(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.
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 E1 I. The former is coupled to a sector E, which is secured on the counter faller shaft or rod B1. 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 B1, 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 E1, which is caused to pull upon the sector E. In this way the counter faller rod B1 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 F1, 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 L1. 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.
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.