AN IMPROVED APPARATUS FOR PREVENTING SEWING MACHINES FROM MISSING STITCHES WHEN WORKING
Year: 1880

page_text: PROVISIONAL SPECIFICATION left by Amand Ulysse Lorinet and Zacharie
Prudent Aubertelle at the Office of the Commissioners of Patents on the 5th
February 1880.
"
AMAND ULYSSE LORINET, Schoolmaster, and ZACHARIE PRUDENT AUBERTELLE,
Marchant de Machines à Coudre, à Chalons-sur-Marne (Marne), France. AN
IMPROVED APPARATUS FOR PREVENTING SEWING MACHINES FROM MISSING STITCHES
WHEN WORKING."
Inall sewing machines the thread which passes through the eye of the needle
should, for each stitch, form a loop into which is introduced either a hook of
some kind in machines making a chain stitch, or a shuttle of variable form in
other machines. In order that this loop may be constantly seized by the hook
or by the shuttle it is highly important that it should be perfectly regular.
If the thread is followed from the moment that the needle passes through the
work to the lowest point to which the needle descends it will be seen, in this
journey, stretched on both sides of the needle; the above mentioned loop is produced
by a slight rising of the needle varying from, say, 1/1 to 1 of an inch ("2 to 4
millemètres "). As at this moment the thread is not stretched above the seam it
does not rise with the needle, and mostly forms on the two sides of it two loops
more or less regular.
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But this thread having been folded somewhat closely in the eye of the needle
several inconveniences often arise therefrom, for example,―
1°. When the needle rises for the formation of the loop the thread, preserving its
fold, descends by the eye on one side or the other of the needle without forming a
loop, thence one or more stitches are missed.
2°. The loop formed behind the needle incommoded by the channel or guide
in which this needle works causes the other loop to deviate and escape the
shuttle or the hook which should seize it, and this is another cause of missed
stitches.
3°. Further, this same loop, formed behind the needle, pushed back by the
bottom of the channel or guide often turns round the needle and comes to the
front. Then the two threads being seized at the same time the thread inevitably
breaks short off.
We will now set forth the principle upon which our improvement is based.
We assumed that if while the needle was rising for the formation of the loop we
could lift the thread a little more all these inconveniences would disappear.
In

page_text: fact, the loop which forms behind the needle would be entirely done away with
and the aforesaid third defect no longer exist, but, further, the fold formed in the
eye of the needle being also slightly raised up, and resting, however slightly,
against the bottom of the channel or guide instead of hindering, as before, would,
on the contrary, aid the thread to form the indispensable loop. This loop would,
it is true, be a little smaller, but quite sufficient, because it would have the essential
advantage of always being absolutely regular, and directed exactly forward, nothing
behind it inducing it to turn to one side or the other it could no longer escape
from the shuttle or the hook, the result would therefore incontestably be that
there would be no more missed stitches or broken thread by reason of a double
loop.
Description of our apparatus reduced to its simplest form:-
Starting from the above observations we have invented, to obtain the raising or
relifting of the thread without injuring the regularity of the sewing, a spring nipping
the thread so as to allow it to slide only when drawn by a force equivalent to a weight
of from / to, of an ounce (" 10 to 20 grammes,") or if necessary a little more,
according to the power of the machine; this spring is fitted in the groove of a lever
fixed by one end to the head of the machine; this lever is bent so that one extremity
presents itself in the passage of the thread, a stop prevents it from rising further than
required, and a spring keeps it raised unless drawn down by a contrary power.
There is fixed to the needle-holder a stud, forming point of pressure, so placed that
when the needle-holder is just at the end of its journey downwards, this point of
pressure lowers the corresponding point of the lever from, say, 18 to 1 of an inch
(" 3 to 5 millimètres") according to the machine. As the point of pressure is between
the fulcrum and the extremity of the lever, this extremity, where the thread is
pressed by the spring and held in a small notch or recess made in the lever, lowers
to a greater extent than the needleholder (say 1% or 1 more) and then rises again
to the same extent, bringing back in this latter movement, firstly, the length of
thread which would have formed a loop behind the needle, and further from 1 to
1 of the other loop, which then remains of perfect regularity.