(318) When the first layer of yarn is wound, and the winding faller is assuming its position to wrap on the second, the initial point of its traverse is a little raised. In this way the yarn is gradually wound in layers, which are represented by the angular lines springing from the lines =A E= and =D F= towards the spindles. During this period the enlargement of the diameter of the cop bottom is proceeding until at the points =E F= the full diameter of the cop is reached. As soon as this occurs the initial point of each layer is gradually raised, and the length of the traverse is slowly diminished as the completion of building is approached, until at the termination of a cop the angle of the layers is shown by the lines =G H= and =I K=. There are thus two adjustments shown to be necessary—first, the starting point of each traverse of the winding faller requires altering; and second, its extent also needs regulation.
(319) These two objects are attained by the regulation of the copping rail =P=, as shown in Fig. 161. The ends of this rail rest upon inclined “copping” plates =Y X=, which are fastened together by the rod =W=, and which receive, as will afterwards be described, an inward movement during the building of the cop. It was shown that the locking of the faller lever and its vertical movement leads to a corresponding movement of the faller. If, for instance, the faller locking lever fell an inch, the winding faller sector would be oscillated and the faller wire drawn upwards. The rate of the ascent of the latter is absolutely relative to the period of the descent of the locking lever. Referring now to Fig. 165, which is a small diagrammatic sketch of the copping rail and its supports, suppose the line =G H= to represent the top of former, =O P= the latter, and =L= the bowl at the foot of the locking lever, if =L=, starting from the left hand position, be supposed to travel in the direction of the arrow =V=, it will be seen that it will fall to the extent indicated by the space =Y Z=. If, on the other hand, the slides =O P= are moved into the position shown by the dotted lines, the rail =G H= will also fall into that indicated in a similar manner. The result is that if =L= now makes the same traverse as before it will rise a little as indicated by the space =W X=. The effect on the winding faller would be that in the first case it would be raised, and in the second it would be depressed to an extent corresponding to the depression of the locking lever. The extent to which this elevation or depression is made depends upon the vertical traverse of the locking lever, and the ratio of the distance of the point of junction of the sector =C= with the faller shaft and that of the faller wire from the same rod. If, for instance, this proportion was 1:2, an elevation of the locking lever half an inch would result in a depression of the faller an inch. It is therefore necessary, during the inward run of the carriage, to provide for the inclination of the carriage to such an extent as to secure the requisite traverse of the faller wire. As the amount of such traverse varies during the building of the cop, it follows that the inclination of the copping rail must be varied correspondingly.