An Improvement in Folding Rules.
Year: 1899

page_text: Date of Application, 23rd May, 1899
Complete Specification Left, 21st Feb., 1900-Accepted, 31st Mar.,
1900
An Improvement in Folding Rules.
JAMES GEORGE LILLEY, Architect, and FREDERICK WILLIAM LILLEY, Publican,
both of Lilley's Hotel, Margate, Kent, do hereby declare the nature of this
invention to be as follows:-
This invention is 66
an improvement in folding rules," which consists of a
piece of strong metal about an inch and a quarter in length and is wrought
so as to form a slide that can. be moved to and fro over each joint, thus causing
the folds to be perfectly rigid when the rule is in use. When the rule is finished
with these slides may be pushed back, and the rule closed. A great advantage in
useing this invention will be found when working with a rule that has been
in use some time as the joints get very loose and consequently cause the ends
to repeatedly fall down.
Dated this 22nd dow of Now 1800.
JAS. G. LILLEY,
F. W. LILLEY.
We, JAMES GEORGE LILLEY, Architect, and FREDERICK WILLIAM LILLEY,
Publican, both of Lilley's Hotel, Margate, in the County of Kent, 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:-
The object of our invention is to enable the knuckle-joints of folding rules
such as are in common use to be locked in the open position, the invention
being applicable to all the joints of the rule so that when locked the rule will
remain rigidly extended without any tendency to fold up whilst in use as so
frequently happens at present in the case of rules whose joints have become
slack through wear.
The invention consists essentially in the combination with each knuckle-joint
of the rule, of a sliding bolt which is contained in a dovetailed groove or seat
in the end of the one limb of the rule and adapted to be projected into engage-
ment with a similar dove-tailed groove or socket in the meeting end of the
adjacent limb, the bolt being normally kept retracted in its seat whilst the rule
is folded up, and slide into engagement, with the socket on the other limb when
the rule is extended, the bolt when so projected lying partly in both limbs of

page_text: the rule in a position tangential to the axis of the joint so as to prevent angular
movement of the one limb relatively to the other.
The invention is illustrated in the accompanying drawings forming part of
this specification, wherein Figure 1 is a face view of the middle joint of a
folding rule to which our invention is applied, Figure 2 being a cross section
on line 2-2, Figure 1. Figure 3 is a face view of one of the end or quarter-
joints of a rule provided with our improved locking device, Figures 4 and 5
being respectively a longitudinal section on line 4-4 and a cross section on
line 5-5 Figure 3.
Referring to Figures 1 and 2 which shew the middle joint of a folding rule
in the extended position, the limbs A B of the rule, when moved about the joint C
(whose axis is perpendicular to the plane of the rule) so as to be brought into align-
ment with one another as illustrated, are locked in that position as shewn, by means
of the bolt D which slides parallel to the edge of the rule in a groove a in the inner
face of limb A and engages in a similar groove b in the inner face of limb Band in
alignment with groove a when the rule is open. When the rule is to be folded
up, the bolt D is retracted from limb A and housed in the groove b in the limb B
wherein it is retained by the dovetailed or undercut cross-sectional form of the
bolt and groove as illustrated in Figure 2. The bolt D is provided with a
knob d upstanding preferably from its rear end, by which to push the bolt along
the groove in locking and unlocking the joint, the knob d being received in a
corresponding depression in the face of that end limb (if there be any) which
folds over on to the face of the limb B when the rule is completely closed.
Referring now to Figures 3, 4 and 5, which shew one of the end or quarter-
joints. of a rule in the extended position, the limbs A E of the
rule, when moved about the joint F (whose axis lies in the plane of
the inner face of the two limbs when extended) so as to be brought into align-
ment with one another as illustrated, are locked in that position as shewn, by
means of the bolt G which slides in a groove a¹ in the inner face of limb A and
engages in a similar groove e in the inner face of limb E and in alignment with
groove a when the rule is open. When the rule is to be folded up, the bolt G
is retracted from limb E and housed in the groove a¹ in limb A, wherein it is
retained by the dovetailed or undercut cross-sectional form of the bolt and groove
as illustrated in Figure 5. The bolt G is provided with a knob 9 upstanding from
its rear end, by which to push the bolt along the groove in locking and unlocking
the joint, the knob 9 being received in a corresponding depression g¹ in the face
of limb E when the rule is closed
As the axis of the joint pin F lies in the same plane as the inner face of
limbs A and E, with which surface the bolt G is also flush, it is necessary, in
order to give passage to the bolt when the rule is extended and locked, to cut
away the underside of the pin F for a distance corresponding to the width of
the bolt G, which is thus free to slide through the notch so formed, as shewn in
Figures 4 and 5.
The dovetailed grooves a¹ and e in which the bolt G slides may be formed in
one with the plates a² e¹ of the corresponding members of the hinge joint F.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, we declare that what
we claim is:
1. The herein described means for securing the joints of folding rules in the
open or extended position, consisting in the combination with each joint of the
rule of a locking bolt sliding in a dovetailed groove in the one limb of the
rule and adapted when the joint is opened to be projected into engagement with
a similar groove or socket in the adjacent limb, the bolt when so projected being
partly received in both limbs in a position tangential to the axis of the joint so
as to prevent angular movement of the one limb of the rule relatively to the
other, substantially as specified.

page_text: 2. The herein described means for securing the end or quarter-joints of folding
rules in the open or extended position, consisting in the combination with each
such joint of a locking bolt sliding in a dovetailed groove formed in the inner
face of the one limb of the rule and adapted when the joint is opened to be
projected into engagement with a similar groove or socket formed in the inner
face of the adjacent limb, the hinge pin of the joint being cut away or notched
on the underside so as to give passage to the bolt, substantially as specified..
Dated this 21st day of February 1900.
A. M. & WM. CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.