In hand-loom linen damask the shot is struck up when the shed is about half closed; the warp is held so firm in the loom that there is no spring in it, and the weft does not rebound. A cleaner surface is thus made on the cloth than if the weft was struck up in a closed or cross shed.
In a single-acting machine the faults in the cloth are more readily seen than with a double-acting one, as, in case of a hook missing the knife, in a single machine it would show in a short time, whereas in a double-lift machine one hook of the pair might be missing the knife and the other taking it, so that it might be some time before it would be observed. One of the tail cords breaking might have a similar effect.
The foregoing gives a general description of working the jacquard; but no hard-and-fast lines can be laid down—a little variation may be necessary at any time, to suit circumstances and the class of work.
JACQUARD STOP MOTION
When working with two cylinders, one may happen to be turned at a time when it should not, and thus put the cards out of rotation. Many attempts have been made to overcome this difficulty by stopping the loom when the cards get out of the proper order, but none of the methods adopted have ever gained much favour. Recently a new motion has been patented, and is being applied to machines by Messrs. Devoge & Co., of Manchester. It is called the ‘Devoge jacquard stop motion.’
Fig. 44
[Fig. 44] shows how it may be applied to a machine. The hooks A and B and the needles E and F are those here used to work the motion. They may be at either side of the machine, but should be at the side of the belt handle. One hook must belong to the front cylinder needles, and the other to the back ones. The hook A requires a lingo attached to it to draw it down after being lifted. The hook B is attached to a lever connected to the side of the loom, so that when one end is raised a hammer on the other end pushes off the belt handle (a lever and bracket are supplied for the purpose). C C1 is a wire bell-crank lever with a turn or loop on it at D to act as a spring. The fulcrum is at L, on a piece of iron bolted to the edge of the machine; the lower end of this lever passes through an eye in the hook A at C1, and the upper end passes through an eye in the needle E. There is a spring on the point of the needle E, between the face-plate and the eye, which the lever goes through, and which holds the needle back as shown.
Each time the hook A is raised the lever presses forward the needle E, and with it the hook B, which would then be raised by the lower griffe, unless the card pressed the needle back again and pushed it off. Thus, by having a hole cut in the cards for the needle F, and none for the needle E, the hook B would never be raised; but if a hole is cut for E in a card following one in which a hole was cut for F, the hook B would be raised and the loom stopped. It is, therefore, only necessary to arrange the cutting of the cards to allow the loom to work when they are following each other in rotation; but as soon as one card gets out of order the loom should be stopped, though, perhaps, not till it has run for a few shots. Thus—