Control of Latches
It will be noted that needle o in Fig. 16 has just started to rise and the stitch that was in the hook has opened the latch and still has it under control. When this needle gets up to the position of needle p it has passed the point where the stitch can control the latch, therefore, other means must be provided or it would be very liable to fly up and close the hook, in which case it would be impossible for the hook to catch the yarn for the next stitch. When this happens we have what is called a drop stitch, and after the yarn had passed there would be no stitch on the needle.
Fig. 18.
Flat Latch Needle Machine.
To provide against this there is used in this type of machine a long narrow thin bristle brush set over the needles and at the proper angle and distance to just clear the latches. This brush is shown in Fig. 19. The letter a indicates the brush alone, and at b is shown the brush in the fixture which carries it. The letter c indicates the brush carrier. Fig. 20 is a view looking down from above the machine and shows the brushes, a and b, set ready to operate in the machine. So as not to confuse the reader I will say here that all previous illustrations presenting this part of the machine have shown it with the brushes removed in order to make clear the operation of the needles.
Fig. 19.
Latch Brushes.
One Mounted in its Holding Clamp, or Fixture.
Fig. 21.
Tubular Fabric Made on a Flat Machine.
Fig. 20.
Position of Latch Brushes When on the Machine.
A fabric made according to the foregoing explanations would be what is known as a jersey fabric (see Figs. 12 and 13), but it would be a flat piece of fabric when finished. Perhaps to make it plainer I should say that if the fabric were laid out on a table it would be a single thickness, and if it were to be made into a garment it would be necessary to double it over and sew the edges together to make it tubular, or in the form of a bag. If we wish to make the fabric tubular on the machine to save the labor of seaming it, and also prevent the unsightly seam, it would be necessary to use the needles in both plates, front and back. The cams would then be set by means provided, which will be explained later, so that when the carriage is moved in one direction, say from left to right, the front cams will operate the front needles and the back cams will be put out of operation; and when the carriage is moved from right to left, the back cams will operate the back needles and the front cams will be put out of work.
Fig. 22.
Jersey Fabric Made on
a Machine With 24 Needles
to One Inch.
Fig. 23.
Jersey Fabric Made on
a Machine With 2½ Needles
to One Inch.
By continuing the operation of the machine in this manner of having only the front cams operate while moving the carriage in one direction, and only the back cams operate when the carriage is moved in the opposite direction, there would be produced a tubular fabric as shown in Fig. 21. The yarn must of a necessity go across from front needles to back ones, and from back ones to front ones each time the direction of the movement of the carriage is changed, thereby closing up both sides of the fabric.