“OPEN-SHED” JACQUARD.
Several open-shed Jacquards have been patented. That of Wilkinson’s is illustrated at Figs. [122] and [123]. A and B are a pair of hooks, which are connected by a cord passing round a pulley, W. This pulley works on a pin at one end of the thin plate C, and at the other end of the plate is another pulley, X. The neck cord E passes round this pulley to the bar D, to which it is fastened. It is obvious that when one hook of the pair is lifted, say, 4 inches, and the other is at the bottom, the pulley W will be lifted 2 inches; and as the cord E is fast to D, the harness threads will be lifted 4 inches, the same as the hook.
FIG. 122.
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.