Improvements in Door Chains.
Year: 1895

page_text: Date of Application, 6th July, 1895
T
1000 Annanted
25th Anc 1896
Date of Application, 6th July, 1895
Complete Specification Left, 10th Mar., 1806 Accepted,
25th
4pc 1896
PROVISIONAL SPECIFICATION.
Improvements in Door Chains.
We, WILLIAM HENRY TONKS, Managing Director of Tonks Limited, of
Moseley Street, Birmingham, in the County of Warwick Manufacturers, and
JOHN BURN, of Showell Green Lane, Sparkhill near Birmingham, aforesaid,
Tool Maker do hereby declare the nature of this invention to be as follows:-
The object of our invention is to increase the security of the door chain, that is,
to more effectually prevent the surreptitious disengagement or unfastening from
the outside of the door of the door chain from the stud or holding plate; and
further to simplify and economize the manufacture of the holding or stud engaging
plate of the door chain.
Instead of engaging the stud end of the door chain with a longitudinal slotted
trough case fixed on the door as usual, we use with the door chain a holding or stud
engaging plate of the following construction.
We make the holding or stud engaging plate from a circular disc of sheet brass
or other hard and ductile sheet metal and we give to the greater part of the said
disc a convex or domed figure leaving a flat marginal edge by which the holding
plate may be attached to the door. In the convex. or domed part of the circular
holding plate a spiral or scroll slot is made for receiving the necked stud at the
free end of the door chain. The said spiral or scroll slot commences at the centre
of the dome part of the holding plate and terminates near the marginal edge of the
said plate and at that part of the plate nearest the edge of the door. The central
part of the scroll slot constitutes the entrance to the said slot and is enlarged
sufficiently for the passage into and out of it of the necked chain stud, the width
of the other part of the scroll slot only being sufficient for the neck of the stud to
travel in.
In securing the door chain to the door the necked stud of the door chain is passed
into the central enlarged part of the scroll slot and moved in the narrow part of the
said slot nearly through a circle until it reaches the end of the slot nearest the edge
of the door. The chain is thereby secured to the door, the conformation described
of the scroll slot making it difficult or practically impossible to effect from the
outside of the door the disengagement or unfastening of the necked stud of the
chain from the holding or engaging plate attached to the back of the door.
In order to strengthen the holding or stud engaging plate of the door chain, a
This back
back disc preferably of thin sheet steel may be applied to it.
strengthening disc may be fastened to the holding or stud engaging plate by
closing the edge of the latter over the edge of the back disc; or by pinning the
two parts together at their marginal edges. The holding or stud engaging plate
may however be used without the strengthening disc referred to; but we prefer
to use it.
D
th day of July 1895
W. T. WHITEMAN,
Agent for the Applicants.

page_text: We, WILLIAM HENRY TONKS, Managing Director, of Tonks Limited, of
Moseley Street, Birmingham, in the County of Warwick Manufacturers, and
JOHN BURN of Showell's Green Lane, Sparkhill, near Birmingham, aforesaid,
Tool Maker, do hereby declare the nature of our 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 increase the security of the door chain, that is,
to more effectually prevent the surreptitious disengagement or unfastening from the
outside of the door of the stud of the chain from the stud engaging or holding
plate and further to simplify and economize the manufacture of the holding or
stud engaging plate of the door chain.
Instead of engaging the stud end of the door chain with a longitudinal slotted
trough case fixed on the door as usual, we use with the door chain a holding or stud
engaging plate of the following construction.
We make the holding or stud engaging plate from a circular disc of sheet brass
or other hard and ductile sheet metal and we give to the greater part of the said
disc a convex or domed figure leaving a flat marginal edge by which the holding
plate may be attached to the door. In the convex or domed part of the circular
holding plate a spiral or scroll slot is made for receiving the necked stud at the
free end of the door chain. The said spiral or scroll slot commences at the centre
of the dome part of the holding plate and terminates near the marginal edge of the
said plate and at that part of the plate nearest the edge of the door. The central
part of the scroll slot constitutes the entrance to the said slot and is enlarged
sufficiently for the passage into and out of it of the necked chain stud, the width of
the other part of the scroll slot only being sufficient for the neck of the stud to
travel in.
In securing the door chain to the door the necked stud of the door chain is passed
into the central enlarged part of the scroll slot and moved in the narrow part of the
said slot nearly through a circle until it reaches the end of the slot nearest the edge
of the door. The chain is thereby secured to the door, the conformation described
of the scroll slot making it difficult or practically impossible to effect from the
outside of the door the disengagement or unfastening of the necked stud of the chain
from the holding or engaging plate attached to the back of the door.
Figure 1 of the accompanying drawing represents in elevation a door chain
constructed according to our invention applied to a door and in its fastening
position;
Figure 2 is a horizontal section of the same on the dotted liner, a Figure 1;
Figure 3 is a vertical section of a portion of the same on the dotted line y, y
Figure 1;
Figure 4 represents in elevation and Figure 5 in horizontal section the said door
chain with the necked stud occupying the large central opening in the stud engaging
plate through which central opening it is passed into and engaged with or passed
out of and disengaged from the scroll or spiral slot in the plate. The chain is
indicated in dotted lines in its unfastened position in Figure 4.
The same letters of reference indicate the same parts in the several figures of the
drawing.
a is the chain carrying plate fixed to the door jamb b as usual and c is the chain
terminating at its free end in the necked stud c³, c²; c¹ being the necked part of the
stud and the head of the same.
d is the circular domed stud engaging plate, fixed to the door e the said plate d
having in it the scroll slot d' the said slot commencing at the large central opening d

page_text: and terminating near the marginal edge of the domed plate d at the side nearest the
opening edge of the door e. The domed plate d has a flat marginal portion d
through countersunk holes in which the fixing screws f,f, pass in attaching the-
said domed plate to the door.
The head c² of the necked stud c', is of a size somewhat less than the central
opening in the domed stud engaging plate d but greater than the width of the
scroll slot d passing out of the said central opening the said slot being of such
a width only as wili permit the neck c¹ of the stud c¹, 2 to work in it without
difficulty.
In attaching the free end of the chain e to the domed stud engaging plate d the
head of the stud c¹, c² is passed through the central opening d² as represented in
Figures 4 and 5 and the neck c' of the said stud c¹, c² is passed through the scroll
slot into the position represented in Figures 1, 2 and 3 when the door is securely
fastened.
If the door e is opened the pull on the chain immediately causes the stud c', c² to-
travel to the end of the slot near the marginal end of the domed plate d and it is
practically impossible in consequence of the conformation of the slot d¹ to effect the
disengagement of the chain and the opening of the door from the outside.
In order to strengthen the holding or stud engaging plate of the door chain, a
This back.
back disc preferably of thin sheet steel may be applied to it.
strengthening disc may be fastened to the holding or stud engaging plate by
closing the edge of the latter over the edge of the back disc or by pinning the two-
parts together at their marginal edges.
Although we have described and represented a stud engaging plate d with a
spiral or scroll slot of only one convolution we wish it to be understood that a stud
engaging plate of large size and having a spiral slot of two or more convolutions
may be employed but for ordinary purposes the spiral or scroll slot represented
answers well. And although we prefer to give to the stud engaging plate a domed
figure yet the said plate may be flat. In this case, the wood of the door at the
back of the slot is cut away to permit the necked stud of the chain to work in
the slot.
Having now particularly described and ascertained the nature of our invention.
and in what manner the same is to be performed we declare that we claim as our
invention of "Improvements in door chains."".
Making the stud engaging plate of the door chain from a circular disc of sheet
metal, preferably domed, the said plate having a scroll or spiral slot made in it for
the stud part of the door chain to engage with, the said slot passing out of a central
opening of a size larger than the head of the stud and terminating near the marginal
edge at the side of the plate nearest the opening edge of the door substantially as
herein before described and illustrated in the accompanying drawing.
Dated the Tenth day of March 1896.
WILLIAM HENRY TONKS.
JOHN BURN.