Cotton Weaving and Designing / 6th Edition

by John T. Taylor

WHITESMITH’S DROP-BOX.

The principle of Whitesmith’s motion is probably the best for any number of boxes. It is usually made for four, and the change may be made with certainty from one box to any other. The arrangement for working four boxes in a loom is illustrated at Figs. [78], [79], [80]. The principle will be best understood by referring first to [Fig. 80]. The four different positions of the boxes are here shown. The boxes are connected to the ring or strap of an eccentric at the point E, and at A the position of the parts is shown when the boxes are at their lowest point. The eccentric, F, on the shaft has a lift of one box, and therefore by causing it to make half a revolution intermittently every two picks, the boxes would be alternately lifted and dropped a space of one box, as will be seen by referring to C ([Fig. 80]), where it has made half a revolution from its position at A. It will be seen that E is one box higher at C than at A. Starting again from the first position, as at A, by turning the outer ring halfway round and leaving the eccentric stationary, there will be a lift of two boxes. This is shown at B ([Fig. 80]). Again starting with the first position, as at A, if we turn the outer ring halfway round, and at the same time turn the eccentric F half-round, we lift a space of three boxes—that is, from the first to the fourth box. The position of E in this case is shown at D ([Fig. 80]). We thus see how from the bottom box any other of the four can be reached. By turning the eccentric halfway we lift one box, by turning the ring halfway round we lift two boxes, and by turning both ring and eccentric halfway round we lift three boxes. If we are at the third box, as at B ([Fig. 80]), and we wish to reach the second box or one lower, by turning the eccentric half a revolution and the ring half a revolution we shall get the position required. It will thus be seen that any one of the four boxes may be reached at will. At [Fig. 79] another view of the eccentrics and boxes is given. The wheel H is keyed to the shaft on which the eccentric is fixed, and riding loosely upon this shaft is another wheel, I, of the same size, to which a fork, K, is attached. This fork fits on to a pin at the back of the ring, and thus by turning the wheel I the ring can be moved independently of the eccentric. If the wheel H is moved it moves the cam, and if the wheel I is moved it moves the ring. Referring now to [Fig. 78], the wheel H is shown. This wheel is driven by a wheel, I ([Fig. 79]), twice its size. On the face of the wheel L there are four pins, and by lifting the lever OP at O, the pulling hook M is dropped round one of the pins, and the hook being moved forward by the crank Q will cause the wheel L to make a quarter of a revolution and the wheel H to make half a revolution, and therefore the eccentric is moved half a revolution. On the same stud as the wheel L there is another wheel exactly the same size and with four pins; this wheel (which cannot well be shown in the diagram) gears into the wheel I shown in [Fig. 79]. There is also another pulling hook which works along with M. This second pulling hook is operated by another lever like OP. There are two levers, X, which are lifted by the cards, and by lifting X, either, or both, of the pulling hooks may be dropped, and either of the wheels I or H ([Fig. 79]) turned half a revolution, but always in the same direction.

FIG. 78.

FIG. 79.

FIG. 80.

The wheel L and its companion are prevented from turning too far by a strong friction arrangement.

This motion may be adapted to work six boxes, or even more. For six boxes there is another eccentric inside the first eccentric, which can be worked independently; this will, of course, require a third pulling hook, and so on.

Many loom-makers have patented arrangements on the same principle, which do away with the pulling hooks M, and it is probably in this direction that the motion may be improved.

The Whitesmith principle is simple, and positive throughout, and it is difficult to see why it is not in more general use. It is generally admitted by those who have had practical experience of drop-box looms on this principle that it is the best. There are other drop-box motions, but the foregoing are the chief kinds.