Take-Up Motion
Another important consideration is to make proper provision for a reliable take-up motion, so that the goods may be taken away from the reed while weaving without any liability to variableness. This liability was present in many of the earlier looms and exists in some of the mills today. The old-time fine ratchet gear, even when provided with a number of pawls, is always liable to erratic picking, which alone will ruin an otherwise perfect piece of goods and materially change the cost of manufacturing. A slight irregularity of picking may not be discernible in non-elastic goods, which will be satisfactory so long as the variableness is not easily seen and a reasonable average of picks per inch is maintained. But in elastic goods, where the contraction takes place after they leave the press rolls, every irregularity is revealed and intensified so there is no room to take chances. The only safe way is to employ picking gears making one tooth to each pick of the loom, and then to change the gears when different picking becomes necessary.
In many of the existing looms there has been no adequate provision made for the weaver to let the web back to the reed mechanically when a joining becomes necessary through the breaking of the filling while weaving, or where a quill may have run off unnoticed. It is almost impossible to make a joining satisfactorily without proper mechanism being provided for this purpose. In some of the slow running looms provision is made for this by the operation of each set of rolls independently (see Fig. 1), by means of the ratchet gear and pawl A and worm motion B. This plan has the one disadvantage of taking up too much space between the individual pieces. Where the fabric woven is say four or five inches wide, and the space will admit, it is all that can be desired, and the individually weighted rollers C associated with the motion are admirably adapted to variable pressure.
For the very narrow elastic fabrics, which require considerable roller pressure to hold the web snug and firm while weaving, and where it is necessary to make very accurate joinings after a break has occurred, a better movement is one in which the web roll is placed on the main take-up shaft in the form of a sleeve. It is carried around by the shaft as it turns while the goods are being woven, but can be released and turned both backwards and forwards by a conveniently placed hand wheel, which operates a series of differential gears. This movement is entirely independent of the movement of the main take-up shaft drive.