IMPROVEMENTS IN FURNACES FOR STEAM GENERATORS AND FOR OTHER PURPOSES to be as follows:
Year: 1885

page_text: I JOHN CRESSWELL BRENTNALL of Norris Hill, Heaton Norris in the County of
Lancaster Gentleman do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN FURNACES FOR STEAM GENERATORS AND FOR OTHER PURPOSES
to be as follows:-
"
My said Invention relates more particularly to the furnace grates of steam
generators but it is also applicable to other descriptions of furnaces. The bars
composing my improved furnace grate are arranged longitudinally in the furnace
flue and are supported at the front and back upon bars rollers or anti-friction
bowls so as to be capable of a to and fro sliding motion. To impart the said
to and fro motion to the bars I provide a series of tappits or cams which work
within or between suitably formed recesses or projections formed in or upon the
bars. The said cams are fixed upon a revolvable shaft which extends across
the front of the furnace and is driven by any suitable means. Each cam is
duplex in formation the curve for advancing the bar being in a different plane
from the curve for retracting the same and the entire number of cams is divided
into two, three or more sets the members of which are arranged in rotation and
act in a correspondingly different manner upon the corresponding sets of bars. In
operating the grate the whole of the bars are simultaneously advanced the required
distance a movement which is effected by a portion of the cams which is identical
in all. Suppose the grate bars are divided into three sets I arrange that at the
end of the forward stroke each alternate third bar in the series is withdrawn by
the second portion of its corresponding cam the alternate bars of the remaining,
two thirds are next withdrawn by their corresponding cams and lastly the
remaining bars constituting one third of the grate are also withdrawn, so that the
whole of the bars resume their original position to be again simultaneously
advanced and withdrawn in sections as described. To assist in feeding the fuel
forward I provide a pusher projection or shoulder on the outer end of each bar
which when the bars are advanced carries the fuel forward. As only a certain
number of the bars are drawn back at a time the fuel does not return at the back-
ward stroke, so that the tendency is always to carry the fuel forward with each
simultaneous advance of the grate bars. If desired the transverse of the bars at
different points in the breadth of the grater may be caused to vary for example
"

page_text: it might be considered advisable to give a greater transverse to the side bars than
to those in the centre. To obtain this result the gap or recess at the end of these
bars is correspondingly modified or the throw of the cams might be increased.
In some cases an adjustable piece is fitted to the end of the bar so as to alter the
gap or recess and thus increase or diminish the traverse of the bar. The bars may
be made slightly broader at the back of the furnace so as to approach each other
more closely and thus diminish the air supply at the back of the furnace and they
may be similarly brought together at the front to prevent the green coal fed to the
grate from dropping through between the bars. My improved furnace grate may
be stoked by hand but I prefer to supply the fuel from a hopper.
A deflecting plate is applied in front of the bars which rests upon and co-operates
with the aforesaid pushers to assist in preventing the fuel from being drawn back
with the retracted bars. To regulate the supply of fuel I employ a regulator
placed between the hopper and the furnace. The said regulator is preferably made
hollow and capable of being raised and lowered by chains or a rack and pinion or
by other means whereby it can be placed at the desired height above the grate
bars. Air is admitted at the top to the hollow regulator and passes to the furnace
through perforations in the back of the regulator. The supply of air to the said
hollow fuel regulator is governed by a hinged lid or by slides louvres or other
means.
COMPLETE SPECIFICATION.
Improvements in Furnaces for Steam Generators and for
other Purposes.
"
I JOHN CRESSWELL BRENTNALL of Norris Hill, Heaton Norris in the County of
Lancaster, Gentleman do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN FURNACES FOR STEAM GENERATORS AND FOR OTHER PURPOSES
and in what manner the same is to be performed' to be particularly described and
ascertained in and. by the following statement and accompanying drawings
My said Invention relates more particularly to the furnace grates of steam
generators but is also applicable to other descriptions of furnaces.. The bars
composing my improved furnace grate are arranged longitudinally in, the, furnace
flue and are supported at the front and back upon bars, rollers or anti-friction
bowls so as to be capable of a to and fro, sliding motion. To impart the said
to and fro motion to the bars I provide a series, of tappits or cams which work
within or between suitably, formed recesses or projections formed in or upon the

page_text: bars. The said cams are fixed upon a revolvable shaft which extends across
the front of the furnace and is driven by any suitable means. In operating the
grate the whole of the bars are simultaneously advanced the required distance
and withdrawn in sections. I provide a pusher, projection or shoulder on the
outer end of each bar which when the bars are advanced carries the fuel forward..
The bars may be made slightly broader at the back of the furnace so as to approach
each other more closely and thereby diminish the air supply at the back of the
furnace and the said bars may be similarly brought nearer together at the front
to prevent the green coal fed to the grate from dropping through between the bars.
My improved furnace grate may be stoked by hand but I prefer to supply the
fuel from a hopper.
..
And in order that my said invention may be fully understood I will now proceed
more particularly to describe the same reference being had to the annexed sheet
of drawings and to the letters and figures marked thereon.
As has been already said the bars composing the grate are arranged longitudinally
in the furnace in sets of three each bar of the set being operated by its corre-
sponding cam. Figs. 1, 2 and 3 are side views partly in section of the three
bars a, b. and c. composing such a set for example as is shown in the plan view
Fig. 6 of the drawings. The bars are supported at the front and back upon bars,
rollers or anti-friction bowls x. so as to be capable of a to and fro sliding motion..
In Fig. 1 the bar a is shown as having been pushed inward. In Fig. 2 the bar b. is
shown half withdrawn and in Fig. 3 the bar c. is at the end of its outward stroke.
The respective bars a, b and c, are operated by cams d. e. and f. which are carried
by a revolving shaft g. which extends across the front of the grate and is driven
in any suitable manner. All three of the bars are moved inward simultaneously
by a portion of the curves of the cams which portion is similar in position in all
of the cams, the said portion being marked in the cam d, e¹ in the cam e, and
f¹ in the cam f. As the shaft g. revolves in the indicated direction, these three
parts are brought simultaneously into contact with the surfaces a¹ b¹ and c¹ of the
bars a, b. and c. so that the bars are simultaneously moved inward. After this
simultaneous advance the bars are withdrawn progressively the bar a being first
moved outwards by its cam, then the bar b. and lastly the bar c. after which the
simultaneous advance of all three is repeated and so on. In order that the bar a.
may dwell at the end of its outward stroke until the bars b. and c. have in their
turn been brought out, the cam d. is made duplex in formation the part d' acting
on the surface a¹ to push the bar inward and the part d² acting on the surface a³
to push the bar outward the curves d¹ and d³ acting in different vertical planes. It
will be observed that the part d¹ of the cam d. is narrow and leaves the surface a¹
as soon as the bar a. has been pushed in allowing the bar to be immediately with-
drawn by the part d³ which is considerably more extended, the said extended
curve d² providing for the dwell which takes place after the outward return of the
bar a.
The surface a¹ is recessed at one side as shown by the dotted lines, so as
to allow the curve d³ to pass in advance of the part d' and without acting on the
bar. As the second bar b. has a dwell of equal duration at the end of both the
inward and outward strikes the cam e. is so shaped as to effect this and may act
on the surfaces 61 and 63 in the same vertical plane. The third bar c. is operated
by the duplex cam f. which is so shaped as to give the longest dwell to the bar c.
when at the end of its inward stroke. The bar is pushed inward by the curve fl
of the cam which is of the extended form shown so as to give the required dwell
at the end of the inward stroke, the surface c³ of the bar being recessed out as
shown by the dotted lines so as to allow the curve f. of the cam to pass when the
bar is pushed inward. Fig. 4 is an end view partly in section of the three bars
composing a set with their corresponding cams. To assist in feeding the fuel
forward I form an elevation at or near the end of the bar as shown at h. h¹ in
Fig. 1 or I cast or fix a suitable shoulder, projection or pusher on the bar and
about or immediately beneath the furnace door i. which elevation projection or
pusher carries the fuel forward at each simultaneous advance of the bars. As the

page_text: bars are drawn back in sections as hereinbefore described the fuel does not return
with the backward strokes but is fed continuously forward. I do not confine
myself to the form of pusher shown as the same may be varied. To obtain a
varying air supply at different points in the length of the grate I form the bars of
a greater breadth at the back of the furnace than towards the middle portion so
that towards the back of the furnace the bars approach each other more closely
than at the centre of the length of the grate whereby the air supply is diminished
at the back where the fuel has become so much thinner than at the front as to
require a correspondingly diminished supply of air. To prevent the green coal fed
from the hopper or by hand from falling between the bars at the front of the grate
I may make the bars wider at the foot end so that they approach each other more
closely immediately beneath the feed or I may cast the bars with comparatively
narrow perforations or slots k. whereby sufficient air can be admitted without
having inconveniently wide spaces. Fig. 5 is a section of one of the bars at the
line A. B. Fig. 1 showing the said air space or slot k. Although I have described
my improved furnace grate as consisting of a series of sets of three bars to the set
it will be evident that the set might be composed of a greater number of bars
than three.
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed I declare that what
I claim is
1. The fire bars and the actuating cams formed, arranged and acting as and for
the purpose set forth and indicated.
2. The pushers, projections, elevations or shoulders cast or formed on or fixed
to the bars of traversing furnace grates for advancing the fuel substantially as
described and shown or any mere modification of the same.
3. The air spaces between the longitudinally arranged bars of movable furnace
grates varying in width in different parts of the length of the furnace substantially
as and for the purpose set forth and indicated.
Dated this 12th day of April 1886