AN IMPROVEMENT IN LOCKING SCREW NUTS
Year: 1875

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane,
in the County of Middlesex, Patent Agent, for the Invention of
"AN IMPROVEMENT IN LOCKING SCREW NUTS."-A communication from
abroad by Finis Langdon Bates, of Carrollton, in the County of
1
COMPLETE SPECIFICATION filed by the said Alexander Melville Clark
at the Office of the Commissioners of Patents, with his Petition
and Declaration, on the 3rd May 1875, pursuant to the 9th Section
of the Patent Law Amendment Act, 1852.
5
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Datant & cant cand areating

page_text: 0
me, my executors, administrators, and assigns, Her Royal Letters Patent
for the same, and have made solemn Declaration that it has been com-
municated to me from abroad by Finis Langdon Bates, of Carrollton, in
the County of Carroll, and State of Mississippi, United States of America.
NOW KNOW YE, that I, the said Alexander Melville Clark, do
hereby declare that the following Complete Specification, under my
hand and seal, fully describes and ascertains the nature of the said
Invention, and in what manner the same is to be performed, in and
by the following statement, reference being had to the accompanying
Drawing (that is to say) :-
The object of this Invention is to provide efficient means for pre-
venting the nuts of screw bolts from working off by means of the jarring
or vibration to which the parts held by the bolt are subjected, and it
consists in a nut having a screw thread which does not extend through
the nut, but acts as a smoother to cut the outer threads from the bolt
and bind the nut.
In the accompanying Drawings A is the bolt, and B the nut. In
cutting the bolt the thread is cut, as in the ordinary bolts, flush with
the end. In cutting the thead through the nut the tap is not passed
clear through, but being a plug tap it is stopped so as to leave about one-
fourth of the distance through the nut uncut, as seen in the Drawing.
When the nut is turned on the uncut portion of the nut strips the outer
threads of the screw, or bevels them down even with the surface of the
body of the bolt; this binds the nut on the bolt so that it cannot be
started back without a great exertion of force. If by means of wear or
shrinkage the bolt should be loosened the nut can be turned up still
further, and the bolt tightened with the same result. In ordinary cases
two or three threads of the bolt forced down in this manner will be
sufficient to bind the nut, but I do not confine myself to any particular
number of threads or length of space.
Having described the nature of the Invention, and the manner of
performing the same, I declare that what I claim as new and desire to
secure by Letters Patent is, a nut having its threaded portion extending
partly through the aperture, in combination with an ordinary screw bolt,
so that when the nut is applied the uncut portion of the aperture of the

page_text: nut will strip one or more threads from the bolt, substantially as and for
the purpose specified.
In witness whereof, I, the said Alexander Melville Clark, have
hereunto set my hand and seal, this Third day of May, in the
year of our Lord One thousand eight hundred and seventy-five.