IMPROVED MEANS OF LOCKING NUTS ON SCREW BOLTS
Year: 1876

page_text: LETTERS PATENT to James Henry Greathead, of No. 2, Storey's Gate, West-
minster, in the County of Middlesex, for the Invention of "IMPROVED MEANS
OF LOCKING NUTS ON SCREW BOLTS."
aled the 12th April 1876, and dated the 2nd February 1876.
PROVISIONAL SPECIFICATION left by the said James Henry Greathead at the
Office of the Commissioners of Patents on the 2nd February 1876.
JAMES HENRY GREATHEAD, of No. 2, Storey's Gate, Westminster, in the County
of Middlesex. "IMPROVED MEANS OF LOCKING NUTS ON SCREW BOLTS."
My Invention relates to means of locking nuts upon screw bolts, that is to say,
preventing the nut from being turned backwards by vibration, and thereby
becoming slackened. For this purpose I cut a longitudinal chase or groove along
the screwed part of the bolt and after the nut has been screwed on it I drive into
this chase a key or pin which partly imbeds itself in the thread of the nut, and so
prevents it from turning. The key or pin so driven in may remain in its position,
or it may be withdrawn, the driving of it in having had the effect of upsetting to
a certain extent the threads of the nut in the part facing the chase of the bolt, and
so producing an impediment to the turning round of the nut.
Instead of cutting the chase on the exterior of the bolt it may be cut along the
interior of the nut.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said James Henry Greathead in the Great Seal Patent Office on the
1st August 1876.
JAMES HENRY GREATHEAD, of No. 2, Storey's Gate, Westminster, in the County
of Middlesex. "IMPROVED MEANS OF LOCKING NUTS ON SCREW BOLTS."
My Invention relates to means of locking nuts upon screw bolts, that is to say,
preventing the nut from being turned backwards by vibration, and thereby
becoining slackened. For this purpose I cut a longitudinal chase or groove along
the screwed part of the bolt and after the nut has been screwed on it I drive into
this chase a key or pin which partly imbeds itself in the thread of the nut and so
prevents it from turning. The key or pin so driven in may remain in its position
or it may be withdrawn, the driving of it in having had the effect of upsetting to a
[Price 4d.]

page_text: certain extent the threads of the nut in the part facing the chase of the bolt, and
so producing an impediment to the turning round of the nut.
Instead of cutting the chase on the exterior of the bolt it may be cut along the
interior of the nut.
DESCRIPTION OF THE DRAWINGS.
Fig. 1 represents a side view partly in section of a bolt with a nut locked
thereon according to my Invention; Figure 2 is an end view of the bolt with the
nut removed; and Fig. 3, an end view with the nut on the bolt. A chase or
groove a is cut along one side of the bolt, and after screwing on the nut a key b is
driven into the chase.
I prefer to make the key with its face sloped off so as to present a sharp edge (as
shewn in Figure 2), that enters like a chisel partly into the thread of the nut and
prevents it from turning backwards unless the key b be withdrawn longitudinally.
Figs. 4, 5, and 6 represent respectively a part longitudinal section, and an end
view without and with a nut, of a bolt in which the key b and the groove for it
are arranged so that by screwing up the nut the key can be slackened for facilitating
its removal.
The shape of the groove and key for this purpose is shewn to an enlarged scale
in Fig. 7. The key b when the nut tends to unscrew itself becomes firmly sup-
ported at its back and inner side, its chisel edge entering the thread of the nut;
but by screwing the nut forwards so as to tighten it on the bolt the key b becomes
canted into the position indicated by the dotted lines, its edge being thus with-
drawn from the nut thread and itself being freed so that it can be removed, where-
upon the nut can be screwed farther or unscrewed.
Figs. 8, 9, and 10, by views similar to those given in Figs. 1, 2, and 3, shew a
modified arrangement, the bolt instead of having a groove or chase cut in it having
part of its side flattened off, and the key b being of triangular shape, with its base
resting against the flat side of the bolt, and its edge entering the thread of the
nut. It is obvious that the key either in this case or in that shewn in Figs. 1, 2,
and 3 might be simply a round or square pin driven in so as to upset a little the
edges of the nut threads, and might itself be withdrawn, the upsetting of the
threads being generally sufficient to prevent the nut from unscrewing itself.
It may also be readily understood that the chase instead of being formed in the
side of the bolt might he cut in the interior of the nut. The key or pin b may be
somewhat bent or twisted before being driven in, so that it may have a certain;
spring serving to hold it in the chase.
Figs. 11, 12, and 13 shew a modification wherein the bolt has a slot cut through
it, and the key b is made flat and sufficiently wide to extend across the bolt, and
have its edges bearing against or cutting into the thread of the nut on opposite
sides.
Figs. 14 and 15 shew a similar construction with a cut c extending throughout a
considerable part of the length of the key b, so as to make it capable of springing
a little in its width. The edges of being sloped the nut can be screwed up,
springing them inwards, but they prevent it from screwing itself off.
Having thus described the nature of my Invention and in what manner the same
is to be performed, I claim locking nuts on screw bolts by means of a key or pin
driven into a longitudinal chase or groove in the bolt or the nut after the nut has
been screwed home, substantially as herein described.
In witness whereof, I, the said James Henry Greathead, have hereunto set my
hand and seal, this Thirty-first day of July, in the year of our Lord One
thousand eight hundred and seventy-six.
J. H. GREATHEAD. (L.S.)