Fig. 180.J.N.
(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 F1, 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 M1 M2 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 M1 is compressed by the oscillation of the quadrant axle acting through the crank S and its connections, the other spring M2 being then out of compression. As soon as the end of the outward run is reached a boss on the counter faller shaft B1 comes in contact with the underside of the catch lever Q and raises it, thus freeing the rod M. The spring M1 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 M2 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 M2 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 M2 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.
Fig. 181.J.N.
(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.
Figs. 182 and 183.J.N.
(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.