An Improved Screw-bolt and Method of Locking Nuts on such Bolts.
Year: 1893

page_text: Date of Application, 1st Sept., 1893-Accepted, 7th Oct., 1893
COMPLETE SPECIFICATION.
An Improved Screw-bolt and Method of Locking Nuts on
such Bolts.
We, JOSEPH HARRISON, of 13, Farrell Street, Port Melbourne, in the Colony
of Victoria, Ganger, and ROBINSON RITSON, of Newlands, Coburg, near Melbourne,
in the Colony of Victoria, Carpet Salesman, do hereby declare the nature of our
invention and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement:—
Our invention relates to nut locks, and consists primarily in an improvement
in the construction of screw-bolts, whereby they may be made self locking upon
ordinary nuts.
The improvement may be quickly and inexpensively embodied in any ordinary
screw-bolt, thus extending the applicability of the invention to the innumerable
cases in which no efficient or suitable nut locking device is already in use.
Notwithstanding the vast number of inventions for locking nuts, now known, we
believe there are none so simple, inexpensive, and perfectly proof against stripping,
vibration or other common causes of the nuts eventually working loose, as our own.
Referring now to the accompanying sheet of drawings,
Figure 1 shows our improved bolt in side elevation, and Figure 2 is a view partly
in section showing the bolt connecting two objects together and with an ordinary
nut screwed on and locked by the method hereafter described.
The
The same letters of reference are used on each figure to indicate like parts.
A represents a screw-bolt of any shape or size. B represents a slot sawn or
otherwise made in its screwed end and extending any required distance.
depth of the slot must be sufficient to extend a slight distance (such as a quarter of
the depth of the nut) further than the outer face E of the nut when the latter is
screwed home; and where in any particular case the slot is found to be too short,
a washer or like means should be employed to preserve this condition.
The slot B is not a mere slit but is wide enough to allow of easy cleaning out of
the same, when clogged with dirt and to facilitate the compression of the opened
ends, shown in Figure 2 to the original diameter so as to enable the nut to be
removed when required. In such sized bolts as are shown in the drawing we
prefer the slot to be at least one sixteenth of an inch wide.
Our method of locking the nut on the bolt, when the nut is screwed home in
such a way that part of the slot extends within the body of the nut, is simply to
open the outer ends of the slotted bolt as shown in Figure 2, in which position
the threads of the bolt are forced close into the worm of the nut, so that it is
impossible for the nut to turn, to loosen, or to strip the thread off the bolt, and
so that the strength or holding power of the bolt is greatly increased over that of
a straight bolt.
The locked nut, although proof against being tampered with by persons without
special appliances may nevertheless be removed when required, by the use of a
powerful wrench. It is an important feature that when a powerful wrench is
employed to unscrew the nut, the nut itself brings back the ends of the bolt to
their original position, so that the same nut and bolt can be repeatedly used, the
thread of the bolt remaining uninjured, which would not be the case unless our
wide slotted bolt were used.
In order to enable the nut to be more easily put on a bolt that has been locked
and unlocked before, we prefer to have the first thread of the screw of the bolt F
tapered off slightly as shown in the Figures so that the bolt has not quite its full
diameter at the outer end of the slot.
Various elaborations or modifications of this invention might be made in details

page_text: whilst preserving the essential features thereof, the nature of which we have set
forth, attaching special importance to the wide slot.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that
what we claim is :-
1. A self-locking screw-bolt as A having at its end a slot as B substantially as
and for the purposes set forth.
2 The method of locking a nut such as C on a screw-bolt such as A consisting
in expanding the ends of the bolt outwardly, and so as to force the screw thread
tightly into the worm at the outer end of the nut substantially as described and
illustrated.
3. In combination with a screw-bolt as A, the wide slot as B and the tapered
end to the thread of the bolt as F, substantially as and for the purposes set forth.
Dated the 21st day of July 1893.
JOSEPH HARRISON.
ROBINSON RITSON.