Type of Fabric Produced
Before going into the mechanical construction of the attachment we will to some extent analyze the fabric to find out what must be done to produce it. Referring to Fig. 87, which is a photographic reproduction of a fabric made on the machine under discussion, it will be noted that both the design and the ground are in solid colors. The rectangular figures which might be called the design are in solid black, while the squares, both the large ones and the small ones, which would be the ground, are solid white. It should be understood that there are two yarn carriers used in making this fabric, one for the white yarn and one for the black, and that these carriers are changed every round; that is, one round of white, and one round of black, alternating throughout the fabric.
Now inasmuch as we know that the fabric is made in the plain stitch, it is quite obvious that in order to make this design means must be provided to permit only those needles to knit which are making the white ground on any course in which the carrier with the white yarn is being used. Similarly only those needles making the black design must be permitted to knit on the course in which the carrier with the black yarn is used. The needles or wales, of course, run vertically in the fabric, while the rectangular design is diagonal, therefore it is plain that the number of needles or their relative positions must be changed each course.
In this fabric the design is brought out on one side only, the back plate, and the needles on the opposite side or front plate are knitting each time the carriage is moved across the machine as explained in detail later. This may be plainly seen in Fig. 87, where the corner is turned over to show the back of the fabric.
Fig. 85.
Back and End of Jacquard Machine Showing Details of Necessary Movements.
Now to find the method of selecting the proper needles at the proper time we will refer first to Fig. 86, which is a photographic reproduction of the cam system used in this machine; also to Fig. 90, which is a drawing of a cross section of the needle plates. It will be noted in Fig. 90 that there are two separate needle plates. The top one is for the needles proper, while the lower one is for the auxiliary needles.
These two plates are in perfect alignment, both as to the surface and the needle tricks or slots. In the double jacquard the front plate would be in two parts and a duplicate of the back plate, but in the single jacquard the front side would have what is the upper plate on the back side only, and would use the short needles as shown at b, Fig. 89.
Fig. 86.
Construction and Arrangement of Cams and Locks in Dubied Jacquard
Machine.