Improvements in the Mechanism of Latches and in Latch Mechanism of Locks.
Year: 1893

page_text: Date of Application, 23rd Sept., 1893
Complete Specification Left, 23rd June, 1894-Accepted, 28th July, 1894
PROVISIONAL SPECIFICATION.
Improvements in the Mechanism of Latches and in Latch Mechanism
of Locks.
We, CHARLES WILLIAM TONKS, ENOCH TONKS and ARTHUR GEORGE
TONKS, trading together in co-partnership as Enoch Tonks and Sons, of
35 Temple Bar, Willenhall in the County of Stafford, Lock Manufacturers, do
hereby declare the nature of this invention to be as follows:-
This invention relates to the mechanism of latches and latch mechanism of locks
in which the latch bolt head is pressed outwards, and the door furniture returned
to its normal position after it has been moved to draw in the latch bolt, by means
of a weight instead of by means of the spring employed in ordinary latch
mechanism. In latch mechanism of such description the weight frequently acts
with too short a leverage to exert the required force in returning the door furniture
to its normal position, and thus if the door spindle should rub against the joinery
in turning, or if there should be other cause of friction in the portion of the
mechanism by which the door furniture is returned to its normal position, it is
occasionally found that the bolt fails to latch.
Now, the object of this invention is to construct springless latch mechanism in
such manner that the weight exerts a much greater leverage than heretofore in
returning the door furniture to its normal position after it has been moved to
unlatch the bolt, whereby the proper return action of the mechanism is ensured
notwithstanding any friction of the spindle against the joinery, or other friction in
the portion of the mechanism by which the door furniture is returned to its normal
position, which is likely to occur in practice.
According to this invention a weighted lever is pivoted near to the forward end
of the lock or latch case. This lever is formed with a part which passes down-
wards from the pivot and with a part which passes backwards towards the binder
end of the case, and is formed at its hinder end with an enlargement which
constitutes the weight. The latch bolt tail is short and the hinder end is
pivotally connected with the lower end of the downward portion of the weighted
lever. A secondary tail-piece or link is pivotally connected at its forward end
with the downward part of the weighted lever as near to the pivot centre
thereof as may be convenient, and is formed at its other end to engage with
a follower carried by the door spindle or otherwise with a part operated by
the door furniture, or if employed for a latch bolt which is pulled back by means
of a sliding knob the secondary tail-piece or link is connected with the sliding
knob. When the latch mechanism is used in the same case with locking
mechanism, the backward portion of the weighted lever carried out from the
lower end of the downward part so as to pass below the key-hole, and the
secondary tail-piece or link is curved down for a portion of its length for the same
purpose.
Latch mechanism constructed in the manner above described permits of the use
of a very long weighted lever, and the secondary tail-piece or link being connected
with the weighted lever very near to the pivot centre thereof, as described, causes
the weight to act with great force in pulling forwards such tail-piece or link and
consequently returning the door furniture to its normal position.
Dated this 22nd day of September 1893.
STEPHEN WATKINS,
Wolverhampton, Agent for the Applicants.

page_text: Improvements in the Mechanism of Latches and in Latch Mechanism.
of Locks.
We, CHARLES WILLIAM TONKS, ENOCH TONKS and ARTHUR GEORGE
TONKS, trading together in co-partnership as Enoch Tonks and Sons, of
35 Temple Bar, Willenhall in the County of Stafford, Lock Manufacturers, 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 the mechanism of latches, and latch mechanism of locks,
in which the latch bolt head is pressed outwards, and the door furniture returned
to its normal position after it has been moved to draw in the latch bolt, by means
of a weight instead of by means of the spring employed in ordinary latch
mechanism. In latch mechanism of such description the weight frequently acts
with too short a leverage to exert the required force in returning the door furniture
to its normal position, and thus if the door spindle should rub against the joinery
in turning, or if there should be other cause of any considerable friction in the
portion of the mechanism by which the door furniture is returned to its normal
position, it is occasionally found that the bolt fails to latch.
Now, the object of this invention is to construct springless latch mechanism in
such manner that the weights exerts a much greater leverage thau heretofore in
returning the door furniture to its normal position after it has been moved to
unlatch the bolt, whereby the proper return action of the mechanism is ensured
notwithstanding any friction of the spindle against the joinery, or other friction in
the portion of the mechanism by which the door furniture is returned to its normal
position, which is likely to occur in practice.
According to this invention, the weight is made to act with a greater leverage in
returning the door furniture to its normal position after it has been moved to
unlatch the bolt than in pressing outwards the bolt itself, and thus while the weight
exerts only the required force in pressing outwards the bolt it acts with greater
force in returning the door furniture to its normal position.
In arranging the mechanism whereby the weight is caused to operate in the
manner described a weighted lever is pivoted near to the forward end of the lock
or latch case. This lever is formed with a part which passes downwards from the
pivot and with a part which passes backwards towards the hinder end of the case,
and is formed at its hinder end with an enlargement which constitutes the weight.
The latch bolt tail is short, and the hinder end is pivotally connected with the
lower end of the downward portion of the weighted lever. A secondary tail-piece
or link is pivotally connected at its forward end with the downward part of the
weighted lever, at a point between the pivot centre of the lever and the pivot
connection of the bolt with the lever, and preferably as near to the pivot centre of
the lever as will pernit of the mechanism being conveniently operated through the
medium of the door furniture; and the secondary tail-piece or link is formed at its
other end to engage with a follower carried by the door spindle, or otherwise with
a part operated by the door furniture (such as a back follower), or if employed
with a latch bolt which is pulled back by means of a sliding knob the secondary
tail-piece or link is connected with the sliding knob. When the latch mechanism
is used in the same case with locking mechanisin, the backward portion of the
weighted lever is carried out from the lower end of the downward part so as to
pass below the key hole, and the secondary tail-piece or link is curved down for a
portion of its length for the same purpose.

page_text: In order that the invention may be clearly understood, we will proceed to-
describe the same with reference to the accompanying drawings, which illustrate
(by way of example) the invention applied to the latch mechanism of a mortice
lock.
Figure 1 is an elevation of the lock with the cap-plate removed so as to expose
the interior mechanism. The latch bolt is shewn in its outward or latched position,
with the weight consequently down.
Figure 2 is a corresponding view to Figure 1, but shews the latch bolt to be
drawn back or unlatched and the weight consequently raised.
The weighted lever A A' A' is pivoted at a near to the forward end of the lock
case. This lever is formed with a part A which passes downwards from the pivot a,
and with a part A' which passes backwards towards the hinder end of the case, and
is formed at its hinder end with an enlargement A2 which constitutes the weight..
The tail of the latch bolt C is short, and is pivoted at e to the lower end of the
part A of the weighted lever. The secondary tail-piece or link D is pivoted at d
to the part A of the weighted lever in position much nearer to the pivot centre a
of the lever than is the pivot centre c thereto; and the link D is formed, in the
arrangement illustrated, with a slotted openinge through which the bush of a
double-horned follower E passes, and with upward and downward lugs gg against
one or other of which one or other of the horns h of the follower presses as the door
furniture is turned to either hand. Whichever way the door spindle is turne.l,
therefore, one of the horns h presses against one of the lugs y and moves back the
link D, and consequently draws back the latch bolt C and raises the weight A²:
and immediately the force used to turn the spindle ceases to be exerted, the
weight A falls and in falling moves outwards the latch bolt C and pulls forwards
the link D until both the lugs are, respectively, against both the horns of the
follower E, thus returning the door furniture to its normal position again. The
formation of the hinder end of the link D is similar to that frequently adopted for
the hinder end of a latch bolt tail which is to be operated direct by a double-
horned follower. It will be seen that the arrangement described permits of the
use of a very long weighted lever, and that the weight operates with a very great
leverage in pulling forwards the link D, compared with its leverage in moving
outwards the latch bolt C. The weighted lever A A'A' is shaped as shewn to
clear the follower and hinder end of the link D and the key-hole, and the link D is.
shaped also to clear the key-hole.
The parts marked ii are pieces of leather or other soft material dovetailed into
the top and bottom edges, respectively, of the weight, to deaden the sound as the
weight is stopped against the rivets jj, respectively, such a means of deadening
sound being commonly applied to weighted latch mechanism.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is :-
1. The improvements in the mechanism of latches and latch mechanism of locks,.
according to which a weight used to press outwards the latch bolt and to return:
the door furniture to its normal position after it has been moved to unlatch the bolt
is made to act with a greater leverage in returning the door furniture to its normal
position than in pressing outwards the bolt itself, substantially as described for the
purpose set forth.
2. The improvements in the mechanism of latches, and latch mechanism of locks,
which comprise a weighted lever fulcrumed within the case and pivotally connected
with the latch bolt, and a secondary tail-piece or link pivotally connected at one
end with the lever between its fulcrum and pivot connection with the bolt and
formed at its other end to be operated by the door furniture, substantially as.
described.
3. The means or combination of parts by which a weight is caused to press.

page_text: outwards a latch bolt and to return the door furniture to its normal position after
it has been operated to unlatch the bolt, substantially as described and shewn by
the drawings herewith, for the purpose set forth.
Dated this 20th day of June 1894.
STEPHEN WATKINS,
Wolverhampton, Agent for the Applicants.