Improvements in and connected with Bakers' Ovens.
Year: 1891

page_text: Date of Application, 7th Feb., 1891
Complete Specification Left, 7th Nov., 1891-Accepted, 19th Dec., 1891
PROVISIONAL SPECIFICATION.
Improvements in and connected with Bakers' Ovens.
1, FREDERICK SMITH of No. 23 York Street Lambeth in the County of
Surrey, Oven Builder, do hereby declare the nature of this invention to be as
follows:-
The objects of my invention are to save fuel by producing a more complete
combustion thereof and I consequently avoid to a very great extent the production
of smoke. Increased facilities for working are also given by my improved con-
struction of oven and parts relating thereto.
I divide the firebars of the furnace into two lengths the front ones being some-
what longer than the back ones. The front bars slope about 3 inches towards the
back and the back bars from the lowest part of the front bars are about level, or I
may make the two sets of 'bars in one length of the described shape. At the end
of the furnace nearest the inside of oven, I employ a butting lump" formed of
either iron or firebrick or a combination of both and fixed so that the
upper portion
is about level with or it may even be 2 or 3 inches above the floor of the oven.
This butting limp I continue inside the furnace below the bars and provide an
opening from it into the ashpit. Through this opening air is conducted to a slot or
holes in the upper part: This part is sloped so that the air escapes in a slanting
upward direction but below the slope or between it and the furnace bars and below
the latter the lump is formed vertical so that the air exit hole or holes in the lump
shall not be choked with fuel, cinders or ashes and in order to still further assist in
preventing the fuel from coming near or over the air-holes I may provide the lump
with a horizontal ledge or beading on the vertical wall.
I
The rear part of the furnace and the part over the butting lump is contracted in
height so as to give a sight opening of about 5 inches only between the furnace
crown or covering and the butting lump. The front portion of the furnace on the
other hand make as high as practicable for the purpose of containing a large
quantity of fuel at this part, the object being to save continual stoking and to
enable the gases of the fresh fuel to be liberated and pass over a hanging bridge
hereinafter described mingled with air supplied from an upper furnace door on to
the incandescent fuel at the farther end of furnace and there burnt. For this
purpose the hanging bridge is arranged at the top part of furnace and about or just
beyond the middle of its length so that there is a contraction of the height from
the under side of the bridge to the nearest part of the furnace bars leaving an
opening of about 6 or 7 inches and about 2 inches between it and the crown of the
furnace. This hanging bridge may be constructed of iron, firebrick or other
'suitable material and preferably is provided with channels or grooves so as to allow
the air to pass by it through the fuel. I also provide a space or passage behind
the hanging Bridge by which the mixed smoke and gases are brought down to the
hotter or back portion of furnace and consumed. This arrangement also creates a
suitable draught to furnace near the furnace doors.
In place of the ordinary door at present in use I employ two doors an upper and
a lower one the object being to enable the furnace to be charged quite full at this
end above or quite level with hanging bridge by the lower door and after the
furnace has been partially charged thereby, the lower door is then closed and so
prevents the fuel from falling into the ashpit.
In the lower door a hole having a door or slide is provided for the purpose of
passing a poker in, which latter may be of the ordinary kind or preferably one
having a swivel piece at the end which will be in line with the handle when passed

page_text: through the door and on meeting with resistance of the fuel will turn at right
angles and form a rake so as to push the incandescent fuel beyond the hanging
bridge to the back or level bars at oven end of furnace. This poker is preferably
made tapering at the end so as not to disturb the fuel too much on being
withdrawn.
To facilitate this mode of stoking I employ side lumps which at their upper part
are stepped back slightly a portion of their length so as to form a lodgment for the
fuel above, which when coked together, will permit of the lower or red fire being
pushed from under it towards the oven end without falling in, thus ensuring a mass
of incandescent embers over which the smoke inust pass.
Having thus the facility for placing a large quantity of fuel in the front part of
furnace at one time and the gases being gradually liberated and burnt, by this
means the smoke is consumed which would otherwise be liberated by continual
stoking.
Each door is or may be provided with a latch to keep it closed, and the catch of
upper door is preferably duplicated or stepped so that the door can be fixed open a
certain distance to admit air to front portion of furnace to mix with smoke and
gases as before mentioned. For the same purpose I may also arrange a hopper
above the furnace doors which conducts the fuel through the top of furnace and
the air may be admitted from the ashpit. Also for the purpose of economy and for
more quickly heating the oven I utilise the waste heat of the brickwork of the
oven and form, air flues under the bed and conduct the air thus heated into the
ashpit to supply the furnace. For this purpose I employ an inner arrangement of
doors to ashpit to prevent the air from entering in the ordinary way. Provision is
made for closing these flues by doors after the oven is heated.
make the windage of the back bars considerably less than heretofore to
prevent too rapid combustion of fuel at that part thus forming a reserve of incan-
descent fuel for burning the smoke on its way to the oven.
I illuminate the interior of the oven somewhat in the manner described in my
Patent Specification No. 1336 of 1883 but modify that arrangement so that the
gas burner cannot be left alight or inside the oven when the oven door is about to
.be or is closed. This is accomplished by a part of the door or latch coming in
contact with or acting upon the gas fitting which prevents the door from latching
or it may be made to turn the gas off thereby in either case preventing a possible
explosion.
In order to prevent dust or other matter from accumulating at the lowest part
of the oven door frame I form a space at cach side from front to back so that when
the door is beieg shut any dust or other matter may be pushed away and not be
compressed behind it, thus enabling the door to fit more closely and keep in the
steam and heat. I also, provide a lever attached to the staple for operating the
latch on the oven door which has the effect of keeping said handle cooler because
it is not absolutely fixed on to the latch and is further away than is usually
the case.
This handle may be made hollow in order to assist still further the keeping cool
thereof.
1 provide a double action register or damper over the crown or other part of the
oven covering both the smoke and steam flues and provide a projection on front of
the register on which the handle rests and which also forms a support and guide
therefor.
Dated this 7th dov at Dah 1001
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.

page_text: COMPLETE SPECIFICATION.
Improvements in and connected with Bakers Ovens.
I, FREDERICK SMITH, of No. 23 York Street, Lambeth, in the County of
Surrey, Oven Builder, do hereby declare the nature of my said invention and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
The objects of my invention are to save fuel by producing a more complete
combustion thereof and I consequently avoid to a very great extent the production
of smoke. Increased facilities for working are also given by my improved
construction of oven and parts relating thereto.
In the accomnanvine drawings

page_text: This bridge should have ample play in the brickwork at each end to allow for
expansion by heat. And in order to absorb and utilize the heat and to keep this
bridge cooler I may form it hollow as shewn to serve as an air flue D2 with
outlets D and open at each end for the cool, air, to enter. I also continue the
passage D' downwards behind the hanging bridge D' between it and the lump O by
which the mixed smoke and gases are brought down to the hotter or back portion
of furnace and consumed. This arrangement also creates a suitable draught tö
furnace near the furnace doors.
In place of the ordinary door at present in use I employ as stated two doors an
upper one E and a lower one E the object being to enable the furnace to be
charged quite full at this end above or quite level with hanging bridge D by the
lower door E and after the furnace has been partially charged thereby the lower
door is closed and so prevents the fuel from falling into the ashpit while the upper
door is left partly open for admission of air and is also available for replenishing
the upper part of the furnace as required.
In the lower door E a hole having a door or slide Ex is provided for the purpose
of passing a poker in, which latter may be of the ordinary kind but. preferably as
shewn in Figures 8 and 9 one having a swivel piece F at the end which will be in
line with the handle when passed through the door and on meeting with resistance
of the fuel will turn at right angles against a stop F¹ and form a rake so as to push
the lower layer of incandescent fuel beyond the hanging bridge D to the back end
of the furnace bars at oven end of furnace. This poker is preferably made
tapering at the end as shewn so as not to disturb the fuel too much on being
withdrawn.
To facilitate this mode of stoking I employ side lumps which at their upper part
are stepped back slightly a portion of their length that is to say formed with
recessed parts G so as to form a lodgnient and holding key for the fuel, above,
which when coked together, will permit of the lower or red fire being pushed from
under it towards the oven end without falling in, thus ensuring a
incandescent. embers over which the smoke must pass on its way to oven.
mass of
For the
Each door is or may be provided with a latch to keep it closed and the catch of
upper door E¹ is duplicated or stepped so that the door can be fixed open a certain
distance to admit air to front portion of furnace to mix with smoke and gases as
before mentioned: Instead of the doors hinged as shewn I may use doors swinging
on horizontal pivots or the upper door alone may be of such construction.
same purpose I may instead of the arrangement shewn provide a hopper above the
furnace doors as shown in dotted lines which conducts the fuel through the top of
furnace such hopper being provided with an upper and a lower sliding door in front
as shewn. The air may be admitted from the ashpit to the underside of the furnace
bars in the usual manner but for the purpose of economy and for more quickly
heating the oven I prefer to utilize the waste heat of the brickwork of the oven
especially on the hottest or furnace side of same and form air flues H as shewn in
Figs. 3 and 4 under the oven bed. The flue at the furnace side is partly filled
with bricks H' as shewn which absorb surplus heat at this place and give it up to
the air passing among them thus utilizing this part of the oven for baking by
abstracting the surplus heat from this part of the oven bottom, such heat heretofore
usually rendering this part unfit or too hot for baking purposes, the air thus heated
being conducted into the ashpit to supply the furnace. For this purpose I employ
an arrangement of inner doors I to ashpit to prevent the air from entering in the
ordinary way. The hot air from the ashpit rises up between the furnace bars and
through the split bridge or butting lump B but part of it may also be led to the
upper front t-part of the furnace by a pipe or pipes if desired.
Provision is made for closing the inlet to these flues by means of the door H³
after the oven is' heated.
By this construction of furijace and mode of firing the relative proportions;
dimensions and position of parts being substantially as described and showii I am
enabled to keep a large bulk of fuel in the furnace and to cause the air supplied

page_text: from the upper door E to pass above the upper layer of fuel and through the
fue D in the direction of the arrows and on its way thereto combining with the
gases arising from the upper layer of fuel while the gases arising from the lower
layer of fuel will chiefly pass through the incandescent fuel at the lower inner part
indicated by the line Pip and commingling with the hot unconsumed air and gases
from the passage D' and with the hot air from the split bridge B be consinned
while passing through the bridge throat C. There will thus be no obnoxious
smoke and much less frequent stoking and replenishing of fuel than ordinarily the
case.
illuminate the interior of the oven somewhat in the manner described in my
Patent Specification No. 1336 of 1883 but modify that arrangement so that the gas
burner cannot be left alight or inside the oven when the oven door is about to be or
is closed. K K K K Figure 5 is a swivelled gas pipe with burner K³ arranged
to work in the recess Q Figures 2 and 5 and having a stop washer with nut K
which keeps it from passing out of connection with the stock frame L of the oven.
The desired action is accomplished by a part of the door M or as here shewn the
end of the latch M' coming in contact with or acting upon the swivel head K* of
the gas fitting which as shewn in the dotted line position Fig. 5 prevents the door
from latching; or it may be made to turn the gas off thereby in either case
preventing a possible explosion.
In order to prevent dust or other matter from accumulating at the lowest part of
the oven door frame I form as shown in Figs. 6 and 7 a space or recess L' at cach
side which tapers off to nothing from front to back so that when the door is being
shut any dust or other matter may be pushed away and not be compressed behind
it, thus enabling the door to fit more closely and keep in the steam and heat. I also
as shown in Figs. 2, 3 and 5 provide a bowhandle or other lever M attached to the
staple M³ for operating the latch M' on the oven door M which has the effect of
keeping said handle cooler because it is not absolutely fixed on to the latch and is
further away than is usually the case. This handle may be made hollow in order
to assist still further the keeping cool thereof.
I provide a double action slide or damper N Figure 3 on the register frame over
the crown or other part of the oven such damper covering either the smoke or
steam flue and provide a projection or boss N* on front of the register frame on or
in which the handle rod N¹ rests and which also forms a support and guide
therefor.
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.
First. The improved construction of furnace substantially as herein set forth
having upper and lower furnace doors, side lumps with recesses which act as keys
for holding the layer of fuel in the upper part of the furnace and a hanging bridge
with flue above it and between the back of it and the back lump.
Second. The improved construction of furnace substantially as described with
reference to the drawing having an upper door E' and a lower door E with stoking
hole and slide Ex side lumps with recesses G a hanging bridge D with flue D
slanting furnace bars A. split bridge B and a closable ashpit which is supplied with
air heated by the brickwork of the oven and available for use above and beyond
the furnace bars.
Third. The construction of poker or rake with articulated end and stop as
described and shewn.
Fourth. The flue H under the oven bed with bricks H' in the hottest part of the
brickwork for absorbing the surplus heat thereof and by heating the air admitted
to such flue rendering this part of the oven available for baking in combination
with a closable ashpit substantially as described and as shewn on the drawings.
Fifth. The means for preventing the gas burner for lighting the interior of oven

page_text: from remaining alight therein when the oven is closed substantially as described
and shewn.
Sixth. The application of slanting recesses L' at the sides of the oven stock for
the purpose of preventing accumulation of dust, obstruction to the shutting of door,
and consequent loss of steam and heat substantially as described and shown.
Seventh. The application to oven door latches of a lever handle which is jointed
to the staple and passes through a slot in it substantially as described and shewn.
Dated this 7th day of November 1891.
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.