Improvements in Ovens.
Year: 1897

page_text: Date of Application, 21st May, 1897
Complete Specification Left, 19th Feb., 1898-Accepted, 20th May, 1898
Improvements in Ovens.
I, WILLIAM WALLINGTON HARRIS, Manager of A. M. Perkins & Son, Limited, of
43, Regent Square, in the County of Middlesex, do hereby declare the nature of
this invention to be as follows:-
Ovens such as those known as Perkins' steam ovens are now heated by rows of
pipes containing highly heated fluid-usually one row just below the baking plate
or floor of the oven and another inside the oven just below the arched roof which
is above this plate. One end of the pipes in each row is made to project out
through the back wall of the oven-the ends of the pipes of the lower row serve as
fire bars for the heating fire and are heated by it whilst those of the upper row
are heated by the hot gases from the fire rising up through the outlet chimney
flue. Air is admitted to the fire through an ashpit below the fire the amount
admitted being controlled by the extent to which the ashpit door is opened-the
draft is also regulated by a sliding damper plate in the chimney flue which can
be drawn out more or less by a rod extending from it through a passage formed
through the back of the flue and through a removable plate at the end of this
passage.
If proper attention is paid to regulating the draught this arrangement serves
very well but if through carelessness the damper and ashpit door are left wide
open the fire may become so intense as not only to injure the brickwork of the oven
but even to destroy the tubes.
The object of my invention is to obviate the risk of accidents of this kind. In
order to ensure that the outlet chimney shall not be opened beyond a regulated
fixed amount by the drawing out of the damper I apply just above the damper a
second damper which like it has a rod extending back from it through the
same passage as that through which the lower damper rod extends. The dampers
are carried within an iron frame which extends through the passage and across
the chimney flue. The side edges of the lower damper rest on horizontal flanges
formed along the bottom of the sides of the frame. The upper damper is some-
what wider than the lower damper and its side edges rest on projections which
extend upwards from the horizontal flanges clear of the sides of the lower damper.
The back end of the frame is closed by a cover plate through a slot in which both
the damper rods extend. On the under side of the upper damper are two small
projections which can drop into notches in the top of the projections on which
the damper slides-a number of such notches are made in each projection so that
by lifting the damper until the projections upon it are clear of the notches the
damper can be drawn back or slidden in to more or less open the chimney flue
and the damper can then be again lowered to allow its projections to enter other
notches and so the damper can be set to limit to any desired extent the amount
to which the chimney flue can be opened.
The slot in the cover plate through which the damper rods extend is made too
small to allow of the upper damper being raised by its rod sufficiently to lift the
projections out of the notches so that the upper damper can only be shifted when

page_text: the cover plate has been taken off. A suitable fastening may be provided to
prevent its being shifted. The extent to which the rod of the upper damper
extends out beyond the cover plate indicates at all times to what extent this damper
is opened or closed.
To regulate the extent to which the ashpit door can be left open I form the
door to turn upwards on fixed pins the pins enter slots in hinges which extend
up from the top of the door. Projecting cam pieces are made to extend inwards
from the lower part of the door to rest on the bottom of the ashpit frame, the slots
above mentioned being of such a length as to allow them to do so the length
of the cam pieces limits the extent to which the door can be left open. When
the door has to be set wide open to allow of the ash pit being cleaned out this can
be done by turning the door upwards beyond a horizontal position at the same
time drawing it forwards-then by letting the door slide back parts of the slotted
hinges may be allowed to pass below lugs on the end frame of the ash pit and the
door be thereby held from turning back into its closed position.
In place of holding the end frame of the ash pit to the brickwork by dog bolts
let into the brickwork as heretofore I hold it in place by lugs projecting up from
it and entering slots in the top or cover plate of the ash pit and by dowels cast
on the cover plates which fit into holes in the bottom flange of frame so that it
is held in place by these plates and lugs and by the brickwork. This renders the
construction much more durable.
Improvements in Ovens.
I, WILLIAM WALLINGTON HARRIS, Manager of A. M. Perkins & Son, Limited, of
43, Regent Square, in the County of Middlesex, 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:
Ovens such as those known as Perkins' steam ovens are now heated by rows of
pipes containing highly heated fluid usually one row just below the baking plate
or floor of the oven and another inside the oven just below the arched roof which
is above this plate. One end of the pipes in each row is made to project out
through the back wall of the oven the ends of the pipes of the lower row serve as
fire bars for the heating fire and are heated by it whilst those of the upper row
are heated by the hot gases from the fire rising up through the outlet chimney
flue. Air is admitted to the fire through an ash pit below the fire the amount
admitted being controlled by the extent to which the ashpit door is opened-the
draft is also regulated by a sliding damper plate in the chimney flue which can
be drawn out more or less by a rod extending from it through a passage formed
through the back of the flue and through a removable plate at the end of this
passage.
Figure 1 of the drawings annexed shews a longitudinal section of such an
oven. A is the upper row of pipes and B the lower row. C is the furnace door
and D the ash pit door. E is the sliding damper in the chimney flue. F is the
baking plate or floor in the body of the oven.
If proper attention is paid to regulating the draught this arrangement serves
very well but if through carelessness the damper and ash pit door are left wide
open the fire may become so intense as not only to injure the brickwork of the oven
but even to destroy the tubes.

page_text: The object of my invention is to obviate the risk of accidents of this kind. In
order to ensure that the outlet chimney shall not be opened beyond a regulated
fixed amount by the drawing out of the damper I apply just above the damper a
second damper which like it has a rod extending back from it through the
same passage as that through which the lower damper rod extends. The dampers
are carried within an iron frame which extends through the passage and across
the chimney flue. The side edges of the lower damper rest on horizontal flanges
formed along the bottom of the sides of the frame. The upper damper is some-
what wider than the lower damper and its side edges rest on projections which
extend upwards from the horizontal flanges clear of the sides of the lower damper.
The back end of the frame is closed by a cover plate through a slot in which both
the damper rods extend. On the under side of the upper damper are two small
projections which can drop into notches in the top of the projections on which
the damper slides a number of such notches are made in each projection so that
by lifting the damper until the proejctions upon it are clear of the notches the
damper can be drawn back or slidden in to more or less open the chimney flue
and the damper can then be again lowered to allow its projections to enter other
notches and so the damper can be set to limit to any desired extent the amount
to which the chimney flue can be opened.
The slot in the cover plate through which the damper rods extend is made too
small to allow of the upper damper being raised by its rod sufficiently to lift the
projections out of the notches so that the upper damper can only be shifted when
the cover plate has been taken off. A suitable fastening may be provided to
prevent its being shifted. The extent to which the rod of the upper damper
extends out beyond the cover plate indicates at all times to what extent this damper
is opened or closed.
Figures 2 to 6 shew various views of a pair of sliding dampers arranged in the
above manner.
Figure 2 is a longitudinal section of the dampers and the iron frame within
which they are carried.
Figure 3 is a plan view partly in section of the same.
Figure 4 is a view of the outer end of the frame and Figure 5 is a cross section
on the line a b Figure 3.
Figure 6 is a longitudinal section on a larger scale taken through one of the
small projections on the under side of the upper damper and of one of the notched
bars on which this damper rests.
G is the upper damper and H the lower damper. The iron frame which carries
them is formed of two castings I J placed one above the other. The side edges of
the lower damper rest on inner flanges I¹ of the lower casting I-the casting J
rests on the outer flanges 12. The side edges of the upper damper rest on the top
of the upwardly projecting portion of the casting I. Notches 13 are formed in
the top edge of this part of the casting into which small projections G' on the
underside of the upper damper can enter. K is the outer back plate secured to
the back end of the two parts of the frame I J. K¹ is a slot in this plate through
which pass the two rods I J which extend back from the two damper plates. The
lower damper can be pushed forwards or backwards by its rod and so opened or
closed in the ordinary manner but as above explained the position of the upper
damper can only be altered after the back plate K has been first removed.
To regulate the extent to which the ash pit door can be left open I form the
door to turn upwards on fixed pins the pins enter slots in hinges which extend
up from the top of the door. Projecting cam pieces are made to extend inwards
from the lower part of the door to rest on the bottom of the ash pit frame, the slots
above mentioned being of such a length as to allow them to do so-the length
When
of the cam pieces limits the extent to which the door can be left open.
the door has to be set wide open to allow of the ash pit being cleaned out this can
be done by turning the door upwards beyond a horizontal position at the same
time drawing it forwards-then by letting the door slide back parts of the slotted

page_text: hinges may be allowed to pass below lugs on the end frame of the ash pit and the
door be thereby held from turning back into its closed position.
In place of holding the end frame of the ash pit to the brickwork by dog bolts
let into the brickwork as heretofore I hold it in place by lugs projecting up from
it and entering slots in the top or cover plate of the ash pit and by dowels cast
on the cover plate which fit into holes in the bottom flange of frame so that it
is held in place by these plates or lugs and by the brickwork. This renders the
construction much more durable.
Figure 7 is a longitudinal section of an ash pit door mounted in the above
manner and of the frame which carries it. Figure 8 is a plan partly in section of
the frame. Usually the ash pit is provided with two or more such doors side by
side as shewn in front view at Figure 9-on the right hand side of this figure the
frame only is shewn the door being removed. Figure 10 is a cross section of the
ash pit cover.
In these figures L is the outer end frame held in place by an upwardly pro-
jecting lug entering a slot in the top of the ash pit cover M-and by other
lugs M projecting downwards from the bottom of the two sides of the ash pit
cover M entering holes in its bottom plate L³.
N is the ash pit door arranged to turn upwards as usual. Each door has a pair
of projections N1 standing up from it in each of which is a slot N. A rod Ô is
passed through these slots and through lugs L³ which project out from the frame L
and forms a hinge pin upon which the door can be turned. P is the cam piece
projecting inwards from the lower part of the door to rest on the bottom plate of
the outer end frame L-these cam pieces as above stated limit the extent to which
the ash pit door can be left open. N³ is a handle by which the ash pit door can
be raised or lowered. The dotted lines in Figure 7 shew the position of the ash
pit door when turned upwards beyond a horizontal position. R R are the pro-
jecting lugs on the end frame L below the ends of which the ends of the projecting
hinge plates N¹ pass when the door is allowed to slide a short distance downwards
and which then hold the door open.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:-
1. The arrangement of the two dampers one above the other one capable of
being drawn in or out in the ordinary manner and the other adapted to be set in
any desired position and incapable of being moved from that position except when
the end plate of the frame which carries the dampers has first been removed.
2. The arrangement of the two dampers one above the other in one frame cach
having a rod extending from it and passing out through a slot in the outer end
plate of the frame-one damper having projections on its under side to enter
notches formed in the portions of the frame on which this damper rests and the
rod projecting from this damper restrained from being raised so that the projec-
tions cannot be lifted from the notches and the damper moved endwise so long as
the rod is so restrained from being raised.
3. The arrangement of the two dampers and the frame which carries them sub>-
stantially as hereinbefore described and illustrated in the drawing annexed.
4. The arrangement of the ash pit door so mounted that it can be turned
upwards and also slide a short distance up and down and provided at the bottom
with an inwardly projecting cam piece with can rest on the bottom of the ash pit
frame to hold the door more or less open as required.
5. The arrangement of the ash pit door mounted in the above manner and the
fixed lugs acting to hold the door wide open after it has been turned up beyond a
horizontal position.
6. The arrangement substantially as herein before described and illustrated in
Figures 7 to 9 of the drawings annexed for carrying the ash pit door or doors so 5

page_text: that they can either be held open to any desired limited extent or held wide
open.
7. Locking the outer end frame of the ash pit to the top or cover plate of the
ash pit so as to retain it in place substantially as herein before described.
LT
1
1900
W. W. HARRIS.