The letter d in Fig. 17 designates the yarn carrier through which the yarn passes, and which guides the yarn along the path of the hooks of the needles. After having moved the carriage clear across the working needles, and finishing a course of loops, the carriage is moved back in the opposite direction and another course is put on. This is done in exactly the same way except that the cams must necessarily push or slide the needles up and down on the opposite sides of the cams: i.e., the butts slide up on the right hand side of the V-cam or cam a-3 in Fig. 16 and down the right hand side of cam a-1, or stitch cam. This operation is continued until the fabric is of the desired length.
Needles are operated at a rate of speed that would make 500 or more stitches per minute per needle if the machine would keep them in continuous operation, but in practical work they make from 50 to 200 stitches per minute according to the size of the machine as more time is consumed as a rule in the movements of the machine between the stitches than is used in the actual knitting operation. On account of this speed of operation the latches of the needles must be under control at all points in the cycle of knitting; that is, from f to g in Fig. 16.
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.
