Fig. 10. Showing Arrangement of Hooks, Needles, Etc.
A needle board or plate for a 400-machine, has 416 holes, arranged in 52 rows with 8 holes in a row. The rows are divided by a groove into 26 rows on each side. There are also grooves at each end of the needle board. The grooves are for the lacings which hold the cards together.
The lacing naturally makes the card occupy more space at the ends and center, because it passes along the upper and under sides of the card, and if there were no grooves in the needle board, the needles would have to be made longer so as to allow the points to protrude farther out from the needle board; or when the card was in contact with the needle points, the hooks would not be pressed back far enough to prevent them from being lifted. The grooves are also a great saving on the lacing of the cards, for if it came in close contact with the needle board every time the cylinder was drawn in, the lacing would soon be cut, and this often causes the breakage of cards.
Fig. 11. Showing Loops for Springs.
The reason for the extra rows of needles, is to allow the selvedge to be worked by that row of hooks; also because a jacquard sometimes has patterns added that require additional harness at the front and back of the comber board, and the extra needles are used for the working of the extra harness.
A spring box is seldom used on American machines to hold the springs that press back the needles, but where the spring box is dispensed with, a longer loop is made on the back end of the needle (see Fig. [11]) and the spring is placed on the loop, with the cotter, which holds the needles. The spring box, however, is most certainly of value if it is made to fit squarely in the framework of the machine. The springs are kept cleaner and consequently will give good results; and if a spring should break, it can be replaced more readily in a spring box than if it were on the end of a needle.
There is, however, one disadvantage in using the spring box, for when the hole, through which the bolt, which holds the box in position, passes, has become worn, some of the needles will be pressing against the edge of the spring instead of the center, unless care is taken in fixing on the box. This causes the needles to stick in the box, preventing the hooks from working as they ought to do.