Jacquard Weaving and Designing

by T. F. Bell

Fig. 28

Figs. 28 and 29 show two varieties of these motions. A is the cylinder head; C, the catch for reversing the cylinder; F, the spring for returning the catch to its position; E, a cord which hangs down, with a knob on the end of it, in a convenient position for the weaver to catch and work the motion. In [Fig. 28] the motion is on the opposite side of the machine to the shears, but might be on either side, and the weaver has to raise the shears to turn the cylinder, which she can easily do by catching the knob for raising the shears in one hand, and working the reversing motion with the other. The cylinder must be full out for this motion to turn it properly, and this prevents the weaver from tearing the cards on the needles, as she might easily do by trying to turn the cylinder when it is too close in. In [Fig. 29], B is the shears for turning the cylinder, and both it and the pushing catch, C, pass through a keeper or bracket, D, on the side of the machine. There is a rise on C a little back from the point, and when the cord E is pulled down C is shot forward by the lever, which has its fulcrum at G, and in going forward the rise on it comes into contact with the bend in the shears, and raises them up so that it can turn the cylinder when it catches on the head of it. Both these are good and convenient motions. For the latter the cylinder should be about half-way out when the cards are being turned back.

Fig. 29

Sometimes the cylinder may not be completely turned by the shears when the machine is working, by reason of the cards catching, or if the shears are too long, or it may arise from other causes. In this case the cylinder would come in with one corner against the needles, and be pressed heavily against the needle plate. Some of the levers would probably be broken, or the cylinder might be shot out of its bearings and fall, breaking the yarn, or perhaps injuring the weaver. To avoid this, small snecks, as at H, Figs. 28 and 29, are set so that when the cylinder is square it will pass over them; but if turned angularly its lower edge will catch on the point of the sneck, as the cylinder is coming in, and turn it square. The sneck is held up with a spring so as to allow the cylinder in turning to depress it. Sometimes the sneck, as at H, is liable to cause broken shots; for if the weaver turns back the loom, and the cylinder moves out sufficiently far to be turned to its angular position, and remains there, it will, in coming in, be turned square by the sneck, and thus a card would be passed over without a pick being put in for it. This is sometimes remedied by putting the sneck above the cylinder, instead of below it, which would turn it the reverse way; but this might come wrong at other times. The better plan is to keep it below, and let the weaver get to understand what she is doing, as it is not very difficult to learn.

The setting of a jacquard machine for working consists in adjusting the cylinder motion so as to bring in the cylinder at the proper time, and press it sufficiently close against the face-plate to keep the hooks clear of the knives of the griffe, without pressing it too close; and regulating the lifting of the griffe to suit the time for shedding, and to give the size of shed required. The shed must be open for the shuttle to pass through; the time for picking is when the cranks of the crank-shaft of the loom are at the bottom centre, therefore the shed should be almost fully open at this time. The lifting of the griffe can be made a little earlier or later to suit circumstances, but very little alteration can be made, as it takes a full revolution of the crank to raise and lower the griffe. Further consideration will be given to jacquard shedding after double-acting machines have been explained.

The motion for working the cylinder, if an independent one, should be rigid and strong; for if there is any spring in it, though the cylinder may be brought in sufficiently close when there is much cutting on the card, if a blank card or one with very little cutting on it comes on, the extra pressure on the needles, especially with a large machine, may prevent it from getting in sufficiently close to clear the hooks from the griffe. With self-acting motions there may sometimes be some trouble in this way, as the weight of the griffe may not be sufficient to press in the cylinder. In this case the griffe may be weighted, or may be allowed to drop quicker, or the lifting rod and lever may be made to assist in pressing it down somewhat.