WEAVING, PLAIN LOOMS, SHEDDING, PICKING, BEATING-UP, OTHER
MOTIONS, MODIFICATIONS OF LOOM, SPLIT MOTIONS.
The last process of manufacturing, and the one in which all the
preceding ones culminate, is weaving. This has for its object the
combination of the warp and weft yarns, interlacing one with the other
in such manner as to produce a firm texture, fitted for the varying
uses to which cotton cloth is adapted--for warmth, for ornament, for
trade purposes--for sale. The power looms of the present day, as
employed in the cotton industry, vary very little in construction
in the most widely separated districts, unless for very different
classes of work, then what modifications are required consist of extra
mechanism added to our common type--the plain loom.
THE PLAIN LOOM.
The machine required for the weaving of plain cloth, or cloth in which
each end of weft and twist is interwoven alternately and on the face
of which no figure is shown, is simple. The warp yarn is contained on
a beam, the weft is placed in a shuttle, and the loom consists of the
necessary framework and mechanism for holding the warp in the required
position, passing the weft between alternate warp threads.
A general view of the loom is shown in Fig. 21, whilst a detailed
representation is given in Fig. 22.
[Illustration: FIG. 21.--PLAIN LOOM. (Front View.)]
[Illustration: FIG. 22.--PLAIN LOOM. (Back View.)]
In the process of weaving it is necessary to hold the warp somewhat
tightly, each portion at the same tension, and to obtain this condition
the cloth is pulled forward by the taking-up roller as it is woven; but
the warp is held back by the friction of weighted chains or ropes on
the collars of the beam. The warp passes upwards from the beam, over
the back rest, and thence to the back of the healds; between the back
rest and healds are the lease rods--a large one with a smaller rod
nearer the healds. By means of these rods the warp is separated into
equal portions, two ends passing alternately over or under the thick
rod; those passing over the thick one also run under the thin rod. The
rule commonly observed for four healds is to have the ends passing the
first and the third heald over the thin rod, and those drawn through
the second and fourth over the thick rod, and consequently under the
thin one. The first heald is the one nearest the front of the loom; the
draft is 1, 3, 2, 4, and applies to plain cloth, although the first and
second healds are worked as one, and the third and fourth together.
Respecting the two ends which pass together at the lease rods, the
one through the front heald is to the left of the one through the
third heald; whilst with the other couples, the end through the more
forward heald is to the left of the other. The weaver, bearing these
rules in mind, can thus find the place of any broken end. The healds
are suspended on each side of the heald roller A by means of straps
and cords, which are shown. The portion of the heald roller supporting
the back healds is larger than for the front ones; this is to make the
former when lifted make the shed at the same angle as the front healds.
Below are seen the crank shaft B, and the tappet shaft C, driven from
it at exactly half the speed. The latter shaft bears the picking plates
H and shedding tappets K. The slay, supported by the slay-sword[2] D
on the rocking shaft is shown also. It carries the reed at E, held in
position by the slay-cap F. The back rest at G, over which the warp
passes, and the weight levers and driving pulleys are also noticeable
parts. The cloth is woven pick by pick, and the whole action of the
loom may be comprised in repetitions of the operations contingent on
putting in one pick. Supposing the warp to be in position and the whole
machine in weaving order, the first movement is to open the warp into
two parts, and is called shedding; the second is to pass the shuttle
through the opening thus made, called picking; and thirdly, to beat up
the weft close to the pick last put in--technically, to the fell of
the cloth. In addition to these, auxiliary movements are taking place
for winding on the woven cloth, keeping it distended, and checking the
motion of the loom in case of accident.
[2] In addition to the references given in the text, each article is
shown on Plate V.
SUNDRY FITTINGS FOR LOOM.--FIG. 21.
The illustrations on the opposite page represent a number of the
various cast-iron parts which form a loom.
1 Back Bearer
2 Swing Rail
3 Brake
4 Brake, with Loose Clip
5 Stop for Bobber Wire
6 Gib for Crank Arm
7 Cotter for Crank Arm
8 Short Strap for Crank Arm
9 Step for Pin for Slaysword
10 Block for Crank Arm
11 Brass Steps for Crank Arm
12 Long Strap for Crank Arm
13 Bracket for 2-rod Vibrator
14 Eccentric for Vibrator
15 Crank Wheel
16 Swing Rail Brackets
17 Counter Twill Wheel
18 Large Twill Wheel
19 Small Twill Wheel
20 2 by 1 Leaf Tappet
21 2 by 2 Leaf Tappet
22 Large Tappet
23 Plain Tappet for Twills
24 Twill Bowl
25 Large Heald Boss
26 Small Heald Boss
27 Radius Bracket
28 Tappet Wheel
29 Slay Sword for Loose Reed
30 Slay Sword for Loose Reed
32 Slay Sword for Fast Reed
33 Pulley
34 Strap Fork Bracket
35 Strap Fork Bracket
36 Brake Stud and Bracket
37 Taking-up Catch Bracket
38 Brake Lever
39 Frog Plate
40 Frog for Opposite Side
41 Strap Fork Bracket
42 Bush for Old-make of Looms
43 Binder Boss for Twill Shaft
44 Dollhead Bracket for Twills
45 2 by 2 Leaf Dollhead
46 Small Tappet
47 Plain Treadle Bracket
48 Plain Treadle Grate
49 Dollhead for 2 by 1 Twills
50 Plain Dollhead
51 Change Wheel
52 Rack Wheel
53 Strap Fork Bracket
54 Frog (spring handle side)
55 Picking Bowl Stud
56 Loom Side Cap
57 Yarn Beam Bracket
58 Picking Bowl
59 Picking Bowl Collar
60 Picking Boss
61 Top Plate for Picking Stick
62 Under Plate for Picking Stick
63 Square Hole Cap
64 Picking Plate
65 Picking Neb
66 Hat for Picking Shaft
67 Foot-step for Picking Shaft
68 Swan Neck
69 6in. Ruffle
70 Fly Wheel
71 4in. Ruffle
72 Spring Bracket for Picking Shaft
75 Incline
76 Weft-fork Holder
77 Weft-fork
78 Brake Lever Rest
79 Bowspring Bracket
80 Bowspring
81 Upright Temple Spring
82 Under Spring
83 Small Spring
84 Knocking-off Finger
85 Hinge Spring
86 Front Plate for Slay
87 Bracket or Rest for Stop Rod
88 Finger for Loose Reed Stop Rod
89 Stop Rod, Rest, and Bracket
90 Heater Spring
91 Heater
92 Brake Wheel
93 Flange
94 Beam Wheel
95 Carrier Wheel
96 Cloth-rod Finger
97 Taking-up Lever Catch
98 Taking-up Lever
99 Three Leaf Treadle Grate
100 Twill Treadle Bowl
101 Twill Treadle Bracket
102 Long Twill Treadle Bracket
103 Treadle Bowl
104 Treadle Bowl Pin
105 Four Leaf Treadle Bracket
106 Four Leaf Treadle Grate
107 Holding Catch Bracket
108 Holding Catch
109 Carrier Wheel Stud
110 Carrier Wheel Stud Bracket
111 Treadle for Small Tappet
112 Twill Treadle
113 Change Wheel Boss
114 Taking-up Catch Lever Bracket
115 Back Lever Stud for Reverse Way
116 Binder
117 Duckbill
118 Slay Stud
119 Regulating Finger
120 Slay-stud Bolt
121 Hook for Chain on Cross-rail
122 Boxwood Strap Guard
123 Fly Spindle
124 Shuttle Guide
125 Slay Plate
126 Spring Hook
127 Swell
128 Incline Tumbler
129 Organ Handle Bowl
130 Organ Handle
131 Box End
132 Box End Spring
134 Tricker
135 Loose Reed Weft Grate
136 Loose Reed Weft Grate Neb
137 Fast Reed Weft Grate Neb
138 Fast Reed Weft Grate
139 Bow Spring Bracket
140 Weight Lever Spring
141 Under Beam Lever
142 Under Beam Lever Bracket
143 Weft Lever Bracket
144 Hammer
145 Temple Spring
146 Greyhound Tail
147 Hammer Stud
148 Hammer-stud Bracket
149 Tumbler Bracket
150 Tumbler Neb
151 Weight Lever Hook (reverseway)
152 Weight Lever (reverseway)
153 Usual Weight Lever
154 Plain Treadle for Large Tappet
155 Vibrator Lever
163 Loose Clip for Brake
164 Back Bearer Bracket
165 Crank Shaft Bush
166 Brake Weight
167 Fast Reed Brake
168 Weft Lever Stud
[Illustration: PLATE V.--PARTS OF PLAIN LOOM. _To face p. 56._]
SHEDDING.
Shedding is very important, and more so in figured cloth than in plain;
for it is by the shedding in its varied character that fancy cloth
is principally produced. For plain cloth, a two-leaved or two-plated
tappet is fixed on the tappet shaft, acting on a bowl fixed to the
end of a lever, as shown in sketches of looms. There is one lever or
treadle to each plate, and the heald worked by it is attached at the
centre by wire, and a small corded cross-piece of wood, called a lamb.
From the sketch it will be seen that, as the tappets revolve, the
healds are alternately lifted and depressed, opening the shed in the
warp. The shed for one pick will have the front heald at the top, and
the back one at the bottom; whilst for the next pick their positions
are reversed. The tappets are of rather peculiar form, a common shape
for plain being shown at Fig. 28.
Working on the centre S the eccentricity obtained is employed in
depressing the healds, but by an intermittent movement. The shed must
be opened quickly to economise time, but must be left open sufficiently
long to enable the shuttle being picked through. A reference to the
shape of the plate in Fig. 28 will show this. From N to H is the
portion for depressing the heald, from G to H being an arc of a
circle and the part by which the heald is held stationary, while G M
corresponds inversely with F N, and allows the heald to rise. It is
necessary for the eccentricity to be equal at each shed, a point which
may be tested by noticing if the sway of the beam is the same at each
shedding. To get this, the treadles must be level when the healds are,
and the centre of the bowl directly under the centre of the shaft. The
bowl should be in contact with the tappet during the whole revolution,
and thus give an easy tread--jerky motion in either treading or picking
being very detrimental to good weaving. A good shed should be almost as
large as the shuttle at the point where it passes through, quite clear
from obstructions of any kind, and the lower half of it not too low,
or, as it is termed, not “bottoming” too much, for when too low the
warp is frayed by the movement of the slay.
A point regarding which weaving technologists often enter into profuse
arguments and diagrammatic illustration, may here be summed up in
a few words. The line of warp when the healds are level should be
below a line drawn from the temple to the back rest, and the lower
the healds are in this respect the better is the cover on the cloth,
although attention must be given to the remarks in a previous paragraph
regarding bottoming. Whether the lowness of the warp line is produced
by depressing the healds or raising the back rest is immaterial.
When plain cloth is woven in a twill loom, the tappets act above the
centre of the treadle, and of course are of smaller size, the healds
being connected to the end of the lever opposite to the fulcrum.
The calculation of the size of the shed from given dimensions of the
tappets and treadles forms a good example in leverage. Suppose the
stroke of the tappet, or the distance through which it moves the
treadle bowl (represented in Fig. 28), between the outer and inner
circles is 3-1/2 inches. The treadle is 30 inches long, the treadle
bowl being 25 inches from the treadle pin, and the healds connected 15
inches from the pin or fulcrum at N. Then the movement of the heald
from its highest to its lowest level is equal to the distance moved
through by the point N--_i.e._, 2·1 inches--for if the bowl moves 3-1/2
inches, the point N moves (3-1/2 × 15)/25 = 2·1 inches. This gives the
size of the shed at the healds. Suppose the heald in question is 7
inches from the fell of the cloth, the shuttle passing through the shed
2 inches nearer to the cloth, then the size of the shed at the heald
multiplied by 5 and divided by 7 gives its size at the point where the
shuttle passes through, or (2·1 × 5) ÷ 7 = 1·5 inches.
There is a slightly different shedding arrangement adopted in some
looms, frequently so in Yorkshire, but rarely in Lancashire. This is
the Bradford gear shown in Fig. 23. The tappets are placed outside of
the loom, and the treadles are connected to the healds through jacks
at the top of the loom. A leaf or projection on the tappet in this
arrangement causes the heald to rise, not depressing it, as in the
previously described arrangement.
[Illustration: FIG. 23.--BRADFORD LOOM.]
PICKING.
Among cotton looms the over-pick or Blackburn pick is commonest.
Attached to the tappet shaft are picking plates, one at each side of
the loom. As the picking arrangement at one side is similar to that at
the other, a single description applies to both.
The picking plate ends in a point and acts on an upright picking shaft
through a stud affixed to the latter. The point is removable and is
lengthened in broader looms about 1/8 inch for every 10 inches wider
reed space. At the top of the picking shaft is a picking stick, an arm
of some 30 inches long, carrying a band connected with the shuttle
box of the slay. It is now necessary to describe the slay. This is a
beam of wood along which the shuttle is passed through the shed and by
which the reed is held to beat up the weft. Its length is about 3 feet
more than the width of the cloth being woven, the space at each end
being taken up by the shuttle boxes. These are cavities open at the top
and at one end just sufficiently wide to hold one shuttle. Parallel
to the bottom of the box or fly-plate is a spindle carrying a hard
piece of horny substance called a picker. To the top of this the band
from the picking-stick is attached, whilst at the bottom the shuttle
rests against it. The back of the box forms an angle of 86° with the
fly-plate--thus, as it were, forming a dovetail into which the shuttle
is bevelled to fit. The space between the boxes is called the shuttle
race; it is not absolutely level, the middle point being from 1/8 to
1/4 inch lower than the boxes, the greater depression being for wide
looms.
It will be easily seen how the revolution of the picking plate actuates
quickly the picking shaft, and consequently the end of the stick, with
an increased speed. The blow is transmitted to the picker and the
shuttle driven across the slay into a similar box at the other side.
When a new shed has been formed by the healds it is driven back again.
A smooth pick is most desirable, and for this reason the stud on the
picking shaft must be set so as to receive a smooth _side_ blow from
the plate, neither a downward nor an upward one. This is a point in the
tackling of looms which receives the attention of every good overlooker.
The shuttle used in the ordinary classes of cotton goods is of box or
some other heavy wood pointed and tipped at each end with iron. The
usual length is about 13 inches and depth 1-3/8 inch. Care must be
taken that it is smooth at all parts where it comes in contact with the
twist, free from knots or other flaws, which, should they give, would
make havoc among the threads.
The weft is in cop form, and fits on a peg inside the shuttle, the
loose end from the cop nose being drawn through the shuttle eye by
a strong inhalation of air by the weaver. To prevent excessive waste
the manufacturer should obtain yarn well copped, the cops hard, free
from nicked places caused by the minder having his ends down; clear
apertures at the bottom of the cop, which should also be free from
backlashing--that is, ends hanging slackly below and over-lapping those
previously wound on. Weft cops, or pin cops, should be five inches
in length, and as thick as the shuttle will admit of. Weft yarn is
selected according to its evenness, good cover or nap, and cleanliness.
BEATING UP.
The shot or pick of weft often being put through the shed, is at a
distance of five inches from the woven cloth, and requires pushing
up into close contact with it. The motion of the slay performs this
operation. As explained on page 60, the slay is a beam of wood carrying
a reed, and having a reciprocating motion to and from the fell of
the cloth, imparted to it by the cranks on the shaft (Figs. 22 and
43.) The beam is supported on two vertical rods, called slay swords,
attached near the bottom of the loom to a vibrating or “rocking” shaft.
The slay is away from the cloth or front centre a sufficient time to
give opportunity for the propulsion of the shuttle through the shed.
Were the crank-shaft at the same level as the slay-sword pin, the
dwell at each end of the stroke would be exactly equal--a dwell of
some duration, however slight, it is obvious, there must be. However,
the centre of the crank-shaft is at a lower level than that of the
connection of the crank-arm with the slay-sword ears, and thus the slay
dwells longer at the healds than at the cloth. As the slay makes some
200 strokes per minute, the variations of speed at the back and front
centres are scarcely observable, but by means of exact measurements a
certain amount of dwell may be traced at the back centre.
By describing a circle to represent the movement of the crank, and at
a distance from it drawing to scale an arc of a circle to represent
the movement of the slay, we can prove the foregoing remarks. In Fig.
24 the circle referred to is shown, and also the line A E representing
the stroke of the slay. By observing the position of the ends of
the connecting rod E^1, when in contact with the circle at the back
centre, and also when the slay is at front centre, we find that it has
travelled over from E^1 to A^1, which is more than half of the circle.
Then assuming that the crank-shaft runs at one even speed, we would say
that the slay takes longer time going forward than coming back. Again,
by measuring the movement of the slay from A to B at the front, and
from D to E at the back, these parts are found of equal length, but
by extending from these points our crank-arm of equal length in every
case, we find that to move the slay from B to A and back occupies a
space on the circle from B to B^1, while to move the slay from D to
E and back occupies a space from D^1 to D^1 obviously greater, from
which fact we assume that the slay occupies a longer time at the back
than at the front, an arrangement purposely contrived so as to get
theoretically a longer dwell. The difference between the arcs D^1 D^1
and B B^1 is approximately 15°. Calculating at 180 picks per minute,
we get the difference between the time of dwell at front and back to a
seventy-secondth part of a second--to a practical mind not a very great
consideration.
[Illustration: FIG. 24.]
The shuttle race is made of hard wood laid on the beam, and in addition
to the depression at the centre is also rather wider at the middle of
the race--at that point bulging out slightly against the reed, which is
kept in contact with it by the slay cap at the top and the reed case
at the bottom. Care must be taken to keep the ends of the reed from
projecting in front of backboard, or the shuttle will be thrown out.
LOOSE AND FAST REEDS.
To obtain a firm blow at the cloth the reed is made to strike it at
right angles, for if the angle were more obtuse or acute a loss of
force would be entailed by a consequent downward or upward stroke
imparted to the cloth, the line of action not being in the same plane
as the line of reaction.
With regard to the firmness of the beating up, we have to consider the
merits of fast and loose reed looms.
In weaving, an accident which not infrequently occurs is the stoppage
of the shuttle when it has only traversed a portion of the distance
across the warp. A case of this shuttle trapping causes the breakage
of more or fewer ends, and consequently arrangements are made for
preventing much damage, either by arresting the motion of the loom
suddenly, in case of a fast reed, or by having a reed hanging loosely
behind the shuttle so as to give way in case of a “mash.” The latter
arrangement is preferable, as there is not the sudden concussion given
to the loom, which causes the vibration and straining of every part,
so objectionable in the fast reed loom; the loose reed can, however,
only be used for light and medium cloths, as the reed is too lightly
fixed to give a strong beat-up. In the case of the loose reed, the slay
cap holds the upper part of the reed in a slot, the bottom part being
pressed against the shuttle race by a strip of wood (completing the
reed case) attached to the stop rod. When at the fell of the cloth, the
stop rod is held firmly by a spring, and a fairly strong blow can be
given to the cloth; but at all other portions of the slay’s movement
nothing holds the reed but a weak spring acting on the casing, and if
the shuttle traps, the reed flies out, while a finger on the stop rod
knocks the loom handle off, stopping the machine without unnecessary
concussion. This latter advantage enables the loose reed loom to be run
at a speed of some 30 or 40 revolutions more than the fast reed.
[Illustration: FIG. 25.]
_Fast Reed Loom._--Here the loom is stopped suddenly in case of the
shuttle being stopped in the shed. From Fig. 25 the arrangement will
be understood. A swell attached to the shuttle box is placed so as to
project into it when the box is empty, and through an L-lever A drops a
catch so as to strike the frog B and arrest the motion of the slay. The
frog moves a short distance and puts the loom brake in action before
checking the motion of the slay. This is done by means of the rod C.
The catch is attached to the slay sword and rests on the lever A. When
the shuttle is in the box, and as the slay is on the top centre, the
protector rides above the frog about a quarter of an inch; it is only
when the shuttle has not landed in its place that the loom is stopped.
There is an arrangement for the swell to be released at the time
picking takes place, so as not to give unnecessary obstruction to the
shuttle.
TAKE-UP MOTION.
[Illustration: FIG. 26.]
Among cotton looms the positive take-up motion is generally used. The
cloth as woven is, by this arrangement, drawn on the cloth roller a
certain distance at every pick, the amount of take-up being regulated
by wheels. Fig. 26 shows a sketch of the arrangement. The construction
is similar for almost all looms, but there are different gears and
sizes of wheels used. In Dickinson’s gear the rack wheel of 50 teeth
receives its motion from a pawl, worked by one of the slay swords. On
the same stud is the change wheel: this gears with the stud wheel, 100
teeth, firmly connected with the pinion of 12 teeth, driving the beam
wheel 75. The beam or sand roller is 15 inches in circumference, and is
covered with glued sand, perforated tin, or some pointed substance, to
hold the cloth firmly. The fabric is wound on the cloth roller below
this by means of contact with the sand roller. The change wheel is
varied to give changes of picks in the cloth, a larger wheel giving
fewer picks in the quarter inch. Each gear has a constant number
associated with it, called a dividend. If the number of teeth in the
change wheel be divided into this dividend, it gives the picks in a
quarter inch of cloth. Imagining that a change wheel, having the effect
of only one tooth in a revolution, could be applied, then the dividend
is the number of picks that the loom would run before the sand roller
advanced a quarter of an inch. Suppose 528 dividend is taken, this
represents a change wheel supposed to have one tooth. If a wheel of
66 teeth be put on, only 1/66 as many picks to the quarter will be
inserted--_i.e._, 528/66 = 8 picks.
The method of obtaining the dividend for any ordinary gear is--
(Rack wheel × Carrier wheel × Beam wheel)/
(Pinion wheel × number of 1/4 inches in circumference of taking-up roller)
afterwards adding 1-1/2 per cent. for shrinkage of the cloth after
being released from the tension of the loom.
Thus, Dickinson’s gear is--
(50 × 75 × 100)/(12 × 60) = 520.
Add 1-1/2 per cent. = 7.8
-----
Dividend 527.8
The principal gears in use in Lancashire are:--
+------------------------+------+-------+-------+------+--------+-----+
| | | Stud | | |Circumf.| |
| | Rack | and | | Beam |Take-up | |
| |Wheel.|Carrier|Pinion.|Wheel.|Roller. |Divi-|
| | | Wheel.| | | |dend.|
+------------------------+------+-------+-------+------+--------+-----+
|J. Harrison & Sons, now}| | | | | | |
| J. Dugdale & Sons }| 50 | 100 | 12 | 75 | 15 | 528 |
| | | | | | | |
|H. Livesey & Co. }| | | | | | |
|Willan & Mills }| | | | | | |
|J. Dugdale & Sons }| 50 | 120 | 15 | 75 | 15 | 507 |
|J. & R. Shorrock }| | | | | | |
| | | | | | | |
|Butterworth & Dickinson | 50 | 100 | 12 | 75 | 15 | 528 |
|W. Dickinson & Sons | 50 | 120 | 15 | 75 | 15 | 507 |
|Geo. Keighley | 50 | 140 | 15 | 78 | 14-1/2 | 637 |
|Pickles | 24 | 89 | 15 | 90 | 15 | -- |
+------------------------+------+-------+-------+------+--------+-----+
Pickles’ gear also has a swing pinion 24, and 2 change wheels; to find
the change wheel required, multiply the change wheel on the rack stud
by the picks per quarter inch, and divide by 9--
Equal to 4 teeth per pick for a 36 change wheel.
" 3 " " " 27 " "
" 2 " " " 18 " "
By using this motion, which is shown on Fig. 23, both heavy and light
pick cloth can be woven without a great variation in the wheels.
To weave heavy pick cloth with, say, the first-named motion, the rack
wheel might be increased to 60 from 50, and the dividend would then be
634.
In some looms a letting-off motion works in conjunction with the
take-up, to release the yarn on the beam at a fixed rate.
THE WEFT STOP MOTION.
A reference to the invention of this very ingenious and useful
apparatus is made in Chapter I. Its object is to stop the loom on the
breakage of the weft, or when the cop is finished. Unsightly gaws or
goals in the fabric are thus prevented, and the weaver enabled to
attend to more looms. A lever is fixed to the breast beam (Fig. 27),
hinged at one end, and arranged so as to rest against the starting
handle E. The lever carries a bent fork C, which projects into a grid
D in the slay at the moment that the crank is at the fore centre. The
grid is let into the back board of the slay between the reed and the
shuttle box at the starting side of the loom. On the tappet shaft is
fixed a projecting cam or sector, raising one end of a bent lever C,
the lower part of which is called the greyhound tail, and the upper
part, which ends above the breast-plate, from its peculiar form is
dubbed the hammer. The fork before referred to is balanced, and its
back end hooked and resting on the hammer.
[Illustration: FIG. 27.]
When there is weft in the loom the fork is prevented by the thread from
passing through the grid, and its back part is thus lifted clear of the
hammer. Should the weft be broken, the loom is stopped thus: The sector
raises the greyhound tail at the moment that the slay is at the fore
centre, and there being no weft to raise the fork, it is caught by the
hammer, and the lever to which the fork is attached pulled forward,
when, as previously referred to, the spring handle is released and the
loom stops. Manifestly the motion must be set so as to act when the
shuttle is at the fork side of the loom.
THE BRAKE.
A good brake contributes greatly to the manufacture of even cloth;
should the stopping arrangements be ineffective, thin places and
cracks will be inconveniently numerous. Usually the brake is a simple
lever acting on a brake pulley at one end, whilst at the other it is
regulated by an inclined bracket connected with the starting handle.
When the handle is pushed forward, the brake lever is lifted; when
the knocking-off takes place the end of the brake lever drops and the
leathers come in contact with the pulley, stopping the loom. Additional
brake power may be made by altering the leathers or weighting the brake
lever.
TEMPLE ROLLERS.
The cloth as it is woven tends to contract in width in consequence of
the tension at which it is wrought lengthway, and to counteract this,
temple rollers are used. For commoner heavy fabrics the roller and
trough is used, and consists of a fluted roller cut in the manner of
a screw at either end, one end with left-hand thread and the opposite
end a right-hand. Thus a spiral row of points is left at each end of
the roller, and it is fixed in the loom, so that as the roller revolves
the points distend the cloth. The roller is fixed in a trough for
convenience in attaching to framework. Lighter fabrics are woven with
side temples. These are small rollers acting only for a distance of 3
to 4 inches at the selvages of the cloth. Two pairs are usually used
at each side, the contrary-thread spiral arrangement being preserved;
a bar of iron connects the two sides. In the latter arrangement the
weaver can see the cloth from the moment it is woven, which is not
possible with the roller and trough, as some two inches are hidden
under the roller: the cloth is not held so firmly at the middle of its
width.
TIMING.
All the contrivances just described are required to work harmoniously
in order to produce the desired results, each coming into action at
the proper time. In plain cloth weaving, when the crank is at the fore
centre, the reed touches the cloth at right angles, and the healds
are slightly open, forming a new shed. As the slay moves backwards
just in front of the bottom centre, the picking band is tight and just
commencing to move the shuttle. At this point the healds are full open
and remain so until the crank has passed the back centre, when, as the
shuttle has arrived in the opposite box, the shed begins to close.
Before the slay has reached the front again, indeed when just past the
top centre, the healds are level; an advantage is thus gained in having
the rods crossed on the weft at the time it is beaten up, holding it
firmly. The sector lifts the greyhound tail for the weft stop motion
at the moment that the reed touches the cloth, when the fork would be
lifted if there were weft in the loom. This only happens, of course,
every alternate pick, when the shuttle is at the fork side of the slay.
Generally the monkey tail on the slay sword moves the take-up pawl
as the slay moves back, just dropping the holding catch as the crank
reaches the back centre.
The reed is held tightly in a loose reed loom when the slay approaches
the front. Of course, the timing of the motion varies under different
circumstances; if cloth is being woven as wide as the loom will
possibly admit of, or if the shuttle boxes be short, then picking
necessarily must take place later, as the shuttle starts so close to
the cloth; consequently, shedding must be later or the shed will close
before the shuttle is through. Of course in this case the pick must
be stronger, as the shuttle has more friction in its traverse. Other
circumstances also affect the timing.
THE POSITION AND FIXING OF THE LOOMS.
In a weaving shed the looms are driven from shafting running parallel
to the looms when looked at lengthway. Drums on the line shafts drive
the loom pulleys by means of straps. Of these pulleys there are two,
generally about 9 inches diameter for a 40-inch loom. One pulley is
loose on the shaft, the other keyed to it--the former to carry the
strap when the loom is stopped. The looms are in groups of four, with
an occasional row of couples for two or three loom weavers. The four
arrangement is adopted for convenience to the weaver, as the looms
having the starting ends contiguous, he has little walking for the
purpose of setting on the machines. Thus, two “hands” of loom are
required, those with the starting handle at the right-hand side being
named right-hand looms, and _vice versâ_. There is little difference in
construction--the crank-shaft is longer in one than the other for the
purpose of having two straps on one driving drum. Many parts, such as
crank-shafts, slays, shuttles, forks, brackets, etc., are required to
be of two “hands,” each for its own hand of loom.
In view of a case of having to remove looms or fix new ones, a few
remarks on the general arrangements for fixing them may not be
unacceptable. The line shaft runs over the space between the warp beams
of the looms. A line must be marked on the floor with chisel or other
convenient instrument parallel to this shaft and exactly below it. By
dropping a plumbline from various parts of the shaft, the starting
points can be obtained for stretching a line to mark from. The same
arrangement is adopted at every third shaft, as the intermediate ones
may be measured. From these lines the distance at which the loom feet
are to stand may be measured, just leaving convenient space for getting
between two full beams in each loom.
The ends of the loom must be set parallel also, so that on looking
down the shop a straight row of machinery will be observed. A line for
setting the outside loom feet may be measured from the pillars, after
getting the first pair of looms in suitable position. To test the
accuracy of these measurements, the breast beam of each loom, as fixed,
must be examined in a line with the breast beam of the previously
deposited one. After the correct position is obtained, each loom must
be levelled up by thin sheets of wood packing placed under the feet as
required. Holes are then drilled in the floor, wood pegs inserted, and
long iron nails driven home.
A good passage round each group of four looms cannot be too greatly
valued, and likewise a broad alley here and there running the whole
length of the shed.
LOOM TACKLING.
A loom requires a considerable amount of repairs and renewals, the
performance of which is delegated to an overlooker (sometimes called a
tackler or tuner) placed over each hundred looms. If on fancy goods,
fewer looms are under the control of one man; if plain narrow goods are
woven, more. His work is to keep the looms supplied with warps, gait
them up, repair or tackle the loom when necessary, provide weavers,
and, especially in a small place, perform rather multifarious duties.
When the weavers’ beam has been placed in the loom, having the healds
and reeds attached to the warp, the overlooker draws the gears forward,
placing a weight rope or chain round one beam ruffle, and, if a loomed
beam, fixes the reed. The healds are slung loosely to the heald roller
straps, and then the twist attached to the sand roller. If old healds
are used, the lap end of a former cut is placed on the roller, and the
warp tightened. If new healds have had the warp _drawn in_, a lap end
is attached to the roller and the twist tied to it, care being taken to
draw up any ends which may be ruffled. The temple is fixed so as to
revolve in the direction required to distend the cloth. Then with the
cranks near the top centre, the healds are levelled by means of the
cords below being attached to the lambs and treadles. After a little
manœuvring so as to make the shed _bottom_ nicely, whichever heald is
down, to get the healds level all across, and clear of any obstruction
or drooping ends, the lease rods are put in. The second and back healds
are raised when the back rod has to be put through the front, the third
being up for the thin rod. A few picks of weft being put through by
hand, a start is made after finishing the weighting of the beam and
changing the pinion, if necessary. The weighting is somewhat important;
for light cloths, fine yarns and light picks less weight is required
than for the heavier classes of goods. More weight is required for full
beams and under certain other conditions.
It is impossible to enumerate all the little points in the management
of looms, which it is the overlooker’s duty to perform; and only long
practical experience can teach their proper performance. However,
neglecting the derangements, which cause faults in the cloth, and
which will be treated of in the next chapter, we will refer to some
of the commoner mishaps. The shuttle flying out of the loom is caused
generally by some obstruction in the shed, floats, projecting reed,
top of shed too low or bottom too high, or by a crooked spindle or bad
picker. Cops flying off the shuttle peg may be attributed to too large
holes in the cop, or shuttle spring too weak or unpacked. When the
loom does not knock off when the weft is done, the fork may be bent
and thus lifted by grate, an end of weft may be hanging to the shuttle
sufficiently long to catch in the cloth and lift the fork. But for
the cause of this, and also of the loom knocking off when weft is not
broken, the weft stop-motion must be carefully watched. The picking
may sometimes be so strong as to throw the shuttle out of the loom, or
so weak as to allow it to be trapped by the closing shed. By judicious
setting of plate and bowls, any desired result may be obtained.
When by the shuttle binding too tightly in the box, etc., a fracture of
the weft is made, it is said to be “cut.”
THE WEAVERS.
The average weaver runs four looms, but in many sheds provision is
made for three, or even two-loom weavers, whilst qualifying themselves
for the higher number. In some North-East Lancashire towns five and
six-loom weavers are not infrequent on narrow strong goods. The
weaver’s duties require some little skill, and consist of piecing up
the broken ends of warp and drawing them through the heald and reeds,
filling the shuttles with weft and placing them in the loom as those in
working become empty, oiling, doffing “cuts,” putting in the coloured
headings--an important part of dhooty weaving--oiling, and performing
simple repairs.
The wages obtainable on ordinary goods, such as shirtings and printers,
should not be less than 11s. per pair, to give satisfactory results,
while 12s. 6d. per pair on dhooties and simplest fancy goods is good.
The waste in this process is important, four per cent. being allowable
on common yarns, say 36’s, this being reduced on finer and consequently
better copped yarns (weft).
The foregoing remarks apply to the weaving of plain cloths only, and
that by the most usual methods. In any process whatever, it may be that
some variation will be found to exist, and, before concluding this part
of the subject, the modifications of the one standard type of loom may
be referred to.
In shedding, the tappets may sometimes be placed on a third shaft,
driven from the tappet shaft, and termed a twill shaft, because by
altering the tappets and the speed the loom may be made available for
weaving twills. When the tappets are fixed to the twill shaft they are
smaller than those fixed to the tappet shaft.
SETTING OUT TAPPET.
The setting out of a tappet is an important problem. Two circles
must be described round the same centre, the difference in the radii
being the stroke of the tappet--thus, say A B or C D in Fig. 28 is
3-1/2 inches, then that is the stroke of the tappet. This is also the
radius of the smaller circle. The large circle must now be apportioned
according to the number of picks to the round in plain cloth, say
two. The circle is then divided into two parts by E F. Suppose we
wish the healds to be still during two-thirds of a revolution of the
crank-shaft, then as E A F represents a whole revolution, divide it
into six parts where marked, place four of these parts from G to H for
the dwell, and leave E G to form part of the lifting, and F H part of
the depression of the healds.
[Illustration: FIG. 28.]
The movement of the rising healds commences, however, before the
falling heald has come to a pause; therefore we must trespass into the
lower half to an extent equal to E G and H F, thus obtaining by drawing
a diameter through G and the centre, also through H and the centre,
the parts G J and H K for the rise and fall respectively. Divide C
J now into six parts by radii to the centre, also divide by arcs of
circles transversely, to these radii, the space between the small and
large circles into six parts, then by drawing a line diagonally through
the figures thus formed, we get a line G M giving an easy fall from the
large circle to the small one, and by similar treatment a rise on the
opposite side from N to H.
This is the theoretical construction of a plain tappet, from M to N
being the dwell from the heald when up. N to H the depression, and H
to G the dwell for the heald when down; and it will be noted, that
although G H is apparently larger than N M, the time of dwell is the
same in each case, in consequence of the arc N M being so much nearer
the centre. In practice, the hollows N and M may be found rather fuller
than shown here. This method of construction applies to tappets with
an increased number of picks to the round, a point which will be found
described in Chapter VI.
The speed of tappets is an important subject for calculation in
connection with the loom. When the tappets are on the tappet shaft they
are always plain, and are driven at half the speed of the crank-shaft,
in consequence of the latter shaft only representing one pick, while
the tappet shaft,[3] carrying two picking plates, represents two
picks. Should the tappets be on the twill shaft, and driven from the
tappet shaft, then the calculation is simple--_e.g._, say four picks
to the round are required, then the crank-shaft must revolve four
times for the twill shaft once. The tappet shaft must revolve half as
many times as the crank-shaft--that is, twice--and the ratio between
the speeds is as 2 to 1, which is also the ratio of the wheels, say
16 and 32, or 20 and 40, the larger wheel being on the twill shaft.
In this case the rule is to divide the number of picks to the round
by 2, which will give the ratio of the wheels gearing the tappet and
twill shafts. Occasionally, the shaft carrying the tappets is driven
from the crank-shaft direct, and the ratio of the gearing will be
as one is to the number of picks to the round--say 6 picks to the
round--then such a pair as 12 and 72, or 15 and 90, will be required.
Obviously, for a large number of picks, an intermediate pair would have
to be inserted--say 13 picks to the round must be woven, the wheel on
the crank-shaft being 25 and the last wheel on the same shaft as the
tappets is 65. Then, to get the size of the pair of intermediate wheels
on the stud, multiply 13 by 25 and divide by 65, which will give the
ratio of the size of the two wheels:--
(13 × 25)/65 = 325/65 = 65/13
These, or a multiple of these, are the wheels required, which may be
proved:--
(65 × 65)/(25 × 13) = 13 picks to a round.
[3] The term tappet shaft is used here in the sense understood in North
Lancashire--_i.e._, the shaft driven from the crank-shaft and carrying
the picking plates and tappets if plain.
SPLIT CLOTHS AND MOTIONS.
Split cloths are sometimes woven in the ordinary loom when narrow
widths are required and a perfect selvage is not a necessity. Thus, a
40-inch loom may weave a cloth with a few empty dents at the centre,
whilst on each side of the space thus caused the warp threads are
crossed (on the gauze principle) between each pick to make a firmer
selvage than could be got by ordinary lifting. The weft threads are
then slit along this space by a sharp knife, giving two cloths, each 20
inches wide. One system of forming the selvage is by having an extra
loop attached to the top stave of one heald, and carrying a thread
which is drawn through the other heald. By correct drafting this thread
can be made to lift at every pick first on one side of its neighbouring
warp thread and then on the other.
The same object is attained in a split motion, patented by J. & R.
Shorrock, and Taylor, of Darwen. By means of eyeletted straps revolving
round a tightened warp thread, the doup or crossing threads drawn
through the eyelets make a very firm selvage when slit.
The picking motions require a few further remarks. For some goods,
especially fancies, the under pick is used. In this case the picking
stick is rather longer than the slay sword, and is fixed parallel to
it, projecting from the rocking shaft through the shuttle box and
picker. The loom, Plate VII., possesses the under-pick arrangement. It
is driven by means of the picking plate acting _downwards_ on a lever
centred at one end, whilst carrying at the other end a strap fixed to
the picking stick about four or five inches from the bottom end of it.
The scroll or side pick is a favourite one for velvet looms. The
picking plates are fixed on the _crank_-shaft, and consist simply of
a disc of metal carrying a lug so as to catch against a latch or lug
on a short inclined shaft at the loom side. This shaft at the bottom
end actuates by means of a strap and picking stick fixed as in the
under-pick loom. Obviously, the picking from each side of the loom must
be done alternately, and the plates at the loom side are arranged so
as to act only once in two revolutions of the crank-shaft. This motion
is obtained by means of a scroll plate on the crank-shaft carrying a
groove forming an inner and outer ring in the plate; in this works a
slide in the inner ring for one pick, then traversing the outer part of
the groove for the second pick. This slide regulates the latch on the
short shaft. When in the outer ring the latch is lowered so as to be
caught by the lug on the picking plate, but is out of the way when the
sliding piece is in the inner ring. Of course, when the slide is in the
inner part of the groove at the right-hand side of the loom, the slide
of the left-hand picking scroll is in the outer ring, so as to pick
alternately. This picking arrangement is very compact.
[Illustration: PLATE VI.--SHEDDING MOTIONS. _To face p. 79._]
SPEEDS.--AVERAGE SPEED OF NEW LOOMS.
Reed Space. Picks per Minute. If Double Cylinder
Plain. If Dobbied. If Drop Boxes. Jacquard.
32 inches 240 190 190 190
44 " 200 175 175 175
54 " 180 160 160 160
66 " 150 150 150 150
On goods with ordinary headings, the stoppages for changing shuttles,
piecing ends, etc., should not be more than one minute in twelve, or 8
per cent.
REED SPACE.
The reed space of a loom is measured from backboard on the one side
to the fork grate on the other. Thus, what is called a 40-inch loom
measures 45 inches reed space, and in it it is usual to weave cloth up
to 41 inches wide, although it is possible to weave 42-1/4-inch cloth
in it. A 26-inch loom has a 30-inch reed space, and will weave to 28
inches. In wider looms the reed space is about six inches above the
nominal size of the loom.
TOP MOTIONS.
In Plate VI. are shown a number of top motions to keep the healds tight
when worked from below. Each is self-explanatory, and by imagining the
effect of changing the heald or healds which are up for others, the
value of each arrangement will be seen. For example--take H, a 3-shaft
motion, two up. If No. 2 be required up and No. 3 down, the change
is made without any movement of the top pulley; if No. 1 be required
down and the other two up, it will be drawn down a distance equal to
the size of the shed--say 2 inches; whilst the small pulley being
connected to a step pulley on the larger one, is only lifted half that
distance--say 1 inch. Now, if the small one be raised 1 inch and No. 3
heald be kept still, No. 2 heald will lift 2 inches--the height desired.
It will be noted that a top motion is adapted only for one number of
healds, and that the same number must be up in successive picks. Should
different numbers be up at consecutive picks, a spring top as at S is
used.