Needles. The illustration Fig. [27] shows the arrangement of needles in a double action machine. The first needle at the top marked A, controls the hook B, passing down in regular order until the bottom needle in the right hand needle board, marked C, controls the hook D. The first needle in the left hand or bottom needle board, marked E, controls the hook F, which is the partner to D, that is, F and D control the same harness threads, as will be noticed by the connection at the bottom G. The eighth needle in the bottom needle board, marked H, controls the hook K, which is the partner hook to B. The bottom set of needles is exactly like the top set. They are placed in the same relative position, but work from the opposite direction.
There being two cylinders on this type of machine, one passes in as the other is going out. Both cylinders turn toward the machine as indicated by the arrows, and a glance at the two cards A and B with holes marked 1 and 2, and needles marked the same will show the two hooks F and D control the same harness threads.
Fig. 28. Showing Levers, Supports and Studs.
It will be noticed that one hook has the top bend bent backward, while the other bends forward in the same direction as the lower bend of the hook. The reason for this latter is that it would require more space in the grate and the needles would have to be longer, which would make a broader machine if the same shape of hook were used; so that by the use of these hooks, considerable space is gained.
When cutting cards for a double action machine, each card is cut from the design singly, just the same as if cutting cards for a single action machine. After the cards are cut, they are divided, the odd numbers from the even numbers, so that when laced they form, as it were, two sets of cards, one set being placed at one side of the machine and the other set at the other side of the machine.
A double action machine is composed of double the number of working parts that are on a single action machine, but they are placed so as to work in different directions, with the exception that with an independent cylinder motion only one eccentric rod is used, and the eccentric is placed on the pick cam shaft. But if the cylinders are operated by a spindle motion, a slotted crank arm is attached to the lifting rod of each griffe and the cylinder is moved out as the griffe to which it is attached is raised, one cylinder moving out from contact with the needle board as the griffe, that comes in contact with the hook controlled by the needles of that board, is raised, at the same time the other cylinder is passing in towards the needle board while the second griffe is descending.
