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.
[Illustration: Fig. XCVI.]
[Illustration: 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.
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.
[Illustration: Fig. XCVIII.]
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.
[Illustration: Fig. IC.]
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.
[Illustration: Fig. C.]
[Illustration: Fig. CI.]
[Illustration: Fig. CII.]
Fig. C., hooks at rest.
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.