IMPROVEMENTS IN SCREWS. BOLTS, AND NUTS
Year: 1876

page_text: LETTERS PATENT to Samuel Hubbard James, of Lyddington, Uppingham, in
the County of Rutland, Civil Engineer, for the Invention of "IMPROVEMENTS
IN SCREWS. BOLTS, AND NUTS."
Sealed the 12th December 1876, and dated the 25th October 1876.
PROVISIONAL SPECIFICATION left by the said Samuel Hubbard James at the
Office of the Commissioners of Patents on the 25th October 1876.
SAMUEL HUBBARD JAMES, of Lyddington, Uppingham, in the County of Rutland,
Civil Engineer. "IMPROVEMENTS IN SCREWS, BOLTS, AND NUTS."
For the purpose of description I will assume that the bolt or screw is placed
vertically so that the head is below or in the lower position.
For bolts or screws having only one direction of strain I form the thread so that
the upper and lower sides thereof are both deflected downwards or towards the
head or direction of strain thereon more or less from the horizontal line, but it is
not intended that both these deflections should be necessarily of the same angle.
When a strain is put on a bolt or screw so formed the tendency is to press the
thread towards the horizontal line, thereby increasing the diameter of the outer
part of the male thread, and contracting or drawing in the edge of the female
thread, thus gripping tighter as the pressure increases and preventing the slip or
play which is inseparable from the form of ordinary screw threads, for with them
the male thread is contracted and the female expanded.
In screws or bolts liable to receive opposite strains the threads must be made so
as to give the same tendency to expand the male thread by the strain thereon
whichever side such strain may come, and this is done by deflecting both sides of the
thread away from each other and towards the directions of strain, and not towards
each other and away from the directions of strain as is the usual practice. This
class of screw or bolt will be found especially useful for joining plunger or piston
rods or other similar work, or in places subject to strains in alternate directions.
I do not limit myself to any particular inclination of thread, or any particular
form, whether it be round, flat, or otherwise, but the especial feature of novelty and
the main principle of the Invention consists in making the general direction of that
side af the thread opposing the strain form more or less of an acute angle with the

page_text: direction of the strain, so that when the pressure is applied it will tend to expand
the male thread and contract the female thread.
The nuts or female screws require no further description except that they must
respectively fit their bolts or screws.
The Invention can be applied to screws made of metal, wood, or other material,
as also to common metal screws driven into wood or other material without the use
of a separate nut.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Samuel Hubbard James in the Great Seal Patent Office on the
13th March 1877.
SAMUEL HUBBARD JAMES, Civil Engineer, of Lyddington, Uppingham, in the
County of Rutland. "IMPROVEMENTS IN SCREWS, BOLTS, & NUTS."
I form my threads so that the upper & lower sides thereof are both deflected
towards the head. The tendency of such a bolt or screw when strained is to
increase the diameter of the male thread & contract the female, as also to force
increasing sections into decreasing grooves, thus augmenting the lock or grip. This
applies to any angle of deflection or form of thread, whether round, flat, or other-
wise, provided the side opposing the strain is under cut.
In order that my said Invention may be more clearly understood & readily
carried into effect, I will proceed aided by the accompanying Drawings more fully
to describe the same.
Figure 1 represents a section taken through a bolt & nut by which it is shewn
that the upper & lower sides of the threads of the screw are deflected towards
the head, that side of the thread (shewn by the direction of line A, B,) upon which
the strain bears being under cut, thus making the angle A, B, C, acute or less than
the quadrant.
Fig. 2 represents the elevation of a bolt & nut. The nuts should respectively
fit their own bolts, but it is not absolutely necessary that they should do so, for if
desired they can be made with or without a slit or slits (S), shewn in Figures 2
& 3, cut in a line parallel with the axis of the bolt or inclined thereto, as shewn
by dotted line in Figure (2), by which means the act of screwing tight causes the
split to partially close & mechanically counteract any inequalty in the fit, if
such there be. Moreover the nuts may be totally divided into two or more sections,
as in Figure 4, & still be serviceable.
The Invention can be applied to any form of screw with or without the use of a
separate nut as in the case of ordinary square cut wood screws. They can be manu-
factured in a similar way to the ordinary method by taps & dies, the latter either
of the solid description or composed of two or more parts.
I therefore claim that this Invention consists in making that side of the thread
opposing the strain form more or less of an acute angle with the direction of the
strain, so that when pressure is applied the tendency of the male thread is to
expand & the feinale to contract; & also the employment in connection therewith
of a nut, if desired split in a direction similar to the axis of the bolt.
In witness whereof, I, the said Samuel Hubbard James, have hereunto set my
hand & seal, this Twelfth day of March, in the year of our Lord One
thousand eight hundred & seventy-seven.
S. H. JAMES. (L.S.).