Improvements in Nut Locks and Bolts.
Year: 1894

page_text: COMPLETE SPECIFICATION.
Improvements in Nut Locks and Bolts.
I, DAVID MERCIER FULTON, of 304 Robert Street in the City of Baltimore
and State of Maryland, United States of America, Merchant, do hereby declare the
nature of my invention, and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :-
In the description of the said invention which follows, reference is made to the
accompanying drawing forming a part hereof and in which,
Figure 1 is an exterior side view of a bolt and its holding and lock nuts
constructed in accordance with my invention.
Figure 2 is a section of the upper part of Figure 1.
Figure 3 is a top view of the lower nut.
Figure 4 is an exterior side view of the two nuts before the completion of the
locking operation, as will hereinafter fully appear.
Referring to the drawing A is a bolt having a right hand thread a cut in the
usual manner.
B is the holding nut having a thread corresponding with and adapted to fit the
one a.
b
Around the thread a of the bolt A is cut a shallow angular spiral groove 6 having
a pitch much greater than that of the thread a. The depth of this groove is about
one third to one-half of that of the thread a, consequently the said thread is not cut
through or its strength materially reduced.
C is the locking nut having a thread constructed to fit the groove b, see
Figure 2.
The adjacent faces of the nuts B and C have radial teeth of a common size and
shape. The shape of these teeth is shown particularly in Figures 1, 3 and 4, and
it will be seen that they have straight faces d and e, the ones d being practically
parallel with the axis of the bolt and the others e inclined. These teeth serve to
lock the nuts when the same are brought together.
In the operation of the invention, the holding nut is screwed down tightly to its
proper position onto the piece to be held, and then the locking nut C screwed on the
bolt in a reverse direction until it comes in contact with the holding nut.
The teeth of the two nuts when first brought into contact appear as shown in
Figure 4, and to fully lock the nuts the holding one B is slightly unscrewed or
until the locking nut C is drawn down and its teeth fully engaged with those of the
nut B. The teeth then appear as shown in Fig. 1.
The advantage in having the groove b of a coarser pitch than that of the thread a,
is that a very slight circumferential movement of the holding nut is required to lock
it, the locking nut coming down more rapidly to meet it. In other words, in the
locking operation the two nuts approach each other but with different speeds, and
the holding nut moves outward only about one-half the distance that the locking
nut moves inward. By this means the slackening of the holding nut is hardly
perceptible.
As before briefly stated, the spiral groove does not sever the thread a but
merely notches it, as shown in Figure 1, and the integrity of the thread is not
destroyed, or the effectiveness of the bolt impaired to any appreciable extent.
Where the thread is entirely cut through, it forms short spirals and has little
strengthening effect on the body of the bolt.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:
A bolt having an ordinary holding thread, and holding nut with teeth on its upper
surface, and a spiral groove of greater pitch and of less depth than the holding
thread, combined with a locking nut having a thread adapted to fit in the spiral
groove and provided with surface teeth corresponding with those on the holding
nut, substantially as specified.
Dated this 10th day of July 1001
DAVID MERCIER FULTON.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.