How A Sewing Machine Functions; Theneedle - Pfaff 260 Service Manual

How a Sewing Mact.ine Functions
Household sewing machines all make the conventional lockstitch. This type of
stitch consists of on upper (needle) and a lower (bobbin) thread locked together ·
in the material being stitched. The lock of threads is pulled to the middle of
the fabric so that the seam has the same appearance top and bottom.
Every sewing machine designed to produce this type of stitch must hove the
following component ports and assemblies:
1. a needle
2. a sewing hook, complete with bobbin case and bobbin
(typical of any lockstitch sewing machine)
3. a take-up lever
. 4.
an upper and a lower tension mechanism
5. a feed dog
6. Stitch forming and feeding mechanisms
7. a bobbin winder.
The Needle
In contrast to the hand sewing needle, the machine sewing needle has the eye
near its tip. It penetrates the material at every stitch, carrying the thread
down through the hole it has mode in the fabric. As it rises after reaching
the lowest point of its stroke, the thread bulges out on the short-groove side
of the needle to form a loop above its eye. This loop is entered ot the correct
time by the point of the shuttle or sewing hook (figs. 1 & 2).
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Fig. 1
Fig. 2
Sewing machine needles are available in many different varieties and sizes,
and are classified into several groups, or systems.
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