IM- PROVEMENTS IN FURNACE GRATES, AND IN MODES OF AND APPARATUS FOR ACTUATING THE SAME SO AS TO STIR THE FIRE, AND IN SOME CASES MAKE THE FURNACE SELF-CLEANING.
Year: 1875

page_text: LETTERS PATENT to Thomas Henderson, of 13, Harland Road,
Birkenhead, in the County of Chester, for the Invention of "IM-
PROVEMENTS IN FURNACE GRATES, AND IN MODES OF AND APPARATUS FOR
ACTUATING THE SAME SO AS TO STIR THE FIRE, AND IN SOME CASES MAKE
THE FURNACE SELF-CLEANING.
"
Sealed the 26th October 1875, and dated the 26th April 1875.
PROVISIONAL SPECIFICATION left by the said Thomas Henderson at
the Office of the Commissioners of Patents, with his Petition,
on the 26th April 1875.
I, THOMAS HENDERSON, of 13, Harland Road, Birkenhead, in the
County of Chester, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN FURNACE GRATES, AND IN MODES OF AND APPARATUS
FOR ACTUATING THE SAME SO AS TO STIR THE FIRE, AND IN SOME CASES MAKE THE
FURNACE SELF-CLEANING," to be as follows:-
This Invention has for its object the mechanically stirring of the fuel
in a furnace in a more thorough, simple, and economical manner than it

page_text: has hitherto been performed. For this purpose I use an apparatus
resembling a bell-crank lever in cross section, both cranks of which are
employed in moving the bars.
1st. In its simplest form applied to the roar of a furnace it consists
of a piece of angle iron placed horizontally and transverse to the
furnace with the angle downwards, which angle rests loosely at each
end in a notch in suitable brackets. Upon the two edges of this anglo
iron the ends of the movable bars rest, the latter having lugs cast to
them to prevent them slipping on the angle iron. When the other ends
of the bars are pulled forward or pushed backward, as the case may be,
the angle iron is tilted, causing the one edge to rise and carry the move-
able bars with it. The instant, however, the pressure exerted on the
other end of the bar is removed the unbalanced weight of the furnace
on the one edge of the angle iron causes the wholo to fall to its normal
position (in which the moveable bars rest on both edges of the angle
iron). By this means when the bars are alternately fixed and moveable,
the danger of the moveable bars being left by mistake out of their
normal position, and consequently exposed to the destructive action of
the fire is entirely obviated.
2nd. In a more elaborated form of the same apparatus, and applicable :
equally to both ends of the furnace; it consists of a shaft placed
transversely to the furnace working in bearings at each end, and having
two flanges with cylindrical extremities cast thereon. Theso flanges
stand at an angle of from 45 to 90 degrees with each other. In the
normal position one of these flanges is practically vertical, the other
inclined or horizontal. Every alternate fire-bar is notched so as to rost
on the vertical flange, so that when the axis is rotated through a small
are the motion given to the bars resting thereon is approximately hori-
zontal. The remaining bars alternating with the former ones have
notches or forked projections resting on the other rounded flange, so
that when the flanged shaft is rotated through a small arc, as already
described, it may give an approximately vertical motion to the bars
resting upon the last-mentioned flange. A shaft of this description can
be placed at cach end of the furnace; they require no connectors to
communicate the motion, the bars moved horizontally causing the rear
shaft to work in conjunction with the front shaft.
The two sets of bars are so constructed as to clear the flange that
works the other set, with this exception, that when the bars moved

page_text: vertically sink to the level of the bars moved horizontally they rest on
the "vertical" flange which retards their further descent and holds all
the bars in their normal position. The motion of the shaft in the other
direction can be limited by the working lever actuating the shaft
coming in contact with the furnace front, or a cam actuating the lever
by means of transmitted power. The natural tendency of the bars when
free is to rest on the "vertical" flange, and thus their surfaces are all
at the same level. The apparatus may, however, be frequently advan-
tageous arranged so that the vertical moving bars shall pass below the
level of the others during a portion of the stroke, by which arrange-
ment the fuel is gradually carried to the front or rear end of tho
furnace, and there discharged as ash or clinkers.
The front shaft can be worked by a lever or in any other desirable
manner from a cam or excentric on a "Ilenderson's Mechanical Stoker,"
as described in Letters Patents granted me, Number 2509 of 1872, and
Number 2812 of 1874.
Instead of the flanged or winged shaft, already described, I frequently
prefer in practice its mechanical equivalent, a winged casting working
loose or koyed on to a plain shaft.
3rd. Another modification, when the alternate bars are stationary, is
to have the moveable bars supported at the rear end on the vertical
flange, the horizontal flange lying on the brackets, so that by the move-
ment of the bars in the direction of the horizontal flange the angle iron
(or its equivalent the double flanged shaft) is tilted upon the edge of
the horizontal flange, and thus rises very rapidly and has a still stronger
leverage tending to assume the normal position. The front shaft is also
differently constructed, the vertical flange remaining practically as
before, but the horizontal or oblique flange being represented solely by
a small protruberance on one side of the verticle flange, which bearing
against the lug on the moveable fire-bar as the "vertical" flange passes
the vertical line tho protruberance (in rising) raises the bar very rapidly,
thus giving to the fire-bar a horizontal and vertical movement with one
operation. This form of shaft can also be used for a hinder shaft if
desired.
4th. My Invention can be casily modified so as to be applied to
transverse bars. By supporting the transverse bars at each end on one
or, in some cases, two longitudinal bearing bars made to rock or reci-

page_text: procate by machinery similar to that already described, or in any other
convenient manner. The bearing bars at each side of the furnace arc
made to reciprocate alternately with each other.
5th. When two sets of transverse bars are used with a bearer down
the middle, the side bearers can be made stationary, if desirable, or
reciprocating alternately with the central one, but the central bearer or
bearers must be made to reciprocate.
I sometimes arrange two central reciprocating bearers on cach side of
a stationary bar rising to the surface of the firc-grate, with air spaces
on each side, or preferably cast all three central bars together with air
spaces, and make the whole reciprocate.
When bearers at opposite ends of a set of fire-bars have to reciprocate
in opposite directions, I usually make their "bell cranks" loose on the
shafts, and work each bell crank on the front shaft from different
excentrics, or when two side bearers and a central one are used, the
central one can be loose and the side ones keyed to the shaft, when two
excentrics or cams will be enough.
6th. The Invention is applicable to almost all kinds of boilers and
furnace grates, especially those of marine boilers (to which no other
form of rocking bar has yet been successfully applied.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thomas Henderson in the Great Scal Patent Office
on the 26th October 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
HENDERSON, of 13, Harland Road, Birkenhead, in the County of Chester, 2
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Lotters Patent, bearing dato the Twenty-sixth day of April, in the year of
our Lord One thousand eight hundred and seventy-five, in the thirty-
eighth year of Her reign, did, for Herself, Her heirs and successors, 3
give and grant unto me, the said Thomas Henderson, Her special licence,
that I, the said Thomas Henderson, my executors, administrators, and
assigns, or such others as I, the said Thomas Henderson, my executors,

page_text: administrators, and assigns, should at any time agree with, and no
others, from time to time and at all times thereafter during the term
therein oxpressed, should and lawfully might make, use, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "INPROVEMENTS IN
FURNACE GRATES, AND IN MODES OF AND APPARATUS FOR ACTUATING THE SAME
SO AS TO STIR THE FIRE, AND IN SOME CASES WAKE THE FURNACE SELF-CLEANING,"
upon the condition (amongst others) that I, the said Thomas
Henderson, my executors or administrators, by an instrument in writing
under my, or their, or one of their hands and seals, should particularly
describe and ascertain the nature of the said Invention, and in what
manner the same was to be performed, and cause the same to be filed
in the Great Seal Patent Office within six calendar months next and
immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Thomas Henderson, 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, reference being had to the accom-
panying Drawings, and to the figures and letters of reference marked
thereon:-
This Invention has for its object the mechanical stirring of the fuel
in a furnace in a more thorough, simple, and economical manner than it
has hitherto been performed. For this purpose I use an apparatus
resembling a bell-crank lever in cross section, both shanks of which are
employed in moving the bars.
#
1st. In its simplest form applied to the rear of a furnace it consists
of a picce of angle iron A, Figure 4, placed horizontally and transverse
to the furnace with the angle downwards, which anglo rests loosely at
each end in a notch in suitable brackets B. Upon the two edges of this
rest, the latter having lugs
angle iron the ends of the moveable bars
cast on them to prevent them slipping on the angle iron. When the
other ends of the bars are pulled forward or pushed backward, as the
case may be, the angle iron is tilted, causing the one edge to riso and
carry the moveable bars with it. The instant, however, the pressure
3 exerted on the other end of the bar is removed, the unbalanced weight
of the furnace on the one edge of the angle iron causes the whole to
fall to its normal position (in which the moveable bars rest on both

page_text: egdes of the angle iron). By this means where the bars are alternately
fixed and moveable the danger of the moveable bars being left by
mistake out of their normal position, and conscquently exposed to the
destructive action of the fire is entirely obviated.
2nd. In a more elaborate form of the same apparatus and applicable
equally to both ends of the furnace (shown in Figures 1 and 2); it
consists of a shaft D, placed transversely to the furnace, working in
bearings B at each end, and having two flanges with cylindrical
extremities cast thereon. These flanges stand at an angle of from 45 to
90 degrees with each other. In the normal position one of these
flanges is practically vertical, the other inclined or horizontal. Every
alternate fire-bar is notched so as to rest on the vertical flange, so that
when the axis is rotated through a small arc, the motion given to the
bars resting thereon is approximately horizontal. The remaining bars
alternately with the former one have notches or forked projections
resting on the rounded horizontal flange, so that when the flanged shaft
is rotated through a small arc, as already described, it may give an
approximately vertical motion to the bars resting upon the last-mentioned
flange. A shaft of this description can be placed at each end of the
furnace, they require no connectors to communicate the motion, bars
moved horizontally causing the rear shaft to work in conjunction with
the front shaft.
The two sets of bars are usually so constructed as to clear the
flange that works the other set, with this exception, that when the
bars moved vertically sink to the level of the bars moved horizontally
they rest on the vertical flange, which retards their further descent and
holds all the bars in their normal position. The motion of the shaft in
the other direction can be limited by the working lever made to fit on
projection E and actuating the shaft coming in contact with the furnace
front, or by a cam actuating the lever by means of transmitted power.
The natural tendency of the bars when free is to rest on the "vertical"
flange, and thus their surfaces are all at the same level. The apparatus
may, however, be frequently advantageously arranged so that the
vertically moving bars shall pass below the level of the others during a
portion of the stroke, by which arrangement the fuel is gradually
carried to the front or rear end of the furnace and there discharged.
The front shaft can be worked by a lever, or in any other desirable
manner, from a cam or excentric on a Henderson's Mechanical Stoker,

page_text: as described in Letters Patent granted me, Number 2509 of 1872, and
Number 2812 of 1874.
Instead of the flanged or winged shaft, already described, I frequently
prefer in practice its mechanical equivalent, a winged casting working
loose or keyed on to a plain shaft.
3rd. Another modification, especially when the alternate bars are
stationary, is to have the moveable bars supported at the rear end on a
vertical flange, the horizontal flange lying on the brackets, so that by
the movement of the bars in the direction of the horizontal flange the
angle iron (or its equivalent the double flanged shaft) is tilted up on the
edge of the horizontal flange, and thus rises very rapidly and has a
still stronger leverage tending to assume the normal position (this is well
shown in Figure 2). The front shaft is also occasionally differently
constructed, the vertical flange remaining practically as before, and the
horizontal or oblique flange being represented solely by a small pro-
tuberance on one side of the vertical flange bearing against the lug on
the moveable fire-bar. As the "vertical" flange passes the vertical
line the protuberance (in rising) raises the bar very rapidly, thus
giving to the fire-bar a horizontal and vertical movement with one
operation. This form of shaft can also be used for a hinder shaft, if
desired.
4th. My Invention can be easily modified so as to be applied to
transverso bars (sco Figures 5 and 6). In this case I support the
transverse bars G at each end on one, or in some cases, two longitudinal
bearing bars made to rock or reciprocate by machinery similar to that
The bearing
already described, or in any other convenient manner.
bar at each side of the furnace, are made to reciprocate alternately with
cach other.
5th. When two sets of transverse bars are used with a bearer down
the middle the side bearers can be made stationary, if desirable, or
reciprocating alternately with the central one, but the central bearer or
bearers must be made to reciprocate.
I sometimes arrange two reciprocating bearers on cach side of a
stationary bar, rising to the surface of the fire-grate, with air spaces on
5 each side, or preferably cast all three central bars together with air
spaces, and make the whole reciprocate.
6th. When the bearers at opposite ends of a set of fire-bars have to

page_text: different eccentrics, or when two side bearers and a central one are used,
the central one can be loose and the sido ones keyed to the shaft, when
two eccentrics or cams will be enough.
7th. The Invention is applicable to almost all kind of boilers and
furnace grates, especially those of marine boilers (to which no other
form of rocking bar has yet been successfully applied).
What I claim as my Invention is,—
1st. The mode of working moveable fire-bars by means of a double- 1
flanged axis, both flanges being simultaneously employed in supporting
and moving the bars.
2nd. The mode of actuating moveable fire-bars on the bell-crank
principle, in which the bars rest on the one flange and the whole turns
on the other flange, for the purposes described.
3rd. The moveable longitudinal bearers for transverse fire-bars and
mode of actuating the same, substantially as described in part 4 or any
mere modification thereof.
4th. The combination of the angle iron A or its mechanical equivalent
with moveable fire-bars.
5th. The special arrangements of apparatus for actuating moveablo
fire-bars, substantially as described in the foregoing Specification.
In witness whereof, I, the said Thomas Henderson, have hereunto
set my hand and scal, this Nineteenth day of October, in the
year of our Lord 1875.
]
2
2
THOMAS HENDERSON. (L.S.)
Witness,
W. P. THOMPSON,
British & Foreign Patent Agent,
6, Lord Street,
Liverpool,