No matter how close to the edge of the fabric the yarn guide may be stopped, unless the yarn is kept taut the selvage will not be perfect, therefore a very insignificant appearing but quite important adjunct called the yarn take-up spring is provided to do this. There is one provided for each yarn guide and their position in relation to the machine may be seen at the top of the yarn stand in Fig. 45, while one is shown in detail in Fig. 51. The spring is a coil spring turned around the stud, f, and attached at the inner end. The outer end is a part of this spring straightened out as at b, with an eye turned in the end at d.
Fig. 51.
Yarn Stand and Take Up Spring.
By turning the top of the stud f away from you it will put more pull or tension on the spring, and by turning toward you less. The yarn is drawn from the bobbin, e, through an eye directly over the bobbin, then through a hole in the tension stud at a, then through an eye of the spring, then down through another eye in the stand at g, and directly to the yarn guide of the machine. The tension a prevents the spring from drawing any yarn from the bobbin, therefore it will always draw the slack yarn from the yarn guide and keep it taut at all times. There must be a take-up spring for each thread in use and that means that there are sometimes as many as eight or ten on one stand.
We have had a drawing of the double lock in Fig. 40, showing the cam side with an explanation of how it works and its advantages, so now we will show only the top carriage side in Fig. 52, with its appurtenances for the automatic changes. Bear in mind that when slides or plungers are mentioned in the following explanation reference is made to Fig. 52, and when cams are mentioned reference is had to Fig. 40.
Stitch Changes
Fig. 52.
Top Side of Carriage Directly Over Locks, Dubied Automatic
Double Lock Machine.
Slide a operates on cams 1b and 4b to change from plain to cardigan, or vice versa, and is used in making the full cardigan stitch. Slide b and g, working in conjunction with d and e, are for changing the length of stitch, which will be explained more fully later. Slides c and f are for changing the yarn carriers to change colors. The exchange of carriers at the end of each course in order to keep the cotton carrier feeding into the cams that are leading (where cotton and worsted or wool is used) is another matter and should not be confused with this. Slide h operates on cams 2b and 3b to change from plain to half cardigan, or vice versa, also on these cams together with cams 2c and 3c to make the French rack or false knop. Slides i and j operate cams 1a, 2a, 3a and 4a to make tubular work, or to be more explicit, they raise one pair of these cams up out of operation while the other pair knit only on one side alternately and in this way knit jersey fabric in tubular form.
To go back to slides b and g, in order to understand this explanation it will be necessary to return again to Fig. 40. What are called the stitch cams, or cams 1 to 10, are attached to the cam plates through elongated slots, the ends of which may be seen at the top and bottom of the cams. The cams, though attached to the plate, may be easily moved lengthwise of these slots. On the under side of the plate is a coil spring with one end attached to a stud in the cams, while the other end is attached to the bottom edge of the plate. These springs will always draw the cams to the lowest end of the slots if nothing is placed in the way. Bear in mind that the bottom of the lower plate is the lower edge and the bottom of the top plate is the top edge, in the drawing.