Improvements in Revolving Stokers.
Year: 1892

page_text: Date of Application, 8th Nov., 1892-Accepted, 17th Dec., 1892
⚫ COMPLETE SPECIFICATION.
[Communicated from abroad by NATHANIEL WATERMANN PRATT and THE
BABCOCK AND WILCOX COMPANY, of New York, in the United States of
America, Steam Boiler Manufacturers.]
Improvements in Revolving Stokers.
I, WALLACE FAIRWEATHER, C.E., of 62 Saint Vincent Street in the City of
Glasgow, Chartered Patent Agent do hereby declare the nature of this invention
and in what manner the same is to be performed, as communicated to me to be
particularly described and ascertained in and by the following statement:-
My invention relates to improvements in revolving stokers and in the accom-
panying drawings which illustrate the invention.
Figure 1 is a longitudinal sectional elevation of a water tube steam boiler
showing a modification of the invention applied thereto;
Figure 2, a longitudinal section of Figure 1, on the line -a;
Figure 3, a front elevation of the lower portion of the structure;
Figure 4, a cross-section on the line y-y, Figure 2, looking from the front
toward the back;
Figure 5, an enlarged plan view in detail of the grate frame.
Figure 6, a cross section of Figure 5, on the line;
Figure 7, a cross-sectional detail at the line, Figure 5;
Figure 8, a side view partly in section, of the revolving grate shown in detail,
taken opposite the dumping point; and
Figure 9, a side elevation showing a modification.
Figures 10 and 11 are enlarged side and front views respectively showing in
detail the propelling mechanism of the grate and feeder detached from the other
parts;
Figure 12 is a longitudinal sectional elevation on the line - Figure 13 of a
furnace and another modification of rotary grate, adapted to a steam boiler;
Figure 13, a front elevation;
Figure 14, a horizontal section on the line y-y, Figure 12;
Figure 144 is an enlarged sectional elevation on the line 3" of Figure 14 of the
devices for rotating the disc 50 looking from the inside of the same devices shown
in Figure 13;
Figure 15, a horizontal section on the line -, Figure 12;
Figure 16, a front sectional elevation of a similar grate showing the feature of
improvement in the bridge;
Figure 17, a partial front elevation partly in section showing a modified form of
dumping device;
Figure 18, a horizontal sectional view of the same on the line ¹-x¹;
Figure 19, a partial front elevation of a further modification of the dumping
device;
Figure 20, a sectional front elevation on the line y'-y', Figure 21, showing the
same in a different position :
Figure 21, a vertical section on the line - Figures 19 and 22 and
Figure 22, a horizontal section on the line 2-2, Figure 19.
My invention is applicable to a water tube boiler, as shown in the accompanying
drawings or to any form of boiler other than the water tube, and the object is to
provide an automatic stoker having a maximum amount of grate surface at the
hottest portion of the fire, and adapted therefore to promote perfect combustion of
the fuel before the products are discharged. The object is also to construct a
travelling grate such as will require a small power to actuate it and upon which

page_text: and of its feed mechanism.
of the fuel win oner tie it any resistance to the working of the grate
My invention consists of a rotary grate composed of dumping sectors journalled
on radial axes aside from their centres of gravity in the carrying frame; or broadly
stated having a preponderance of weight upon one side of their axes said sectors
bearing on their preponderating sides upon a circular track. The track is inter-
rupted or, depressed at a portion thereof, whereby the sectors are caused to drop by
gravity and discharge their loads in succession at a point of rotation succeeding
the fire.
My invention also consists in a novel construction of the furnace adapted to such
rotary grate, and of a radial bridge covering the sectors at their dumping point and
a certain juxtaposition of the fuel feeder with reference to the bridge.
My invention also comprises certain novel mechanism for actuating the grate
automatically in given relation to the feeder..
In order to enable others skilled in the art to which my invention appertains to
understand and use the same I will proceed to describe a machine embodying the
details of its preferred construction, explain its operation, and substantially point
out in the appended claims its novel characteristics.
1, is a circular grate which may be placed wholly or partly underneath the boiler
as the circumstances require.
In the drawings Figure 1, the furnace is shown placed half outside of the boiler
front; the outside portion being covered with a dome 2, the thrust of which is
received by a cast ring 5, in addition to which there is a wrought iron band 3, the
ends of which are fastened at the point 4, 4, to the front wall of the boiler. The
wrought iron band takes the thrust of the upper outside portion of the ring of
thrust blocks supporting the dome, and the case ring 5, in which this ring of thrust
blocks is set rests upon a second circular casting 6, built into the wall, which also
forms the track upon which the grate is revolved and supported.
The grate 1 is composed of a series of sectors trunnioned radially in the hub 7,
and periphery 8, of the circular frame 9. The hub and periphery of the frame 9,
are joined together by a series of radial arms 10, composing a wheel-like frame as
separately appears in Figure 5, the frame being built up, or cast in one piece
according to its size.
The frame 9, is supported by rollers 11 upon the circular track 6, built into
the brickwork, and the studs 12, upon which the said rollers revolve are firmly
fixed to the periphery of the frame 9, and project inwardly also, to form trunnions
upon which the outer ends of the grate sections rest. The trunnions 12 and 15 of
the grate sectious lie in an axis aside from the centre of gravity of said sections,
and each section has a stud 13, carrying a roller 14, running on the same track
casting as the rollers 11, which support the frame 9. The circular track has a
depression at the dumping point 16, as shown in Figures 2, 3, 5 and 8. In all
parts of the revolution of the grate and its frame 9, the grate sections are held level
by means of the double supporting points of the trunnions 12 and the rollers 14,
except at the point of depression 16, and at this point, the weight of the grate and
the ashes thereon causes it to drop and discharge the ashes, assuming the position
indicated by dotted lines 17, Figure 8; the roller 14 dropping and running up again
on the incline of the depression as the grate rotates in the direction of the arrows
whereby the grates are replaced in a horizontal position ready to receive a fresh
supply of fuel.
The entire weight of the grates and their supporting frame 9, is sustained by the
circular track 6, at the periphery of the frame, and the central portion of the grate
surface which would otherwise be inefficient and difficult to clean, is blanked out by
a central pier 23, of firebrick supported by an iron column 24. This central
pier carried up in the middle of the furnace is put in for the purpose of cutting
out the centre of the grate in order to get more room for pivotting the inner ends
of the sections of the grate in the hub and to avoid subjecting that portion of the
furnace to the fire in which no movement could be imparted to for dumping. A

page_text: bridge plate 25, covered with firebrick extends from the central supporting pier
to the outside edge of the furnace of sufficient width for a single section of the
grate to pass under, and be completely covered by it during that portion of the
revolution of the grate in which the section is dropped for dumping off the ashes
and restored to a level position to receive fresh fuel. The bridge 25, closes the
opening, preventing the access of air from the ashpit to the furnace or dropping of
fuel from the furnace to the ashpit during the operation of clearing. The coal is
banked against the declining side of the bridge opposite the feeding point, and the
ashes are banked against the opposite declining side of the bridge as the grates
rotate so that the spaces between the surface of the level grate and the edges of
the bridge are practically sealed to prevent ingress of draft at the dumping point,
which would result in lowering the temperature of the furnace by the introduction
of cold air.
The
The grate bearing frame 9, is preferably revolved by means of a pawl 26, and
ratchet rack 27, attached to its lower periphery, (or a worm meshing into a worm
gear on the lower edge of the ring can be used). The pawl 26, and its carrying
lever 31, fulcrumed at 32, is actuated from a countershaft 28, and eccentric 29
(or crank), as indicated in Figures 10 and 11, which countershaft is in turn
operated by a pawl 30, and ratchet wheel 33, keyed thereon, which said pawl 30,
receives reciprocative motion through the rod 36, by an eccentric (or crank) 34, of
a shaft 35, suitably located above the boiler as indicated in Figure 1.
lever 37 of the pawl 30 has the rod 36, adjustably connected thereto so as to obtain
a longer or shorter leverage to vary the stroke of the pawl 30, taking up a greater
or less number of teeth on the ratchet wheel 33 thereby varying the surface speed
of the grate carrying the coal faster or slower. Each revolution of the ratchet
wheel 33 causes the pawl 26 to travel one tooth of the ratchet 27 and the speed of
the grate may be further varied by rendering the leverage of the lever 31, also
adjustable according to the point of attachment of the rod 38 thereon.
The coal is fed through a hopper 39 by means of a crushing and feeding device 41
shown in Figures 1 and 3, which crushes any large lumps and measures out a given
amount at each revolution, showering the same through the opening 40, in the
brickwork down upon the grate. The feeder 41, is composed of a spirally bladed
wheel that catches the lumps of coal between the edges of its blades and the
adjacent edges of the surrounding casing, and by reason of its spiral form tends to
distribute the bulk of the coal to the outer or larger surface of the grate. The
speed of the feeder 41, is made variable in a corresponding manner to that
employed in the grate propelling mechanism. The feeder 41 is turned by the
worm gear 42 keyed to its shaft, the worm 43 upon the countershaft 44, engaging
with it and the said countershaft bearing a ratchet wheel 45, that is operated by
the pawl 46 and rod 47 connected to the pawl lever 48 at variable distances from
its fulcrum and reciprocated by a separate eccentric 49, on the shaft 35.
It is to be observed that I provide an upturned flange 50 to the margins of the
grates that nearly fills the space above their periphery. The space that is left
which is essential to its free rotation is sealed by the fuel that is banked up against
the said margins and the spiral shaft of the feeder 41 contributes to this feature in
the manner before stated. The space at the inner margins of the grate about the
central pier is likewise sealed and the undue passage of air at any other portions
than through the grates themselves is thereby prevented.
The chief object of the upturned flange 50, is to cut off the draught from the
portion of fuel adjacent the side walls of the furnace and prevent rapid combustion
opposite the movable joint between the grate and the wall, which would cause
clinkers to form and clog the movement of the rotary frame.
In operation the coal makes nearly a complete circuit of the grate surface being
showered down upon the grate at a point adjacent to the bridge 25, refilling the
sectors as soon as they pass from under the bridge. Abundant surface is thereby
given for the fire to progress through the body of coal as fast as it rotates and to

page_text: thoroughly ignite it as it approaches the centre of the furnace and also to effectually
complete the process of combustion as the residue is carried away in rotation toward
the dumping point. It will also be observed that the coal is fed into that portion
of the furnace covered by the dome for the purpose of becoming heated up to the
point of incandesence and iguiting on top of the fuel as it travels forward, due to
the reflected heat from the dome, which heat is received from that portion of the
fire which is already at its best point of combustion.
The proper relative speed of the feeder and of the grate are conveniently
adjusted by the levers 37 and 48 according to the required conditions of temperature
or the quality of the fuel.
With some fuels it may be desirable to give each section of the grate a half
revolution so that such which receive coal in the first revolution would be under-
neath in the second one and so on alternately the grate turning completely over to
dump its ashes, this however would take more space underneath the covering bridge
and also a greater proportion of the circumference of the circle.
The modification illustrated in Figure 9 consists in providing the circular track
at the dumping point with a depressible section that is counter-balanced by a weight
of such gravity that when the roller of a loaded grate passes upon the depressible
section, the latter drops so as to dump the grate about its pivot and as the load is
discharged the grate is overbalanced by the weight and the section of track restored
to its normal position restoring the grate.
The depressible section of the track is borne upon an arm 21, fulcrumed at 19,
upon any suitable part of the stationary framework above the track. The arm 21,
has also a lever 20, projected rigidly from it upon which the counter balancing
weight 18, is attached acting as a tumbling bob and is rendered adjustable by means
of a set screw. The depressible section of track 21, has a lip, that fits under the
adjacent edge of the fixed portion of the track when the section is up, and served as
a stop to prevent the passage of the section above its proper level.
As the grate rotates in the direction of the arrows the wheels first pass over the
depressible section, but do not depress it being fixed to the rim but as the rollers
advance upon the section the load of ashes upon the grate overcomes the weight 18
depressing the section to the position shown, the grate assuming the position
represented by dotted lines. The ashes being discharged into the ash pit beneath,
the weight of the grate is insufficient in itself to overbalance the tumbling bob, and
is therefore restored to a level position.
The entire operation being momentary is completed before the grate frame has
rotated sufficiently to interfere with the replacement of the roller at the level of
the track.
The operation is repeated similarly upon each sector of the grate as the same
advances to the dumping point and proceeds therefrom in continuous rotation.
It is to be understood that the grate sectors are not necessarily journalled
eccentrically in order to operate as herein described but may be centrally journalled
and weighted upon one side of their axes to dump by gravity within the meaning
of my invention.
In a further modification of my invention consisting of a horizontal rotary grate
made up of a series of sectoral radially pivoted sections which are dumped auto-
matically by the movement of the grate so as to completely discharge each of their
loads in succession after the fuel is burned, there is a central pier supported through
the core of the rotary frame and from this pier to the front of the arch covering
the grate, there is a bridge under which the sectors pass while they are being
dumped and are then supplied with fresh fuel as they resume a horizontal position.
There is therefore an essential relation between the sectors and the bridge: the
latter acting to prevent the admission of an undue amount of air through the frame
when a sector is thrown out of its normal position; and my present invention there-
fore also includes a certain improved construction of the bridge covering the
dumping point of the sectors, whereby the fuel is fed over the bridge to replenish

page_text: the sectors as soon as they pass out; said fuel itself forming a seal to prevent the
admission of air on the replenishing side of the bridge which would interfere with
the proper course of draught through the incandescent body of fuel.
.
My invention also consists of certain novel mechanism for dumping the grates
and restoring them to a normal position.
My invention also consists in a novel construction of the rotary frame carrying
the grate.
Referring to Figures 12 to 22 which represent this part of my invention 1, is.a
circular grate which may be placed wholly or partly underneath the boiler, as the
circumstances require. In these drawings the furnace is shown placed half outside
of the boiler front; the outside portion being covered with a dome 2, the thrust of
which is received by a cast ring 5 in addition to which there is a wrought iron
band 3, the ends of which are fastened at the points 4, 4, to the front wall of the
boiler. The wrought iron band takes the thrust of the upper outside portion of the
ring of thrust blocks supporting the dome, and the cast ring 5, in which this ring of
thrust blocks is set, rests upon a second circular casting 6, built into the wall,
which also forms the track upon which the grate is revolved and supported.
The grate 1 is composed of a series of sectors trunnioned radially in the hub 7
and periphery 8 of the circular frame 9. The hub and periphery of the frame 9
are joined together by a series of radial suspending rods 10, composing a wheel-like
frame in which the hub is suspended from the rim. The frame 9, is supported by
rollers 11, upon the circular track 6, built into the brickwork.
The grate frame may be rotated by any suitable means such as a ratchet 29
placed on the bottom of the rim 8: the pawl mechanism 26 engaging therewith.
23 is the central pier, supported through the hollow core or hub 7 of the grate upon
the column 24. Between the pier 23 and the front arch of the dome 2, is suspended
the bridge 25, over which the fuel is fed from a hopper 39 by means of a spiral
feeder 30. This feeder is driven by means of a sprocket wheel 31 on its shaft or
other suitable gearing.
The sectors 40, of the grate are trunnioned at 41, 42, radially in the frame 7, 8:
the trunnions being central to the grates, balancing them. When the sectors
reach a point in rotation under the feeding plate 43 of the bridge they are dumped
automatically so as to completely discharge the burned fuel and in so dumping they
make a complete half revolution upon their trunnions; the grates being double
surfaced so as to burn the fuel upon either side.
It is obvious that a variety of devices may be employed to dump the grates and
I will therefore proceed to describe certain various forms for illustration.
In Figures 12, 13, 14 and 144 the ends of the trunnions 42 are squared. The
grate rotates in the direction indicated by arrows. 50, is a dish fixed to the inner
end of a short shaft that is mounted in bearings in the vertical web of the track 6,
and has a groove 51 which is horizontal when the dish is at rest and through which
groove the squared heads of the trunnions pass. When the square head reaches
the middle of the groove 51 so that the axis of the grate sector is coincident with the
axis of the dish 50, the latter is quickly given a half turn dumping the sector and
restoring the same to a normal but reversed position whence it is carried along to
receive fresh fuel by the continuous revolution of the grate frame; the trunnion
head passing freely out of the said groove.
In Figures 12, 13, 14, the mechanism for giving the dish 50 its half revolution
consists of a segment 52, engaging with a pinion 53, on the shaft of the dish 50
which segment is provided with a tumbling bob 54, attached to its shaft tending to
restore it to a normal position when moved out of the same. 55 is a lever fulcrumed
at 57 bearing an inclined face or flange 56 on its upper end and connected at its
lower end to the segment by a connecting rod 58. As the projecting trunnions 42
approach and. come in contact with the flange 56, of the said lever, see Figure 14*
the same is moved so as to tilt the segment and the tumbling bob revolving the
pinion. a half turn reversing the horizontal position, of the groove 51 to an opposite

page_text: horizontal position before a succeeding trunnion passes into it. The flange 56 is
sufficiently prolonged to maintain such reversed position of the dish until the
trunnion entering it has reached the central position before referred to and the
weight 54 then being released the same quickly reverses the pinion dish and grate
sector before the trunnion has passed said central position in the groove 51.
The device shown in Figures 17 and 18 is similarly operated, differing only in
construction; a rectilinear rack 60, being substituted for the segment 52. The
rack 60 moves upon rollers 61 on the horizontal plate 62 and in a normal position
(shown by dotted lines) abuts on the end of the frame 63 of the plate. The lever 55
in this instance bears the tumbling bob 54, on its arm 65, and bears an inclined
surface 56, see dotted and full lines Figure 17 which impinges on the upper sides
of the square trunnion heads as they approach and pass under moving and retaining
the pinion 53 and its grooved dish 50, in a reversed position as before until a
succeeding trunnion reaches the centre of the groove then dumping the grate by
the fall of the weight.
In Figures 19 to 22 inclusive instead of a grooved dish I employ a tumbling
block 70 having mortised ends 71, 72, which fit the square trunnion. This block
bears a pivotal roller 73 which operates about the segment shaped cavity or
guide 74. The surface of this guide consists of a flat or horizontal plane surface 75,
an inclined plane surface 76, and a segmental cylindric surface 77 concentric with
the line of intersection between the said horizontal and inclined surfaces. To the
pivot of the roller 73 is attached a weight 78 by a small cable 79, passing over a
pulley 80, whereby the tendency of the block is to assume the position shown in
Figures 19 and 22. When the grate trunnion approaches and enters the mortise 71,
the block 70 is advanced by the motion of the grate frame until the roller 73,
reaches the inclined plane, 76, ascending the same until reaching the position in
Figure 20 in which the grate sector is partially dumped, the tension of the cable
in a line aside from the axis of the trunnion pulls the pivot of the block over in an
arc parallel with the surface 77 of the guide until a position corresponding again
with Figure 19 is reached completely overturning the sector. The trunnion then
leaves the mortise 71 as the grate rotates and the mortise 72 remains in position to
receive the succeeding trunnion.
Referring now to Figure 16 I illustrate in cross section the terminus of the
feeding hopper. The plate 90, fulcrumed at 91 in the throat of the hopper rests at
its free edge on the surface of the grate. The fuel descending through the
hopper 39 is fed by gravity. I utilize the motion of the grate itself as the means
of carrying away the fuel from beneath the column as fast as required. In order
to accomplish this it is necessary to form a continuous inclined surface 92, 90, from
the base of the vertical column of fuel to the surface of the grate such surface
approaching the grate very closely at its termination. The hinged plate 90 is
provided for this purpose but offers a yielding under surface to the grates which
have been dumped so that should any clinkers remain which would interfere with
the passage under the plate 90 were it rigid and stop the grate rotating mechanism
such obstructions will be yielded to. A bank of incoming fuel is thus constantly
maintained upon the bridge, which seals the space that would otherwise be left
between the bridge and the grate at 95 and moreover the actual contact of the
plate 90 with the grate further insures such closure of the space.
The space 96, at the opposite side of the bridge at which the grate approaches
is always filled with the ashes preceding their discharge thus sealing the remaining
side of the bridge.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed as communicated to me I
declare that what I claim is :-
1. In a revolving grate, the combination of a rotary carrying frame, a series of
sectoral grate sections journalled therein on radial axes aside from their centres

page_text: of gravity an interrupted stationary track concentric with the axis of rotation of
the frame, upon which the preponderating sides of the grate sections bear during
a part of their circuit.
2. In a revolving grate, the combination cf a rotary carrying frame, a series of
sectoral grate sections journalled therein on radial axes aside from their centres
of gravity a stationary track concentric with the axis of rotation of the said frame
upon which the preponderating sides of the grate sections bear, a fuel feeder at
one side of the sectional grate and a depression or interval in the surface of the
track at a point in the order of rotation preceding the position of the feeder between
the same and the incandescent body of fuel.
3. The combination with a horizontal revolving grate and a vertical cylindrical
side wall at its periphery of an upturned peripheral flange on the grate having a
non-perforated surface whereby combustion of the fuel adjacent the side wall is
checked.
4. In a revolving fire grate, the combustion of a horizontal supporting frame
having a central hub and a concentric rim; grate sections composing sectors of a
circle trunnioned in said hub and said rim upon axes that are aside from the centres
of gravity of the said grate sections; a circular track concentric with said
supporting frame and upon which it rotates; a depression substantially as shown of
the circular track at the dumping point of the grates; and at the outer margins of
the said grates, rollers that are adapted to travel upon the said circular track, to
normally sustain the sections in a level position, to permit their gravitation at the
point of said depression and to restore their normal position by passage out of said
depression upon an incline of the same substantially as and for the purposes set
forth.
5. In an automatic furnace stoker, the combination with a horizontal revolving
circular grate having movable dumping sections of a feeding hopper located
vertically above said grate at a point succeeding the dumping point of said sectors
in the direction of rotation and adapted to supply fuel continuously and distribute
the same to the grate at a portion of the surface of the latter having a motion
approaching the fire.
6. The herein described means for driving the rotary circular grate at variable
surface speeds from a source of given speed; consisting of a pawl and ratchet
mechanism circumferential to the grate, a pawl carrying lever engaging therewith
actuated by a pawl and ratchet eccentric (or equivalent); the eccentric actuating
pawl being connected with its carrying lever at alternate distances from the fulcrum
thereof, whereby the said eccentric actuating pawl is caused to engage with
a greater or less number of ratchet teeth in the manner set forth.
7. The combination with a rotary grate, of a domed crown having an opening
above one side of the grate for the exit of hot gases an opening above the other side
of the grate for the supply of fuel; said crown presenting a reflecting surface of
refractory material immediately over the fuel during a part of its circuit.
8. The combination in a boiler furnace, of a revolving grate, a domed crown
thereof partly within and partly without the front wall of the boiler, and a flanged
circular frame confining the thrust blocks of the crown.
9. The combination in a boiler furnace of a revolving grate having auto-
matic dumping sectors, a domed crown partly within and partly without
the front wall of the boiler, a fuel feeder and an opening therefor through the
exterior part of the crown, a bridge covering the sectors at an interval of their
circuit immediately preceding their passage under the feeder, and mechanism
substantially as described whereby the sectors are dumped and restored to a
horizontal position under the bridge.
10. The combination with a rotary furnace grate, the frame whereof is cored at
the centre, of a central pier composed of refractory material, projection vertically
through and above the said cored centre, adapted to direct the fuel upon the grate
and above the said pier from a feeding point to a clearing point as described.
11. The combination with the central pier and concentric side walls of a furnace

page_text: and a rotary grate having dumping sectors as described, of a bridge extending
radially from said pier to said side walls above the dumping point.
12. The combination in a rotary grate, of trunnioned sectors, and mechanism for
automatically imparting to said sectors a complete half revolution about their
trunnions at a given point in the revolution of the grate.
13. The combination in a rotary grate of trunnioned sectors, mechanism for
automatically imparting to the same a half revolution about their trunnions at a
given point of revolution of the grate and a bridge covering such dumping point of
the sectors having a vertical cavity to clear the said dumping movement and sides
proximate to the grate surfaces for the purposes set forth.
14. The combination in a rotary grate, of trunnioned dumping sectors component
of the same, a bridge covering the dumping point a vertical gravity hopper above
the bridge, and an inclined surface of the bridge extending from the base of the
hopper to the surface of the grate approaching the same in the direction of its
rotation.
15. The combination in a rotary grate of trunnioned dumping sectors, a bridge
covering the dumping point a gravity hopper, an inclined surface of the bridge
beneath the hopper and a hinged plate terminating the inclined surface resting at
its free edge on the grate.
16. The combination in a rotary grate of a carrying frame, dumping sectors
trunnioned radially therein, squared trunnion heads projecting from the periphery
of the frame, a transversely grooved rotary dish facing the frame in the path of the
said squared heads, a pinion, a segment, a tumbling bob and a tilting lever connected
thereto as described the lever intercepting the path of the said trunnions or other
projections upon the frame whereby the groove in the dish is moved to a horizontal
position reversed from its normal horizontal position and then released when the
head of the trunnion is at its centre.
17. In a rotary grate, the combination of a peripheral frame, a central hub, and
radial suspending rods supporting the hub from the periphery.
Dated this Seventh day of November 1892.
CRUIKSHANK & FAIRWEATHER,
62, St. Vincent Street, Glasgow, Agents.