Improvements in Locking Nuts.
Year: 1888

page_text: Date of Application, 7th Dec., 1888
Complete Specification Left, 3rd Oct., 1889-Accepted, 9th Nov., 1889
PROVISIONAL SPECIFICATION.
Improvements in Locking Nuts.
I, ROBERT MARSHALL, of Endrick Bank, Honor Oak Park, in the County of
Surrey, Engineer, do hereby declare the nature of this invention to be as follows:-
According to my invention 1 construct lock nuts as follows. The thread of the
nut is formed of a sufficiently larger diameter than that of the screw bolt, to admit
between the two a helically wound wire, which fits on the outer side into the thread of
the nut and on the inner side into that of the bolt, so that the wire forms the actual
thread of the nut into which the bolt screws. The one end of the wire coil being fixed
in any suitable manner to the nut, while the other end is unattached, the action will
be as follows:-
When the nut is turned on the bolt in the same direction as that in which the coil
of the wire runs, when starting from the fixed end, the nut will turn freely, because
the frictional pressure of the bolt against the wire helix will tend to uncoil and con-
sequently widen the latter, but if it be attempted to turn the nut in the contrary
direction, the frictional contact between the wire helix and the bolt will tighten the
grasp of the wire upon the bolt to such an extent as to prevent the nut from
turning.
The force with which the wire holds the bolt will depend partly upon the number
of coils employed and partly upon the nature of the surfaces in contact; thus if the
edge of the wire be formed with serrations lying in the direction in which the nut is
free to turn, comparatively few coils would suffice, and in that case, only part of the
nut might be formed in the manner above indicated, the remaining part being made
to fit the bolt in the ordinary manner. But for the sake of simplicity of construction,
I prefer to construct the nut with the wire helix extending throughout its length, in
which case the friction of ordinary smooth surfaces is found sufficient to produce the
above described effect.
A simple and effective way of securing the one end of the wire helix to the nut
consists in forming the end surface of the latter with a notch, into which the end of
the helix is bent, so that on removing the end from the notch, the helix no longer
exercises the gripping action, and the nut can consequently be removed. In manu-
facturing square nuts for the purposes of my invention I prefer to roll the bar from
which the nuts are formed with a longitudinal groove in the middle of one side, so
that when the nuts are cut off, they will have a groove on each side of the bolt hole,
into either of which the end of the wire can be bent.
It will be evident that the converse of the above described arrangement might be
used, that is to say, the one end of the wire helix might be fixed to the bolt instead of
to the nut, so that the helix would screw through the nut with the bolt, and would
bind against the thread of the nut when this was turned in the contrary direction to
that in which the helix runs from the fixed end. But as this would require the wire
helix to extend the whole length of the thread of the bolt, it would obviously not be so
practical an arrangement as that above described.
Dated this 7th day of December 1888.
ABEL & IMRAY,
Agents for the Applicant.

page_text: UDI LUIM
SPECIFICATION.
Improvements. in Locking Nuts.
1, ROBERT MARSHALL of Endrick Bank Honor Oak Park, in the County of Surrey,
Engineer do hereby declare the nature of this invention and in what manner the same
is to be performed to be particularly described and ascertained in and by the following
statement:
According to my invention I construct lock nuts as follows. The thread of the nut
is formed of a sufficiently larger diameter than that of the screw bolt, to admit
between the two a helically wound wire which fits on the outer side into the thread of
the nut and on the inner side into that of the bolt, so that the wire forms the actual
thread of the nut into which the bolt screws. The one end of the wire coil being
fixed in any suitable manner to the nut, while the other end is unattached, the action
will be as follows:-
When the nut is turned on the bolt in the same direction as that in which the coil
of the wire runs, when starting from the fixed end the nut will turn freely because the
frictional pressure of the bolt against the wire helix will tend to uncoil and con-
sequently widen the latter. But if it be attempted to turn the nut in the contrary
direction, the frictional contact between the wire helix and the bolt will tighten the
grasp of the wire upon the bolt to such an extent as to prevent the nut from turning.
The force with which the wire holds the bolt will depend partly upon the number of
coils employed and partly upon the nature of the surfaces in contact; thus, if the
edge of the wire be formed with serrations lying in the direction in which the nut is
free to turn, comparatively few coils would suffice, and in that case, only part of the
nut might be formed in the manner above indicated, the remaining part being made
to fit the bolt in the ordinary manner. But, for the sake of simplicity of construction,
I prefer to construct the nut with the wire helix extending throughout its length, in
which case the friction of ordinary smooth surfaces is found sufficient to produce the
above described effect.
A simple and effective way of securing the one end of the wire helix to the nut
consists in forming the end surface of the latter with a notch into which the end of
the helix is bent, so that, on removing the end from the notch, the helix no longer
exercises the gripping action, and the nut can consequently be removed. In manu-
facturing square nuts for the purposes of my invention, I prefer to roll the bar from
which the nuts are formed with a longitudinal groove in the middle of one side, so
that when the nuts are cut off, they will have a groove on each side of the bolt hole
into either of which the end of the wire can be bent.
It will be evident that the converse of the above described arrangement might be
used, that is to say, the one end of the wire helix might be fixed to the bolt instead
of to the nut, so that the helix would, screw through the nut with the bolt, and would
bind against the thread of the nut when this was turned in the contrary direction to
that in which the helix runs from the fixed end. But as this would require the wire
helix to extend the whole length of the thread of the bolt, it would obviously not be
so practical an arrangement as that above described.
Fig. 1 of the accompanying drawings is a longitudinal section of a bolt and nut.
having threads of V form with a helical wire of diamond section applied, this wire
fitting into the grooves of both threads and having one of its end bent over into a
notch in the end of the nut. Fig. 2 shews a similar arrangement of square threaded
bolts and nuts, the helical wire being in this case of rectangular section. Fig. 3
shews a helical wire of circular section applied to a bolt and nut having V threads of
ordinary form. Fig. 4 is an elevation of the helical wire separately and Fig. 5 is a
longitudinal section of the nut with the wire helix in it.

page_text: Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
In combination with a screw threaded bolt and a nut of enlarged diameter, a wire
helix occupying wholly or partially the hollows of both threads and having one of its
ends secured to the nut so as to turn with it, or secured to the bolt so as to be pre-
vented from turning, substantially as and for the purpose herein set forth.
Dated this 3rd day of October 1889.
ABEL & IMRAY,
Agents for the Applicant.