Cotton Weaving and Designing / 6th Edition

by John T. Taylor

In the Hattersley loom, the reserve supply of shuttles that have been previously furnished with weft are retained in a hopper or magazine which is mounted on the breast-beam and facing the shuttle-box on either the right-or left-hand side of the loom. The changing of shuttles may be effected either by the action of the weft-fork only when the weft actually fails from any cause, or else by the operation of a weft-feeler, before the weft completely fails, as desired. In either case a change of shuttles involves a series of six distinct operations which occur in the following sequence, namely: (1) stopping the loom, (2) raising the shuttle-box fender, (3) ejecting the failing shuttle from its box, (4) removing from the magazine another shuttle and placing it in the emptied shuttle-box, (5) lowering the shuttle-box fender back into its normal position, and (6) restarting the loom. These operations, of which the second, third, and fourth are represented by diagrams in Figs. [169], [170], and [171], are accomplished by means of a series of four tappets governed by an indented clutch-wheel, all of which are loosely mounted together on the second-motion or picking-shaft, at the same side of the loom as that on which the driving-pulleys are situated. The clutch-wheel is driven by means of a pinion carried by the loose driving-pulley, and revolves continuously, so that when a change of shuttles is called for, an indent or notch in the clutch-wheel becomes engaged by a lug which, being secured to the tappets, turns these for one revolution, and thereby performs the series of operations just enumerated. Thus, in the event of weft either failing or becoming nearly depleted, either the weft-fork hammer or else the weft-feeler motion, according to the equipment of the loom, first disengages the starting-handle to pass the driving-belt from the fast or driving-pulley to the loose pulley, thereby stopping all the primary movements of the loom, and at the same time putting into operation the series of four tappets which effect the changing of shuttles. Then one of the four tappets raises the shuttle-box front, C, above the shuttle B, as shown in [Fig. 169], to permit of the removal of the shuttle. A second tappet then operates the pusher D, which advances to eject the discarded shuttle from its box, whence it falls into a receptacle, as shown in [Fig. 170]. A third tappet next operates the feeder E, which removes the bottom shuttle from the hopper A and places it in the same shuttle-box as that previously occupied by the ejected shuttle, as represented in [Fig. 171]. The shuttle-box fender now falls sufficiently to prevent the withdrawal of the newly inserted shuttle from the box as the feeder withdraws and returns to the magazine to receive another shuttle in readiness for the next change, after which the shuttle-box front falls to its normal position, and finally the fourth tappet replaces the starting-handle into its operative position to transfer the driving-belt back again from the loose to the fast driving-pulley and thereby re-start the loom.

FIG. 171.

All the movements just described are performed during one complete revolution of the tappets, and involve a stoppage for six picks, corresponding to six revolutions of the crank-shaft. Therefore, in a loom running at a speed of 180 picks per minute, the changing of shuttles would involve a stoppage of the loom for only two seconds.

CHAPTER X
THE PRINCIPLES OF DESIGNING

THE simplest form of interlacing the threads is the plain or tabby weave. In this weave the threads intersect as often as possible, and thus the greatest possible amount of firmness and strength is obtained from a given quantity of material by this weave, with the exception of leno or cross weaving, where additional firmness and strength is obtained by the warp threads being partly twisted round each other in weaving. Plain cloths may be ornamented by using threads of different colours and of different thicknesses, as, for instance, if four picks of blue and four picks of white are alternately put into a cloth, the warp of which is composed of four ends blue and four ends white alternately, a check is formed although the weave is quite plain. A check may also be formed on a plain cloth by using one or more thick threads at intervals in both warp and weft.

There is, of course, a limit to the number of threads of a certain count which can be put into a plain cloth. Assuming that the counts of warp and weft are equal, and that the number of picks per inch required is the same as the ends, the number of threads per inch which can be satisfactorily put into the cloth would not much exceed half the number which could be placed side by side in one inch. Some allowance must be made for the threads being bent out of a straight line and for compression. This branch of design will be treated of more fully in a subsequent chapter, but it will be obvious that this limit to the number of threads of a given count which can be used in a plain cloth renders the weave unsuitable for heavy fabrics. If a plain cloth is very heavy and thick, it must of necessity be coarse.

FIG. 172.