FIG. 25.
Fast Reed Loom.—Here the loom is stopped suddenly in case of the shuttle being stopped in the shed. From [Fig. 25] the arrangement will be understood. A swell attached to the shuttle box is placed so as to project into it when the box is empty, and through an L-lever A drops a catch so as to strike the frog B and arrest the motion of the slay. The frog moves a short distance and puts the loom brake in action before checking the motion of the slay. This is done by means of the rod C. The catch is attached to the slay sword and rests on the lever A. When the shuttle is in the box, and as the slay is on the top centre, the protector rides above the frog about a quarter of an inch; it is only when the shuttle has not landed in its place that the loom is stopped. There is an arrangement for the swell to be released at the time picking takes place, so as not to give unnecessary obstruction to the shuttle.
Take-up Motion.
FIG. 26.
Among cotton looms the positive take-up motion is generally used. The cloth as woven is, by this arrangement, drawn on the cloth roller a certain distance at every pick, the amount of take-up being regulated by wheels. [Fig. 26] shows a sketch of the arrangement. The construction is similar for almost all looms, but there are different gears and sizes of wheels used. In Dickinson’s gear the rack wheel of 50 teeth receives its motion from a pawl, worked by one of the slay swords. On the same stud is the change wheel: this gears with the stud wheel, 100 teeth, firmly connected with the pinion of 12 teeth, driving the beam wheel 75. The beam or sand roller is 15 inches in circumference, and is covered with glued sand, perforated tin, or some pointed substance, to hold the cloth firmly. The fabric is wound on the cloth roller below this by means of contact with the sand roller. The change wheel is varied to give changes of picks in the cloth, a larger wheel giving fewer picks in the quarter inch. Each gear has a constant number associated with it, called a dividend. If the number of teeth in the change wheel be divided into this dividend, it gives the picks in a quarter inch of cloth. Imagining that a change wheel, having the effect of only one tooth in a revolution, could be applied, then the dividend is the number of picks that the loom would run before the sand roller advanced a quarter of an inch. Suppose 528 dividend is taken, this represents a change wheel supposed to have one tooth. If a wheel of 66 teeth be put on, only 1/66 as many picks to the quarter will be inserted—i.e., 528/66 = 8 picks.
The method of obtaining the dividend for any ordinary gear is—
(Rack wheel × Carrier wheel × Beam wheel)/(Pinion wheel × number of 1/4 inches in circumference of taking-up roller)