THE MULE.
(264) The last process in the production of yarn is that in which the
rovings, obtained in the manner described, are elongated and twisted
into a thread. To many persons this is known as “spinning,” although
strictly speaking, that phrase is applicable to the whole range of
treatment by which cotton is converted into yarn. Using the term,
however, in its narrower sense, spinning may be either an intermittent
or continuous operation, that is, the rovings can be twisted for a
portion of the time only during which the machine is working, or for
the whole of that period. Although the latter system is the most
ancient, for the last century the former has been more generally
pursued. It is, therefore, advisable to describe first the machine by
which it is carried out.
(265) This is known as the “mule,” and owing to the practical
automaticity of its mechanism, as the “self-acting” mule or “self
actor.” It is without exception the most interesting of the whole
series of machines used in cotton manufacture, combining an intricate
sequence of mechanical movements with great ingenuity. As a further
consideration will show, one piece or part of the mechanism used
performs work widely diverse in its character at different periods,
and it is this fact which renders the mule so difficult a machine to
understand. The time occupied in completing the cycle of operations
which constitute mule spinning is so small that the action of the
various parts must be very rapid and certain. In order to understand
the description which follows, it will be advisable to define the
stages or periods which succeed each other and form the entire process.
(266) In order to facilitate the grasp of the subject by the reader,
it will be better to describe first and briefly the essential or
primary parts of the machine. These are shown in Fig. 148, which is a
purely diagrammatic representation. The roving bobbins =A= are fitted
on a skewer and placed in the frame or creel arranged at the back of
the machine, being held in an almost vertical position. The roving
=R= is guided as shown to the nip of triple lines of drawing rollers
=B B B=. From the rollers the roving passes to the tip or point of a
steel spindle =H=, sustained by an upper bearing or bolster =O=, and
a footstep =N=. These are fixed in wooden rails which form part of
a box or frame =I=, known as the “carriage.” The carriage is fitted
at convenient distances along its length, with cross brackets, in
each end of which bearings are formed for the axes of the pulleys
or runners =P=. These rest upon the edges of oblong iron bars or
“slips” =Q=, which are securely fastened to the floor of the room. The
spindle receives a rapid rotary motion, being driven by a band =M=,
carried tightly round a small =V= grooved pulley or “warve” fixed on
the spindle, and a light roller =K= extending longitudinally of the
carriage, and fastened on a shaft =T=. The roller—or more correctly the
“tin roller”—=K= is suitably driven, and, it will be easily understood
that the direction and velocity of =H= will depend upon those of
=K=. In its passage to the spindle the roving is taken under a small
guide wire =D=—known as the “faller wire” or shortly the winding
“faller”—fastened on the outer end of a curved arm or “sickle” secured
on the shaft =F=—known as the “faller shaft.” The roving also passes
over a second wire =C=—called the “counter faller”—which is fixed in
a similarly shaped arm fastened on the “counter faller shaft” =E=. By
the oscillation of the shafts =E F=, the winding faller and counter
faller are elevated or depressed, thus enabling the finished yarn to be
wound into the spool or “cop” =G=, which is made of the shape shown.
The above form the essential portions of a mule and their respective
functions can now be explained.
(267) The rollers =B= perform the same office as those used in the
drawing and roving machines, namely, the attenuation and delivery of
the roving. Each of the three lines revolve at different velocities,
that of the front line being the superior one, with the result that
roving which, as was shown, has been already considerably reduced in
diameter is still further attenuated prior to being twisted.
(268) The roving is wrapped round the spindle two or three times in
commencing operations, being sometimes rendered adhesive by paste, and
sometimes wrapped on a paper tube placed on the spindle. Being thus
held at one end by the spindle, and at the other by the nip of the
front rollers, the rotation of the former will necessarily further
twist the partially twisted roving. On the degree of twist—that is the
number of turns per inch—depends the amount of roving delivered by the
rollers in a given time, as explained in paragraph 234.
(269) In the roving machines the relative positions of the spindle
and front rollers are fixed, but in the mule an important variation
in this practice occurs. The carriage I receives by suitably arranged
mechanism an alternate movement from and towards the roller =B=. During
the period they are delivering roving it is drawn away from them until
it has travelled about 63 inches, when its motion ceases. While this
traverse is taking place the spindles are revolving, and twist is
therefore being introduced into the roving. The cessation of the motion
of the carriage is accompanied by a similar stoppage of the rollers
and spindles, and there is then a number of lengths of yarn—each 63
inches—held in tension by them. This traverse of the carriage is called
its “stretch” or “draw.”
(270) The yarn, as thus spun, requires winding upon the spindle, so as
to form the cop, but before doing this it is necessary to free two or
three turns which are wrapped on the spindle between its point and the
point or “nose” of the cop. This operation is called “backing off.” In
order to effect it the roller =K= has its motion reversed for a short
time, so as to give the necessary backward rotation to the spindles.
The slack yarn thus produced is taken up, first, by the ascent of the
counter faller, and, second, by the descent of the winding faller. The
former rises sufficiently to preserve the tension of the yarn as it is
freed, and the latter is drawn down so as to assume a proper position
to commence winding when the operation of backing off is completed.
(271) As soon as this stage is finished the inward traverse of the
carriage =I= commences, an operation which is accompanied by the
forward revolution of the spindles, which thus wrap or “wind” on to
the cop the 63 inches of twisted yarn. The rollers during winding are,
of course, stationary. By the time the carriage has again reached its
innermost point the full length of yarn is wound, and during that
period the faller has risen from the base of the upper cone of the cop
to its nose. This ascent is a gradual one, and causes the yarn to be
wound in finely pitched spiral coils upon the cop. With the termination
of the inward traverse or “run” of the carriage winding ceases, the
winding faller and counter faller wires are released, and the whole of
the operations begin anew.
(272) It is now possible to define the various stages in the whole
process of mule spinning. These are as follows:—
First. The period during which roving is being delivered and twisted.
During it, the rollers are revolving at a defined speed; the carriage
is being drawn outwards at a constant rate; the spindles are revolving
rapidly at a velocity definitely relative to that of the front roller.
During this period the faller and counter faller are held in the
position shown in Fig. 148, being quite clear of the yarn.
[Illustration: FIG. 148. J.N.]
Second. The period during which the movements just named are stopped.
The roller driving gear is detached; the mechanism by which the
carriage is drawn out is stopped; the spindles are stopped because
of the transfer of the driving strap to the loose pulley and the
consequent cessation of the motion of the driving band; and preparation
for the engagement of the faller and counter-faller with the yarn takes
place.
Third. This is the period of “backing-off.” During it the driving band
is driven in the contrary direction to its normal one, and the spindles
are reversed. The faller wire is drawn down, depressing the yarn; the
yarn between the nose of the cop and spindle point is uncoiled; the
counter faller rises and takes up the slack yarn; and the faller is
“locked.”
Fourth. During this period “winding” takes place. The rollers are
stationary; the carriage is “running in” at a variable speed; the
spindles are revolving in the same direction as when twisting; and the
winding faller is operated so as to guide the yarn on the cop.
Fifth. The carriage comes to rest; the faller and counter faller are
released; the roller driving gear is re-engaged; the strap is moved on
to the fast pulley and the driving band put in motion; and the drawing
out gear is again engaged.
With this the cycle of movements is completed, and the whole of the
operations begin anew.
(273) There are thus five periods, viz., 1st, twisting; 2nd,
arrestation; 3rd, backing-off; 4th, winding; and 5th, re-engagement. In
addition to these, when fine yarns are spun, there is sometimes a sixth
period, which takes place immediately after the termination of the
first as at present defined. This is a period of supplementary twisting
after the rollers have stopped. This operation is sometimes known as
“twisting at the head,” and will be dealt with at a later stage.
(274) It is thus indicated that at various times one part of the
mechanism performs different functions. The rollers revolve for the
whole or part of the first period and remain stationary afterwards. The
spindles revolve at a constant and maximum velocity in their normal
direction during the first period, at a slower but constant velocity
in the reverse direction during the third period, and at a variable
speed in their normal direction during the fourth stage. The carriage
makes its outward run at a regular speed during the first period, is at
rest during the second and third, and makes its inward traverse at a
variable speed during the fourth. The winding faller remains stationary
and free from contact with the yarn until the third period, when it
makes a rapid descent to the winding point, after which it first
descends quickly to its lowest point, and then ascends slowly to the
nose of the cop during the fourth. The counter faller remains below and
out of contact with the thread during the first and second periods, and
ascends during the third, remaining in contact with and sustaining the
yarn until the termination of the fourth.
(275) This preliminary explanation will enable the detailed description
following to be more easily understood and appreciated. As there are
many variations in the construction of the mule it is desirable to
select one of the most widely used, and for this reason the machine
constructed by Messrs. Platt Brothers and Co. has been chosen for
description. Front and back perspective views of the machine are given
in Figs. 149 and 150. The Parr-Curtis mule is also largely employed,
and many modifications of it exist. All the root principles which are
contained in the machine are, however, found in the Platt machine. That
is to say, it contains mechanism founded upon certain rules which are
essential to all mules, so that, although the details may be, and are,
varied, the main features are identical. A detailed description of its
mechanism, therefore, will enable the subject to be fully understood,
but, at the close of the chapter, particulars will be given of special
features in other makers’ machines. To enable the construction of the
machine to be more fully grasped, a series of diagrammatic views are
given of each motion separately, and the reference letters are arranged
so that each part is marked with the same letter in all the views in
which it occurs, although the same letter, in some cases, refers to
various parts in different diagrams.
[Illustration: FIG. 151. J.N.]
(276) It may be first explained that the greater number of the parts
by means of which the required motion is given to the various portions
of the mechanism are contained in a longitudinal framing placed in
the centre of the machine, this part of the mule being called the
“headstock.” At right angles to the headstock, and at each side of it,
the rollers and carriages extend for the entire length of the machine.
The arrangement of a “pair” of mules is clearly shown in Fig. 151,
the machines being usually placed with their headstocks zig-zag to
one another. The carriage of one mule is coming out while that of the
one opposite to it is at the roller beam, this arrangement permitting
the free movement of the workman attending to the machines, and
preventing the broken threads in each machine requiring piecing at the
same time. It might, perhaps, be explained that “piecing” is always
effected when the carriage is making the first part of the outward
run, so that some inconvenience would arise if both carriages were in
that position at the same time. A special motion is sometimes fitted
by which each carriage is released alternately by the movement of the
carriage opposite to it. Referring now to Fig. 151, =H= represents the
headstocks of the two mules, =E= the lines of rollers, =F= the end
frames, and =O= the carriages. It will be noticed that the headstock
divides the machine into two portions of unequal length, each of which
contains its own rollers and spindles. The special object of this is to
enable the mules to be placed in closer proximity than could be done
if both sides were of the same length, and the headstocks were placed
quite opposite to each other.
(277) The rollers are in three lines, and are borne in brackets or
stands fastened to longitudinal iron “roller beams,” sustained at
intervals by light frames or “spring pieces.” The lower lines of
rollers are finely fluted, and are made of the same superior quality
of iron as those used in the roving frames. Their diameter is usually
an inch, but this varies with the staple to be spun. The front line of
top rollers are generally of Leigh’s loose boss type, cloth and leather
covered, and are weighted by a saddle, stirrup, and lever weight. The
middle and back lines are “common rollers,” also covered in the same
manner. The front lines of the right and left-hand set in each mule are
coupled by a short shaft, and the second and third are driven from the
first.
[Illustration: FIG. 149.]
[Illustration: FIG. 150.]
(278) The carriage has a rectangular frame, being built with strong
longitudinal timbers, securely tied together by cross pieces. These
carry, as was shown, the bolster and footstep rails. On the cross
cast-iron “muntins” the bearings for the tinroller shafts are fastened.
The carriages at each side of the headstock are coupled by a strong
iron frame, to which they are securely fastened. This is known as the
“square,” and carries some of the mechanism for giving motion to the
spindles and building the cop.
(279) The tin roller is generally six inches in diameter, and consists
of a series of cylinders made from sheets of tinned iron, securely
soldered together. In each end of the rollers so formed an iron disc
is fastened, and the lengths are coupled by means of short shafts. The
whole of the lengths are thus connected, and a bearing is placed at
each junction, so that the tin roller is well sustained throughout.
The rollers in each of the two carriages are coupled by a short shaft,
extending across the square, and carried by means of pedestals, fixed
to the latter. On this short length of shaft the driven tin roller
pulley is secured, as will be hereafter fully described.
(280) The spindle is made of steel, and is from 13-1/2 to 18 inches
long, according to the class of material being dealt with. For coarse
counts and for “twist” yarn a larger cop is made, and the spindle is of
necessity longer. For 32’s twist yarn a spindle about 17 inches long
is used, and its diameter varies from 3/8ths inch to less than 1/8th
inch. The part between the two bearings is called the “haft,” and that
above the bolster—on which the cop is wound—the “blade.” The spindle
is thickest in the haft, terminating in a small foot, but the blade is
tapered throughout. Great care is taken with the spindles to ensure
their accuracy, and they can, therefore, be run at velocities as high
as 11,000 revolutions per minute without vibration. The extra diameter
of the haft ensures the necessary resistance to flexure caused by the
pull of the driving band. The latter is a thin cotton cord-made of the
best grades of cotton—passed tightly over the spindle warve and the
tin roller. It is highly important that the bands should not be either
too tight or too slack. In the one case the friction generated would
be excessive and detrimental, and in the other the twist would not be
fully put into the roving, which would be said to be “slack twisted.”
Varying atmospheric conditions materially alter the tension of the
bands, and their proper piecing is only to be mastered after long
practice. The spindle is disposed in the carriage at a varying angle,
to suit the material being spun.
(281) The description of the general construction of the machine thus
given clears the ground for the detailed explanation which follows.
For convenience it will be as well to begin by describing the mode of
obtaining the motion of the spindles. This is illustrated in Fig. 152,
which is a diagrammatic representation of the course of the bands and
driving pulleys. The mule is driven from the line shaft, or a counter
shaft by means of a strap passing over the pulley =A= fastened upon the
shaft =C=. The latter is termed the “rim shaft,” and upon it the loose
pulley =B= is also placed. Free to revolve and slide upon the same
shaft is the spur wheel =A^{1}=, formed with a large internal cone, the
exact object of which will be hereafter described. The fast pulley is
about 5 inches wide, and the loose pulley 5-1/4 inches, the diameter
being about 15 inches. Thus, when the strap is on the fast pulley it is
also partially on the loose pulley, which is always revolving. At the
other extremity of the rim shaft a double, treble, or quadruple grooved
pulley =C^{1}= is fixed, which is called the “rim.” Over this the
endless cord or band driving the spindles is passed—being known as the
“rim band”—its course being clearly shown by means of the arrows. It
will be noticed that it is first passed round a carrier pulley on the
carriage square, and then round the tin roller pulley on the tin roller
shaft =T=, being then taken round the carrier pulley =Y= fixed at the
end of the headstock frame, afterwards returning to the rim pulley. It
will, of course, be understood that the explanation just given relates
to the course of the rim band, considered as a single rope. When the
rim is double or treble grooved, corresponding arrangements must
necessarily be made in the rim band course. The rollers =E= are driven
from the rim shaft by the train of wheels and the side shaft =G= shown,
and the drawing out of the carriage is effected by the band passing
round the scrolls at =H= and round the pulley =Z=. This will be more
particularly described presently.
(282) Particular reference will now be made to Figs. 153 and 154,
which are respectively longitudinal sections of the driving gear and
back view of the same. The loose pulley =B= has formed upon its boss
a spur pinion =B^{1}=, from which, by means of a carrier wheel, the
side shaft =D= is driven. On the other end of this shaft a pinion
=D^{1}= is fixed, which gears with and constantly drives the spur
wheel =A^{1}=, this being the object of the overlapping of the driving
strap previously referred to. The wheel =A^{1}= is formed, as shown,
on its inner side with a large internal conical surface, which, at
the proper moment, engages with a corresponding leather-covered
surface formed on the pulley =A=. This engagement takes place for the
purpose of backing-off, and the cone =A^{1}= is therefore known as
the “backing-off cone” or “friction.” The engagement of the friction
cone with the fast pulley causes it first to act as a brake, and the
strap having been moved upon the loose pulley it then exerts sufficient
force to revolve the backing-off cone in the contrary direction. To
enable this contact to take place a ring groove is formed in the boss
of the backing-off wheel, in which a claw engages, which is oscillated
as afterwards described. The effect of this arrangement is that the
rotation from the loose pulley =B= of the friction wheel =A^{1}=,
whilst it is engaged with the fast pulley =A=, causes the rim shaft
to be rotated in the opposite direction to that normal to it. The
direction in which the various parts revolve normally is clearly shown
by the arrows. The extent of the backward movement of the rim shaft
depends, of course, entirely upon the length of time during which the
friction cone =A^{1}= is allowed to engage with that on the pulley =A=,
this being regulated by the amount of yarn to be unwound.
(283) The rollers =E= are driven from a pinion =G^{1}= fastened on the
rim shaft, by means of which the shaft =G= is revolved, and motion is
thus given to a bevel wheel loose upon the short shaft coupling the two
front lines of rollers. One half of a toothed or claw clutch is formed
on the boss of the wheel, the other half of which is secured to but
slides upon the coupling shaft, being formed with a ring groove on its
boss into which the two arms of a claw are fitted so as to engage and
disengage the clutch.
[Illustration: FIG. 152. J.N.]
[Illustration: FIGS. 153 AND 154. J.N.]
(284) On the boss of the bevel wheel is a spur wheel which, by means
of the train of wheels shown, communicates the forward movement to the
“back” shaft =H= on which are fixed the scrolls =H^{1}=. On these the
ropes or bands shown are wound, being attached to the carriage as shown
in Fig. 152. As the carriage extends to the right and left of the
headstock, as explained, the back shaft =H= is similarly extended, and
has placed upon it a number of scrolls at suitable distances apart, on
which other bands are wound. This enables the carriage to be evenly
drawn out throughout its entire length. The method of attaching the
bands to the end frames of the carriage is shown in Fig. 155, and it
will be seen that there is power of adjustment given, which enables
the carriage to be “squared” or kept parallel with the roller beam.
The last of the train of wheels =P^{1}=, by which the back shaft is
driven, is loose upon it, and forms one half of a clutch, the teeth of
which are peculiarly shaped. The other half =P= slides upon the boss
of a disc which is keyed upon the shaft, and has a ring groove in its
boss, being ordinarily pushed up to its position by a spiral spring
surrounding the back shaft and kept in compression by a stop hoop or
collar which can be set up as desired. This, combined with the peculiar
construction of the teeth, enables the clutch to open and its teeth to
glide over one another in the event of any obstruction being offered
to the free outward run of the carriage. The forked end of an =L=
lever fits in the groove in the clutch, being oscillated as afterwards
described.
[Illustration: FIG. 155.]
(285) The bevel wheel on the outer end of the taking-in side shaft
=D= gears with a similar one fixed on the upper end of the vertical
shaft =I=, on the lower end of which is loosely placed the friction
cone =K=. With the latter the hollow cone =I^{1}= engages, this being
able to slide in a vertical direction on a disc keyed to the shaft.
It is usually kept out of gear by means of a hinged forked lever,
the fork of which fits in the groove shown in =I^{1}=, and which is
sustained at its free end so that it can be readily released to allow
the sudden engagement of the friction cone. On the half cone =K=, at
its underside, is cast a small bevel pinion; which engages with a bevel
wheel =K^{1}= fixed on the shaft =L=, extending transversely of the
headstock at the back. Spirally grooved or “scroll” pulleys =L^{1}= are
fixed on the shaft =L=, on which ropes are wound, these being attached
to the carriage square as shown in Fig. 168, page 212. An additional
scroll is fitted on the shaft =L=, and is set at such an angle that
when the rope is fully drawn off the other scrolls it is wound on the
additional one. When the friction cone is in gear the ropes are wound
on to the scrolls, and the carriage is drawn in. From the fact that
these scrolls are employed, and that their object is to draw in the
carriage, the shaft =L= is called the “scroll” or “taking-in” shaft,
and the friction cone is commonly styled the “taking-in friction,” or,
more shortly, the “friction.”
(286) The means just described are those which are in use on a large
number of mules constructed by Messrs. Platt, and worked satisfactorily
until the speed of the rim shaft was largely increased. Up to about
750 revolutions the train of gearing driving the taking-in side shaft
could be used, but as the rim is now run at speeds as high as 900
revolutions it is the practice to drive the taking-in side shaft by
means of a grooved pulley fastened upon it, and driven by a separate
band from the counter shaft. In this way much of the strain is taken
from the rim shaft, and the use of gearing obviated for the taking-in
and backing-off. When this method is adopted—as is now almost generally
done—there are many advantages gained, and it is the most modern
practice.
(287) Another method of driving, also largely employed by Messrs.
Platt, is a patented system of duplex driving. This is shown in plan
in Fig. 157. Instead of using one belt only, by means of which the
power is transmitted, two narrower ones are employed, each of which is
2-3/4 inches wide. The fast pulleys =A= are also 2-3/4 inches on their
face, while the loose pulleys =B= are 3 inches wide. The strap guide
is made, as shown, double, and the distance which it has to traverse
is only half that which is usual. The advantages of this arrangement
are derived both from the smaller width of the belts, and the shorter
distance they need moving. The diminished width causes the belt to be
more pliable and less rigid, and in consequence the pressure applied is
more readily responded to. The shortened traverse enables the change of
the belts to be made more easily and in less time, and, in consequence
of the latter fact, the time the edges of the belts are pressed upon by
the guider is reduced. This reduction involves considerably less wear
of the strap edges, which, alike on this account and because of their
easier and less strained motion, are found to have a much longer life.
The smooth action of the belts produces another effect. It enables the
full speed of the rim shaft to be more readily reached, and so tends to
increase the production of the machine. The makers have now constructed
a large number of mules with this arrangement, and its use is steadily
extending.
(288) The mechanism just described is that on which depends the driving
of the whole of the parts, and its mode of action can now be easily
explained. Beginning with the commencement of the outward run, when the
rim band is traversing in its normal direction, the rollers commencing
to deliver yarn, and the spindles revolving, the position of the parts
is as follows. The strap is on the fast pulley, and the rim shaft is
revolving. The backing-off friction is out of gear, the necessary
motion is given to the roller shaft, and as the claw clutch is engaged
the front line of rollers is revolved, roving being delivered. At the
same time the back shaft is driven, the clutch on it being in gear, and
the carriage is drawn out. The scrolls on the back shaft are shaped
so as to allow the carriage to move at a constant velocity. While the
carriage is running out the rim band is giving the required revolution
to the tin roller shaft, and the spindles rotate in consequence at
their normal velocity. The carrier pulley on the square shown in Fig.
152 is arranged at such an angle that the rim band passes freely on
to and from the pulley on the tin roller shaft. A similarly accurate
setting is given to the guide pulleys at the back of the headstock,
the wear of the bands being much reduced in consequence. The velocity
given to the carriage is slightly in excess of that of the surface
speed of the rollers, so that the roving is a little stretched. The
excess of the carriage traverse is from 1 to 3 inches, and is known as
its “gain.”
(289) When the carriage reaches the termination of its outward run,
or, as is commonly said, the end of its stretch, it becomes necessary,
first to arrest and then to reverse its movement, these operations
necessitating a complete change in the positions of the various parts.
The chief agent in making these changes is the shaft =M=, placed
parallel to but a little higher than the rim shaft. It is known as
the “cam shaft,” and plays an important part in the operation of the
machine. It is entirely distinct both by position and function from the
rest of the mechanism, and a separate view of it and its connections is
given in Fig. 156, which is a detached sectional elevation.
(290) Hinged to one side of the headstock framing is the lever
=T=—known as the “long lever”—at each end of which pins are fastened,
which carry the bowls =R R^{1}=. Fastened to the carriage by bolts are
two horn brackets =S S^{1}=, to which power of adjustment is given.
The underside of the brackets is curved, and they are fixed at such a
height, that, as the carriage approaches either end of its run, one
of them will engage with the bowl or runner carried on a stud fixed
in the end of the long lever, as shown very clearly by the dotted
lines. At the outer end of the long lever, the bell crank lever =Q= is
pivoted, and is ordinarily drawn towards the end of the long lever by a
spiral spring =O=. In this way, when the latter has assumed a position
in consequence of the pressure of the horn brackets =S S^{1}=, the
pressure of =Q= upon it prevents it from moving until a similar force
is again applied. In short, the long lever is locked.
(291) On the cam shaft three cam or eccentric surfaces are placed,
marked respectively =W Y= and =Z=. These are shown with their
connections in detached views. The cam =W= is compounded with the male
half of the friction clutch =X=, and can slide along with the half
clutch upon a feather key fixed in the shaft. The other half of the
clutch is loose upon the shaft, and has formed upon its boss a spur
pinion which, as shown in Fig. 153, engages with the teeth of the
backing-off wheel =A^{1}=. Thus the continuous rotation of the latter
leads to a similar movement of =X=, and, as a consequence, the latter
is always in a state of readiness to rotate the cam shaft. A spiral
spring surrounds the cam shaft, being sunk into a recess in the bearing
and continually pressing upon a flange formed on the sliding half of
the friction clutch, thus tending to force the latter into gear. On the
inner side of the flange two cam surfaces are formed, as shown at =V=,
with which the nose of the rocking or escape lever engages. The latter
is connected by a short rod to the end of the long lever, the whole
attachment being very clearly indicated in the illustration. Suppose
the end of the lever to be in the position shown in the left hand view
of =V=, the friction clutch would then be engaged, and the cam shaft
would revolve until the outer cam surface on =V= came into contact with
the end of the lever, when the sliding half clutch would be disengaged
and arrested, and the motion of the cam shaft would cease. In this
position the parts remain until the long lever is again moved, this
time having its inner end depressed by reason of the contact of the
bracket =S^{1}=, and bowl =R^{1}=. The nose of the escape lever is
then moved off the outer cam surface into the flat or level portion
of the inner cam course. This permits the re-engagement of the
friction clutch, and the cam shaft makes the second half turn, causing
the inner cam course to engage with the nose of the lever and again
disengaging the friction clutch. The raised cam surfaces on =V= are
directly opposite one another, so that the cam shaft can only make a
half turn before it is disengaged. The next movement of the long lever,
which takes place at the end of the next outward run, is caused by the
engagement of =S= and =R=, and the escape lever nose is then moved on
to the level surface of the outer cam course. This alternate movement
of the long lever takes place, as will be readily understood, when the
carriage reaches the termination of its inward and outward runs.
(292) If it be assumed that the carriage has reached the end of its
outward run, and the cam shaft has made a half revolution, three things
take place. The back shaft clutch is disengaged, and the shaft ceases
to revolve; the roller clutch is detached, stopping the delivery of
roving; and the cam =Y= is moved into such a position that the strap
lever can traverse so as to allow the strap to pass on to the loose
pulley.
(293) The back shaft clutch is controlled by the internal cam =Z=, in
which a bowl on a pin fixed in the bell crank lever =Z^{1}=, Fig. 162,
page 201, to which reference will be made for this part of the subject,
works. In the groove of the sliding half =P= of the clutch, the forked
end of the lever =T= fits, this lever being hinged at its lower end
and having a horizontal arm, the end or nose of which rests upon the
horizontal limb of the rocking lever =Z^{1}=. Thus, when the latter is
rocked so as to make an upward movement, the lever =T= is raised, and
causes a disengagement of the clutch =P P^{1}=. The back shaft is thus
freed, and all motion of the carriage ceases.
(294) The rollers are disengaged by the cam =W=, which acts upon the
cranked lever shown, the vertical arm of which is forked and fits in
the groove in the loose half of the roller clutch =I=. When the cam is
in the position shown in Fig. 156, the rollers are engaged, but when
the cam shaft makes its half revolution the lever is oscillated and the
clutch is detached. As previously noted, the cam course is formed in
the loose half of the friction clutch =X=, which thus serves a double
purpose.
(295) The compound strap guide lever is placed almost vertically, as
shown in Fig. 158, being hinged upon a pin in the headstock frame. The
part =G= carries a short pin on which a small runner or bowl can freely
revolve. While the carriage is running out, the bowl is at the point of
the cam =Y=, but when the half revolution of the cam shaft is made it
assumes a position at the base of the cam. These two positions are very
clearly shown in the right hand bottom corner of Fig. 156. This allows
the strap to move, in a manner more particularly described afterwards,
on to the loose pulley, so that the backing off friction can be engaged.
[Illustration: FIG. 156. J.N.]
[Illustration: FIG. 157. J.N.]
(296) It has thus been shown that the half revolution of the cam
shaft causes the stoppage of the motion of the carriage, rollers,
and spindles. This is the second stage or period, and it is at once
followed by the third. Before passing on it is worth while reiterating
that there is a decided advantage in the constant rotation of the loose
half of the clutches =X= and =A^{1}=, their engagement being made more
rapidly and with less strain. The power derived from the portion of
the strap upon the loose pulley is sufficient to rotate the cam shaft,
and cause it to make the changes. It is also capable of maintaining the
steady rotation of the backing-off and taking-in friction clutches, so
long as these are not in gear, or communicating motion to the spindles
or carriages.
(297) The strap guide arrangement is shown in detail in Fig. 158. The
guider is fixed at the upper end of a lever =F=, which is hinged, as
shown, at its lower end to the heel of the lever =G=. =F= has also an
arm =F^{1}=, which is coupled to a horizontal limb of the lever =G= by
the spring =S=. The two or compound levers are therefore constantly
drawn towards each other. The lever =G= is secured on a short shaft,
and has a second spring =Q= attached, which pulls it in the direction
of the arrow, when it is freed by the rotation of the cam =Y=. A short
stud bowl is fixed in =G=, and the pull of the spring presses it
constantly against the cam. Coupled to a short arm, fixed on the shaft
to which =G= is secured, but at the other side of the headstock, is the
horizontal lever =H=, the outer end of which is drawn upwards by the
spring =P=, fastened to the framing. A shoulder or recess is formed in
=H=, which ordinarily engages with the fixed catch =L=, by which the
strap guide lever is locked in position when the strap is on the fast
pulley. On the inner end of the rim shaft a worm =K= is formed, which
gears with a worm wheel compounded with a spur pinion, which, in turn,
gears with the spur wheel shown. On the spindle of the last-named wheel
a small crank =O= is keyed, the outer end of which has a pin, carrying
a bowl, fixed in it.
(298) The action of this mechanism is as follows: The revolution of the
rim shaft causes the crank =O=, which is, at the commencement of the
outward run, just clear of the nose of the lever =H=, to revolve. By
the time the outward run is completed, the crank will have made almost
a complete revolution. When the necessary twist has been put in the
yarn, the crank =O= comes in contact with the front end of the lever
=H= and releases the catch =L=. Immediately this happens the spring =Q=
acts, and the strap guide lever oscillates, causing the strap to glide
upon the loose pulley.
(299) This step having been accomplished, the next operation is to
engage the backing-off friction. As shown in Fig. 158, the boss of
the wheel =A^{1}= is formed with a ring groove, into which a claw
fastened on a short stud fits. The lever =D= is also fixed on the same
stud, so that any movement given to it is communicated to the claw and
backing-off friction. The lower end of the lever is forked and passes
over a rod =X= extending along the side of the headstock. This rod
is guided by a bracket fixed to the side of the frame, and has the
two stop hoops =X^{1} X^{2}= fastened on it. Between the stop hoops a
spiral spring, always in compression, is threaded upon the shaft, one
end pressing against the lever =D=, and the other against the hoop
=X^{2}=. It will be readily understood that the compression of the
spring will tend to push the lever =D= in the direction of the arrow,
until its motion is stopped by a link connected with the slide in the
arm, to which is fastened the lever =H=. It is essential that the
engagement of the backing-off clutch should be practically simultaneous
with the transferring of the strap from the fast to the loose pulley,
and it is therefore desirable that the spring on =X= should be put in
compression a little before the actual traverse of the strap.
(300) This is accomplished by means of the swinging lever =V= shown in
Fig. 162. This is hinged upon the square, and is formed, as shown, with
an open mouth, at the upper part of which is an angular projection or
lip. Pivoted on the framing is the lever =L=, the horizontal arm of
which carries a small runner, which engages with the incline of =V= as
the carriage runs out. The lever =V= cannot, until the termination of
the stretch, be swung upon its pivot by reason of its connection with
the faller locking lever =A=. When, therefore, the bowl in the lever
=L= engages with the incline of =V=, the lever =L= is oscillated, so
that the spring on =X= is further compressed. The spring is, therefore,
in a position to push the backing-off lever forward, as soon as the
latter is freed. The engagement of the lever =L= with the lever =V=
takes place a few inches before the carriage arrives at the end of its
outward run.
(301) When the outward run is completed, and the cam shaft begins to
revolve, the lever =D= has sufficient pressure on it to push it over
if it were free to move. Reverting again to Fig. 158, the horizontal
lever =H= and the arm previously referred to are coupled by a small pin
in the latter, which takes into a slot in the former. When, therefore,
the lever =H= is locked, the vertical lever =D= cannot move, but when
the unlocking of the lever =H= by the crank =O= occurs, the oscillation
of the strap lever draws, by means of the arm, the lever =H= in the
direction of the arrow. This permits the spring =X= to extend and push
the lever =D= forward and so engage the backing-off friction. This
movement is rapid and nearly simultaneous with the transferal of the
driving strap. The mechanism is set to permit the backing-off friction
to come gradually into gear for the purpose of acting as a brake, as
was explained in paragraph 282.
(302) The friction cones being engaged and the strap placed on the
loose pulley, the rim shaft is driven in the contrary direction, thus
reversing the spindles. It therefore becomes necessary to take up the
yarn as it is delivered from the spindles. This is effected by means of
the faller and counter faller, as indicated in paragraph 270, and the
precise mode of action of these can now be described.
(303) The faller arms =M= and =U=, as shown in Fig. 161 (page 205), are
sickle or crescent shaped, so that they can readily pass down between
the cops without touching them. The arms are keyed on the winding
faller and counter faller rods =B B^{1}= at convenient intervals,
and the wires are threaded through them. The latter are thus well
sustained, and do not deflect to any appreciable extent, this being
fatal to the effective building of the complete set of cops. The rods
or shafts =B B^{1}= are borne by brackets fastened to the carriage, so
that their axes are quite parallel to the centre line of the carriage.
The winding faller shaft is oscillated by suitable mechanism, by which
at the proper moment it is drawn downwards, while the upward movement
of the counter faller is regulated from the winding faller. There is
an important difference in the action of these parts. As the winding
faller is to act as a guide to the yarn during winding, it is essential
that it is, at the beginning of each inward run, in the correct initial
position for that purpose, and that, when it has reached that position,
it shall be locked. On the other hand, the function of the counter
faller being merely to maintain the tension of the yarn during winding
and backing-off, it is necessary that it should be free, so as to bear
constantly against the underside of the threads without exercising an
undue strain. The pressure thus exerted should be a little in excess of
the downward pull of the whole of the threads which are being spun in
the machine, but not so much in excess as to prevent the counter faller
yielding a little if from any cause an extra pull is put upon the
threads. In other words, the action of the winding faller is positive,
while the counter faller acts as a regulator of the yarn tension.
In order to maintain this relation it is desirable to establish a
connection between the descent of the faller and the ascent of the
counter faller. This is done by making the latter dependent on the
former, and by leaving it free after it has been released.
[Illustration: FIG. 158. J.N.]
(304) The controlling mechanism is shown in Fig. 159, which is a
representation of the parts affecting the counter faller. Hinged, as
shown, to a bracket on the underside of the carriage is a lever =J=,
to which are attached two chains =E^{1} I=. The former is coupled to
a sector =E=, which is secured on the counter faller shaft or rod
=B^{1}=. If it is assumed that the latter is free to rotate, as it
is, the pull exercised by the lever =J= would be sufficient to cause
it to do so. But until the winding faller makes its descent so as
to assume the winding position, as afterwards described, the weight
of the lever =J= is taken by the chain =I=, which at its upper end
is fixed to the hook shown. The latter is hinged to the bracket or
lever =S=, the other arm. of which rests upon the counter faller rod
=B^{1}=, and thus limits the upward movement of the winding faller.
A steady torsional pull is exercised upon the bracket =S=, so as to
draw the chain =I= upwards, by the spring =V=, attached as shown. The
unwinding of the two or three coils of yarn during backing-off takes
place during the time the winding faller is descending. Immediately
backing-off is completed, the carriage begins to run in, and the yarn
is wound. It is therefore necessary for the counter faller to rise,
so as to take up any slack yarn. Unless this is done, the yarn—owing
to its tightly twisted condition—runs into small loops or kinks,
technically known as “snarls.” The oscillation of the winding faller
rod =B= has caused a similar movement in =S=, and, as a result, the
chain =I= becomes slackened and ceases to sustain the lever =J=. As,
therefore, the carriage =O= begins to run in the lever =J= descends,
and the whole of its weight is borne by the chain =E^{1}=, which is
caused to pull upon the sector =E=. In this way the counter faller rod
=B^{1}= is oscillated, and the counter faller wire =M= is raised. The
extent of its upward movement is regulated solely by the tension of the
threads, which is sufficient to act as a counterbalance to the lever
=J=. In order that this equilibrium shall be sufficient to preserve
the necessary tightness of the threads, without any danger existing of
either slack threads or of the counter faller being unyielding when an
extra strain is put upon the yarn, balance weights can be added at the
end of the lever =J=, as shown. In this way the necessary sustainment
of the yarn threads is obtained without any likelihood of straining or
breakage. When the carriage has completed its inward run the weight
of the lever =J= is relieved by the roller =W=, so that the faller,
when released, as afterwards described, can easily assume its proper
position during spinning or twisting.
(305) While the counter faller is being freed in the manner described
the downward movement of the faller is also proceeding. Referring now
to Fig. 160, which is a detailed view of the faller arrangement, the
faller shaft has fixed on it an arm or backing-off finger =D=, to which
is fastened one end of a chain =E=. One end of =E= passes round the
small bowl =F=, and its other end is fastened to a snail or scroll
=G= mounted on the tin roller shaft. The snail is geared by a ratchet
clutch which engages only when the tin roller is revolving during
backing-off, being disengaged during the whole period of spinning. The
size of the snail is arranged so as to draw down the faller finger =D=
during the period of backing off to such an extent that the faller is
brought into the proper position for the commencement of winding. In
dealing with the latter operation it will be shown that the faller
is a little below the cop nose when winding begins, and then rapidly
descends until the base of the upper cone is reached. At present it
is only necessary to note this fact, as it has a somewhat important
bearing on the mechanism being described. During the period of the
faller descent a pull is exercised on the rod =F^{1}=, by which the
bowl or runner =F= is carried. The other end of =F= is hinged to the
“locking” lever =A=, to which the curved arm or sector =C= is hinged
at its upper end. This arm is fixed on the faller shaft, so that the
oscillation of the latter, which is caused by the pull of the chain
=E=, gradually raises the “locking” lever =A=. This elevation goes on
until the shoulder or bracket =K= is high enough for its under side to
slip over the small bowl fixed in the lever or slide =L=. The latter is
at the end of a lever hinged at one end to the carriage and carrying
the runner or bowl =L^{1}=. This is drawn along with the carriage, and
the lever is consequently called the “trail” lever. As soon as =K=
slips on to the bowl in =L= the “locking” lever and faller are said to
be “locked,” and are then in a position to begin winding. This action
is practically simultaneous with the termination of backing-off. This
method of locking the faller is now general, having quite superseded
the older method of locking at the top.
[Illustration: FIG. 160. J.N.]
(306) In order to render the action of backing-off more perfect, and
to ensure that the slack of the yarn, as it is unwound, shall be taken
up by the faller, Messrs. Platt Brothers and Company have adopted
the mechanism also shown in Fig. 160. The reversal of the direction
of rotation of the spindles takes place a little in advance of the
downward movement of the faller, and it is therefore found that a short
length of yarn is unwound before the faller presses upon it. The actual
extent of the unwinding is relatively greatest when the cop is almost
built. It therefore becomes necessary to expedite the action of the
backing-off chain as the cops are built, so that the faller is drawn
into contact with the yarn at the earliest moment. A little reflection
will show that at the period when the cops are beginning to be built
the faller wire has a much longer distance to travel than when they are
almost finished. As will be afterwards shown, the period at which the
faller is locked is gradually made earlier as building proceeds, so
that a much shorter traverse of the faller prior to locking takes place
correspondingly. Thus, for instance, if it has to be depressed one
inch before it touches the yarn at the commencement of a set of cops,
the relative proportion of that distance to the whole traverse prior
to locking is less than when the traverse is so much diminished at the
end of a set. Thus it follows that a degree of lagging permissible at
one stage is absolutely detrimental at the other. From this it may
be deduced that an earlier and accelerated motion of the faller is
necessary in order to take up the slack yarn during backing off.
[Illustration: FIG. 159. J.N.]
(307) It is hardly practicable to fit a motion of absolute accuracy to
effect this purpose, but an approximation to it can be obtained. It
is, therefore, arranged that at the beginning of a set the backing-off
chain shall be slack, and during building shall be gradually tightened
until at the end of it is nearly in a state of tension. The snail is
proportioned so as to give a quick downward movement to the faller, and
in combination with the arrangement about to be described gives very
good results. Referring again to Fig. 160, attached to the snail =G=
is a second chain, the other end of which is fastened to a lever =H=,
hinged on the bracket shown. The other end of =H= rests on an inclined
plate =N=, which slides on a bedplate fastened to the floor. The plate
=N= is fastened to the copping plate connecting rod—afterwards referred
to—which passes through a horn fastened on =N=. As the copping plate is
moved in, =H= is also caused to assume the position indicated by the
dotted lines, =N= having also moved in. The effect is that a pull is
put upon the snail which gradually rotates it, and causes it to wind
on the slack of the chain =E=, so that, when backing-off occurs, the
faller is drawn downwards at an earlier moment. The restoration of =N=
to its original position accompanies that of the copping plate, and is
made at the beginning of a new set of cops.
(308) The various movements in connection with backing-off having
thus been described, it is necessary to show how the traverse of the
faller is obtained during the inward traverse of the carriage. This is
shown in Fig. 161, page 205, which is a separate view of the copping
or building mechanism. The faller “locking” lever =A= is, as has been
described, raised until the shoulder =R= slips on to the slide =L=, in
which position it remains until it is released at the termination of
the inward run. On the underside of =L= a small bowl or runner =L^{1}=
is carried, which rests upon the upper surface of a longitudinal, or
“copping” rail =P=, made of a strong section. If the latter was placed
in such a position that its upper surface was horizontal, it is plain
that the slide =L= would receive no vertical motion during the period
that the runner =L^{1}= was traversing it. In consequence the sickle
=U= would remain in one position during the same time. But if the
rail =P= is raised at one end so that its upper edge is inclined, the
slide =L= will, during the run in of the carriage, receive a vertical
traverse corresponding to the difference in the altitude of the two
ends of the copping rail. That is to say, if one end of the rail
was six inches from the floor line, while the other end was seven,
=L= would ascend or descend to the extent of one inch while it was
travelling from one end to the other of the rail =P=. The question as
to whether it would ascend or descend depends entirely upon which end
of the rail was highest. From this it may be inferred that by varying
the angularity or profile of the copping rail any desired traverse,
either regular or intermittent, could be given to the slide =L=. Now it
was shown that the winding faller sickles are keyed on the shaft =B=,
which is oscillated by the backing-off finger =D= fastened upon it.
The latter being jointed to the “locking” lever =A=, it follows, that,
as the latter is raised, the winding faller moves in an arc, which
corresponds in length and direction to the length and inclination of
the copping rail.
(309) It is necessary when the carriage arrives at the end of its
stretch to lock it in that position during the time that backing-off
is taking place, and the motions of releasing the counter faller and
locking the winding faller are in operation. A reference to Fig. 162 is
necessary to understand this part of the mechanism. That illustration
is a diagrammatic representation of the mechanism relating to locking
the carriage, and the engagement and disengagement of the taking-in
gear. The parts are not in their working position, but are projected
so that their operation may be better understood. The actual relative
position of the various motions is shown by the diagrammatic sketch in
the right hand top corner of Fig. 162. Upon the carriage =O= a bracket
=O^{1}= is fixed, which carries at its outer end a pin or catch, with
which the hook at the end of the horizontal arm of the =L= lever =S=
can engage. The hook readily falls over the pin in =O^{1}=, as the
carriage is pushed up to it near the end of its traverse. The lever
=S= is coupled in the manner shown to the horizontal rod =R=, which,
at its other end, is jointed to a bell crank lever =U^{1}=. The rod
=R=, on account of its function, is termed the “holding-out catch rod.”
The lever =U^{1}= is in turn connected with the rod =U=, jointed at
its upper end to the lever =W=, which is coupled to the horizontal arm
of the lever =Z^{1}= by the connecting rod =M=. A connection is thus
established between the cam =Z= on the cam shaft and the “holding-out”
catch lever =S=. During the run out of the carriage the friction
clutch =I^{1} K= is disengaged by means of the lever =W=. The rod =R=
is also locked by the small vertical slide =S^{1}=, which engages with
the catch notch formed in it. The movement of the backing-off rod =X=,
which is hinged to the lever =L=, causes the projecting arm in the
lever =Y= to be pushed under the end of the lever =W=, thus sustaining
the latter and preventing the engagement of the upper half =I^{1}= of
the taking-in friction with the lower half =K=. This action occurs just
before the termination of the outward run, being a little in advance of
backing-off, but simultaneous with the compression of the backing-off
spring on =X=. Whatever movement of =W= may take place after the arm
on =Y= is thus projected into the path of the end of the lever =W=,
the friction cannot fall into gear until the support of the arm is
withdrawn. The whole of these parts are thus locked together, and
fall into gear simultaneously. It will be noticed that the connection
between the lever =S= and the rod =R= is such that the latter can
make a certain movement forward before the lever falls. Further, the
carriage can be arrested during its outward run by the pedal lever
fixed to the floor.
(310) The action of the mechanism is as follows: When the carriage
arrives at its outermost point the connecting rod =R= is unlocked, and
is free to move. In this way the catch lever =S= can be easily raised
by the bracket on the carriage =O=, over which it falls, and securely
holds it, the slot in the rod =R= permitting this movement. In this
position it remains during the whole period of backing-off, when in
a way which is afterwards described, it is released simultaneously
with the taking-in friction with which, as shown, it is connected. The
locking of the carriage is the last operation requiring explanation
before proceeding to deal with the movements, which, together, make
up the fourth stage or period. This is the one in which the nicest
problems require solution, and in which the mechanism used is the most
ingenious.
(311) The first step in commencing to wind is, of course, to release
the carriage and draw it in. Before proceeding to show how this is
effected, it will be as well to recapitulate and describe the position
of the various parts. The strap is entirely upon the loose pulley; the
backing-off friction clutch is in gear; the spindles are revolving in
the opposite direction to that normal to them; the winding faller is
drawn down and locked in a position a little below the nose of the cop;
the counter faller is held just out of contact with the threads, but
free to rise as soon as an inward movement of the carriage occurs; the
roller and back shaft clutches are disengaged; and the upper half of
the taking-in friction is out of gear with the lower, but revolving
with the vertical shaft on which it slides.
(312) When the chain =E= (Fig. 160) has sufficiently raised the faller
locking lever =A= to permit it to lock, the swinging lever =V= is
suddenly drawn back. An examination of the drawings, either Fig. 160
or Fig. 161, will show that so long as the face of the locking lever
presses against the face of the slide no lateral movement of the
former is possible. Further, the connection established between the
locking lever =A= and the lever =V=, by means of the lever =F^{1}=,
ensures that as soon as the inward movement of the lever takes place
when locking occurs, the lever =V= must necessarily oscillate on its
pivot. This movement of the lever =V= causes its lower jaw to exercise
a pressure upon the lever =L= in the contrary direction to that
previously noted, and so draws the stop =X^{1}= in contact with the
bottom of the backing-off lever =D=. This action is aided by the spring
on the backing-off rod, which is free to extend, and its whole force
can be exerted on the lever =D=. In this way =D= is drawn back, and the
backing-off clutch is disengaged.
(313) The same movement draws away the supporting piece on the vertical
lever =Y=, and allows the upper half of the taking-in friction to fall
into gear with the lower half, this action being aided by the spring
=Q=. The slot in the end of the connecting rod =M= permits the upward
movement of the left hand end of the lever =W= to be made rapidly and
freely. In this way the engagement of the friction clutch is a very
quick one. This upward movement of the lever =W= is communicated, in a
manner described, to the holding out catch, which is also raised nearly
simultaneously, and the carriage released.
[Illustration: FIG. 162. J.N.]
(314) It is, of course, highly essential that all the three releasing
motions shall be accurately “timed,” so as not to take place either
before or after the proper moment. Accordingly, ample means of
adjustment are provided, both on the rod =X= by the regulation of the
stops =X^{1}= and =X^{2}=; on the connecting rod =M= coupling the
levers =Z= and =T=; and also on the holding-out rod. In this way it
is possible to secure that simultaneous movement of the three parts,
which is so essential for effective working. It is obvious that the
backing-off friction and holding-out catch must be released before the
taking-in friction gears, but the interval between these is so slight
that they occur practically simultaneously.
(315) The taking-in friction being in gear, the rotation of the
loose pulley is, by the train of wheels shown, communicated to the
“scroll” shaft, on which the taking-in scrolls are fixed. These have
bands attached to and wrapped round them when the carriage is at the
roller beam. As the carriage runs out, the bands, which are fastened
to it, are drawn off the scrolls, the scroll shaft being then free
to revolve. The engagement of the taking-in friction reverses this
process and winds on the bands, thus drawing up the carriage. It will
be observed that the scrolls vary in diameter, being about 9 inches
in the largest part, and about 3 inches in the smallest. The reason
of this construction is to give a varying traverse to the carriage,
so as to start it easily, and bring it up to the back stops gently.
The scrolls are designed so that, so long as they are revolving, they
exercise a pull upon the carriage which is steady and constant. In this
way, over-running is avoided, but to prevent any possibility of it a
scroll =L^{1}=, shown in a detached position in Fig. 153, is fixed on
=L= at an angle of 180 degrees to the others, the point of attachment
of its rope being diametrically opposite that on the other scrolls.
Thus when the bands on the drawing out scrolls are unwound, that on
the “check scroll” is wound and vice versa. The purpose of this scroll
is, as its name indicates, to check any tendency to over-running,
which it effectually does. In all mules above a certain length, it is
desirable to provide some means whereby the carriage shall be drawn in
evenly throughout its length, and shall not be in danger of twisting
or warping. The scroll shaft, it will be noticed, only extends across
the headstock, so that the bands can only exercise any pull on the
square, and if no other points of attachment were made, the carriage
would at its extremities lag behind the centre. A considerable amount
of friction would be thus caused, and the spindles at the end of the
carriage would not take up the full length of yarn. It was shown that
the back shaft is, during winding, disengaged, so that it is only
necessary to establish a connection between it and the scroll shaft,
to enable the carriage to be drawn in at several points throughout
its length, instead of at one only. Accordingly, the scroll shaft is
extended, and an extra scroll shown in Fig. 154 at the right hand side
is fitted, from which a band is taken to a drum upon the back shaft.
Thus the back shaft is converted into a taking-in shaft, and during
that operation revolves of necessity at a variable speed given to it by
the scrolls. In this way the carriage is kept parallel to the roller
beam throughout its course, and comes up to the back stops along its
entire length at one time.
(316) The arrangements for taking-in having thus been described, it now
becomes necessary to describe the operation of winding. Before doing
so, it will be better to deal with the problem to be solved, and it
will aid in understanding it if the construction and method of building
the cop be described. For this purpose a reference to the diagrams
given in Figs. 163 and 164, page 207, is necessary. The cop is built,
as before explained, upon the blade or taper part of the spindle, and,
when finished, is of the shape shown in Fig. 163, viz., a cylinder with
conical ends. The central part of the cop, =E G K F=, is cylindrical,
and at the top and bottom of this part are two cones. The lower cone,
=A E B C F D=, forms what is known as the “cop bottom,” and the upper
one, =G H I K=, the “nose,” although the latter term is more often and
strictly applied to the extreme apex at the points =H I=. As previously
stated, the yarn may be wound either upon the bare spindle, upon a
short paper tube, as indicated by the thick line inside the cop bottom,
or upon a similar tube the whole length of the cop. The use of paper
tubes of this character is preferable, especially in cases where the
cop is likely to be much handled, as it prevents it from being crushed
in, and enables the introduction of a skewer for subsequent winding
without there being any danger of the cop being pierced or “stabbed,”
this being a fruitful source of waste.
(317) In commencing to wind, the yarn is wrapped on the lower part of
the spindle in close coils or spirals for a length of a little more
than an inch. The whole of one stretch is wrapped upon this space, and
when the next stretch requires winding, it is laid upon the previous
layer, and so on until the double cone =A E B C F D= is produced. The
length of the traverse of the winding faller wire, or the length of
each layer vertically, is called the “chase” of the cop or faller.
From this point the yarn is wound in successive layers, beginning
always at a higher point, until the final traverse is obtained by which
the winding is conducted upon the surface or nose represented by the
letters =G H I K=. It was stated in paragraph 311 that the winding
faller wire, when the winding faller is locked, is in a position a
little below the point =H I=. As soon as the carriage begins to run
in, the vertical movement of the winding faller locking lever begins,
and is so arranged that the first movement of the wire is a rapid
downward one. The effect is that the yarn is laid on the nose of the
cop in coarsely-pitched descending spirals, as shown in Fig. 164, these
extending downwards until the winding faller wire reaches a point
opposite the base of the upper cone, in this case shown in Fig. 163
at =K=. From this point a slower ascent of the winding faller wire
is made, so that the yarn is laid in the more finely pitched spirals
shown, until the nose of the cop is reached. By this time the carriage
has arrived at the roller beam, and the whole of the 63 inches of yarn
has been wound.
(318) When the first layer of yarn is wound, and the winding faller is
assuming its position to wrap on the second, the initial point of its
traverse is a little raised. In this way the yarn is gradually wound
in layers, which are represented by the angular lines springing from
the lines =A E= and =D F= towards the spindles. During this period the
enlargement of the diameter of the cop bottom is proceeding until at
the points =E F= the full diameter of the cop is reached. As soon as
this occurs the initial point of each layer is gradually raised, and
the length of the traverse is slowly diminished as the completion of
building is approached, until at the termination of a cop the angle
of the layers is shown by the lines =G H= and =I K=. There are thus
two adjustments shown to be necessary—first, the starting point of
each traverse of the winding faller requires altering; and second, its
extent also needs regulation.
(319) These two objects are attained by the regulation of the copping
rail =P=, as shown in Fig. 161. The ends of this rail rest upon
inclined “copping” plates =Y X=, which are fastened together by the
rod =W=, and which receive, as will afterwards be described, an inward
movement during the building of the cop. It was shown that the locking
of the faller lever and its vertical movement leads to a corresponding
movement of the faller. If, for instance, the faller locking lever fell
an inch, the winding faller sector would be oscillated and the faller
wire drawn upwards. The rate of the ascent of the latter is absolutely
relative to the period of the descent of the locking lever. Referring
now to Fig. 165, which is a small diagrammatic sketch of the copping
rail and its supports, suppose the line =G H= to represent the top of
former, =O P= the latter, and =L= the bowl at the foot of the locking
lever, if =L=, starting from the left hand position, be supposed to
travel in the direction of the arrow =V=, it will be seen that it will
fall to the extent indicated by the space =Y Z=. If, on the other hand,
the slides =O P= are moved into the position shown by the dotted
lines, the rail =G H= will also fall into that indicated in a similar
manner. The result is that if =L= now makes the same traverse as before
it will rise a little as indicated by the space =W X=. The effect on
the winding faller would be that in the first case it would be raised,
and in the second it would be depressed to an extent corresponding to
the depression of the locking lever. The extent to which this elevation
or depression is made depends upon the vertical traverse of the locking
lever, and the ratio of the distance of the point of junction of the
sector =C= with the faller shaft and that of the faller wire from the
same rod. If, for instance, this proportion was 1:2, an elevation of
the locking lever half an inch would result in a depression of the
faller an inch. It is therefore necessary, during the inward run of
the carriage, to provide for the inclination of the carriage to such
an extent as to secure the requisite traverse of the faller wire. As
the amount of such traverse varies during the building of the cop,
it follows that the inclination of the copping rail must be varied
correspondingly.
[Illustration: FIG. 165. J.N.]
(320) Referring again to Fig. 161, the ends of the copping rails
have pins fixed in them, on which are anti-friction bowls, which run
upon the edges of the copping plates. The latter are duplicated, so
as to sustain the rail at each side, and thus maintain its vertical
position. At one side of one of the plates =Y= is an ear =S^{1}=,
which is threaded to correspond with a square threaded screw =S=
passing through a fixed bracket fastened to the floor. In this way
the screw =S= is free to revolve, but cannot make any longitudinal
movement. On the end of the screw =S= a ratchet wheel is fixed with
which a pawl =S^{2}= engages, which is oscillated so as to move the
wheel one tooth at convenient times. The speed of the revolution of
the screw varies according to the counts being spun, the elevation of
the point of locking being more quickly effected when coarse yarns are
being made than when the finer varieties are produced. Whatever may
be the velocity at which this elevation is accelerated, the profile
of the copping plates is such that the inner end of the copping rail
=P= is lowered at a more rapid rate during the formation of the cop
bottom than at a subsequent stage. The reason of this will be easily
comprehended, if the description of the mode of building the latter
be borne in mind. It was then shown that the traverse of the winding
faller rapidly increased in extent until the full length of the cop
bottom was built. It, therefore, follows that the descent of the
locking lever must be largely increased at this period at a quick rate,
in order to produce the result indicated. When the outer end of the
copping rail begins to descend at a rate which more nearly corresponds
to that of the inner end, it gradually approaches to the horizontal,
and the vertical motion of the slide, locking lever, and faller is
proportionately limited.
(321) The regulation of the winding faller as just described was the
one which was usual until recent years. It has been found necessary,
however, to obtain a more accurate regulation, so as to ensure that
the faller wire shall be in its correct position when locking occurs,
especially during the period between the beginning of a cop and the
attainment of its full diameter. It is now customary to attach to the
front end of the copping rail a loose plate =Q=, which is hinged at one
end to the rail, and which carries at its outer extremity a pin and
bowl resting upon a third inclined plate =Z=. By varying the profile
of the plate =Z=, the regulation of the faller during the early part
of its traverse can be accurately made and the proper position of the
wire ensured. As a glance at the illustration will show, the upper
edge of the copping rail is not straight, but is shaped so as to give
a variable speed to the slide =L= in its vertical movement. The proper
shaping of the copping rail gave rise to some difficulty, and it will
be seen that the loose copping rail =Q= is shaped so as to produce the
proper effect, while being much more easily adjusted.
[Illustration: FIG. 161. J.N.]