FIG. 123.
If one hook of the pair is lifted and it is required to keep the same ends of warp up for the next picks, the hooks being connected round the pulley W, one hook going up as the other comes down will keep the harness cords stationary, and the hooks A and B can be lifted alternately one up, one down, without moving the cord E, which will all the time be keeping the warp ends up. The shed thus obtained is similar to that in a Keighley dobby; the ends, when once they are lifted, stay in that position until they are required to come down. The principle can be applied to either double-lift single-cylinder or double-lift double-cylinder machines.
Another view of the pulleys is shown at [Fig. 123], where the pulleys and other parts are lettered as in the previous figure. Each pair of hooks in the machine has these pulleys attached, and therefore it will be understood that the pulleys must be rather thin in order to enable them to be placed in a space equal to the size of the Jacquard machine. The advantage which a satisfactory machine on this principle would possess lies in the fact that the jerk which occurs in ordinary double-lifts when the weight is passing from one hook to another in each pair is done away with. This jerk causes breakage of the neck cords, and many efforts to overcome the annoyance have been made. This principle of open shed may be applied to dobbies such as the Blackburn dobby.
THE SPLIT HARNESS.
The split harness is an ingenious method of increasing the size of pattern which can be woven on a given Jacquard. What is termed a “double-scale” split harness consists of two adjacent lingoes being connected to each hook in the machine. Thus with a 400s machine there are 800 mails in a pattern. A few lingoes are shown at [Fig. 124] tied up in the manner of a double-scale harness. The connections to four hooks are shown. Underneath the comber-board a loop is made in the harness thread, and shafts SS, either wood or metal, are inserted through the loops in each row in the harness. These shafts are worked by the spare hooks in the machine, and in the places where the ends are left down by the Jacquard, the shafts, being lifted to a given ground pattern, will weave the ends singly. In [Fig. 124] the shafts are shown lifted to weave a plain or tabby ground, every alternate one being lifted. Hooks No. 1 and No. 2 are lifted by the Jacquard, and hooks 3 and 4 are left down, and it will be seen that where the hooks are down, half the ends will be lifted by the shafts. The ends, when lifted by the Jacquard, cannot be woven separately with this harness, and therefore the bindings in the figure will show in twos, which, unless the harness is a fine one, has a tendency to make the cloth appear coarse. Satin or twill grounds may be woven. In fact, the ends left down by the Jacquard may be woven singly to any pattern which repeats on the number of shafts used, or into the number of rows which the harness is deep in the comber-board. Of course either the figure or the ground may be woven singly, according to the way the pattern is designed, but not both.
FIG. 124.
In silk weaving, harnesses are built on this principle to a threefold scale—that is, with three mails attached to each hook—and as in the double-scale a figure repeating on 800 ends can be woven on a 400s machine, so with a threefold scale a 1200 figure can be woven on a 400s machine. In this case the bindings in the figure will be in threes, but the ground ends may be woven quite singly by the shafts.
This principle is only adapted for very fine reeds in cotton goods, but is often used in silk manufacture, where 300 or 400 threads per inch are not uncommon.