principle will be quite clear. The
design shows a dot on the first and fifth ends on the first pick, and
therefore a hole will be cut in the card opposite the first and fifth
needles.
[Illustration: FIG. 129.]
Suppose the griffe A to be lifted for the first pick, it will lift the
first and ninth ends. The second card has holes opposite the second and
sixth needles, and when the griffe B is lifted for the second pick, it
will lift the fourth and twelfth ends in the warp or lingoes in the
comber-board. The third card has holes opposite the fourth and eighth
needles, and as on the odd picks the griffe A lifts, it will lift the
seventh and fifteenth ends in the warp. If this is followed out it will
be found that the ends are lifted in the order 1 4, 7 2, 5 8, 3 6, or
eight end satin is woven. Fig. 131 shows the method of putting the dots
on point paper for four end twill (one and three). The principle is the
same as in the preceding case, and is very simple when understood. A
hole opposite the first needle on the first pick causes the first end
to be lifted, and a hole opposite the same needle for the second pick
causes the second end to be lifted. Any figure can be put upon the
cloth, with the following limits as regards the bindings: firstly, an
end cannot be lifted for two successive picks; secondly, every end must
be left down an odd number of picks.
[Illustration: FIG. 130.]
[Illustration: FIG. 131.]
From this it will be seen that a five end satin cannot be woven, nor
can a weft figure be put on a warp ground. Plain grounds can be woven,
and cord grounds of various kinds are also suitable for the harness.
DAMASK OR TWILLING JACQUARDS.
These Jacquards are now extensively used for weaving linen, damasks,
and similar fabrics, and are used where pressure harnesses were
formerly used. The pressure harness puts a great strain on the warp,
and requires a longer distance between the cloth and the warp beam than
is usually allowed for in power looms; therefore much ingenuity has
been expended on these Jacquards with the view of obtaining a large
design without using several ordinary Jacquards above each loom, with
the accompanying great expense in cards and other attachments.
The principle of damask attachments and twilling Jacquards is entirely
different to the principle of the pressure harness, and for fine silk
fabrics which require a very large extent of pattern and woven on the
hand loom, the pressure harness on the principle shown at Fig. 126 is
not likely to be replaced.
[Illustration: FIG. 132.]
[Illustration: FIG. 133.]
In the pressure harness a number of warp threads are placed in each
mail, the number of threads varying from five to sixteen; but in the
twilling Jacquard only one end is drawn in each mail, and a separate
hook is required for every end. The advantage comes in making each
needle serve for several hooks and in making one card serve for several
picks. One of the first inventors of this kind of Jacquard was Mr.
Barcroft, of Newry, Ireland, and it has been improved since by him and
others. The principle is illustrated at Figs. 132 and 133. There may
be any number of hooks to each needle. In the illustration there are
three. The machine is necessarily a single-lift, the griffe goes up
and down every pick. Only two needles are shown, operating six hooks.
When the top needle is pressed back it will press back the hooks 1, 2,
and 3, and when the bottom needle is pressed back it will press back
the hooks 4, 5, and 6. These hooks are bent at the bottom as in the
diagram, and a bar or rod A is passed through each row of hooks the
full length of the machine. These bars A are lifted by the twilling
hooks, shown in the diagram in dotted line. These hooks are placed at
the sides of the machine: two hooks for each long row of the ordinary
hooks, or one for each end of every bar, A. The blades of the griffe
are movable about the centres EE, and at each end of the blades and
immediately behind each twilling hook (dotted) there is a projecting
piece, P, also shown in a dotted line in the diagram.
Now, when the griffe is at the bottom, the blades are operated by a
pegged barrel, and by turning the blades one at a time out of the way
of the hooks as the blade M is turned, it is obvious that a whole row
of hooks can be left down which would otherwise be lifted.
Turning the blade has also another effect. On the front of the blade at
each end, as previously pointed out, is a projecting piece, P, and when
the blade is turned, this projection pushes the twilling hook in front
of it (dotted) on to the next blade of the griffe, and the twilling
hook is lifted. The bottom of the twilling hook is fastened to the end
of a bar, A, and the bar is lifted, thus lifting a whole row of hooks
which would otherwise be left down. In this manner it is obvious that
by operating the blades of the griffe in regular order, the figure can
be woven warp twill and the ground weft twill, or _vice versâ_. At Fig.
133 the position of the six hooks is shown after the griffe is lifted.
It will be seen that the blank opposite the top needle pressed the
first, second, and third hooks back, and they would all three have been
left down but for the bar A being lifted. The hole opposite the bottom
needle leaves the fourth, fifth, and sixth hooks over the griffe, and
they would all have been lifted but for the blade M being turned, which
also caused the bar A to be lifted. It will be obvious that the twill
must repeat on the number of bars A, or on the number of rows of hooks,
in the machine, exactly as in a split harness the ground weave must
repeat on the number of shafts or rods used under the comber board. In
these machines, as in the pressure harness, the same card is pressed
against the needles two, three, or more times in succession, so as to
give a great extent of pattern with a small number of cards. The number
of times a card is pressed against the needles depends on the number
of hooks there are to each needle, and on the relative amount of warp
and weft in the fabric. If there are three hooks to a needle and the
same number of picks as ends per inch, the card should be used three
times in succession, but sometimes there are more picks per inch than
ends, in which case each card should be used oftener; and sometimes, as
in silk damasks, there are 400 or more warp threads per inch and 100
picks, and supposing there were eight threads in a mail, it would make
a step of eight ends in the warp; therefore, to make the steps in the
weft balance it would be necessary to bring the same card against the
needles only twice in succession.
Fig. 134 is another arrangement for weaving damask. It is called
a damask attachment, and was patented by Tschorner and Wein. Its
construction differs from ordinary twilling Jacquards, but the
principle is much the same.
Each needle is twisted round several hooks, and the knives are operated
separately by cams at the side of the machine. The illustration shows
one of the knives left down, leaving down a row of hooks which would
in the ordinary course have been lifted, and one of the bottom lifters
is taking up a row of hooks which would in the ordinary course have
been left down.
[Illustration: FIG. 134.]
The foregoing are the chief kinds of Jacquards and harnesses (except
lenos) attached thereto, but there are many combinations of shaft and
Jacquard or mail harness which need not be mentioned in a book of this
size. We may mention a system, sometimes called half harness, in which
only half the ends are drawn through the Jacquard harness, and the
other half through shafts in front or behind. A double-sized figure may
thus be formed.