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Cotton Weaving and Designing / 6th Edition cover

Cotton Weaving and Designing / 6th Edition

Chapter 23: DOUBLE-SHED JACQUARD.
By John T. Taylor
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About This Book

A practical manual that systematically explains the stages and machinery used in preparing cotton yarn and producing woven cloth, beginning with winding, warping, sizing, beaming, and looming. It surveys hand and power looms, drop and circular box looms, dobbies, jacquard and leno weaves, and specialized techniques such as terry looms, card cutting, and lappets. A chapter on automatic weft-replenishing devices describes emerging mechanization. The book also presents the principles and methods of textile design and figured patterning, and supplies calculations, worked examples, and numerous diagrams to guide students and practitioners in planning, setting up, and troubleshooting weaving operations.

DOUBLE-SHED JACQUARD.

Double-shed Jacquards are used chiefly in weaving heavy goods where a very large and deep shuttle is required to hold a reasonable quantity of weft. The principle of this machine will be easily understood from Fig. 121. A is connected to the crank shaft of the loom and moves the end of the lever BC up and down, the fulcrum of the lever being at E. The bottom board or plate F is therefore moved up and down, and in doing so the griffe G is made to move oppositely, the bottom plate coming down as the griffe goes up, and vice versâ. This is effected by the top levers PR and QS, which are centred at O. One end of the griffe is connected to Q, the other end of the griffe is connected to P. This gives firmness and strength to the machine. These Jacquards are usually made very heavy, as they are chiefly for heavy work.

FIG. 121.

Only a few hooks are shown as an example, but the machines can be made any size. When all the hooks are resting on the bottom board, which will be when the bottom plate is at the top of its stroke, the card is pressed against the needles and selects the hooks to be lifted in the usual manner, after which the griffe rises as the bottom board sinks. Thus an extra deep shed is produced without the griffe having so far to lift as would otherwise be the case. The shed produced is a centre shed, all the ends coming to the centre every pick.