I. Double Lift Single Cylinder Jacquard Machine.
The principle of this machine consists in raising the warp-threads any number of times in succession without allowing the shed to close, thus performing the work in nearly half the time, and with less wear and tear on the warp.
[Fig. XCVI.] represents the sectional cut of one row across all the griffe-bars. The machine selected for the illustration is of the 12-row type. Jacquard machines of this description have two hooks to one needle; therefore in the drawing twenty-four hooks are represented. Two griffes are provided, each working every alternate hook.
Fig. XCVI.
Fig. XCVII.
In [Fig. XCVI.] the sectional cut of both griffes is shown, and in [Fig. XCVII.] the top view of both griffes; the first set is represented shaded, the second black. The former requires hooks Nos. 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, and the latter Nos. 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24.
This arrangement permits either hook to be lifted separately by the griffes, and a corresponding elevation of the leash. As these griffes work in opposition, one descends while the other ascends; this motion prevents the leash from dropping the entire length of the cords, since the ascending griffe catches it at half distance as the two griffes pass each other. In this operation the shed is never entirely closed, and a corresponding gain in speed is attained. It will thus be seen that the “double lift” single cylinder has great advantages over the ordinary machine. Of course, the warp-thread must make its complete journeys up and down when called for by the design; but when once up, it need not be brought down until absolutely required by the pattern. The warp is thus subjected to less friction in working, and it is possible to use yarns with less twist and obtain good results.
The advantages arising from not closing the shed may be seen in the following example of a warp-thread working on an 8-leaf satin, in which seven picks are up in succession.
By the single lift machine this warp-thread must travel seven times up and seven times down, thus closing the shed absolutely seven times, with a corresponding wear and tear. The double lift single cylinder arrangement does not require the warp-thread to make these seven complete journeys to the “race-board” of the lay, but instead it makes seven half trips. The saving may be shown by the following analysis: Single lift machine, warp-thread, seven picks up in succession, in 8-leaf satin (warp-face) requiring fourteen complete movements.