Chapter XI: The Mule (3)

(338) In the early stages of winding, when the winding faller is depressed to a comparatively large extent prior to being locked, the vertical position of the lever =Y= is naturally lower than when the winding faller is not pushed down so far. It thus occurs that, when the cop bottom is being formed, which is the stage during which the traverse of the nut is required, and the winding faller is locked at its lowest point, the clearance of the detent catch on =Y= and the teeth on the pulley =S= is least. At this period, therefore, they are most easily engaged by any depression of the counter faller. When the higher initial velocity of the spindle, produced as described in paragraph 336, causes the yarn to be put into tension and the counter faller wire depressed, an engagement of the catch and pulley teeth occurs.

(339) The effect is that the rotation of the toothed pulley is stopped, and the band =Q= is practically gripped by =S= and its fellow pulley =S^{1}=, which are borne by the carriage. Instead, therefore, of slipping over the pulleys as before, the band is drawn along with the carriage and the remaining pulleys are caused to revolve. The force so applied is sufficient to rotate the grooved pulley =P^{1}= by overcoming the resistance of the spring clip, and the bevel wheels and quadrant screw are rotated. The nut is thus moved outwards, and the winding chain relieved as previously described. This causes a slight diminution in the speed of winding, sufficient to relieve the pressure of the threads on the counter faller wire, which rises and breaks the contact of the detent and the toothed pulley. The further movement of the nut is thus arrested.

(340) The necessity for a diminution of the initial velocity of the spindle is strictly relative to the counts of yarn being spun. Some of the finer counts require a very slow traverse of the nut, and there may be practically none during several draws of the carriage. As the nut slowly rises and the locking point of the winding faller is elevated, the period of the engagement of the detent catch and the wheel =S= becomes shorter, and the rotation of the screw is not so prolonged. When the cop bottom is fully formed, the nut is at its most outward point, and the “governing” motion is not therefore required. At this point, the relative positions of the arms =U U^{1}= are such, that the chain =Y^{1}= will not permit the lever =Y= to fall sufficiently to allow its tooth to engage with the wheel. The motion, therefore, falls out of use until the commencement of another set of cops.

(341) The motion of the winding scroll is communicated to the tin roller by means of a catch or “click” plate shown in detail in Fig. 168. On the spindle of the winding scroll =X^{1}= is a spur wheel—indicated by dotted lines—which engages with a small pinion on the tin roller shaft =T=. The whole of this special mechanism is shown in longitudinal section in the right hand top corner of Fig. 168. The pinion is cast in one piece with the disc =V= which is loose upon the shaft =T=. The latter has a pin fixed in it, on which the small catch or “click” =V^{1}= is hinged. The click catch is ordinarily held out of position by the bent spring =W^{1}=, which surrounds the boss of a ratchet wheel =T^{1}=—to which the name of the “click wheel” is given. When the “click spring” =W^{1}= is slightly oscillated in the same direction as the rotation of the ratchet wheel, it allows the click catch to fall into gear with the click wheel. As the latter is keyed upon the tin roller shaft =T=, the engagement with it of the catch causes the tin roller to be revolved, and thus rotates the spindles.

(342) It was formerly the practice to allow the click catch to fall into gear when the disc =V= began to rotate upon the commencement of the inward run of the carriage. It was, however, found that the click catch engaged with the wheel earlier at one stretch than at another, and that, consequently, winding began a little more slowly than it should. The effect of such an occurrence is that a little slack yarn was produced as the carriage was running in, although winding was not taking place. Under these conditions tight winding at the nose throughout was practically impossible. It will be easily understood that, when the click catch is released, it may very readily be left either close to the tooth with which it has to engage or only just over the point of the preceding tooth. In the first case the engagement would take place at once, while in the second instance almost the distance of a tooth would have to be travelled by the click catch before engagement occurred. In hard twisted yarns this is especially objectionable, and its prevention is of importance.

(343) To overcome the defect thus explained a hanging lever =W= is fitted on the tin roller shaft, and the click spring =W^{1}=, instead of fitting on the boss of the disc =V=, fits on the inner boss of the lever =W=, which it clips. A slight oscillation of the lever is, therefore, at once followed by the movement of the spring, and the click catch is engaged. The tail end of the lever =W= comes in contact with a stop =R^{1}= on the holding-out catch rod =R=. When =R= is moved in order to release the catch it causes the lever =W= to move into the position shown by the dotted lines, and so oscillate the spring =W^{1}=. The tail of the click spring passes between a fork formed in the click catch, and thus presses the catch in either direction, according to which side of the fork it gears with. When, therefore, the click spring is oscillated by the releasing movement of the holding-out rod acting upon the lever =W=, the click catch is forced hard up to the tooth with which it is engaging. The continued movement of the rod, if made, has, of course, no further effect upon the click catch, but the parts are quite ready for winding with the click in gear. Immediately the carriage begins its inward run winding commences. Thus, whatever may be the position of the click catch at the end of an outward run, it is always ready for its work before the inward run commences. The weight of the rod =W= is sufficient to keep the click catch disengaged during the whole period of spinning and backing-off.

(344) The whole of the points relating to winding having been considered, the motions used in the fifth and last period require describing. When the carriage is near the completion of its inward run, the various parts are in the following position: The strap is on the loose pulley and the backing-off side shaft is being revolved either by the gearing named, or by its independent band; the back shaft clutch is disengaged and the back shaft is revolving so as to aid in drawing up the carriage; the rollers are disengaged and are not delivering roving; the taking-in friction is engaged, and the scroll bands are drawing in the carriage; the quadrant arm is completing its forward movement, and the spindles are revolving in their normal direction; the winding faller is locked and the wire is approaching the nose of the cop; and the counter faller is in contact with and sustaining the threads. As soon as the carriage arrives at the roller beam, the whole of these motions require changing, so that the different parts shall occupy the positions indicated in paragraph 286.

(345) This operation is mainly the work of the cam shaft, but in part is performed by other mechanism. As soon as the carriage arrives at, or near, the end of its outward run, the horn =S^{1}= on the carriage comes in contact with the anti-friction bowl =R^{1}= in the long lever =T= and depresses it (see Fig. 156). This removes the nose of the releasing lever from the raised surface on =V= and allows the friction clutch =W X= to come into gear. The cam shaft immediately begins to rotate, and the three cams to act upon the various parts in the reverse way to that previously described. The rotation of the cam =Z= (Fig. 156) performs the two functions of disengaging the taking-in friction clutch and engaging the back shaft clutch, the motions of these always being closely related. The cam =W= during the same period allows the roller clutch to go into gear, and the delivery of roving again begins. The rotation of the cam =Y= causes it to exercise a thrust on the pin fixed in =G= (Fig. 158), so forcing the driving strap over on to the fast pulley, this giving renewed motion to the spindles. The same movement causes the lever =H= to be pushed forward until the shoulder formed in it can again engage with the fixed catch =L=, the spring =P= pulling the end of =H= upwards as soon as it is sufficiently far forward. The strap guider is thus again locked when the strap is on the fast pulley. By the time these engagements and disengagements have been made, the cam shaft =M= has made its second half revolution, and the end of the release lever again presses upon the raised surface on the cam =V= and detaches the friction cone =W= from =X=. The cam shaft is thus stopped and remains stationary until the end of the outward run as described in paragraph 291.

(346) The whole of the parts governed by the cam shaft having thus resumed their original position, it remains to be shown how the winding and counter fallers are released, so as to be able to assume their relative positions out of contact with the yarn. The unlocking of the winding faller must be made as late as possible in the inward run, but the exact period at which it is made is affected by the height of the cop nose on the spindle. The termination of winding requires to be made throughout the whole period of building a set of cops, at such a point as to leave sufficient yarn to coil on the spindles between their points and the cop nose. It will be easily seen that this quantity is varying throughout the whole of the formation of the cop, and that the length to be wound on is greatest at the commencement of the cop. This implies the unlocking of the winding faller at a point which is made gradually later, and this is well carried out in the Platt mule. At the lower end of the locking lever is a curved arm or “boot leg,” which, at the termination of the inward run, comes in contact with the fixed stop bracket =G= (Fig. 161). The face of this is so shaped that the moment of unlocking is regulated in accordance with the requirements of the case throughout the whole of the formation of the cop. This is an important point, and requires careful attention. In a special form of mule, made by Messrs. Platt Brothers and Co., for finer counts, the stop bracket is a movable one, and is released by the run of the carriage, so as to slide forward and unlock at the exact moment required. The finer the yarns the more care is required in this respect, owing to their greater liability to breakage.

(347) Referring now to the release of the winding and counter fallers, it is essential that they should leave the yarn free as soon as spinning begins. For this purpose the lever =J= is raised by contact with the small roller =W= (Fig. 159), and its weight is removed from the counter faller shaft, and also from the winding faller. Still further to facilitate the descent of the counter faller, which is sometimes a little sluggish, a stop is placed in the headstock, which engages with a tail piece on the counter faller shaft when the carriage has run in. This arrangement is shown in the dotted lines at the right hand top corner of Fig. 161. The weight of the winding faller connections is, of course, sufficient to lift it quickly out of contact with the yarn.

(348) The operations thus described constitute the fifth period, and at its termination the mechanism is again engaged in the work of spinning or twisting, being at the commencement of another cycle of movements. There is, however, one more piece of mechanism to refer to before the description of this machine can be brought to a close. It was seen that during the period of winding the chain was drawn off the winding scroll during the forward stroke of the quadrant arm. Referring to Fig. 172, which represents a portion of the mechanism relating to the quadrant, it will be seen by the arrows that during the outward run of the carriage, the quadrant =M= also makes its backward stroke. During the same period it is necessary to rewind on the winding scroll the chain =C= which was previously unwound, and this is effected by the cord =S=. =S= is attached at one end to a hook or staple =T=, fixed to the framing, and at its other end to a weighted lever =U=, pivoted on a bracket fixed to the floor. The cord =S=, in its course, passes over the two pulleys shown fixed to the carriage, and its tension is sufficient to cause the pulley on the shaft =X= to be rotated by the inward run of the carriage, thus winding the chain =C= on to the scroll. By the termination of the outward run this operation is concluded, and the chain is ready to act again efficiently as soon as winding recommences. When a “set” of cops—that is, the whole number spun on a mule—is finished, it is “doffed” or stripped from the spindles. As soon as this is completed the winding nut is wound back by hand to the bottom of the quadrant, and the copping plates are also restored manually to their original position.

(349) The description thus given of the machine as made by Messrs. Platt will enable an accurate idea to be obtained of the mechanical movements which are found in the work of a mule. It is true that this special machine differs in some of its details from many of other makers, and that there are motions fitted to it which are not found in other machines. When the latter are used, however, they tend to increase the automaticity of the machine. The winding chain shortening, or, as it is more correctly called, the nosing motion, and the backing-off chain tightening motion, are of this class, both tending to an increased efficiency. The main principles in a machine of this class are embodied in the mule described, and the general explanations given will prove serviceable, whatever may be the make of mule studied.

(350) One of the important points of difference between this and mules of other makes is found in the position of the cam shaft. This, it was seen, is in the Platt machine placed above the axis of the rim shaft. In other cases it is placed, as shown diagramatically in Fig. 173, along the headstock of the mule, and below the centre of the long or “balanced” lever =T=. In this case the cam shaft =K= is a tubular one, and has passed through its centre the shaft =M=, which is suitably driven from one end. The cam shaft is fitted with a friction clutch at =P=, the fixed half being on the tubular shaft. The other half slides on the shaft =M=, being pressed up to the fixed half by the spiral spring shown. On the long lever =T= at the point =L= a pendant cam plate is hung, which surrounds the cam shaft as shown in a detached front view and section in Figs. 174 and 175, and is formed with a slot so as to permit it to rise and fall freely. The cam plate has two raised cam surfaces or courses, against which the end of a pin is pressed by the action of the spiral spring. The pin passes through the half clutch fixed on the cam shaft, and presses against the sliding half on the shaft =M=. Thus when the pin is on the raised part of the cam plate the clutch is detached, while if it is on the lower part the clutch is in gear. When, therefore, the inner end of the balanced lever =T= is depressed, the fall of the pendant plate causes the pin to come upon the lower part of the cam course, and permits the engagement of the clutch. The cam shaft thus makes a half circle turn, and effects the necessary changes for beginning spinning. This causes the end of the pin to run on to the second cam course, and by the time the half revolution is made, it comes on the raised surface and disengages the cam. In this position it rests until the outer end of the long lever is depressed, when a similar action occurs, terminating in a similar way.

(351) The back shaft is also engaged and detached in a different manner. It is driven from the roller shaft by a train of wheels, but the last of the train is a compound one, consisting of a large wheel with a smaller pinion. The latter gears with the back shaft wheel, and is put into or out of gear accordingly, as it is desired to revolve or stop the rotation of the back shaft. For this purpose the compound wheel is borne on a hinged lever, called commonly the Mendoza lever, which is weighted in a suitable manner. The exact origin of the word Mendoza, as applied to this lever, is difficult to define, but it probably arises from the French phrase, _main douce_—Anglicè, the soft hand. However this may be, the function of the lever is to put the pinion into and out of gear with the backing-off wheel, and to effect this, its motion is controlled by a cam or eccentric on the cam shaft. This cam works in a fork in a lever, and the rotation of the cam shaft raises or lowers the Mendoza. The object of the weight is to ensure the full engagement of the pinion and back shaft wheel, so as to obviate any jumping out of gear at the commencement of winding. There is some tendency towards this unsteadiness of driving in the early part of the outward run, and it is desirable to lock the Mendoza lever in position.

(352) Messrs. John Hetherington and Sons employ a special device by which this difficulty is overcome. The mule, as made by them—arranged to be driven with the rim shaft transversely, instead of longitudinally, placed in the headstock—is illustrated in Fig. 176 in longitudinal elevation, and in Fig. 177 in back view. Both views show the method of driving quite clearly. On the outward end of the Mendoza weight a pin is fixed which takes into a fork formed at the upper end of a vertical lever. The fork is shaped with a shoulder or recess, below which the pin referred to can slip when desired to lock the Mendoza in position. A small ear is formed on the vertical lever, through which a set screw is passed, the point of which comes in contact with the end of a horizontal lever centred on a pin fixed in the headstock. The last named lever has a long tail extending outwards toward the carriage. When the carriage comes up to the back stops and the Mendoza lever falls, putting the driving pinion into gear with the back shaft wheel, the long tail of the horizontal lever is raised, and the effect is that the pin in the Mendoza weight passes under the shoulder of the fork in the vertical catch lever, and so firmly holds the Mendoza lever down. As the latter carries the driving wheel, the pinion is kept firmly in gear, and the effective driving of the carriage is obtained. As soon as the carriage has run out a little—by which time it has gained momentum—the horizontal lever is released, and its long end falls, thus freeing the catch or pin in the Mendoza. Sometimes the minder, in cleaning, runs out the carriage a little and then changes the cam, without freeing the horizontal or locking lever. If afterwards the mule is started the carriage endeavours to run in, although the back shaft wheel and its driving pinion are in gear. This leads to breakages, and in order to avoid these, Messrs. Hetherington have arranged a small relieving lever, coupled to the long lever, so that any motion of the latter causes the relieving lever to act and free the Mendoza catch pin, without reference to the position of the horizontal locking lever. This mule is arranged with the extra band for driving the taking-in side shaft =D= referred to in paragraph 286. The band =E= is driven from the counter shaft =R=, and passes round a double grooved pulley on =D=. It is kept in tension by the pulley =F=, carried by a frame which can be moved inwards by the quadrant rack =G= with which a worm gears. The remaining reference letters indicate the same parts as in the other illustrations.

(353) It was shown that to perfect the action of winding at the nose of the cop it is customary to deflect the chain by means of a nose peg. A motion based upon the principle of the deflection of the chain, but in which that object is attained in a different fashion, is shown in Fig. 178 in side elevation, and in Fig. 179 in enlarged detail. This is Dobson and Hardman’s patent, and is made by Messrs. Dobson and Barlow. Two main objects have been aimed at. These are the control of the winding from the faller—so that the relation of the two will be strictly maintained—and the deflection of the chain by a pull from below instead of a push from above. On the faller shaft a tappet is fixed, to which is jointed a lever =J= with an arm or finger =K= secured to it. A bracket =H= is attached to the quadrant arm a few inches from its centre, and its outer edge =H^{1}= is formed into a rack with which two catches engage. These are carried by a lever =G=, which is hung on a pin in the upper part of the bracket =H=. =G= has a projecting shoulder at its outer end, to which is fastened one end of the chain =E= passing over the pulley =F=, and having its other end attached to the lower end of the link =C=. The winding chain =B= is also attached to the link =C=. The lever =G= is formed with an arm =G^{1}=, to which is jointed a double tumbler =I=, each part of which is free to move as required. A projection is cast on =I=, which causes it to rest on =G= when in its normal position. This mechanism acts in the following manner: When a set of cops is begun the lever =G= is at its lowest position relatively to the quadrant rack =H^{1}=, and the winding chain =B= and link =C= are then almost straight. At the end of each stretch the finger =K= comes into contact with the lower part of =I=, which is raised to allow =K= to pass. When the inward run begins =K= causes the projection on =I= to press upon the lever =G= and raise it if the pressure is maintained a sufficient time. Whether this is so or not is determined solely by the vertical position of =J=, which, in turn, is regulated from the winding faller. If the latter is not substantially raised from stretch to stretch the position of =G= in like manner remains unaltered. If this is not the case =G= is a little lifted, and the chain =E= is thus drawn forward a little over the pulley =F=. The result is that a pull is exercised on the link =C=, which is drawn down so that it and the chain =B= no longer represent a straight line. This is equivalent to shortening the chain =B=, and the result is that the necessary acceleration of the winding drum is effected. The chief feature of this motion is the regulation which is obtained from the faller, the position of which fixes the amount of extra _pull_ put on the drum. However slowly the building proceeds the necessary acceleration is made in exact proportion.

(354) In the description of the governing motion, given in paragraph 339, it was shown that the rotation of the screw in the quadrant arm is made during the inward run of the carriage. There are some objections made to this procedure on the ground of the extra tension put on the yarn in the early part of winding, which is of some moment when fine or tender yarns are being spun. In Fig. 180 a side view is given of a motion made by Messrs. Dobson and Barlow, which is designed to obviate the necessity for altering the screw during the inward run, and provide means by which it can be made during the outward run. In lieu of the ordinary grooved pulley on the quadrant axis, a toothed wheel =U= is used, with which a toothed rack =R= can engage under circumstances presently to be described. The rack =R= is carried by a sliding frame =S=, which is fixed upon a longitudinal rod =T=, extending backwards in the headstock, and carried by brackets fastened to the floor. The rack is fitted at one end with an inclined foot, and at the other with a spring, which prevents too deep an engagement of the rack and wheel. The rack passes—during its outward stroke—over a frame fastened to the headstock, in which is a screw =X= on which is threaded the sliding stop =W=. The pitch of the screw thread is varied to correspond with the thread in the quadrant arm =Q=, and the screw is rotated by a ratchet wheel, with which a pawl, oscillated by a finger, engages. At the point =I= a loose tongue is hinged, which at the end of the stroke of the frame engages with the nut =W=. On the winding faller a sector =Y= is fixed, in which a stud, formed with two portions of different diameters, is bolted. On the counter faller a sector =Z= is fastened, carrying a screwed staple, to which is secured one end of a chain, indicated by dotted lines. The chain passes round the bowl =R= at the upper end of the pendant lever =O=, guided in brackets at the front of the carriage. The loose end of the chain is formed into a loop, which can be slipped on to either of the surfaces of the bowl in the sector =Y=. A hinged finger =L= is carried by a bracket on the rod =T=, and has a little range of movement in a circular direction.

(355) In beginning a set of cops the stop =W= is turned back to its proper position, which is determined by the size of the cop about to be spun. The frame =S= is then pushed forward as much as possible, and the chain is slipped on to the smaller portion of the bowl in =Y=. This allows the pendant =O= to fall a little, and its height subsequently is regulated strictly by the position of the fallers. During the outward run the horizontal arm =P=, which forms part of the pendant =O=, engages with the vertical projection on the frame =S= and causes it to move forward. The rack =R= being raised engages with the wheel =U= and rotates it, this movement being consequently communicated to the quadrant nut. Thus the latter is put into position for action during the next period of winding and any straining of the yarn is avoided. As the stroke of the rack is continued, the tongue =I= engages with the nut and causes the rack to drop out of gear with the pinion, and any further movement of the quadrant nut is avoided. It has been shown that the traverse of the latter is gradually diminished as the cop is built, and, in like manner, the inward motion of the stop =W= causes the engagement of the rack and pinion to be limited. This is a sort of “trip” motion very familiar to students of steam engine practice, and is well applied in this case. The slide =S= is drawn back into position by the engagement of the lower end of the pendant =O= with the finger =L=. A slight contact at first between these becomes a firm one by the backward movement of the finger when pressed upon by the pendant =O=, but it will be obvious that, if the latter is too high to move the finger =L=, the rack will remain untraversed until a sufficient depression of =O= takes place. It only remains to be said that once the nut =W= has been set at the beginning of winding, all that is required is for the minder to slip the loop of the chain on the right portion of the bowl in =Y=, and the motion acts automatically until winding is finished.

(356) A somewhat similar attachment has been recently introduced in France, and is the invention of Mons. Dubs. The author is informed by a trustworthy mechanician that the motion acts perfectly throughout winding, and it may, therefore, be well to give a brief description of it. As in the motion of Messrs. Dobson and Barlow, the regulation of the nut takes place during the outward run, and it is unnecessary to again detail the reasons for this course. The chief operating part of the mechanism is the rack finger =A=—shown in its position when in gear—which is hinged on a vertical rod or plunger =K=, sustained in a frame or bearing =S= fastened to the carriage. Referring to Fig. 181, the whole of the apparatus moves with the carriage and is self-contained. Attached to the faller is a connecting rod or link =B=, which is coupled to a hinged lever =O= formed at its outer end with a toothed rack or quadrant finely pitched. With this rack, which has two sets of stepped teeth, two detent catches =H= engage. The lever =O= is hinged to a plunger =L=, which has at its lower end a screwed shank fixed to a plate =F= also secured in the same manner to the plunger =K=. The inner end of the rack lever =A= has a hanging piece =D= which can engage with a catch =E= on the plate =F=, but which in the view is shown out of gear. The downward motion of the inner end of =A= is regulated by the stop screw =R=, and it is coupled by the chain =C= to the counter faller. The spring =M= constantly presses the inner end of =A= down, tending to raise the rack. When the various parts are adjusted the parts =F K= and =L= move together and simultaneously with the lever =O=.

(357) The action of this mechanism is as follows: Assuming that the inward run of the carriage is nearing completion, the lever =G= engages with a stop or bracket fixed to the floor, which causes =D= to fall out of gear with the catch =E=. This leaves the plate =F= and all its connections to the control of the chain =C= and the counter faller. When the faller locks it raises the rod =B= and the lever =O=, which is then held in position by the detent catches =H=. During the first inward run =O= is lifted to its highest point, which, of course, affects all the parts attached to it. Just before the end of each stretch the catches =H= are released, so that the whole of the subsequent regulation depends on the counter faller. As the locking point of the winding faller wire is gradually raised the elevation of the fork at the upper end of =K=—which by reason of the connection of the plate =F= with the lever =O= always takes place—occurs at a gradually lower point throughout building. The effect is that when =D= is released, as described, an elevation of the rack =A= takes place if needed. If not, =D= falls over the catch =E= as the carriage begins to run out and thus locks it, preventing the rack =A= from rising. If, however, the tension on the yarn at the end of winding is such that the counter faller is depressed, the catch =D= cannot recover its position. The end of the rack lever consequently falls on to the stop screw =R=, and the rack is raised into contact with a wheel on the quadrant axis formed with teeth of a similar shape. Thus the screw is given a turn while the carriage is running out, and the nut is in the correct position for winding the next length.

(358) Quite recently Messrs. Curtis, Sons and Co. have constructed a mule in which the cam shaft, as an instrument for making the “changes,” is entirely done away with. A side elevation of the mechanism for effecting this is shown in Fig. 182, and a plan of the same in Fig. 183. The back shaft clutch =F= is formed so that its driving half slides, this being controlled by the action of a lever =L=, connected, as shown, at two points to the rods =R M=. The taking-in friction is placed horizontally, and is controlled by the vertical lever =H= connected with the sliding rod =R=. The lever =F^{1}=, by which the back shaft clutch is disengaged, is coupled by the link going across the carriage—shown in Fig. 183—to the roller clutch box, so that the engagement or disengagement of the roller clutch box is simultaneous with the attachment or detachment of the roller gear. The mechanism for actuating these parts is based upon the principle of the push and pull of spiral springs, a partial application of which was shown in the case of the backing-off rod. On the axle of the quadrant a short arm =S= is fixed, which is coupled with the rocking lever =T=, connected to the sliding boss on the rod =M=. Two springs =M^{1} M^{2}= are threaded on the shaft, and are placed respectively between the sliding boss and stop hoops fixed on the shaft. The rod =M= is coupled at the back to the lever =L=, the function of which is, as indicated, to actuate the back shaft clutch. At the front end of the rod =M= a catch lever =Q= is fixed, which detains it as the carriage is running out. When this happens, the spring =M^{1}= is compressed by the oscillation of the quadrant axle acting through the crank =S= and its connections, the other spring =M^{2}= being then out of compression. As soon as the end of the outward run is reached a boss on the counter faller shaft =B^{1}= comes in contact with the underside of the catch lever =Q= and raises it, thus freeing the rod =M=. The spring =M^{1}= is thus free to extend, and, acting upon the lever =L=, disengages the back shaft and roller clutches. This accounts for one part of the changes; and while it is taking place a catch lever =O=, which had previously been raised, is lowered. When the inward run of the carriage is made by the operation of the same parts the spring =M^{2}= is compressed. On the arrival of the carriage at the roller beam the lever =O= is tripped by a boss on the faller shaft =B=, allowing the spring =M^{2}= to extend and re-engage the two clutches named.

(359) The taking-in or scroll shaft is operated from the rod =R=, which is fitted with one spring only at its back end. This is compressed by the intervention of a second lever, fastened on the same shaft on which the rocking lever =T= oscillates, the compression taking place during the outward run of the carriage. The spring is held in compression by a latch =P=, which engages with a lug on the rod =R=. When the carriage runs in, a boss on the faller shaft releases the latch, and the extension of the spring disengages the taking-in friction clutch. The latter is put into gear by the locking of the faller in the ordinary manner, and is held in gear until the latches =O= and =P= are tripped in the manner described. The spring =R= presses on a collar carried by the lever =H=, and the releasing of the friction is aided by the lever =L=, which comes against the head of =H= when the spring =M^{2}= is extended. The levers =H= and =L= are so arranged that they cannot both act together, so that the two motions of taking-in and drawing-out cannot be in action at the same time.

(360) The angle of the spindle relatively to the vertical line is such as is necessary to suit the material being spun, but there is another feature which it is necessary to mention. As the point of the spindle moves in a horizontal plane, it is obvious that the yarn will pass on to it from the rollers at an angle varying with its distance from them. That is to say, the angle formed by the yarn, in passing on to the spindle, will be more acute when the carriage is near to the rollers than it will be when it is further away. This has a little influence upon the problem of spinning, and an arrangement exhibited at the Manchester Jubilee Exhibition, applied to Messrs. Asa Lees and Co.’s mule, is shown in Fig. 184. In this case there are two carriage slips instead of only one, and these are inclined so as to compensate for the difference in angle. On one of the slips =A= the front carriage runner =D= travels, and on the other the back one =C=. The result is that the inclination of the spindles is slowly altered, with the result that the angle formed by the yarn and the spindle in each case, is nearly the same in all positions. This device worked well, but the difficulty existing does not appear to be great enough to lead to any wide adoption of it.

(361) Having thus described in detail the construction and principles of the mule, it is only necessary to say a few words on the subject of its application to the spinning of the finer counts, which require specially delicate treatment. It is found necessary to fit a few special attachments which are supplementary to the ordinary mechanism employed. In dealing with fine yarns the rollers are stopped a little before the carriage has completed its outward run, and this results in the yarn being a little stretched. A more important result, however, is that if there be any unevenness in the diameter of the yarn, the twist speedily runs into the thin places, which become hardened, and do not easily elongate or draw. The thicker places remaining untwisted are, therefore, drawn down until the full twist runs into them also. This supplementary twisting and drawing is called “jacking,” and its amount varies, of course, with the staple of the cotton being spun, the further movement of the carriage being sometimes as much as five inches. In order to permit the jacking to be effective, it is the custom to put into the yarn very little twist before the roller delivery ceases, after which it is rapidly introduced. This tends to shorten the yarn and puts it in such a state of tension, that unless relieved, it would break. There are two methods of obviating this difficulty. The first is to move the carriage in a little during the period of twisting, and the other to cause the rollers to deliver a short length of yarn. The latter is now the most usual method, and by the adoption of a special engaging motion, the amount delivered can be regulated at will. When long stapled cotton is being spun, it is the practice to cause the rollers to deliver a little yarn during the inward run, while winding is going on. The amount varies, but is about three inches, so that only 60 inches is wound on the spindle during each inward run. Messrs. Platt Brothers and Co. make a very good fine spinning mule with a number of well thought out motions of great ingenuity, a full description of which will be found in the Proceedings of the Institution of Mechanical Engineers, 1880, pages 516 to 527.

(362) Mr. Richard Threlfall of Bolton has devoted himself to the construction of fine spinning mules, and has produced a self-acting machine, which is capable of spinning the highest counts. With a brief description of it as made by him, the present treatment of this machine must be closed. In the Threlfall mule the roller delivery after jacking is effected by a short shaft on which is a catch box, the outer surface of which constitutes a cam course, which is revolved from the twist shaft. On this cam shaft is the first of a train of wheels, which gear up to the roller, and the first wheel has motion given to it by a ratchet and pawl, the movement of the latter being controlled by the throw of the cam. The cam can be set so as to give a whole turn to the rollers, or only one flute, and by means of changes in the train of wheels further regulation can be made. The copping rail is specially constructed, so as to enable short cops of any shape to be easily built. The fallers are arranged so as to be very sensitive in action. The action of the quadrant is aided by a special contrivance consisting of a narrow pulley placed alongside the loose backing-off pulley, but fast on the shaft. Connected to the strap guide is a lever which is coupled to a rod suitably carried in brackets, and on which is a regulating screw and nut. This regulation is provided so that the passage of the strap on to the narrow pulley is effected as desired. The strap is prevented from traversing from the loose pulley by a catch, and the release of the latter is effected by a finger on a bracket fastened to the carriage square. When the latter runs in the finger pushes over a tumbler holding the catch in position and releases the latter. The weight of the parts then throws the strap over on to the fast narrow pulley, and the winding is thus accelerated. By fixing the finger and setting the adjusting screw, this motion may be brought into play at any desired moment. On the faller shaft is a bracket, to the outer edge of which is attached by a bolt or screw a grooved cam surface. To this is attached a cord actuated by the governor motion. By suitably setting the cam, winding is effected during each inward run with equal tension. A brake is applied to the faller shaft, consisting of a lever fastened to the carriage, one end of which engages with an inclined plane, and the other end has a cord attached passing over a pulley on the faller shaft. By tightening the band the faller is held perfectly steady. The combination of the last three motions effectually prevents snarls. A roller delivery motion is added, and the most perfect adjustment of the whole of the movements is provided. The spindles revolve at two speeds, the final or twisting velocity being about 8,000 revolutions per minute.

(363) Such is a description of the most intricate machine in the whole range of textile mechanics, which, although threatened more than once with extinction, is yet more largely used to-day than at any previous time. On it yarn of varying qualities can be spun, either soft or hard twisted. The yarn which is used for warp purposes is more commonly known as twist, and that employed for weft is known by that name. Weft yarn, as will be shown at the end of the next chapter, is always more softly twisted than warp yarn, and the mule spindles revolve in the opposite direction to that employed when the latter is spun. About the question of twists and the system of the arrangement of draughts throughout the whole process of spinning, a few words will be said in concluding the next chapter.

(364) The mule is used in a modified form to produce “doubled” warps-that is, two strands of yarn twisted together. When so employed, the machine is known as a “twiner,” and is constructed with a low creel. With the necessary alterations to suit the circumstances peculiar to the case, the machine is largely employed in certain districts. In its main features, however, it resembles the mule, and does not require a detailed description. Another modified form is used for spinning yarns made from waste, being nearly identical with the machine as employed in spinning fine worsted yarns. The student who is interested in this subject will find a description of the woollen mule in “Spinning Woollen and Worsted,” by Mr. W. S. Bright McLaren, M.A.

(365) A table is appended of actual productions from Messrs. John Hetherington and Sons’ mule. These are given from 74 machines for the ordinary working week of 56-1/2 hours. A great variety of counts are included, all of which were being spun at the same time. An additional table is given of productions from Messrs. Platt Brothers and Co.’s mule. An explanation of the value of the hank is appended to the next chapter.

TABLE 2.

ACTUAL PRODUCTIONS IN A WORKING WEEK OF 56-1/2 HOURS, FROM MESSRS. JOHN HETHERINGTON AND SON’S MULES.

+--------+----------+---------+-----------+
| No. of | Hanks. | Counts. | Hanks per |
| Mule. | | | Spindle. |
+--------+----------+---------+-----------+
| 2 | 77,250 | 39 | 31·14 |
| 4 | 70,750 | 43 | 28·52 |
| 6 | 71,000 | 43 | 28·62 |
| 8 | 75,500 | 41 | 30·44 |
| 10 | 65,750 | 32 | 32·42 |
| 12 | 68,750 | 28 | 33·90 |
| 14 | 61,750 | 36 | 30·44 |
| 16 | 71,750 | 45 | 28·73 |
| 18 | 69,750 | 45 | 27·94 |
| 20 | 72,250 | 45 | 28·94 |
| 22 | 71,750 | 45 | 28·73 |
| 24 | 71,000 | 45 | 28·43 |
| 26 | 71,250 | 45 | 28·53 |
| 28 | 71,250 | 45 | 28·53 |
| 30 | 72,250 | 45 | 28·93 |
| 32 | 73,000 | 42 | 29·23 |
| 34 | 72,500 | 42 | 29·03 |
| 36 | 61,500 | 36 | 29·97 |
| 38 | 66,750 | 32 | 32·52 |
| 40 | 62,000 | 38 | 30·21 |
| 42 | 58,500 | 38 | 28·50 |
| 44 | 62,750 | 36 | 30·57 |
| 46 | 62,250 | 38 | 30·33 |
| 48 | 63,250 | 36 | 30·82 |
| 50 | 60,250 | 38} | 29·35 |
| | | 33} | |
| 52 | 64,750 | 34 | 31·55 |
| 54 | 65,750 | 36 | 32·03 |
| 56 | 65,000 | 40 | 30·52 |
| 58 | 61,750 | 40 | 29·91 |
| 60 | 61,000 | 42 | 29·55 |
| 62 | 60,000 | 42 | 29·06 |
| 64 | 63,000 | 40 | 30·52 |
| 66 | 61,500 | 40 | 29·79 |
| 68 | 61,500 | 42 | 29·79 |
| 70 | 61,250 | 42 | 29·67 |
| 72 | 59,750 | 42 | 28·94 |
| 74 | 65,750 | 40 | 31·85 |
+--------+----------+---------+-----------+
| Total Weight, 59,920-1/2 lbs. |
| Average Counts, 39·53. |
| Average Hanks per Spindle, 29·88. |
+-----------------------------------------+

TABLE 3.

ACTUAL PRODUCTIONS IN A WEEK OF 56-1/2 HOURS OF TWIST AND WEFT YARNS FROM MESSRS. PLATT BROTHERS AND CO’S. MULES.

+-----------------------------------+
| TWIST. |
+-------------+----------+----------+
| No. of | Counts | Hanks |
| Spindles in | spun. | per |
| each Mule. | | Spindle. |
+-------------+----------+----------+
| 1044 | 30’s | 32 |
| „ | 32’s | 31·5 |
| „ | 33’s | 30·65 |
| „ | 24’s | 30 |
| „ | 50’s | 28 |
| „ | 54’s | 27 |
+-------------+----------+----------+
+-----------------------------------+
| WEFT. |
+-------------+----------+----------+
| No. of | Counts | Hanks |
| Spindles in | spun. | per |
| each Mule. | | Spindle. |
+-------------+----------+----------+
| 1280 | 28’s | 33·81 |
| „ | 29’s | 34 |
| „ | 34’s | 31·85 |
| „ | 36’s | 31 |
| „ | 38’s | 30·46 |
| „ | 40’s | 30 |
| „ | 46’s | 29 |
+-------------+----------+----------+

NOTE.--The production of any mule varies of course with the class of cotton used, the amount of twist required, and the length of mules; but the figures given in the tables are, in each case, figures of actual productions.