AN IMPROVED LOCKING DEVICE FOR SCREW BOLTS AND NUTS
Year: 1879

page_text: PROVISIONAL SPECIFICATION left by John Baker Colbran at the Office of
the Commissioners of Patents on the 15th February 1879.
JOHN BAKER COLBRAN, of Upper Holloway, in the County of Middlesex.
" AN
IMPROVED LOCKING DEVICE FOR SCREW BOLTS AND NUTS."
My Invention relates to an improved locking device for screw bolts and nuts,
and is designed to provide means whereby the nut may be readily screwed to the
necessary position upon the bolt, and as readily removed therefrom when required,
but which will remain securely locked in the position in which it has been placed
upon the bolt as long as required.
In carrying the said Invention into practice I form the nut with a cavity or
depression in its outer face or end. The edge or wall of this cavity forms nearly a
circle, a piece of the metal being left at one part projecting inwardly toward the
centre of the nut. This piece is curved in such a manner that one end thereof
extends to or nearly to the edge of the screwed aperture of the nut, and the other
end is nearer to the wall of the aforesaid cavity, that is to say, the said curve in
this piece is of such form that there will be a space left between the outer surface
of the bolt and the inner face of the said piece, which space gradually increases
from one end of this piece to the other end thereof, thereby forming a wedge-shaped
cavity. The two ends of the said piece form shoulders, the deeper of which serves
as a support or abutment for one end of a curved metal spring piece, preferably
made of steel, to bear or rest upon. This curved spring-piece forms a ring open at
one part of its circumference, and is so constructed that it fits within the aforesaid
cavity provided in the face of the nut, and its upper or flat surface is flush or nearly
so with the outer flat face of the nut. A portion of the outer circumference of this
spring piece or ring is cut out, and the piece left at this part is tapered to a thin
edge, the latter being at the point where the ring is open. The part of the metal
left by cutting out this portion is wedge-shaped, and fits the wedge-shaped space
hereinbefore described. The shoulder thus left on the curved spring-piece or ring
comes into such a position with regard to the smaller of the aforesaid shoulders on
the inwardly projecting piece in the nut that a square aperture is left, which is
designed to receive a similarly-shaped key when it is desired to release the nut
from the bolt. The inner face of the wedge shaped portion of the curved spring-
piece or ring is provided with teeth or ribs, which are designed to gripe the bolt.
This curved spring piece or ring is so made that the wedge-shaped portion thereof
springs inwardly, and the whole ring is caused to grasp the bolt in such a manner

page_text: that there is no obstruction when the nut is being screwed on, but immediately
there is any tendency to unscrew the same the grasp tightens upon the nut, and the
greater the strain tending to unscrew the nut the greater will be the force exerted
to prevent it. Consequently the nut will be firmly locked against any strain,
however great. In order to prevent the said curved spring piece from coming out
of the cavity on the nut I may provido one or more small projections on it, which
will fit into corresponding apertures in the nut; or any other suitable means may
be employed for the purpose. If it is desired to remove the nut a key is inserted
in the aforesaid square aperture, and this has the effect of removing the pressure of
the said curved spring-piece upon the bolt, and the nut may then be unscrewed
without obstruction. If found necessary, through breakage or otherwise, the said
curved spring-piece may be removed from the cavity in the nut, and another sub-
stituted for it.
This device is applicable to nuts and bolts of all shapes and kinds, and will be
found specially valuable for uniting the joints of railway rails.