push-type machine

The jacquard machine is an essential addition to looms intended for weaving ornamental designs that are beyond the scope of stave -work. The machine is made in many forms and sizes for different branches of the weaving industry, but its characteristic feature is that it furnishes the means whereby every individual thread in a design may weave differently from all the others. This permits the delineation of all forms and shapes and the fineness of the detail is only limited by the texture, e.g., the number of ends and picks per inch. The action of the jacquard machine is communicated to the warp threads through a system of cords known variously as the harness mounting and jacquard harness. Actually, loom harness ante-dated the jacquard machine by many centuries, and many draw loom harnesses were much more complicated than modern jacquard harnesses. An essential feature of a jacquard is that each hook in the machine can be lifted at will independently of the others. The selection of which hooks shall lift and which shall be left down is made by the designer, by painting marks on squared paper to indicate the hooks that must be lifted on each pick. In cutting the pattern cards, a hole is cut for every mark or filled square on the design paper, and a blank is left for every empty square on the paper. Assuming that each pattern card represents one pick of weft, when the card is pressed against the needles of the jacquard, the blanks push the unwanted needles and hooks out of the path of the lifting griffe; the holes allow the needles to pass through and thus remain stationary, so that the corresponding hooks remain in the path of the lifting griffe and cause the corresponding warp threads to be lifted. Jacquard: Single-lift, single-cylinder - In this machine there is only one griffe which lifts on every pick, and only one pattern cylinder, which strikes every pick. This restricts the speed at which the loom can be operated. Jacquard: Double-lift, single-cylinder - This is the machine in most common use for ordinary jacquard work. There are two lifting griffes and twice as many hooks as in a single-lift machine, but only the same number of needles and one card cylinder. The shed formed is of the semi-open type, which causes less movement of the warp threads, as any threads which require to be up for two or more picks in succession are arrested in their fall and taken up again. Double-lift jacquards give a greatly increased loom production as compared with single-lift machines, as they permit the speed of the loom to be increased to about 180 picks per minute for narrow looms, as compared with 120 to 140 picks per minute for single-lift jacquards. Jacquard: Double-lift, double-cylinder - In this machine there are two sets of hooks and needles, two lifting griffes and two card cylinders, odd picks in one set of cards and even picks in the other set. This permits maximum loom speed, it prolongs the life of the pattern cards, but is open to the serious drawback that spoiled cloth is caused whenever the two card cylinders get out of correct rotation. Jacquard: Cross Border - Fabrics with borders, such as tablecloths, bed quilts, etc., are woven with jacquards with two griffes, two sets of hooks and two card cylinders. The cards for weaving the border are laced together and weave on one cylinder, while the centre cards are on the other cylinder. The loom weaves at the speed of a single-cylinder, single-lift machine, and the change from the border to the centre cards can be made by hand or automatically