Fig. 9. Single Action Jacquard Machine.
The illustration, Fig. [9], shows a jacquard known as the Single Action Machine. The chief feature of this machine is that the same griffe lifts the hooks for every shed, so the griffe must descend before the next shed can be lifted. This allows all the yarn to be lifted from the bottom shed. The single action machine is convenient and well adapted to work when a high speed is not required; ninety to one hundred thirty picks per minute being the most suitable speeds.
In the silk industry the single action machine is extensively used as there is no danger of the cards becoming crossed. This is a very valuable feature as wrong picks are often placed in the cloth by a double cylinder machine through the skipping of the cards.
Construction. The single action is the original idea and is the simplest machine. Fig. [10] shows a sectional view of a 400-hook single machine. The meaning of the term 400-hook is as follows: There are four hundred hooks and four hundred needles in the machine which are in rows of eight hooks and eight needles. It also means that there are four hundred harness threads to one repeat of the maximum pattern that can be woven by the machine. Nearly all machines have a few extra hooks (from 16 to 26) which are often classed with the regular number of hooks, but are chiefly used for extra work, such as selvedge, extra harnesses, etc. A pattern of less than four hundred to a repeat can be woven, by casting out some of the hooks.
Referring to Fig. [10], B is the needle board or plate, through which the points of the needles E protrude three-eighths or one-half inch. C is the griffe which is composed of eight blades; H is the spring box, containing four hundred brass springs which are placed against the back or loop ends of the needles, one spring for each needle. G is the grate through which the hooks F pass.
Needle Plate. In some cases the needle plate is made of wood and in others it is made of metal, but the former is undoubtedly the more economical from every standpoint. Particularly is this shown in the single cylinder machines where the cylinder travels at a faster rate of speed than a double cylinder machine, consequently there is more movement and a larger amount of friction between the needle and needle board or plate, which results in rapidly wearing out the points of the needles if a metal plate is used. Worn needle points cause a large amount of trouble, for in single cylinder machines the cylinder has a tendency to half-turn when the lay is pushed back by hand, and when the cylinder returns to the needle points the corner of the cylinder presses against them and invariably bends a number of the points down on to the plate. This prevents some of the hooks which ought to be lifted from being lifted, and causes some hooks to be lifted which ought to be down.
A composition of powdered black lead and French chalk was used to prevent the needle points from wearing out, but it was discarded because the dust was constantly dropping into the harnesses and yarn, and also was very disagreeable for the weaver.
