Flat Machine Knitting and Fabrics

by H. D. Buck

Explanation of Lamb Type Machine

A study of Fig. 16 should be made in connection with the photographic reproductions, Figs. 17 and 18. Fig. 18 shows substantially the whole knitting machine, while Fig. 17 is a close-up view of that part of the machine which actually does the knitting. Fig. 16 shows the principle used to operate the needles.

This type of machine was invented in 1863 by Isaac W. Lamb, a clergyman, and was made possible only by the invention of the latch needle in England about 1847. It is very simple in construction in the plain models and is the most versatile of all the knitting machines, it being possible to make on it a larger variety of stitches and articles of apparel than on any other machine. It is known as the flat or Lamb type of machine.

It has two flat or straight horizontal plates or beds about one-half inch thick by 6 inches wide, the length of which varies from 6 inches or less to 60 inches or more, according to the width of fabric it is designed to make. These plates are set in a frame, parallel to each other lengthwise, and at an angle of about 90 degrees to each other and 45 degrees to the horizontal. See Figs. 16, 17 and 20.

All flat machines of this type have two needle plates, but for our purpose of knitting jersey fabric we need but one, therefore we will imagine that there are two in Fig. 16 but the back one having no needles in it cannot do any knitting. The needles, as will be noted in Fig. 16, are placed in tricks or slots of which there may be any number from 2½ up to 18 in one inch, according to the size of the yarn to be used. The needles should fit in the slots close enough so that they will not have any chance to tip sidewise, yet they must move easily endwise. The gib c, c, is for holding the needles in the plate, and of course is removed by drawing out endwise when a needle is to be put in or taken out of the plate. The plate is secured in a frame indicated by the letter n in Fig. 16, and the frame is attached to a stationary stand or table.

The cams a-1, a-2 and a-3 are attached to the carriage b, b, b, b, Fig, 17, at a point just below a-1, a-2 and a-3 and the carriage, together with the cams, rests and slides freely back and forth on the ways c, c, while the plate and needles remain stationary. The cams are secured to the carriage in a position so that they come very close to the needle plates. They should be set as close as possible and not rub the plate as they are moved back and forth.

It may be well to explain here that a cam in any machine is a piece of hardened steel of the proper shape and construction to cause some other part of the machine to make the proper movements to perform its functions. In this instance they actuate the needles by coming in contact with the butts.

It will be noted that each one of the needles from e to e, Fig. 16, has a loop in the hook except from the point where they are rising over the cam a-3, and on these the loops rest on the shank. It should be understood that the fabric back of the needle plate has a weight on it, thereby giving to each loop a downward pull. The fabric and weights may be seen in Fig. 18.

Fig. 16.
Principle Used to Form Loops on a Machine.

Now bear in mind that the cams a-1, a-2 and a-3, Fig. 16, are attached to the carriage b, b, b, b, Fig. 17, at points underneath a-1, a-2 and a-3. These cams are moving from right to left and as the lower left hand corner of a-3 is below the line of the butts of the needles from e to e, they, the needles, must of necessity slide upward in the slots along the edge of this cam. When they get to the top it will be noted that the latches of the needles are above and clear of the loops. As the cams move farther along, the cam a-2 comes in contact with the butts and slides them down again. As the needles move downward the hooks catch the thread i which lies in their path, and as at l the stitch that is on the needle closes the latch as the needle slides downward. As the needle moves farther down the hook draws a new loop through the old one, while the latch closing up the hook allows the old loop to slip over the end (needle m), and the pull of the fabric draws it down on to the new loop.

Fig. 17.
Top Side of Carriage, Over Cams.

The thin portions of the needle plate indicated by the letter h in Fig. 16, which extend upwards, are called jacks and these hold that part of the stitch called sinker loops while the needle is drawing through the new needle loop.

Below each needle is a U-shaped spring, j, j, and k, k, Fig. 16, which holds the needles up in the working position. They extend down to and around the bottom of the plate and up against the under side of the plate. The end that is under the plate is a little longer than the end that slides up in the slot below the needle. These U-springs are made so that before they are put in their places on the plate, the ends come together, so when they are spread and pushed on to the plate they act as a clamp to hold the needles in position. They are not attached to the needles, but simply clamp the plate with tension enough to hold them up or down, as the case may be, and the bottom end of the needles rests on them. This construction leaves the knitter in a position to pull d own out of working position as many needles as he may wish, therefore he may make his fabric any desired width by pulling needles down out of the working line or pushing them up into the working line, thereby adding to or taking away stitches.

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.