US1913396A

US1913396A - Domestic type stoker

Info

Publication number: US1913396A
Application number: US317065A
Authority: US
Inventors: Frank W Kay
Original assignee: American Engineering Co Ltd
Current assignee: American Engineering Co Ltd
Priority date: 1928-11-03
Filing date: 1928-11-03
Publication date: 1933-06-13
Anticipated expiration: 1950-06-13

Description

s sheets-sheetl 1 F. KAY

DOMESTIC TYPE sToKER'v Filedr Nov. s, L1928 June 13;y 1933.

4. /44 5, l 4 3% S .Q Y b3 x June 13, 1933. F, w KAY v1,91?396 DOMESTIC TYPE STOKER 'Filecom 3, 192e e sheets-Shasta Ei Z.

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F. w. KAY

-noMEsTIc TYPE sToKER Filed Nov. 5, 1928. 6 Sheets-Sheet 3 June 13, 1933.` F. w. KAY 1,913,396

DOMESTIC TYPEsToKIgR Filed Nav. s, 1928 v s sheets-sheet 4 June 13, 1933. Wr KY DOMESTIC TYPE sToKER e sheets-sheet 5 Filed Nov. s, 1928 June 13, 1933.` F. w. KAY 19,913,396

DOMESTIC TYPE` STOKER Filed. Nov. 3, 1928 6 Sheets-Shes?I 6 4 vso Patented June 13, 1933 mural)y STATES PATENT QFFICE rFRANK W. KAY, F PHILADELPHIA, PENNSYLVANIA', ASSIGNOR i T0 AMERICAN ENGINEERING COMPANY, 0F PHILADELPHIA, PENNSYLVANIA, A CORPORATION 0F PENNSYLVANIA Application led vNovember My invention relates to stokers, and it has for one object the provision of a relatively small stoker particularly applicable for d mestic use, such, for example, as apartment houses and the like. Another object of my invention is to provide a Stoker unit of the character described which may be readi-'lyinstalled in existing.`

furnaces with a minimum alteration.

Still another object of my invention is to provide a stoker comprising means whereby the fuelmay be automatically fed through the usual firing door and the ashes subsequently automatically discharged through the usual ashdoor.

A further object of my invention is to provide a removable stoker unit adapted for household use, small industrial plants, theatres, oilice buildings' and the like, comprising means for feeding lfuel into the furnace, means for moving theY fuel through the furnace, means for crushing the resulting' ashes and common driving apparatus for said means. l z5 A still further object of my invention is to provide a fuel-feeding plunger with a detachable head portion positioned in spaced relation thereto, the head portion. being.

v formed to exert a feeding as well asa spreading action on thefuel.

A still further object of my invention is to provide in combination with a fuel-feeding passage, means whereby the fuel may be spread over a desired portion of the width of the stoker.

Otherpbjects-fand applications of my invention, as well 'as details'of construction and operation, whereby Vmy'invention may be practiced, will be apparent more fully hereinafter, when taken in connection with the accompanying drawings, wlierein l Fig. 1 is a vertical, longitudinal sectional view through a domestic type furnace embodying my invention;

Figs. 2, 3 and L11a-re vertical sectional views taken on the lines 2 2, 3 3, and 4-4, respor-tively, vof Fig. 1; i' f Figs. 5 and 6 are detail, top plan and rear elevational views, respectively, of the fuelspreading means; v

DOMESTIC TYPE STOKER 3, 1928. Serial N'o. 317,065.

Figs. 7 and 8 are similar views of the extension means for use in connection with the structure of Figs. 5 and 6;

Figs. 9 and 1() are transverse, sectional views taken on the lines 9--9 and 10-10 of Fi s. 5 and 7, respectively;

`igs. 11 and 12'are top plan views of the stationary center and side` grate plates, respectively;

Fig. 13 is a side detail, side elevational view of the driving mechanism shown in Fig. 1;

Fig. 14 is an end elevational view of the structure of Fig. '13; and y Figs. 15 and 16 are sectional views taken on the lines 15--15 and 16-16, respectively, of Fig. .13.

' Referring to Fig. 1, the structure therein Shown comprises a domestic type furnace 1 having a front wall 2 provided with an upper opening 3 enclosed by a firing door 4.- and also a lower opening 5 enclosed by an ash door 6. A stoker unit 7 for the furnace 1 comprises broadly a fuel passage 8 which extends through the firing door 4 and opening 3; a grate structure 9 which extends rearwardly from the fuel passage 8 and terminates in spaced relation to a rear wall 11 of the furnace to form an ash pocket 12; an ash crusher 13; a drag or conveyor 14 positioned4 in a passage 15 for removing the ashes in the pocket 12 from the furnace 1 through the ash door 6 and the opening 5 in the Afurnace front wall 2; and common driving apparatus 16 for the `stoker positioned just in front of the furnace wall 2.

whorizontallyfpositioned valve 26. The dis- ConsideringV the stoker unit embodied in charge ofthe fuel through the vertical Side 23 rather than through one of the inclined sides 22. as well as the offsetting of the passage 25 tends to prevent the arching of the fuel in the bottom of the hopper and the consequent closingof the opening 24.

The valve controlled passage 25 is connected to an upper end 27 of a passage 28 which is formed in a ram casing 29. The passage 28 opens into a horizontal passage 31 in the casing 29 intermediate front and Arear ends 32 and 33. Fuel in the passage 31 may be Inoved rearwardly by means of a ram plunger 34 which extends through the open end 32 of the casing 29. The portion of the casing 29 forming the passage 31 is of rectangular` cross section and is provided with a removable bottomwall 35, permitting replacement in the event of damage thereto. The portion of the passage 31 between the rear end 33 thereof and the passage 28 is slightly flared vertically, 'affording the plunger 34 a loose fit when positioned therein. Experience has shown that such construction tends to prevent the pulverizing of the fuel and the subsequent blocking of the passage 31.

The movement of the fuel, as Well as the subsequent spreading thereof, is facilitated by the mounting of a ram or plunger head portion 36 in spaced relation to the main body portion plunger 34 on a rod 37 extending therebetween, asshown in Fig. 1. The plunger head portion 36 is of block-like form and is provided withI a` lower Side 38 .which slidably engages the bottom wall 35 of the passage 31; .

vertical sidefaces

39 and 41 which are positioned in spaced relation to"

vertical side walls

42 and 43 of the ram casing 29, Fig. 5; and front and rear faces`44 and 45; The front face 44 is so beveled that when the ram extension or head portion 36 is moved forwardly, the fuel in passage 29 moves readily over the same with a minimum retarding force. The rear face 45 is so formed that when the head portion 36 is actuated in a rearward direction, a scooplike effect is exerted on the fuel, causing not only a forward bodily movement thereof, but also an upward movement of that portion of the fuel which is directly in engagement with the bottom wall 35 ofthe passage 31. As a result of this upward movement of the fuel, a force is exerted on the head portion 36 tending to maintain the same in sliding engagement with the bottom Wall 35. Therear face 45 is also so formed as to exert notonly lilfting but also a spreading effect on the To this end, l provide the face 45 with la pair of

beveled side surfaces

46 and 47,

46 and 47 cause a desired spreading of the fuel. Each of the

surfaces

46,47 is provided with an upper vertically-extending portion 49 and a lower curved portion 51. The portions 49 afford the principal fuelabutting surface, causing a rearward movement of the fuel, while the portions 51, in combination with the portions 49, tend to exert the desired scoop-like effect on the fuel. Thus, the fuel is not only moved rearwardly during the working stroke of the ram 34 and head portion 36, but also upwardly from the bottoln wall 35, as well as laterally into engagement with' the adjacent portions of the

side walls

42 and 43. i

The ram casing 29 is mounted in the firing door4 and extends into the wall passage 3. In order to cause the further spreading of the fuel, a spreader casing 52 is mounted on the rear end 33 of the ram casing 29, thereby forming an end portionA for the fuel passage 31. The spreader casing 52 comprises rearwardly diverging side walls 53 and 54, a bottom wall 55 and a removable top wall 56. r1`he bottom and

top walls

55 and 56 are slightly flared, as shown in Fig. 1, sothat theV end portion of the passage 31 may also increase in depth. The spreading of the fuel is increased by providing the bottom wall 55 with

rear corner portions

57 and 58 which are flared to a greater extent than a 'central p0rtion 59. i 1

lThe fuel leaving the flared end of the passage 31 moves onto a spreader extension 61, comprising a bottom wall 62 and side walls v63 and 64.

Inner sides

65 and 66 of the Walls 63 and 64 are contiguous to the corresponding sides of the walls 53 and 54, respectively,

thereby forming .continuous diverging walll surfaces. A front flange 66 extends forward.- ly from the spreaderextension 61 and it 1s offset,` as shown in Fig. 1, so as to provide a supporting shoulder for the rear edge .portion of the spreader casing 52. The flange 66 is supported on a cross beam 68, the ends of which are mounted in side walls 69 and 71 of the stoker unit. lA relative movement between the spreader extension 61 and the spreader casing 52 is prevented by a pair of centering

lugs

72 and 73 which fit

complementary recesses

74 and 75 formed in a front edge portion 76 of the extension 61. The offset flange y67 may be extended parallel to the angled sidewalls and 66. Rear end portions 77 and 78 of the

side walls

65 and 66 are respectively mounted on the Stoker side Walls 69 and 71 as shown Lin F ig. 7. Y

The bottom wall 62 of the spreader exten: sion 61 is .provided with a central, rearwardly inclined portion 79 constituting a continuation of the inclined central portion 59 of the spreader casing 52, and also inclined

side portions

80 and 81 constituting continuations of the

spreader casing portions

57 and 58, re-

spectively. The side walls 63 and 64 are preferably hollow, providing air chambers 82 which extend slightly above the upper level of the'fuel bed. Apertures 83 and 84, near the upper sides of the chambers 82, permit the escape of air so as to prevent the formation of dead air pockets. The spreading effect of the plunger head portion 36, the spreader casing 52 and the spreader extension 61 may be Aincreased by means of a spreader melnber 85, Figs. 1, 2 and 5. The member 85 is provided with a pair of beveled side faces 86 and 87 terminating in a vertical -front edge 88 which is substantially in front to rear alignment with the rear edge 48 of the ram extension 36. The member 85 is also formed with a beveled rear face 89 which extends from a transverse rear edge portion 91 forwardly and upwardly,'as shown in Fig. 1. As a re'- sult of the several spreading means, just described, the fuel as it finally passes over a rear edge portion 92 of the spreader extension 61 Figs. 1, 2 and 3 of the drawings. Each of the I four central or intermediate series of grate plates comprises alternate stationary and

movable plates

96 and 97, respectively. The stationary plates 96 of-each intermediate series are mounted in spaced relation on hol'izontal step-like portions 98 of spaced longitudinally extending supporting beams 99, the front ends of which are secured to flange portions 101 of a supporting front beam 68, while rear end portions are secured to the cross beam 93. The longitudinal beams 99 are mounted at 102, intermediate their ends, on a main cross beam 103 which extends between the-Stoker side walls 69 and 71.

Considering further the detail structure of the stationary grate elements 96. of which Fig. 11 is a top plan View and which are shown in section Figs. 1, 2, 3 and 4, each is provided with a rear or exposed portion 106 th-e hollow or recessed under side 107 of which constitutes a grate air chamber. The upper face of the rear portion 106 comprises a pair of horizontal port-ions 108 and 109 e in stepped relation, and a plurality of air openings 111 are provided in the intervening wall 112, affording air outlets for the grate chamber. Similar air openings 113 are formed in the lower rear edge of the plate portion 109. The rear portion 106 may be supported on flanges 114 form-ing the horizontal stepelike portions 98 of the beans 99. illustrated in Figs. 2, 3 and 4.

The rear exposed portion 106 of each of the stationary grates is extended forwardly by means of spaced side edge portions 115 yand 116 Which are also mounted on the 65 flanges 114, as-shown'in Fig. 4. Each of these extensions comprises a horizontal sup. porting portion 117 which directly engages the flanges 114 and is provided with recesses 118 for clamping bolts 119. The bolts. 119 extend through the flanges 114, the recesses 118 and a plate 121. The plate 121 is so mounted as to extend over the opposite recess 118 of the projecting portion 116 of the next stationary grate plate. Each of the extensions 115, 116 is also provided with a vertical wall 122 having a shoulder 123 over-` hanging the horizontal portion 115 and ex. tending longitudinally thereof. A supporting lug 124 extends upwardly from the horizontal portion 115, so that abearing surface 125 is positioned in spaced relation to a beveled underside 126 of the overhanging portion 123.

As shown in Fig. 4,"each of the movable grate plates 97 is provided with depending

side walls

127 and 128, front portions of which are slidably mounted on the supporting

lugs

124, 124 of the spaced, stationary-4 grate project-ions 115 and 116. Inner edges 129 of each of these walls are projected inwardly and beveled complementary to the adjacent overhanging lbeveled portions 123, thereby interlocking therewith so as to pres vent an upward vertical movement of the movable grate plate while permitting a rela. tive longitudinal movement thereof. Inthis manner, the rear end of each of the movable grate plates is slidably interlocked with the extensions 115 and 116 of the next lower stationary grat-e plate. The rear end vof each 100 of the'intermediate movable grate plates is slidably mounted on the horizontal wall portion 108 of the next lower grate plate in the series.

The two longitudinal side 01 terminal se- 105 vries of grate plates also comprise alternate stationary and movable plates. Fig. 12 is a top plan View of one of the stationary plates, wherein it is noted that

forward extensions

131 and 132, which correspond to the exten- 110 sions andl 116 of the stationary grate plate previously described, .are provided with raised supporting lugs 133 for slidably supportingthe

side flanges

127 and 128 of the next higher movable. grate plate. Lugs 134 115 also extend outwardly from the spaced

projections

131 and 132 into recesses 135 and 136 formed respectively in an inner wall portion 137 of the stoker side wall, and into a recess 138 formed in the horizontal portion '120 115 of the next adjacent stationary grate plate. A second pair of lugs 139 may also be extended from the side walls of this stationary grate plate -into similar recesses formed in the Stoker side wall and in the rear portion 106 of the adjacent stationary grate plate. V ertieal movement of the movable grate plate is prevented by means'of i beveled side projections 141 and 142. The projection 141 fits under a. shoulder 143 130 5. grate plate.

formed just above the recess 135 in the stoker side wall. The portion 142 lits a complementary groove 144 in a lower corner of the side wall 127 of the next adjacent stationary Thus, each 'of the stationary grate plates is interlocked with the stoker side wall and a stationary grate plate of the adjacent intermediate series, while each of the movable grate plates is slidably mounted on the next lower stationary grate plate and interlocked with the stoker side wall and the movable grate plate of the adjacent intermediate series.

The passage of siftings Ibetween the upper, front row of movable grate plates and the rear edge portion 92 of the spreader extension 61 is prevented by means of a bar 145 which is loosely mounted in a recess 146 formed in a lower side 147 of the edge portion 92. As shown in Fig. 1 the bar 145 slidably engages the upper sides of the movable grate plates forming the upper row, thereby preventing not only the passage of siftings but also constituting a wind seal preventing air from entering the adjacent portion of the fuel bed and the consequent burning of the edge portion 92 of the spreader extension 61.

Each of the `upper movable grate plates is connected with the next lower movable grate plate in its series by means of a pair of links 148, Fig. 1, pivotally mounted thereon. A pin 149 extends between these links and fits in a recess 151 formed in an end portion 152 of a lever 153 extending upwardly between the links 148. As shown in Fig. 2, each of -the levers 153 is mounted on a cross shaft 154 which may comprise

sections

155 and 156. These sections are journaled in bearings 157 carried by the stoker side walls, as well as the intermediate side beams. Adjacent ends of the

sections

155 and 156 are connected by crank armsv 158 to a longitudinally-extending link 159 passing outwardly of the Stoker through a bearing 161 positioned at the front end thereof.

A rear end of the link 159 is pivotally connected to a second link 162 carried by a rod 163 j ournaled in a bearing 164. The bearing 164 constitutes one part of a cross plate 165 which forms in a connection with the cross beam 93, the end wall 94. The rear end, of the rod 163 is connected by a link 166 to a pivotally-mounted ash crusher 167 which extends across substantially the full width of the stoker. The motion thus imparted to the upper pair of connected grate plates in each \`-,series may be imparted to the next movable grate 4plate by means, of an adjustable lostmotion connection 168, and' from the lastmentioned grate plate to the lower, rear movable grate plate by means of an adjustable lost-motion connection 169. In this way, the alternate movable grate plates of each series maybe reciprocated and the movement there- 173 and 174 and a bottom wall portion 175y which is directly mounted on the longitudinally-extending lower wall section 172. The

latter section may be directly mounted on a floor surface 176. The upper section 170 is formed similar to the intermediate section 171, comprising side wall portions 177 and 178 and a top wall portion 179. Upper edges 181 of the side wall portions 173 and 174 are inclined upwardly and forwardly while corresponding lower edges 182 of the upper wall portions 177 and 178 are oppositely formed so as to fit thereon. The edges 181, 182 thus formed extend upwardly and forwardly from the ash pocket 12 just above the level of the grate surface of the structure 9. The upper side 179 of the top section 170 extends along a line just above the upper level of the fuel bed, terminating at a top side 183 of the side Wall portion 81 of the spreader extension 61. Each of the upper side Wall sections 170 is preferably provided with a plurality of longitudinally-spaced depending tongues 184 which extend under similarly spaced locking lugs carried by the intermediate section 171. These parts are so positioned that the interlocking relation is obtained by first mounting the upper section 170 on the intermediate section 171 and then moving'the former section downwardly. A reverse movement of the upper wall sections 170 is normally prevented by the rear ends of the spreader extension side walls 63 and 64 which are positioned in abutting relation to the front ends of the upper sections 170.

The inner side wall portion 17 4 of each of the intermediate side Wall sections is provided with an air opening 185 which is positioned below 'the grate structure 9. Air may thus pass into the chamber formed by -the upper end intermediate sections 170 and 171, so that an air-back is formed. Inasmuch as it is desirable to have a continuous iow of air through these sections, a series of apertures 186 may be formed in the upper portion of the side Wall 178 of the upper section 170. The air may be supplied to the air-backs inthe stoker side Walls, las well as to the underside of the grate structure 9, through an air passage 187 leading from a fan 188 through the ash door 6. The air passage 187 may comprise an outer` section 189 and an inner section 190.- The outer section is connected to the fan 188 while the inner section extends through the ash door 6 and opens into the -air chamber formed directly beneath the grate structure 9. An outer end of the section 190 serves to support the bearing plate 161.

A bottom wall 191 of the air chamber formed under the grate structure 9 comprises a plurality of cross plates 192 the ends of which are connected by filler plates 193 to the lower side Wall sections 172. The plates o 192 are mounted in spaced relation 'to the floor level 176 so as to form the ash-discharge passage 15. The Wall thus formed extends from the rear end Wall 94 to a removable bottom wall 194 of the air passage 187. -Air is thus prevented from blowing into the ashdischarge passage and is confined to the region immediately below the vgrate structure 9. The ash discharge passage 15 is provided -eral movable parts of the stoker unit 1.

with the ash conveyor 14, the innerv end of which extends into the ash vpocket 12, While the outer end passes through 'the ash door 5 and is connected by a passage 195 to an eXteriorly-positioned ashreceiving recepwhile Figs. 13 to 16, inclusive, illustrate the tioned pin 217. The pin 217 is connected by same in ,different sectional views. As therein shown, a main driving motor 196 is connected by Worm-and-Wheel mechanism 197 to a driving pinion 198 meshing with a gear-wheel 199 mounted on a vertically-extending shaft 201. The upper end of the shaft 20L carries a bevelgear-Wheel 202 which engagesa bevel gear-Wheel 203 mounted on a horizontally- `positioned shaft 204. The bevel gear-wheel 203 -meshes with a bevel gear-Wheel 205 mounted on a shaft 206, an upper end of which carries a crank disk 207. The crank disk 207 has an adjustably mounted bear lng 208'for an outer end of a connecting rod 209, permitting variations in the stroke thereof. An inner end of the connecting rod 209 is securedto the ram 34.

One end of the shaft l204 is secured to a crank disk 211 which carries an adjustably mounted pin 212. The pin 212 is connected bylever 213 and linkage to the ash conveyor 14 and serves to actuate the same longitudinally in the passage 15. Another end of the shaft 204 is connected by a clutch 214 and gear-Wheel mechanism 215 to a third crank disk 216 which carries an adjustably-posilinkage 218 to the longitudinally-movable driving link 159, so that motion may be imparted to the movable grate plates 97 of the grate structure 9. The' driving motor 196 also operates the fan 188, causing a supply ofair under pressure to the underside of the grate structure 9.

In operation, assuming the clutch 214 in its closed position, the energization ofthe driving motor 196 causes the rotation of several crank disks, as Well as the operation of the fan 188. The movement of the crank disk 207 causes the reciprocation of the ram, 34 with its head portion 36, resulting in the feeding of fuel from the hopper 17 through the fuel passage 31. The head extension 36, in combination withthe spreader casing 52, the spreader extension 61 and the spreader block 85, results in the even distribution of fuel over the full width of the Stoker as it passes onto the upper movable grate plates.

The turning of the crank disk 216 results inthe reciprocation of the movable grates in each of the longitudinal series, so that the fuel is slowly passed through the furnace.

The fuel is prevented from engaging the sidel walls of the furnace by reason of the stoker side Walls 69 and 71, which extend above the upper level of the fuel bed. As the ashes discharge from the grate structure 9, the crusher 13 which is also actuated from the crankA disk 216, causes the crushing of the clinkers. The operation of the fan 1.88 also causes a supply of air to the underside of the grate structure 9, thereby, establishing desired combustion conditions inthe fuel bed. The turning of the crank disk 211 through its lever 213 and linkage results in the relciprocation ofthe ash conveyor 14, so that as the ashes drop to the bottom of the pocket 12, they are conveyed through the passage l5 and finally discharged into the recess 195.

Hence, the foregoing stoker structure constitutes a self-contained unit Which may be readily inserted in existing furnaces with a minimum of alteration. The unit automatically functions to cause the feeding of fuel onto the grate structure 9 through the usual firing door 4 from the hopper 17; the move.-

,ment of the fuel through the furnace; the

supply of air to the fuel bed, so as to support combustion; the crushing of the clinkers formed during the combustion of the fuel; and the removal of the ashes through the `usual ash door. By reason of the compactness of the unit, the minimum number of parts, and the ease of control, it. readily lends itself to domestic use, such as apartment houses, or to small industrial plants, such as'are found in theatres, office buildings and the like.

While I have shown only one form of embodiment of my invention, for the purpose of describing the same and illustrating its principles of construction and operation, it is apparent that various changes and modifications may bemade therein, Without departing from the spi-rit of my invention. I'

for domestic use, of a Stoker unit comprising a plurality of stationary and movable grates adapted to support a fuel bed, reciprocatory means for feeding fuel onto said grates, reciprocatory means for removing the ashes from said furnace, common driving apparatus for said means and said movable grates, and means controlled by said common driving apparatus for supplying air under pressure to said grates.

2. Apparatus of the character described comprising, in combination, stoker side walls formed to constitute an air-back, means providing a grate surface extending between said side walls, a fuel-feeding passage, means positioned between said passage and said grate surface, whereby said fuel may be spread in a desired lnanner, said means having side walls also formed to constitute airbacks and positioned contiguous to said firstmentioned air-backs, said first-mentioned stoker walls comprising upper, intermediate and lower sections, said upper and intermediate sections being provided with interlocking lugs detachable upon a relative longitudinal movement, the side walls of said second-mentioned means being positioned to prevent said relative movement.,

3. The combination with a furnace having a firing opening at the front thereof, of means for feeding fuel into the furnace through said firing opening, and a grate structure positioned in said furnace ,to receive the fuel, said grate structure inclining downwardly from said opening and comprising a longitudinal series of interspersed pushers and stationary plates arranged in relatively stepped relation, each of said pushers comprising a forward elevated portion and a rearward relatively depressed portion and having openings intermediate said portions and at the rear end of said lower portion for admission of combustion air to the fuel-bed, means for actuating said pushers to progressively advance the fuel from the top towards the bottom of said grate structure, an ash pit at'the lower end of saidgrate structure, a passage leading from said ash pit to the front of the furnace, means for conveying ashes from the pit through said passage, and a partition extending from the lower end of said grate and underethe latter to the front of said furnace, said partition constituting the upper wall of said ash passage.

4. The combination with "a furnace having a firing opening, of means for feeding fuel into the furnace through said opening, and a grate structure positioned in said furnace to receive the fuel, said structure inclining downwardly from said opening and comprising a longitudinal series of interspersed pushers and stationary plates arranged in stepped formation, each of said pushers andy stationary plates comprisingan elevated forward portion and a relatively depressed rear portion, and each having openings intermediate said forward and rear portions and at the rear ends of said lower portions for admission of combustion air tothe fuel-bed, means for actuating said pushers to advance the fuel progressively over the said structure, aircooled side walls bounding the side edges of said grate structure, an ash pit at the lower end of said structure, and mechanism for discharging ashes from said pit to the front of said furnace.

5. The combination with a furnace having a firing opening, of mechanism for feeding fuel into the furnace through said opening, a grate structure positioned in the furnace to receive the fuel, said grate structure comprising a longitudinal series of pusher elements interspersed with stationary plates, longitudinal beams supporting said stationary plates, means for securing said stationary plates to the supporting beams, and means for slidably interlocking the pushers with lsaid stationary plates, means for actuating said pushers to advance the fuel longitudinally over said grate structure, air-cooled walls bounding the sides of said grate structure and extending above the surface thereof, an ash pit at the lower end of said structure, crushing means operative in said pit, and Va partition extending from the lower end of said structure to the front of the furnace,

said partition forming the. upper wall of a 'passage extending from said pit, and means for discharging ashes from said pit through said passage.

6. The `combination with a furnace having a firin opening, 0f means for feeding fuel to the urnace through said opening, a grate Structure positioned in said furnace to receive the fuel, said structure inclining down wardly from said opening and comprising a longitudinal series of pushers arranged in relatively stepped relation, means for interconnecting the pushers of said series, a pivoted lever operatively connected with said interconnecting means, an operating rod connected with said lever, mechanism for recip-v rocating said rod to effect a. relprocatlon of said pushers, a partition extending from the lower end of said grate structure to the front of the furnace and forming a chamber beneath the grate embracing said rod and lever, an ash pit at the lower end of said grate structure, and a passage extending from said pit and under said partition to the front of the furnace and constituting a discharge outlet for said pit.

7 The combination with a furnace havingv a front wall provided with upper and lower openings, of means for feeding fuel ,into the furnace through lsaid upper opening, a gratei` structure positioned in said furnace to re-' ceive the fuel, said structure comprising a l plurality of movable elements for advancing the fuel longitudinally over the structure, an

ash-crushing element at the terminal end of said structure, an actuating rod extending into the furnace through said lower opening, and means connecting said rod with said 5. movable grate elements 'and said crushing 'element respectively, andv mechanismv for actuating said rod.

8. In a Stoker, the combination with va grate structure including a plurality of re- ,10 ciprocating elements for advancing fuel progressively over said structure, means for feeding fuel to the grate including a reciprocatory-ram, an ash pit, and reci rocatory means associated with said pit or re- A moving ashes therefrom, a pair of horizontal shafts each having a crank, said cranks being connected respectively with the ash-removing vmeans andthe reciprocatory grate elei ments, gearing connecting said shafts, a bevel 'gear carried by one of said shafts, a vertical shaft having a bevel pinion meshing with said gear, a horizontal crank on said vertical shaft operatively connected with the said ram, a motor, and means for operatively connecting said motor with the said bevel gear.

FRANK W. KAY.