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.
Double lift single cylinder machine requiring for the same effect:
Up the first time, = one complete movement. Six times down, } half movements, = six complete movements. Six times up, } Down the last time, = one complete movement. Or eight complete movements.
Showing the utility of the two machines to be to each other as 8 to 14, or 4 to 7.
Fig. XCVIII. illustrates the complete double lift single cylinder Jacquard machine, as built by W. P. Uhlinger, Philadelphia. In this drawing both griffes are distinctly visible; also their mode of operation by means of the double-acting lever. This machine has the set of hooks for each griffe-bar protected by a plate of sheet iron, thus steadying the hooks in their motion, and enabling smaller crooks to be used for the latter.
Fig. IC. represents a double lift single cylinder Jacquard machine as built by Thomas Halton, Philadelphia, attached to a regular broad loom, (Knowles or Crompton), and tied-up for upholstery work. The griffe-bars in this Jacquard machine are constructed of such height that when lifted they never rise above the crooks of the hooks, which are thrown out of operation by the descent of the other griffe.
Fig. CI., hooks 1 and 3, etc., raised, = 2 and 4, etc., at rest.
Fig. CII., hooks 2 and 4, etc., raised, = 1 and 3, etc., at rest.
II. Double Lift Double Cylinder Jacquard Machine.
The principle of this machine consists in the combination of two separate Jacquard machines. Two hooks (one of each machine) are connected to one leash of the Jacquard harness, and as each machine is operated alternately, a high speed is attained, which is the purpose of the machine. For example: 140 picks per minute (speed of loom) only requires 70 picks per minute from each part of the double lift double cylinder.