(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.

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.

(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.

(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 13¹⁄₂ 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 A¹, 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 5¹⁄₄ 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 C¹ 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 B¹, from which, by means of a carrier wheel, the side shaft D is driven. On the other end of this shaft a pinion D¹ is fixed, which gears with and constantly drives the spur wheel A¹, this being the object of the overlapping of the driving strap previously referred to. The wheel A¹ 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 A¹ 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 A¹, 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 A¹ 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 G¹ 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.

(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 H¹. 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 P¹, 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.

(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 I¹ 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 I¹, 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 K¹ fixed on the shaft L, extending transversely of the headstock at the back. Spirally grooved or “scroll” pulleys L¹ 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 2³⁄₄ inches wide. The fast pulleys A are also 2³⁄₄ 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 R¹. Fastened to the carriage by bolts are two horn brackets S S¹, 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 S¹, 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 A¹. 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 S¹, and bowl R¹. 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 Z¹, 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 Z¹. 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 P¹. 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.

(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 A¹, 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 F¹, 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 A¹ 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 X¹ X² 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 X². 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 B¹ 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 B¹ 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.