A New or Improved Instrument or Apparatus for Approximately Indicating the Temperature of the Ovens of Cooking Ranges and Kitchen Ovens.
Year: 1894

page_text: Date of Application, 9th Aug., 1894
Complete Specification Left, 23rd Apr., 1895-Accepted, 1st June, 1895
PROVISIONAL SPECIFICATION.
A New or Improved Instrument or Apparatus for Approximately
Indicating the Temperature of the Ovens of Cooking Ranges
and Kitchen Ovens.
We GEORGE GORDON BRODIE and JAMES DAMREL PRIOR, of The Eagle
Range and Foundry Company, Catherine Street Aston near Birmingham in the
County of Warwick, Ironfounders do hereby declare the nature of this invention
to be as follows:-
Our invention consists of, a new or improved instrument or apparatus for
approximately indicating the temperature of the ovens of cooking ranges and
kitchen ovens, the parts of the said instrument or apparatus being constructed and
arranged substantially as hereinafter described.
The said instrument or apparatus consists essentially of a vertical (or horizontal)
case or box fixed at top preferably to the inner side of the oven door the top of
the case having at front a circular graduated dial situated on the exterior of the
oven door. In the axis of the dial and crossing the case from front to back
is a spindle the said spindle carrying on its front end a pointer or indicator for
indicating on the dial the temperature of the oven. The part of the indicator
spindle situated within the case carries a pinion with which a rack on a quadrant
shaped lever turning on a pivot gears.
The said quadrant shaped lever is operated in the following manner. Situated in
the case and fixed to the case at top and bottom is a bowed or convex strip or ribbon
of iron or steel or other metal or alloy having a lower rate of expansion by heat
than the metal of the case. Bearing against the concave side of the said metallic
strip or ribbon at or about its middle is the free end of a nearly vertical lever
which lever I will hereinafter call the primary lever. The free or upper end of
the said primary lever is headed, one side of the head bearing against the concave
side of the bowed strip or ribbon as hereinbefore described and the other side of
the said head bearing against the short arm of the quadrant lever. The centre of the
primary lever is carried by an adjusting screw passing through the bottom of the
case so that the bearing head of the said primary lever may be arranged to act
On the
at a greater or less distance from the centre of the quadrant lever.
turning of the quadrant lever a pin on its long or quadrant arm is made to raise a
weighted lever which keeps the short arm of the quadrant lever in contact with
the primary lever.
The action of the parts is as follows:-On the heating of the oven the case of
the instrument by expansion is elongated and the bowed metallic strip or ribbon
in the case is more or less straightened. By the partial straightening of the bowed
strip or ribbon the head of the primary lever bearing against the concave side of
the said bowed strip or ribbon is pressed against the short arm of and operates the
quadrant lever, thereby effecting the rotation of the indicator spindle the indicator
of which points on its dial to the degree of temperature to which the oven has
been raised.
On the cooling of the oven the case of the instrument contracting, the bowed
strip or ribbon assumes its normal convex figure and the weighted lever herein-
before described ensures the return of the parts to their normal or "cold" position.
Although we have described the bowed strip or ribbon as fixed to a box or case

page_text: on the oven door yet it may be fixed to a bar, plate or tube and the latter to the
oven door or other part of the oven.
We do not limit ourselves to the mechanical arrangement of parts described by
which the straightening of the metal strip or ribbon operates the index finger or
pointer as various other equivalent arrangements may be adopted for that purpose,
the essence of our invention consisting in the expansion of the case or box, or bar
plate or tube on the oven door, straightening a metal strip or ribbon, the amount of
straightening being indicated on a dial.
Dated this 9th day of August 1804
W. T. WHITEMAN,
Agent for the Applicants.
A New or Improved Instrument or Apparatus for Approximately
Indicating the Temperature of the Ovens of Cooking Ranges
and Kitchen Ovens.
We GEORGE GORDON BRODIE and JAMES DAMREL PRIOR, of The Eagle
Range and Foundry Company, Catherine Street Aston, near Birmingham in the
County of Warwick, Ironfounders, 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 :-
Our invention consists of a new or improved instrument or apparatus for approxi-
mately indicating the temperature of the ovens of cooking ranges and kitchen
ovens, the parts of the said instrument or apparatus being constructed and arranged
substantially as hereinafter described.
The said instrument or apparatus consists essentially of a vertical (or horizontal)
case or box fixed preferably to the inner side of the oven door the top of the case
having at front a circular graduated dial situated on the exterior of the oven door.
In the axis of the dial and crossing the case from front to back is a spindle the
said spindle carrying on its front end a pointer or indicator for indicating on
the dial the temperature of the oven. The part of the indicator spindle situated
within the case carries a pinion with which a rack on a quadrant shaped lever
turning on a pivot gears.
-
The said quadrant shaped lever is operated in the following manner. Situated in
the case and fixed to the case at top and bottom is a bowed strip or ribbon of iron
or steel or other metal or alloy having a lower rate of expansion by heat than the
metal of the case. Bearing against the concave side of the said metallic strip or
ribbon at or about its middle is the free end of a nearly vertical lever which lever
we will hereinafter call the primary lever. The free or upper end of the said
primary lever is headed, one side of the head bearing against the concave side of
the bowed strip or ribbon as herein before described and the other side of the said
head bearing against the short arm of the quadrant lever. The centre of the
primary lever is carried by an adjusting screw passing through the bottom of the
case so that the bearing head of the said primary lever may be arranged to act at
a greater or less distance from the centre of the quadrant lever. On the turning of
the quadrant lever a pin on its long or quadrant arm is made to raise a weighted
lever which keeps the short arm of the quadrant lever in contact with the
primary lever.
The action of the parts is as follows:-On the heating of the oven the case of
the instrument by expansion is elongated and the bowed metallic strip or ribbon in
the case is more or less straightened. By the partial straightening of the bowed
strip or ribbon the bead of the primary lever bearing against the concave side of
the said bowed strip or ribbon is pressed against the short arm of and operates the

page_text: quadrant lever, thereby effecting the rotation of the indicator spindle the indicator
of which points on its dial to the degree of temperature to which the oven has
been raised.
On the cooling of the oven the case of the instrument contracting, the bowed
strip or ribbon assumes its normal convex figure and the weighted lever hereinbefore
described ensures the return of the parts to their normal or "cold" position.
Although we have described the bowed strip or ribbon as fixed to a box or case
on the oven door yet it may be fixed to a bar, plate or tube and the latter to the
oven door or other part of the oven.
Figure 1 of the accompanying drawings represents in front elevation a heat
indicating instrument or apparatus constructed according to our invention fixed to
a portion of an oven door; Figure 2 represents the same in back elevation, the
back closing plate of the case being removed; Figure 3 represents the instrument
in vertical longitudinal section and Figure 4 the same in cross or horizontal section,
the said cross section being taken on the dotted line a, a Figure 1.
Figures 5 and 6 represent a modification of the arrangement figures 1, 2, 3
and 4.
The same letters of reference indicate the same parts in the several figures of
the drawings.
We will first describe the instrument Figures 1, 2, 3 and 4.
a is the iron or steel strip or ribbon by the expansion or contraction of which on
the heating or cooling of the oven the motion of the indicator is obtained. The
said ribbon a is fixed at a², a² to the top and bottom of the containing case 6 which
case is fixed to the oven door A by the screws c, e taking into the sides of the
clip embracing the back and sides of the case of the instrument as is best seen
in Figures 2, 3 and 4. The said case is preferably made of brass but the case may
be made of any metal or alloy having a greater expansion by heat than iron or
steel of which the ribbon is preferably made. As the oven is heated the case /
expanding at a greater rate than the ribbon a the said ribbon becomes less and less
bowed, its middle approaching nearer and nearer to the middle of the case.
motion of the ribbon a is transmitted preferably by the mechanism hereinafter
described to the indicator or pointer d moving over the graduated dial e.
This
The said transmitting mechanism consists of the following arrangement or com-
bination of parts. To the end of an adjustable pin f, the primary lever g is
pivoted the hammer like head of which bears on one side against the bowed
ribbon a and at its other side against the short arm of the quadrant lever h, h²
turning on the pin or centre . The head of the quadrant lever h, h² is toothed
its teeth engaging with the teeth of the pinion wire spindle 2 carrying the
indicator or pointer d. The long arm of the quadrant lever h, is provided
with a pin against which one arm of a weighted lever i bears the said weighted
lever having for its purpose to ensure the quadrant lever h, h² and primary lever g
following the motion of the bowed ribbon a.
When the instrument or apparatus is put together the pin is preferably
adjusted by rotating in one or other direction the nut 2 situated in a slot in the
bottom of the case 6 so that the instrument shall indicate by means of its pointer
and dial degrees Fahrenheit; but it is not essential that the instrument should be
adjusted to any particular scale as the indications may be approximate indications
only.
In adjusting the parts to indicate degrees according to a scale, the nut f' at
the bottom of the case b, is rotated and the screw f, which is prevented from
turning by the screw piu f' bearing against a flat on one side of the said screw f, is
drawn in one or other direction through the bottom of the case b. The hammer
head of the lever 9 is thereby made to act at a greater or less distance from the
pin or centre of the quadrant lever h, 2 and at a greater or less distance from
the middle of the bowed ribbon a.
From the foregoing description it will be understood that as the expansion of
the case 6 takes place at a greater rate than the strip or ribbon a the said strip or

page_text: ribbon is more or less straightened and its straightening motion is transmitted by
the mechanism described to the index finger or pointer if and the heat of the oven
approximately indicated on the dial.
In Figures 5 and 6, the case b is dispensed with the ribbon a being fixed to the
turned out ends a², a² of the tube b which is fixed to the oven door. The instrument
Figures 5 and 6 is preferably covered by a thin sheet metal case k. The other parts
of the instrument or apparatus Figures 5 and 6 are the same as corresponding parts
of the heat indicator first described and are marked with the same letters of
reference. The ends of the ribbon a instead of being fixed to a tube may be
attached to a bar or plate carried by the oven door.
Although we have described the case as being made of brass or of a metal
or alloy having a greater expansion by heat than iron or steel yet the case may
be made of iron or steel and the strip or ribbon a of brass or other metal or alloy
having a greater expansion by heat than the metal of the case. In such an arrangement
however the convex side of the ribbon would be arranged to act on the primary
lever instead of the concave side as herein before described.
Although we find the arrangement or combination of parts described and
represented for transmitting the action of the bowed ribbon a to the indicator d to
answer well yet we do not limit ourselves thereto as other equivalent mechanical
arrangements of parts may be used for that purpose; for example, a light rod
may be fixed at one end to the middle of the bowed strip or ribbon the other
or free end of the light rod carrying a rack for gearing with the toothed indi-
cator spindle, or with a pinion gearing through a series of toothed wheels with
the toothed indicator spindle. Or the case, tube, bar or plate carrying the bowed
strip or ribbon may be arranged horizontally and the middle of the bowed
strip or ribbon be connected by means of a light connecting rod to a crank arm on
the indicator spindle the said connecting rod being jointed at one end to the middle
of the bowed strip and at the other end to the said crank arm.
In this case
the indicator or pointer moves over a quadrant shaped dial instead of a circular
dial.
Our new or improved heat indicating instrument or apparatus is applicable to
ovens heated by solid, liquid or gaseous fuel or by electricity.
Having now particularly described and ascertained the nature of our inven-
tion and in what manner the same is to be performed we declare that we claim
as our invention :-
-:
First. The new or improved instrument or apparatus for approximately indi-
cating the temperature of the ovens of cooking ranges and kitchen ovens
herein before described and illustrated in the accompanying drawings the said
instrument or apparatus consisting essentially of a metallic strip or ribbon fixed at
its ends to the case of the instrument or to a plate, tube or bar fixed to the oven
door or other part of the oven the metal or alloy of the strip or ribbon having
a different rate of expansion by heat from that of the metal or alloy of the
case the expansion or contraction of the ribbon or strip being transmitted
to the indicating finger or pointer substantially as hereinbefore described and
illustrated.
Secondly. In an instrument or apparatus of the kind claimed in the prior
claim, the arrangement of the levers and parts connected therewith hereinbefore
described and illustrated in the accompanying drawings through which arrange-
ment the expansion and contraction of the bowed metallic strip or ribbon of the
instrument is made to operate the indicator or pointer of the same substantially
as described and illustrated; also the modifications of the said transmitting
mechanism herein before described.
Dated the 22nd dar of Anvil 100%
GEORGE GORDON BRODIE.
JAMES DAMREL PRIOR.