An improved means of Preventing Bolts, Screws, and Nuts from Becoming Loose.
Year: 1888

page_text: Date of Application, 23rd Apr., 1888
Specification Accepted, 17th Aug., 1888
RESERVE
An improved means of Preventing Bolts, Screws, and Nuts from
Becoming Loose.
I, AMOS DAVIES, of Griffin Street, Tamworth, in the Colony of New South Wales,
Builder and Contractor, do hereby declare the particulars of my said invention to
be specified and illustrated in and by the following statement, and the Drawings
attached hereto :-
This invention relates to a form of Nut-lock which is capable of being used with
bolts of the ordinary type, the peculiarity consisting not in the mode of the thread, or
the shape of the thread itself, but in the form of the Nut.
It is well known that when nuts and bolts are used in any situation in which they
are subject to vibration, the nuts have a tendency to slack back, and become loose
upon the bolts. Several devices for counteracting this tendency have been tried with
more or less success. The object of this invention is to devise a form of Nut in
which no alteration is made in the form of the thread, but in the form of the Nut
itself.
The "Nut" is made excentric, that is, one side of it is made heavier than the other
side. The Nut thus formed is screwed on to a horizontal or any inclined bolt, so that
the weightier side tends by gravity to advance the Nut on the screw, and tighten the
joint. It is aided in this operation by the combined effects of vibration and wear, so
that the weightier side of the Nut shall always be situated on the down turn. They
are made in a number of grades, the difference between the grades being simply in
the cutting of the thread, which is cominenced at a different point in each one.
But to make my invention better understood, I shall now refer to the four figures
on the accompanying sheet of drawings, in both of which the same letters and figures
of reference indicate corresponding parts.
Figure 1 shows a sectional view of the Bolt and Nut as used for fastening a Rail
and Fish-plates. Figure 2 shows a plan of the Nut as it appears when screwed on to
the Bolt.
A is the Shank, and B the head of the Bolt; (is the Nut, of which one side C¹¹ is
more massive and heavier than the other side C¹.

page_text: A possible alterative device for rendering one half the Nut heavier than the other
half consists in constructing a Nut of two different metals of varying densities, in
which case the Nut need not be made excentric in bulk, but only in weight. D is a
Rail, and E and E are Fish-plates.
Were the Nuts all tapped by the one instrument whilst in the same relative positions
as regards their heavier and lighter sides, a difficulty would be encountered when the
thickness of the joint was such that the Nut being screwed tightly on, if the heavier
side of it should happen to fall on the up turn &, in consequence of which it would
tend to slack back and loosen instead of, as in the opposite case, as illustrated by
Figure 2, to tighten up the joint. To obviate this difficulty I construct Nuts of four
or more grades or gauges, by commencing to cut the thread at four or more different
points of the Nuts, and numbering them accordingly to prevent loss of time in sorting.
Then if a Nut of one grade does not finally rest in a suitable position, one of another
grade will do so, and consequently no inconvenience can arise.
It is the general practice of Bolt and Nut manufacturers to throw to the scrap any
Nuts which happen to be cored excentrically. To these Nuts the principle of this
invention may be applied with facility. It may also be applied to existing Nuts by
shearing a piece off one side (Figure 3, cut off part) and thus rendering them
excentric, as herein before described. Excentric Coach and Set Screws can also be
made by simply forging the head more to one side of the shank than the other
(Figure 4, A Shank; B Head; C" Heaviest side.
Having now particularly described, specified, and illustrated my said invention, I
declare that what I claim to be new and original, is :—
1. An improved means of preventing bolts screws and nuts from becoming
loose, in which one side of the Nut is made more massive or dense than the other side,
which said massive or dense side is caused to be always.on the down turn, and by that
means to tend to tighten up upon the Bolt, which it is caused to do by the combined
actions of gravity and of vibration and wear, substantially as and for the purposes
herein described and set forth.
2. A Nut Lock of the kind herein described, commencing to tap the Nuts at four
or more different points, so that one or other Nut being screwed on to the Bolt, the
more dense or massive side may be located on the down turn, substantially as and for
the purposes herein described and set forth.
In witness whereof, I, the said Amos Davies, have set my hand and seal this
Eighth day of March 1888.