Single and Double Lift.
In the single-lift jacquard, the knife has to lift as often as the loom picks, and should a hook require to be raised several picks in succession, it has to be dropped between each pick and raised again. These defects are obliterated in the double-action jacquard. The machine, [Fig. 64], has two hooks to each needle, they being connected at the bottom to one neck cord. Two sets of knives are used, one lifting when the loom picks from the right-hand side, the other when picking from the left, thus reducing the speed of the knife one-half; whilst as the hooks for one pick are being used, the other knife can be preparing for the next shed, and when lifting, keep up any leash several picks in succession, thus saving time, and so enabling the production to be increased. The [Fig. 64] shows a double-action machine with a single cylinder, 400 hooks and swing batten, giving at least 50 picks per minute greater speed than a single lift with less vibration and strain.
FIG. 63.
[Fig. 63] shows the different shapes of jacquard needles, A being the ordinary one in plan, B another view of the same, C the double-action one, and D another style of single-action needle.
FIG. 64.
DOUBLE-ACTION JACQUARD, SINGLE CYLINDER.
The speed may still further be increased by having a double-action machine with double cylinders and two sets of needles and hooks (see [Fig. 65]).
In this system two sets of cards are employed, all the odd picks on one cylinder and the even ones on the other—thus, the cylinders only revolve at half the speed, causing less vibration and giving an increase of 20 picks per minute. If requisite, this machine can also be arranged as a compound or cross-border machine, carrying two sets of cards of different patterns, only one set in use at once, while, by pulling a handle, the other set can be actuated instead, so as to weave an entirely different pattern in the cloth—e.g., in the heading of a tablecloth, shawl, or handkerchief.
FIG. 65.
DOUBLE-ACTION JACQUARD, DOUBLE CYLINDER.