Improvements in Nut Locking Devices for Screw-Bolts.
Year: 1891

page_text: COMPLETE SPECIFICATION.
Improvements in Nut Locking Devices for Screw-Bolts.
I, THOMAS POINDEXTER POLLARD, of No. 622N, 8th Street, Richmond, in
the County of Henrico, State of Virginia, United States of America, Gentleman,
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 :-
This invention relates to nut locks and is illustrated in the accompanying drawing,
in which
Figure is an elevation of a bolt, grooved and provided with a locking device in
accordance with my invention.
Figure 2 is a cross section of the bolt, the locking device being removed.
Figure 3 is a sectional view in a longitudinal plane of the end portion of said
bolt, locking device, and an improved nut used on the bolt, which nut is shown in
section, while the locking device and a portion of the bolt are shown in elevation.
Figure 4 is an end view of the nut.
Figure 5 is a transverse section on the line of Figure 3 drawn to an enlarged
scale.
Figure 6 is a profile view of the locking device.
Figure 7 a top or face view of the same, and,
Figures 8 and 9 show slightly modified constructions of the bolt and locking
device, whereby a straight instead of a curved locking plate or strip may be
employed with like results as are obtained with the constructions shown in the
other figures.
Figure 10 is a slightly different view of the parts shown in Figure 1.
A in the drawing designates a bolt with screw thread, such as is preferably
used for coupling rails. B a nut and C a locking strip either of a flat or bowed
form intermediate of its ends. Longitudinally of the bolt and cutting through the
screw-threads a is formed a long groove a', the left side a² of said groove standing
about radial to the axis of the bolt, when the said bolt is provided with a right
hand thread, and the other side a slanting toward the periphery. The nut B is
provided with one or more (say from 1 to 8) longitudinal grooves b which are
preferably in cross section of triangular form, and may partly or wholly intersect
the screw threads of the same; the right hand side of these grooves are pre-
ferably made to stand radial, while the left hand side 6 is made to slant as shown.
In this construction the radial sides of the grooves in the nut and of the
groove a in the bolt, stand opposite each other when said grooves coincide, and
thus form abutments for the locking strip C as shown in the drawing. The locking
strip C is preferably of spring metal but not necessarily so and is either bowed as
shown in Figure 6 between its ends or made flat as shown in Figure 8. This
locking device is placed in the groove a of the bolt with its broad side toward
the slanting side a³ of the groove. The act of introducing the locking strip into
its position between the nut and the screw causes it to be slightly compressed
and owing to this it partakes of the character of a spring and binds firmly against
the threads of the nut and the seats provided for its ends in the groove of the bolt
and thus when the nut is turned forward the upper edge of the locking device C will
slide over the threads of the nut but when an attempt is made to unscrew the nut
and one or the other of the grooves b coincides with the said upper edge of the
device C, the said device will expand and enter such coinciding groove, and as the

page_text: backward movement of the nut is continued the said edge of the device C will
become fully seated in the groove of the nut as illustrated in Figure 5, and thus
seated it is impossible to further turn the nut backward.
While the nut B is being turned back into the position in which the device C
will completely check its movement the broad back surface of the spring gradually
approaches the side of the groove b, and when it comes fully in contact with it
the motion of the nut is checked and no blow or jolt will be liable to move it
further back. During this latter described movement the spring or locking
device C assumes a less inclined position with respect to the axis of the bolt, and
consequently its upper edge rises higher with respect to the threads of the
bolt and when the device C is in its extreme locking position which position is
shown in Figure 3. In most cases it will be found desirable to slightly diminish
the depth of the groove a¹ at the shoulder of the thread a and near the end of the
bolt as illustrated in the drawing which can be done without hindering the introduc-
tion or withdrawal of the locking device C.
By reference to the drawings it will be seen that the grooves in which the locking
device is fitted are shown provided with slightly curved or upwardly inclined end
portions a and that the ends of the device Crest upon these portions while the
intermediate portion of the said device bridges or spans the other or nearly
horizontal portion of the groove. By this construction the locking device is kept
from falling out of the groove, and at the same time its ends have a chance to ride
upward on the inclines, while its middle portion is being depressed by the threads of
the nut, and thus the device C is enabled very readily to assume a form under the
pressure of the forward movement of the nut which clears it from said nut, and also
is enabled to resume its locking position whenever the nut is turned back so as to
bring one or the other of the grooves thereof in coincidence with the upper outer
edge of said locking device. The locking device C is preferably constructed with
tapered end portions c which are adapted to the shape of the bottom of the groove a¹
and thus when locking the nut it can bear with the entire length of its lower edge
against the bottom portion of the said groove, a, thereby offer a very firm
resistance to any attempt at violently unscrewing the nut. Instead of the tapered
ends curved ends may be adopted with the same good results.
The radial surfaces a² b as described need not necessarily be radial in the
strict sense of the word but may be more or less leaning in order to prevent the
spring acting or locking device C, assuming a position which would interfere with
its ready operation, or tend to render it inoperative.
In order to remove the nut it must be moved forward to ease the strain upon the
spring acting or locking device C, whereupon, with a pair of pliers or other
suitable tool, the locking device can be withdrawn from the groove a' and the nut
fully unscrewed. In the drawing a hole is shown in the locking device for the
insertion of the implement employed for withdrawing it.
This invention can be used for various purposes and when adopted in machines
having upright bolts the groove a' may be closed at the lower end to a sufficient
extent to prevent the locking device from falling out while not engaged with one
of the grooves b and held by friction in the same.
.
Having now particularly described and ascertained the nature of my inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
First. In nut lock the combination of a screw bolt formed with a groove one
side of which is inclined to a greater extent than the other side, a nut formed with
one or more grooves, one side of which, respectively is inclined to a greater extent
than the other side, and a locking device applied between the nut and the screw
bolt, substantially as described.
Second. A nut lock comprising in combination, a bolt having a longitudinal
groove a which is inclined.at its ends and a locking device bridging or spanning the

page_text: bottom of the groove and resting with its ends upon the inclines, and a nut, sub-
stantially as described.
Dated this 3rd day of March 1891.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.