Loose and Fast Reeds.
To obtain a firm blow at the cloth the reed is made to strike it at right angles, for if the angle were more obtuse or acute a loss of force would be entailed by a consequent downward or upward stroke imparted to the cloth, the line of action not being in the same plane as the line of reaction.
With regard to the firmness of the beating up, we have to consider the merits of fast and loose reed looms.
In weaving, an accident which not infrequently occurs is the stoppage of the shuttle when it has only traversed a portion of the distance across the warp. A case of this shuttle trapping causes the breakage of more or fewer ends, and consequently arrangements are made for preventing much damage, either by arresting the motion of the loom suddenly, in case of a fast reed, or by having a reed hanging loosely behind the shuttle so as to give way in case of a “mash.” The latter arrangement is preferable, as there is not the sudden concussion given to the loom, which causes the vibration and straining of every part, so objectionable in the fast reed loom; the loose reed can, however, only be used for light and medium cloths, as the reed is too lightly fixed to give a strong beat-up. In the case of the loose reed, the slay cap holds the upper part of the reed in a slot, the bottom part being pressed against the shuttle race by a strip of wood (completing the reed case) attached to the stop rod. When at the fell of the cloth, the stop rod is held firmly by a spring, and a fairly strong blow can be given to the cloth; but at all other portions of the slay’s movement nothing holds the reed but a weak spring acting on the casing, and if the shuttle traps, the reed flies out, while a finger on the stop rod knocks the loom handle off, stopping the machine without unnecessary concussion. This latter advantage enables the loose reed loom to be run at a speed of some 30 or 40 revolutions more than the fast reed.
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.