Year: 1886

page_text: Date of Application, 21st July, 1886.
Complete Left, 21st Apr., 1887.
Complete Accepted, 24th May, 1887.
RESERV
I, JAMES SCATTERGOOD of Stour Valley Works, West Bromwich in the County
of Stafford, Manager, do hereby declare the nature of this invention to be as
follows:-
My invention relates to the construction of a nut in such a manner that when it is
screwed on to a bolt it shall hold firmly and not be liable to become loosened and
unscrewed by vibration. For this purpose I form the internal screw thread of the nut
for the greater part of the depth of the nut to fit the thread of the bolt, but I make
the last two or three threads of the nut, that is to say those next the outer or top face
of the nut, of a section somewhat different from the section of the hollows between
the threads of the bolt in which the nut threads have to engage. I make this
difference of sectional form, not by making the threads of the nut deeper or shallower
than the regular threads, nor by making the upper part of the nut hole of a different
diameter from the rest, but by giving, to the profile of the threads, sides that are
inclined at a somewhat greater angle to the axis than the regular threads. The effect
of this alteration of form of a few of the nut threads is that, whilst the bolt
enters the nut freely and engages with the greater part of the depth of the nut,
the few upper threads of the nut are, by farther screwing on the nut, so compressed
that they tightly grip the bolt threads, and the nut is not liable to be loosened by
vibration.
In cases where bolts and nuts are employed to clamp a definite thickness, as
for instance for the fish joints of rails, the nut may have a regular thread through-
out its depth, a few of the bolt threads next the shank being made of a different
profile so that when the nut is screwed up, there is a tight grip where those threads
occur.

page_text: 1, JAMES SCATTERGOOD of Stour Valley Works, West Bromwich in the County of
Stafford, Manager 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 :-
My invention relates to the construction of a nut in such a manner that when it is
screwed on to a bolt it shall hold firmly and not be liable to become loosened or
unscrewed by Vibration. For this purpose I form the internal screw thread of the nut
for the greater part of the depth of the nut to fit the thread of the bolt, but I make
the last two or three threads of the nut, that is to say those next the outer top face of
the nut, of a section somewhat different from the section of the hollows between the
threads of the bolt in which the nut threads have to engage. I make this difference
of sectional form, not by making the threads of the nut deeper or shallower than the
regular threads, nor by making the upper part of the nut hole of a different diameter
from the rest, but by giving, to the profile of the threads, sides that are inclined
at a somewhat greater angle to the axis than the regular threads. The effect
of this alteration of form of a few of the nut threads is that, whilst the bolt
enters the nut freely and engages with the greater part of the depth of the nut,
the few upper threads of the nut are, by farther screwing on the nut, so compressed
that they tightly grip the bolt threads, and the nut is not liable to be loosened by
vibration.
In cases where bolts and nuts are employed to clamp a definite thickness, as for
instance for the fish joints of rails, the nut may have a regular thread throughout
its depth, a few of the bolt threads near the shank being made of a different
profile so that when the nut is screwed up, there is a tight grip where those threads
occur
The accompanying drawing is a section of a nut and part of a bolt according to my
invention, which may be considered to be magnified, so as to shew on a large scale the
difference which is made in the sectional form of some of the threads of the nut. If
for example all the threads of the nut from A to Care of the usual form fitting the
threads of the bolt, the other threads from B to D are such that their sides are inclined
at a somewhat greater angle to the axis of the bolt. Thus the side A having the
usual inclination such that if its outline were prolonged it would meet a centre line at
the point a, the side B has a somewhat greater inclination so that its outline prolonged
meets the centre line at b a little farther from the axis. In a similar manner several
of the threads of the bolt next the shank might have their profile altered, the nut in
that case having a uniform thread of the usual shape. In manufacturing a nut of the

page_text: kind described, it is most convenient first to form the internal screw thread by a tap
such as will produce the threads with thickened bases like those from B to D, and then
to reduce the bases of those from A to C by the use of a plug tap having threads of
the usual form. In a similar way, when a bolt is to be made with several threads next
the shank thickened at their bases, a die may first be used to cut all the threads of the
thickened form and then another die can be applied to reduce the threads farthest from
the shank to the usual form.
Having now particularly described and ascertained the nature of this invention and
in what manner the same is to be performed, I declare that what I claim is :-
Making a nut with several of its screw threads having a profile widened at the base
to be used with a bolt of usual thread, or a bolt with several of its threads having a
profile widened at the base, to be used with a nut of usual thread, substantially as and
for the purpose herein set forth.
ABEL & IMRAY,
Agents for the Applicant.