Improvements in Locks.
Year: 1891

page_text: Date of Application, 12th May, 1891-Accepted. 20th June, 1891
COMPLETE SPECIFICATION.
Improvements in Locks.
We, JOHN BURDON of Muirmadkin, Bellshill, Lanarkshire, Engineer and
MATTHEW BARR BAIRD of 59 Waterloo Street, Glasgow, 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
This invention is a further development of the invention described in the
Specification of the prior Patent of John Burdon, one of the present applicants,
No. 7019, dated 13th May, 1887.
The present invention is designed to simplify and improve the locks as con-
structed under said prior Patent.
And in order that our said invention may be properly understood, we have
hereunto appended an explanatory sheet of drawings, whercon :---
Fig. 1, is an elevation of the lock, as it appears with the closing plate removed
and the bolt withdrawn.
Fig. 2, is a similar view, but with the bolt in section and in its shot position.
Fig. 3, is a horizontal section on the line A, A Fig. 2.
On the drawings the same reference letters wherever repeated indicate similar or
like parts.
In carrying out the present invention we make the bolt a of the lock with two
small bolts b, c, as in our prior Patent, which, when the bolt a is shot, project
outwards at right angles to the said bolt a and prevent its withdrawal from
the socket in the striking plate or boss head (not shown) into which it is shot.
Said bolt a is made hollow and the small bolts b, c, are moved by levers e, f, which,
under this invention, are both centred at the same point on the thin part or plate of
the bolt a.
The levers e, f, at their common pivotal point are preferably stepped
or cut out so as to easily fit one on top of the other, and, at the same time, present
a level upper surface. The levers e, f, are shown centred at . Projecting from
the levers e, f, are projections or pins h, i, which are, preferably, partly flattened on
one side, as shown, although they may be round or of other suitable shape. Fitted
rigidly to the back of the lock, or at any other convenient part, is a cam plate j
having outwardly bent guides or cam slots or grooves k, l, in it, in which work the
pins h, i. The cam plate is for the purpose of guiding the pins h, i, and so pushing
apart or closing together the levers e, f. The cam plate may be of any other
suitable shape than that shown on the drawings, as it is manifest that any shape or
form of plate, providing it has the cam grooves, will effect the desired result
of forcing out or bringing together the levers e, f.
The tumblers m, springs n, and the other fittings of the lock may be the same as
in John Burdon's afore-recited prior Patent or of any ordinary description.
The stump o on the bolt a works as usual in the tumblers m.
a,
The operation of the lock is as follows:-The key being turned so as to lock the
bolt the tumblers m are raised and the bolt is pushed outwards, as the stump o
traverses in the usual way the slot p of the tumblers. As the bolt slides outwards,
the cam platej being rigid, the pins h, i, are guided along the cam slots k, l,
and the levers e, f, are thus forced apart, which action causes them to force out the
small bolts b, c, in which their rounded outer ends are fitted, until said small bolts
assume the position illustrated in Fig. 2. When the key is turned so as to unlock
the bolt a, the action is simply reversed and the bolt assumes the position shown at
Fig. 1.
11
aloon of look in much simplified

page_text: The improvements are applicable to various kinds of locks whether made with
tumblers or wards or other security devices.
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. A lock having small bolts (b, c) operated by levers (e) pivotted at
the same centre on the main bolt (a), substantially as hereinbefore described with
reference to the drawings annexed.
2. In a lock having small bolts (b, c) the combination with the bolts and their
operating levers, of a cam plate () or its equivalent having slots or grooves (k, 1,)
which guide pins or projections on said operating levers, substantially as and for
the purpose set forth.
3. The general arrangement and combination of parts of the improved lock,
substantially as hereinbefore described with reference to the drawings annexed.
Dated this 11th day of May 1891.
H. D. FITZPATRICK,
70, Wellington Street, Glasgow, Agent.