Fig. 159.J.N.
(307) It is hardly practicable to fit a motion of absolute accuracy to effect this purpose, but an approximation to it can be obtained. It is, therefore, arranged that at the beginning of a set the backing-off chain shall be slack, and during building shall be gradually tightened until at the end of it is nearly in a state of tension. The snail is proportioned so as to give a quick downward movement to the faller, and in combination with the arrangement about to be described gives very good results. Referring again to Fig. [160], attached to the snail G is a second chain, the other end of which is fastened to a lever H, hinged on the bracket shown. The other end of H rests on an inclined plate N, which slides on a bedplate fastened to the floor. The plate N is fastened to the copping plate connecting rod—afterwards referred to—which passes through a horn fastened on N. As the copping plate is moved in, H is also caused to assume the position indicated by the dotted lines, N having also moved in. The effect is that a pull is put upon the snail which gradually rotates it, and causes it to wind on the slack of the chain E, so that, when backing-off occurs, the faller is drawn downwards at an earlier moment. The restoration of N to its original position accompanies that of the copping plate, and is made at the beginning of a new set of cops.
(308) The various movements in connection with backing-off having thus been described, it is necessary to show how the traverse of the faller is obtained during the inward traverse of the carriage. This is shown in Fig. [161], page 205, which is a separate view of the copping or building mechanism. The faller “locking” lever A is, as has been described, raised until the shoulder R slips on to the slide L, in which position it remains until it is released at the termination of the inward run. On the underside of L a small bowl or runner L1 is carried, which rests upon the upper surface of a longitudinal, or “copping” rail P, made of a strong section. If the latter was placed in such a position that its upper surface was horizontal, it is plain that the slide L would receive no vertical motion during the period that the runner L1 was traversing it. In consequence the sickle U would remain in one position during the same time. But if the rail P is raised at one end so that its upper edge is inclined, the slide L will, during the run in of the carriage, receive a vertical traverse corresponding to the difference in the altitude of the two ends of the copping rail. That is to say, if one end of the rail was six inches from the floor line, while the other end was seven, L would ascend or descend to the extent of one inch while it was travelling from one end to the other of the rail P. The question as to whether it would ascend or descend depends entirely upon which end of the rail was highest. From this it may be inferred that by varying the angularity or profile of the copping rail any desired traverse, either regular or intermittent, could be given to the slide L. Now it was shown that the winding faller sickles are keyed on the shaft B, which is oscillated by the backing-off finger D fastened upon it. The latter being jointed to the “locking” lever A, it follows, that, as the latter is raised, the winding faller moves in an arc, which corresponds in length and direction to the length and inclination of the copping rail.
(309) It is necessary when the carriage arrives at the end of its stretch to lock it in that position during the time that backing-off is taking place, and the motions of releasing the counter faller and locking the winding faller are in operation. A reference to Fig. [162] is necessary to understand this part of the mechanism. That illustration is a diagrammatic representation of the mechanism relating to locking the carriage, and the engagement and disengagement of the taking-in gear. The parts are not in their working position, but are projected so that their operation may be better understood. The actual relative position of the various motions is shown by the diagrammatic sketch in the right hand top corner of Fig. [162]. Upon the carriage O a bracket O1 is fixed, which carries at its outer end a pin or catch, with which the hook at the end of the horizontal arm of the L lever S can engage. The hook readily falls over the pin in O1, as the carriage is pushed up to it near the end of its traverse. The lever S is coupled in the manner shown to the horizontal rod R, which, at its other end, is jointed to a bell crank lever U1. The rod R, on account of its function, is termed the “holding-out catch rod.” The lever U1 is in turn connected with the rod U, jointed at its upper end to the lever W, which is coupled to the horizontal arm of the lever Z1 by the connecting rod M. A connection is thus established between the cam Z on the cam shaft and the “holding-out” catch lever S. During the run out of the carriage the friction clutch I1 K is disengaged by means of the lever W. The rod R is also locked by the small vertical slide S1, which engages with the catch notch formed in it. The movement of the backing-off rod X, which is hinged to the lever L, causes the projecting arm in the lever Y to be pushed under the end of the lever W, thus sustaining the latter and preventing the engagement of the upper half I1 of the taking-in friction with the lower half K. This action occurs just before the termination of the outward run, being a little in advance of backing-off, but simultaneous with the compression of the backing-off spring on X. Whatever movement of W may take place after the arm on Y is thus projected into the path of the end of the lever W, the friction cannot fall into gear until the support of the arm is withdrawn. The whole of these parts are thus locked together, and fall into gear simultaneously. It will be noticed that the connection between the lever S and the rod R is such that the latter can make a certain movement forward before the lever falls. Further, the carriage can be arrested during its outward run by the pedal lever fixed to the floor.
(310) The action of the mechanism is as follows: When the carriage arrives at its outermost point the connecting rod R is unlocked, and is free to move. In this way the catch lever S can be easily raised by the bracket on the carriage O, over which it falls, and securely holds it, the slot in the rod R permitting this movement. In this position it remains during the whole period of backing-off, when in a way which is afterwards described, it is released simultaneously with the taking-in friction with which, as shown, it is connected. The locking of the carriage is the last operation requiring explanation before proceeding to deal with the movements, which, together, make up the fourth stage or period. This is the one in which the nicest problems require solution, and in which the mechanism used is the most ingenious.
(311) The first step in commencing to wind is, of course, to release the carriage and draw it in. Before proceeding to show how this is effected, it will be as well to recapitulate and describe the position of the various parts. The strap is entirely upon the loose pulley; the backing-off friction clutch is in gear; the spindles are revolving in the opposite direction to that normal to them; the winding faller is drawn down and locked in a position a little below the nose of the cop; the counter faller is held just out of contact with the threads, but free to rise as soon as an inward movement of the carriage occurs; the roller and back shaft clutches are disengaged; and the upper half of the taking-in friction is out of gear with the lower, but revolving with the vertical shaft on which it slides.
(312) When the chain E (Fig. [160]) has sufficiently raised the faller locking lever A to permit it to lock, the swinging lever V is suddenly drawn back. An examination of the drawings, either Fig. [160] or Fig. [161], will show that so long as the face of the locking lever presses against the face of the slide no lateral movement of the former is possible. Further, the connection established between the locking lever A and the lever V, by means of the lever F1, ensures that as soon as the inward movement of the lever takes place when locking occurs, the lever V must necessarily oscillate on its pivot. This movement of the lever V causes its lower jaw to exercise a pressure upon the lever L in the contrary direction to that previously noted, and so draws the stop X1 in contact with the bottom of the backing-off lever D. This action is aided by the spring on the backing-off rod, which is free to extend, and its whole force can be exerted on the lever D. In this way D is drawn back, and the backing-off clutch is disengaged.
(313) The same movement draws away the supporting piece on the vertical lever Y, and allows the upper half of the taking-in friction to fall into gear with the lower half, this action being aided by the spring Q. The slot in the end of the connecting rod M permits the upward movement of the left hand end of the lever W to be made rapidly and freely. In this way the engagement of the friction clutch is a very quick one. This upward movement of the lever W is communicated, in a manner described, to the holding out catch, which is also raised nearly simultaneously, and the carriage released.