Improvements in Arrangements for Locking Screw Nuts or Preventing them from Unscrewing.
Year: 1889

page_text: Date of Application, 7th Sept., 1889
Complete Specification Left, 6th June, 1890-Accepted, 12th July, 1890
PROVISIONAL SPECIFICATION.
Improvements in Arrangements for Locking Screw Nuts or
Preventing them from Unscrewing.
I WILLIAM HENRY MIRFIN of 606 Stockport Road, Longsight, Manchester, in the
County of Lancaster, Mechanical Engineer, do hereby declare the nature of the said
invention, to be as follows:-
My invention for preventing screw nuts from working loose or unscrewing, consists
in using two parts, one part being similar to a washer and so constructed and
arranged as to engage with the article or part against which the washer comes, the
other part is or may be formed like a ring to engage with the screw nut and also
with the said washer, when the screw nut is screwed home so that the screw nut will
be prevented from unscrewing.
The form and shape and construction of these parts may vary without departing
from my invention so long as the part corresponding to the washer engages so as not
to be rotated with the article or part against which the washer comes, and it is also
provided with projections to engage with what I term the lock ring which has corre-
sponding recesses or projections which engage with the said washer and with the
screw nut to prevent it from revolving, and from being disengaged from the part
corresponding to the washer.
The part corresponding to the washer may be formed upon or made solid with the
article or part against which the screw nut is to screw.
In carrying out my invention the washer part if made separate is formed with one
or more projections from that side of it which is to come in contact with the article
against which the screw nut is to act, and this washer, say on its edge, is provided
with say undercut recesses; the lock ring is formed with projections to correspond
with and take hold (when slightly rotated) with the recesses on the lock washer, this
lock ring having a hole through it with sides or parts to engage with the sides of the
screw nut.
My improved locking arrangements are applied to ordinary screw bolts and nuts,
and when used the lock washer is first put into its place over the bolt and is made to
engage with the part against which it is to come, by a projection or projections on
the lock washer coming into a recess or recesses on the fixed article or part, or vice
versa, then the nut is screwed home as tightly as possible against the lock washer,
then the lock ring is placed upon the screw nut and its projections or recesses, as the
case may be, engage with those on the lock washer and then the nut is slightly
unscrewed and the undercut parts of the washer and lock ring engage with each other
and any tendency of the screw nut to unscrew locks them more securely and
prevents the nut from further rotation in the direction for unscrewing, but by
screwing up the nut firmly the lock ring may be released and removed when the nut
can be unscrewed.
The lock washer in some cases is formed to be slightly elastic.

page_text: COMPLETE SPECIFICATION.
Improvements in Arrangements for Locking Screw Nuts or
Preventing them from Unscrewing.
I WILLIAM HENRY MIRFIN of 606 Stockport Road, Longsight, Manchester in the
County of Lancaster Mechanical Engineer 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 and accompanying
drawings:-
:―
My Invention relates to means for preventing screw nuts from working loose or
unscrewing and consists in using two parts one part being similar to a washer so
formed as to engage with the article or part against which the washer comes while
the other part is formed to engage with the screw nut, and also with the said washer
when the screw nut is screwed home so that the nut will be prevented from unscrew-
ing or becoming loose. The form shape and construction of these parts may vary
without departing from my invention so long as the part corresponding to the washer
engages (so as not to be rotated) with the article or part against which the was
comes and is provided with projections or recesses to engage with the locking part
which has corresponding recesses or projections which engage with the said washer
and with the screw nut to prevent it from revolving, and from being disengaged
from the part corresponding to the washer. The part corresponding to the washer
may be formed upon or made solid with the article or part against which the screw
nut is to screw.
The lock washer may in some cases be formed so as to be slightly
elastic.
In order that my invention may be clearly understood I will now proceed
to describe the same with reference to the accompanying sheet of illustrative
drawings.
Fig. 1 is a side view of the screwed end and nut of a bolt the nut being locked
by the means constituting my invention the said means being shown in section.
Fig. 2 is an end view of the bolt and locking means.
Fig. 3 is an edge view of the locking part or ring a.
Fig. 4 is an edge view of the part b which corresponds to the ordinary
washer.
The bolt is lettered c the nut d and the part against which the washer is
pressed e.
The part a consists in the present instance of a ring having a hexagonal hole in
the centre to fit the nut d. It is also formed with six projections a¹ which are
undercut or dovetailed on one side as clearly shown in Figs. 3 and 5.
The washer which has a hole through its centre to clear the bolt c has also six
perforations marked b¹ the said perforations having bevelled edges of the same taper
as the undercut projections and as clearly appearing in the drawings.
These perforations are of the same pitch as the projections a¹ and are intended to
receive the projections. The projections pass easily through the perforations so as to
allow the locking ring and the washer to lie face to face and then by turning the
ring slightly on the washer the undercut projections of the locking ring a engage
with the bevelled edges of the perforations in the washer 6 as clearly shown in Fig. 5,
so that the locking ring and washer cannot be disengaged.
The back of the washer 6 which is shown at Fig. 6 is formed with one, two or
more teeth 62 which enter nicks or recesses cut or formed in the part e against which
the washer is jambed. It will now be clearly understood how the nut d is locked.
In applying the parts I first pass the washer b over the screwed end of the bolt and
lay it against the face e taking care that the tooth or teeth 62 occupy their recesses.
I then screw the nut d home upon the wasber band slip the locking ring a over the
nut the projections a' on the ring a entering the recesses b' in the washer b. This
entering of the projections of the ring into the corresponding recesses in the washer
may require a little manipulating of the nut backwards or forwards but no great

page_text: movement of the nut is required especially where there is a multiplicity of recesses.
This being done and the locking ring and washer lying face to face I then slightly
turn the nut backwards thereby bringing the undercut edges of the projections a¹ on
the locking ring into engagement with the bevelled edges of the recesses 61 in the
washer. This backward locking movement of the nut is very slight and is not
nearly enough to slacken the bolt. The ring and washer are now in locking contact
and as the ring embraces the hexagon nut the nut cannot possibly slacken back and
as the tendency of the nut is always to unscrew, the ring is always held in its locked
contact with the washer.
The tooth or teeth 62 on the washer effectually prevent it from turning so that the
nut d is securely locked and cannot possibly unscrew or become loose.
The projections a¹ on the locking ring and the corresponding recesses in the
washer may be undercut bevelled or inclined on both sides as shown in Fig. 7 or in
the case of a bolt in a perpendicular position the projections and recesses may have
perfectly straight sides as in Fig. 8.
If it is thought desirable to confer elasticity on the washer 6 such washer might be
slightly dished as shown in Fig. 9 and when so formed it might be made of steel
and tempered. The washer might however be made elastic in any other suit-
able way.
Instead of forming the lock ring a to engage with a hexagon nut as described and
shown I also make it to fit a square nut as shown in Fig. 10 and instead of having
six projections and recesses on ring and washer as shown I might have only two or
might have any suitable number less or more than six or two.
Figs. 11. 12 and 13 show a modified form of my nut locking invention. Fig. 11
shows the end of a bolt c the nut d being locked by a saddle clip f corresponding
to the locking ring a in the former Figs.
1
The washer ó is of the shape shown separately at Fig. 12 and has the aforesaid
tooth 62 and also a dovetail slot 61. The saddle clip has a dovetail projection fi
which engages with the slot b'. Fig. 13 shows the saddle clip thus engaging with
the washer.
In using this modification I simply screw the nut home upon the washer 6 and
after bringing it square 1 drop the saddle clip over the nut the dovetail projection
on the clip entering the corresponding recess in the washer and being held thereby.
The nut is thus embraced by the limbs of the saddle clip and is prevented from
shaking loose.
An advantage of this modification is that to lock the nut it is not necessary to turn
it back. The nut may of course be either hexagon or square. To suit the position of
the nut when screwed hard up, I might make several radial dovetail recesses in the
washer, so that the saddle clip could be applied from different angles as shown at
Fig. 14, but in practice it will seldom be found difficult to bring the nut round to
the exact position or angle required. It will be evident that instead of one, for
instance two dovetail projections might be formed on the saddle clip engaging with
two vertical or parallel dovetail recesses in the washer.
I consider that the last described nut locking arrangement is particularly
applicable to the locking or securing of the uuts of fish plate bolts of the permanent
way of railways.
As far as mere detail is concerned my invention is capable of modification to a
certain extent. For example the locking recesses in the washer b might be formed
as nicks or recesses on the outer edge of the washer the projections on the locking
ring a being similarly situated. In some cases also the projections might be on the
washer and the recesses in the locking ring. The teeth 62 on the washer might be
replaced by pegs entering holes in the face e against which the washer is laid or the
teeth or pins might project from the face and enter holes or recesses in the washer
and various other minor divergences from the forms described and shown night be
made without departing from the spirit of my invention. In some cases the washer b
might be dispensed with and the undercut recesses to receive the similarly formed

page_text: projections on the locking ring a might be formed in the material of the object against
which the nut is screwed.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what I
claim is :-
1. Positively locking nuts upon screwed bolts and studs so as to prevent
loosening or unscrewing, by the means and substantially as hereinbefore described
and shown.
2. As means for positively locking nuts upon screwed bolts and studs, a washer b
formed with or carrying a tooth or teeth 62 or pins or otherwise so constructed as to
engage with the surface of the axed object e in combination with a locking ring a
formed to embrace the nut and having dovetailed undercut or other projections a¹
which enter and engage with corresponding recesses 61 in the washer bor
vice versa the parts being arranged, applied and locked substantially as described
and shown.
3. As means for positively locking nuts upon screwed bolts, studs and t'e like, a
washer b formed to engage with the surface or object against which the pressure of
the nut is exerted in combination with a locking clip f formed with a dovetail or
undercut projection f¹ or projections engaging with a similarly formed slot or
recess b₁ or slots or recesses in the washer, the clip engaging with the nut so as to
prevent it from turning substantially as hereinbefore described and as illusi ated.
4. The washer illustrated at Fig. 14 of the drawings having several radial dovetail
slots or recesses to receive the projections on the locking clip f for the purposes and
substantially as described and shown.
5. In combination with the herein before described nut locking arrangements the
employment of an elastic washer substantially as described and shown.
6. As means for locking nuts upon screwed bolts, studs and the like a locking
ring a having undercut or other shaped projections or recesses capable of engaging
with similarly undercut or other shaped recesses or projections formed in or on
the fixed object or surface against which the nut is screwed substantially as described
and shown.
Dated this 5th day of June 1890.
DUTTON & FULTON,
1, St. James Square, Manchester, Agents.