IMPROVEMENTS IN SCREW NUTS
Year: 1880

page_text: LETTERS PATENT to Herbert John Haddan, of the Firm of Herbert and
Company, Solicitors of Patents, of 67, Strand, in the City of Westminster,
Civil Engineer, for an Invention of IMPROVEMENTS IN SCREW NUTS."
A communication from abroad by William Courtenay, of the City, County,
1 of N
"
COMPLETE SPECIFICATION filed by the said Herbert John Haddan at the
Office of the Commissioners of Patents on the 3rd December 1880.
HERBERT JOHN HADDAN, of the Firm of Herbert and Company, Solicitors of
Patents, of 67, Strand, in the City of Westminster, Civil Engineer. "IMPROVEMENTS
IN SCREW NUTS." A communication from abroad by William Courtenay, of the
City, County, and State of New York, United States of America.
1
The object of the Invention is to prevent the loosening of screw nuts by the jar
or trembling of the machinery, or other objects to which they may be applied, and
to that end I propose, first, to construct a nut in two parts in the manner
specifically hereinafter set forth; second, I propose to construct a nut of a
particular material, designed especially to be used as an auxiliary, or jam nut, to
secure the principal nut from loosening, but which may also be used separately.
In the Drawing Figures 1 and 2 represent different views of the nut first spoken
of. A in these Figures represents the exterior part of the nut, which may be
made of iron, brass, or any other material, as well as of any shape of which nuts are
ordinarily constructed, but of sufficient strength and rigidity to perform the
ordinary functions of a nut when reinforced by the part B. This part B is let into
a sink on the bottom of the bearing surface of the nut, preferably to about half the
depth of the nut. The sink and the part B are, as I construct them, square or.
polygonal, so that the two parts cannot turn independently of each other, but the
sides of the sink might be sufficiently roughened to effect this object. The part B
is thicker than the sink in the part A, and therefor projects: beyond the edges of
the latter, so that the part B will come first in contact with the fish-plate or other
object secured by the nut. Of course the same effect would be gained by
constructing a projection on the fish-plate smaller than the edges of the part A, or
if the fish-plate itself were made smaller. The part B should be constructed of a
softer or more yielding material than the part A, and yet have a certain degree of
strength or consistency of its own, and its yield should preferably be more of an
elastic nature. The material known in the arts as vulcanized fibre, and which is

page_text: usually constructed of a vegetable fibre treated with sulphide of zinc, or with
some compound of muriatic or of sulphuric acid, is probably the best for the
purpose, having the precise character of yield desired, combined with the required
frictional qualities. Leather would also serve the purpose very well, and some of
the soft or malleable metals, such as lead. The bolt hole goes through both
parts A and B, and if the screw thread does the same, it will be more perfect, but
in the latter case the thread should be perfectly continuous in both parts, and the
materials should therefore be such as will admit of the thread being cut by one
tool and at the same operation. In screwing the nut down, the parts turn together
and descend until the part B comes in contact with the bearing surface; the part A
continues to descend, and in doing so squeezes the part B between itself and the seat
of the nut, so that it is compressed on to the bolt and seat, either or both, and
grasping firmly, prevents the nut from turning under any jar or trembling action.
This squeezing action of the part A upon the part B, constitutes the principal
feature of this part of the improvements: The second part of the Invention
consists in constructing a nut of the said vulcanized fibre, which nut is principally
designed to be used as a jam, or auxiliary nut, and to be placed under the main nut,
and between it and the bearing surface, as the part D in Fig. 3 of the Drawing;
when so placed it will be squeezed, and to some extent operate in a manner similar
to the part B in the first mentioned nut, and for this purpose the material
possesses a peculiar combination of qualities not heretofore known or made use of.
The fibre nut D may, however, be placed outside of the main nut, and screwed
down upon or with it as jam nuts have heretofore been used, and will in that case
also operate to prevent the main nut from being readily loosened. In some cases
also it may be used independently of any other nut, its combination of strength
and yielding character being such as to give it a firm hold when screwed tightly
home. In Fig. 3, C represents the bolt; D, the auxiliary or jam nut; E, the main
nut of iron or other metal; and F, the fish plate or other object secured by the
nuts.
H. J. HADDAN. (L.S.)