US1058365A - Furnace. - Google Patents

Description

J. HARRINGTON. FURNAGE.

APPLIUATION FILED MAY 15,1911.

1,058,365. Patented Apr. 8, 1913.

2 SHEETS-SHEET 1.

35 @Mmmm l L J. HARRINGTON.

FURNACE.

APPLICATION FILED MAY 15, 1911.

Patented Apr. 8, 1913.

2 SHEETS-SHBET 2.

I To all whom it cmwem.'

srnrns Partitur onirica.

f JOSEPH HARRINGTON, or mnn'smn, Immers. A A

minimos.

pecicati-cn ct Letters Patent. A'appiimmfm mea may 1911. serial No. 627,186.

* 'Patented Apr. 8,1913.

Josnrii HAmiiNjeroN,

i 'Be it known thata cit-izen offthe Unit fstates, and aresident of Riversidedn thecunty of Cook andg| State of illinois,- haveilnvnted certain new: and useful -Improvementslin Furnaces; and; Ido hereby declare that the-following is a fu1l, clear and exactv description.- thereon,l

reference 1 ing-:had '-toithe accompanyingf 'drawings 4 :marked thereon, which lspecification.' 'i

and .to -the 'letters of reference! form a part ofthisl y ff'fls'invention rela-tes to/an im rovedcon-l `:struction in furnaces' of that -kint having ani .lendlessltraveling or chain grate, acting to! carry the f uelrearwardly within the furnace;

dui-ing: the progress of combustion, and a;

' ate whichextends acrossthe furnace abovel device "in thenature of a metal .closure or l.

t e rear end of the grate and beneath a for-l ,ward extension 'ot-the bridge wall that over-i ghangs said rearpart of the grate, with 1ts low'er edge in position for contact with th'e llayer of ashes or burned out fuel which! passes beneath it on the rearward travel ofi the grate, and which 'serves the pur )ose ofx fpreventin the entrance of'air to the urnacel 'j'through t' e space betweenthe rear part of the rate and the said bridge wall.

l inafter described 'and pointed out in the a.p,.

invention consists inthe matters here-l pended claims. n y `A`c1osure or gate embodying my invention.

is made of metal and embraces as its iiiaini .features a; beam or girder which is support# fed'at itsends by the side walls of the furnace;

and extends acrossthe' same above the rear of the traveling grate, together with ai :plurality o,f separate metal bars, sections or- 4b 1 protecting members generally resembling? 'grate bars, that are ung or sustained upon ythe said irder atthe'fi'on't face of the same and )vhic extend vertically or transversely to the girder, and are arranged side by side,

'45 ein such manner as to cover the front surfaceA of'said irder. Said protecting bars, thus arrange serve to prevent contact with the girder itself 'or any part of the layer-of hot ashes,' or partially consumed fuel, which movesrearwardly with the grate, and to also Erevent ltheg'irder from bein unduly heated.

y tlie'action ofthe heat-wit iin the furnace.l The girder1 and protecting barsfare, more-f over, so constructed as ttxacrd a longitudi- .and forwardly between the is produced by the draft Aof t e furnace, sup'- nallyextend'ing a-ir Space 'or duct between- 'the front face of the'girder and.' protect..

ingbars and provision is made lfor Athe ad'- .mission of air to such air spaceorduct at' one or both endsof the (gate, andsaid bars are so sha edor .arrange as toa'ord spaces .between ein for .the passage of air, so .that air will pass constant y from -said space or duct outward or forwardly -through orbe'- twecn the projecfing'fba'rs with the e'ect f preventing the same from becoming injuriously heated, .nthe 4saine nianner'that the grate bars of an ordinary grateare kept cool by thepiss'age ofairthrough the 'spaces between e same. A continuous flow of the air-through the' air space or duct referred to, 'rotecting bars,

lemented,l in cases where. 'found .-necessary, y a blower or air forcingdevice .arranged to deliver the entering air` tosaid space or gate, constructed asl described," isapivotally turn or swing on a horizntalaxis located near its upper edge, and the gate is s'o ai'- -ranged that it-,will normally hazig'in a vertical position, while its lower. ge -will be f free to swing rearwardly from its normal position; this const-ructinnvenabling the ,gate

to yield rearwardly for-the'pur oseof permitting the passage beneatlrito large pieces of unburned fuel 'or clinker, 'carried -rear-A wardly on the grate, and to insure that the lower edge of the ate' shall always be in contact with the sur ace of the layer of ashes or burned fuel; it being understocd that the lower edge of the gate, when the same is in its vertical position, will be at such distance above the top surface of the grate as to provide for the passage beneath it of a layer of ashes of minimum thickness, whilel the rearward yielding of the device lpermits the free passage of a thicker layer of ashes and clinkers, so that the gate is adapted to prevent any passage of' aix! between its lower edge `and the grate, under' .varying conditions with respect.. to the thickness on the grate.d Afdevice embed of the layer of ashes ing my invention also in- `eludeso'ther detai s of constructionlandnrrangement ofthe parte; as will be herein# Aste-W111i@ theeepailin -drewf args-Figure l #s a viewn igerjtica,lsectionr As a further feature of my invention, the

.supported in va manner to permitthe'same to of the rear part of the furnace showing a portion of the bridge wall, a portion of the rear end of the traveling grate and a gate4 embodying my invention in connection therewith. Fig. 2 is a sectional view taken on line 2-2 of Fig. 1 showing the gate embodying my invention partially in elevation and partially in section'. Fig. 3 is a detail section, taken on line 3`-3 of Fig. 2. Fig. 4 is a sectional view, corresponding. generally with Fig. 1, but showing the, gate in changed position. Fig. 5 is a detail view showing one end of the metal beam or gil-der of the gate in side elevation. Fig. 6 is a detail section taken upon line 6 6 of Fig. 5. Fig. 7 is a detail-cross section, taken upon line 7-7 of Fig. 5. `Fig. 8 is a detail longitudinal sect-ion, taken upon line 8-8 of Fig.

5. Fig. 9 is a detail View of one of the shown in the drawings, consists of horizontally disposed fire brick ortiles supported in part by the bridge wall itself and in part by transversely extending metal supportinnr members 9, 9 inserted at their ends in an supported by the side walls 5 and 6.

10 indicates the rear part of the traveling grate, and 1l the rear shaft on which are mounted the rear supporting wheels or pulleys for the grate, one of which is indicated at 12, in Fig. 1.

13 indicates the beam or girder which constitutes the supporting member or body of the gate, and which is provided at its ends with supporting extensions, shown as having the form of journals or trunnions 14, 15, by means of which the said beam or girder is supported on the said side walls 5 and 6. 16, 16, 16 indica-te metal protecting bars or sections which are hung on the girder in such a manner as to extend transversely of the front face of the same. These protecting bars are arranged side by side throughout the entire length of that part of the girder between the inner faces of the side walls 5 and G of the furnace. Said girder 13 is recessed on its forward face so -as to form a longitudinal channel extending the entire lengt-li of the same. In the particular construction shown, the girder consists of an upright web portion, having at its upper margin, forwardly and rearwardly extending flanges 17 and 18, and at its lower margin like forwardly and rearwardly extending flanges 19 :ind 20, said flanges giv ing to the girder the general forni of an I-beam. The flanges at the forward face of the grder are made of considerably greater width than thoseat kt-herear face thereof. The protecting bars rest against the forward edges of the upper and lower forward A flanges 17 and 19 'of the said girder-13, so that the several bars, together with the web and said upper and lower flanges of the girder, constitute the walls of al longitudinal air duct or passage. The said rotecting bars are, moreover, so constructe so as to permit the passage of air between the same, and for this purpose they are so constructed that, while portions of their side faces are in contact, in a manner 'to keep thebars properly spaced, openin s or airpassages are formed between the ars." In'thefparticular construction illustrated, the bars' are severally provided in both side faces of each bar, with transverse notches 21, 21, 21, such notches forming spaces 'or channels between the bars, while enabljn the bars to be arranged with parts'of te side f'iibe ofveach bar in contact with that of an adjacent bar, while at the Sametime affording s aces for the (passage of airfrom" thel 'air uctforwar ly between said bars. The said air duct communicates at one or both endswith an air inlet: passage or vpassa es, through which air enters-said duct, eit er through the influence of the draft of the furnace or by the action of a fan or blower.

As shown in the accompanying drawings, each of the protecting'bars or sections v16 is so shaped or constructed at its upper end as to embrace or engage the margins of the flanges 17 and 18,'on the upper edge of the girder 13, and for this purpose sii-id bars are provided each with a rearwardly extending arm 22 (Figs. 1, 4 and 9) adapted-to extend rearwardly from the upper end of t``bar over the top of the girder to the rear margin of the flange 18, and having at its rear end or extremity a notch 23 to receive the rearcircular forni, so that whenthegate, as a whole, `is adapted to swing or rotate on its trunnions 14, 15, the curved top marginsof the several bars will remain' at a uniform distance from the overhanging part 8 of the liridgewall, thereby maintaining a close joint between the upper edge of the gate, as a whole, and said overhanging part of the bridge wall. The curved construction in the arm 22, moreover, ailords, when the arms l are asseinbledon the girder, a longitudinal airspace or channel between the several' :ii-ins and the top` surface of the girder, so

i as to decrease the amouxitof heat that will be transmitted lfrom 'the upper ends of the bars ltothe said grder. v In 'the construction shown in the drawings', the journals or trunnions- 14, l15 are inscribed. When the gate is pivotally, supported,' as shown, it is desirable that the .their bottom surfaces transversely p ".on arcs concentricwith the central a es 01E the'trunnions, as clearly seen in Fig. 6, The

extensions of the passa scribed. 'In the construction shown, pro-- pivotal axis thereof should belocatednear the top of the gateand, for this purpose, the trunnions are arranged with their central axes approximately in line with the top edge of the girder 13, and said trunnions are formed on, or constitute outward extensions of hubs and 31, on the ends of the-girder. Said hubs are inclined upwardly and outwardlyfrom the ends of the girderand have lrved,

hubs 30 .and`31 areA made hollow orrtubiilar; the' passages within the saine forming inward in Athe ltrunnions, and communicating at t eir inner .ends with 'the ends of thefairduct orvchannel' formed between the web of 'thegirderand 'the protecting bars 1 6, ,16,1 16, as hreinbe'fore devision is 4,madejor admission of air through the left-hnnd'trunnion 14, only, although both trunin areipreferably ma e alike,

- and air may be admitted through both trunnions, if desired.

As more show n in Figs. 5,6, 7 and 8, Vt e girder is provided at its end withan upright, forneotion of'thefh'ub 304 with lthe-body of the- -rderg''nn obli uiy Aarranligeed lange 34de wardly extending flange 33, which is joined to the lower flange 19 and extends-iupwardly to the bottom wall of the hub.30,` thereby leaving a space or notch between the .upper end of saidyiange 33 and the end of the upper Hange 17, and e air passage extend,- ing through the trunnion 14 and hub 30, indicated as a Whole by 32, opens at its inne'r end through saidspace or notch, into the longitudinal air duct formed between the gilrder. arid the protect-.in bars, as 'clearly s own in Fig. B, and by. otted lines inFig. 5. In ordeil to-aiford a suitably strong cons own as ing f t ii peredge of the flan "ilinwlardm' *cshort'distance along` `'web of the That one of' impressing bam-1Min@ assess-fed' ad- 'scent tothe'endo the girder is-'as indicated by. dotfediinesdnfxx t 6, ar'ran to overlapnaydr not withl t e forward ledgeof .thelffpri 4t Harige 83, and as the several-protecting rs extend'fov'ero'r across the space between the top'of-sad 'tlange and tliejlpper Hengel?, and'restlin' Contact articularly with the'upper and lower fianges 17-and 19, it will be apparent that the several protecting bars that are located adjacent to the end of the girder will, in effect, form the outer.

wall of the air duct at this point, where clearly seen in Fig.'8. The adjacent or end protecting bar yrest-s against the said shoul- 'der 35 which forms a stop by which said end bar is geld from lateral, outward movement.

Said s oulder 35 is, moreover, arranged in the same 4glane with the end face of the girder'so t at the outer face of the end protecting bar be held by said shoulder fiush with said end face of the girder.

The trunnions 14 and 15 are `mounted to turn-in Vseats formed in bearing blocks 36, 37` that are embedded in the side walls 5 and 6 of the furnace. Said bearing blocks are located at points between the inner and outer faces of-said side walls, this arrangement bringing said blocks at a considera le distance outwardly from the inner face of said side .walls in order that they will/riot be injuriously affected by the heatof the furnace. Open spaces or recesses 38, '39 are formed in the masonry side walls, extending from the. carin blocks 36, 37 'inwardly to the inner' sceso thesaidwalls;saidrecesses being made 0f a size and shape required to permit free movement of the hubs 80 and 3l Whenthe same are swung or oscillated :in the swinging movement of theA gate. Said bearing blocks 36 and 3.7 are preferably made with semi-circular beating-recesses. in their upper faces, adaptedto receive the lower parts of the trunnions, as clearly shownrin connection with the trannion 14 inFig. v3 of'thedrawings'. In connection with the bearing. blocks thus made, metal rprotecting sleeves 40 and 41, (Figs. 2 and 3) are applied to cover :the parts of .the trunnions above and, exteriorfto said bearing blocks, said sleeves being of cylindric form in their parts outsideof the beardng blocks, but being cut away at their lower portions, at their inner ends, soas to fit over and against 'the top and end faces of said blocks.' Suchsleeves are made of such internal diameter as to permit the trunnions The bearmr to turn freely in the same. blocks will`be seated i'n the side walls, an the sleeves will be placedin position and the wall built around them in the process of constructing the walls.

.42, 43 are face lates,which`.are secured by means ofboltsv 45 to the inner faces of seen in Figff, have their forward edges substantially in line with the front face of the gate when'thelatter stands in itsvertical position, so that the plates will not be exposed to the heat. within the furnace when the gate is in its normal position, as shown in Fig. 1, and only t'o a slight extent when swung rearwardly,- as shown in Fig. .4.

In order to permit the protecting bars Ito be placed on the girder in interlocked. relation with the top flanges ofk said girder, as hereinbefore described, the said top flanges are provided, at one point. in the length of the latter, with opposite A notches 46, j 47 (Figs. 5 and?) said notches beinf1r of suitable. sizefor the passage ofl the en( portion of the arm 22 below the notch 23 therein,

through the .rear notch all' ofthe girder and for the passage ofthe inwardly projecting lugs 25 through the forward notch 4G of4 said girder. lt will be understood that in placing the several bars upon the girder, each bar will he so applied to the girder at the point where the notches 46 and -flare located and then slipped eudwise along the gir-der until all of the hars have bcen`properly placed thereon.

As hereinbefore stated, the bars 1G are, in order to prtvide for the passage-,of air between the sanie, provided with transverse grooves or notches 2l, 2l, formed in the side edges of the bars at. intervals along saidside edges from the top to the bottom thereof. 'lhese not-ches, as clearly shown in Fig. 2 are arranged in alternate orstaggered relation in the ease 'of the notches in the o postte sides ot each har, so that. when the ars are. placed together, or Side by' side, the notches in one bar will come opposite the spaces between the notches in the other bar, thereby atl'ordinga large number :if-closely spaced openings for the passage of air bc'- tween each pair. ot adjacent bars. I have, moreover, provided a special construction in notches or air channels at points adjacent to .the upper and lower flanges of the girder,

in order to provide for the cooling of the upper and lower end'portions of the bars, that rest in contact with said flanges. For this purpose, as clearly shown in Fig: 9, intersecting grooves 4S andsl) are formed in each side face of each bar near the upper `end thereof, the grooves 4S being inclined upwardly and forwardly and the groove 49 being vertically disposed, and the 'said grooves being arranged to intersect each other near the rear face of the bar and form an open space opposite the upper forward.

intersecting grooves 26, 27, that meet or in- -tersect each other at the point adjacent to but just above, the lower forwardllange o the girder, this construction permitting the passage of air between the lower. parts of l,"

adjacent barsgto aid in the cooling of the same. The'bars, made generally in the manner described, are provided with a'further .y

sp'eeial featureof construction, by which", when thegate, as a whole, is 'pivotally supported 'and adapted to-swing or yield rearwardly, as hereinbefore described, every al-.

ternate bar will have slight-Swingin `move` 'ment at its lowerend relativel to t e bars at eitherside of the same. T is construetion 'is employed 1n order to -prevent-,the

spaces between the bars from being'closed by adherence vto the side facesthereof, effusible parts of the fuel that may accumulate,in

the form lof clinker on said bars'. In other words, by hanging the bars loosely onfthegil-der, and in suchunanner that' they may have movement-relatively to each other, ad.l herence of clinker to the side faces of ad jacent bars, in a manner to cause one bar to? adhere to another, or to result in the spaces between the bars being .filled or closed by accumulatedl cl1nker material, is lthereby avoided.-4 .Such movement of the bars rela- -tively to each other is secured by providing a loose connection between the upper Aends of a part ortiall of the .bars and the top olf the 4garder,andby so constructing the parts that a greater amount of movement between t-liefbars andthe girder is afforded in the case. ofthe first, third, fifth and other bars than in hecase of the second, fourth, sixth and other ars. rear flange -18 of the girder is arranged to fit closely within `the no tch 23 of each bar, while, in the case of 'the forward notch 24 the same is made of greater width vertically than the thickness ofthe forward edge of the angel'Z that enters said notch. By this construct-ion, acertain amount of `lost motion or p'lay of each bar relatively to said j forward ange, is permitted, the bar turning or swinging about the rearflange as its lower end moves relatively to the girder. This lost motion or play is preferably pro- InA the construction illustrated, the

vided for to some extent in all of the bars, j

but in the case of every 'alternate bar the lug 25.`will be located at a lower lpointvon the bar, as indicated 'by dotted lines in Fig. 9, so as togive a greater amount Lof play or movement to .said alternate bars. As -a rej sult of this. construction, -as shown in Fig. 4, when tl1e`g1rder, as a whole, 1s thrown into a4 rearwardly inclined pos1t1on,the lower ends of one set :of the bars willswing or.

drop away from the lower margins of the the gate is swung rearwardl by the contact therewith of pieces of clin er, or the like, carried rearwardly on the grate. The lower ends of the several protecting bars are preferably extended a short distance below the lower edge or flan e of the girder, in order that the ashes .or urned out parts of the fuel, which are still at a high temperature when they reach the gate, may not come 1o. in girect contact with the lower part of the glr er. It is to be observed that the rotecting ba'rs, extending over the forward ace of the girder,'a's described, are subject not only to the. heat wit-hin the furnace, but also to the heat from the layer of ashes and nearly burned out fuel, on the rear part of the grate, which is carriedagainst and beneath the gate, the lower edge of which is always in contact with the top surface of such layer, in order to prevent the passage of air, beneaththe gate forwardly from the space at the rear of the gate into the furnace. The top port-ion of such layer of g5 4ashes and burned out fuel will, to some extent, at least, accumulate or become banked up against the lower ends of the rotecting bars, but any injurious heating o? the same from this cause as well as from the heat radiated thereon fr the burning fuel and "gases in the f mace, is'prevented by the cooling effect of the air which passes throu h or Abetween said' bars: In other words, t e -said protecting bars are cooled by the pasgrate are similarly cooled. An amp e sup- A.ply of air to effect the cooling of the pro-.

admission passage or passa es at one orbotli ends of the air duct be ind the pro! tecting. bars, and forwardly between the bars. In cases where the air supply thus produced is insuicient, air may be supplied to the arduct from a fan, blower o r air compressin device. 1. It s' to 'understood that the eneral features of my invention may be'app ied to ,g gate which is supported in the lfurnace otherwise than as herein illustrated; it bein l manifest that so far as the use of air-coole rotecting bars is concerned, the same may a plied to a gate which is supported in the urnace, by either of the several means heretofore employed in -connection with gates used. for the saine purpose or in any other desired or preferred manner.

Gates embracing the several features, herebefore described may be variously constructed with respect to the details of construction thereof,and I do not, therefore,

"desire to be limited to the particular features of construction, illustrated in the acthe -sage of air between them, in the same man-- ner that the grate bars of a fuel sup orting com anying drawings and hereinbefore set fort except so far as the same may be herein claimed as parts of my invention.

vI claim as'my invention- 1. In a furnace, the combination with an endless traveling grate, of a movably mounted metal closure oi' gate located above the rear end of the grate vand comprising a girder, a plurality of metal protecting bars supported upon and arranged side by side transversely of said. girder, said girder and protecting -bars being constructed to provide between them a longitudinal .air 1 duct; said bars being adapted for the outward passage of air rom said air duct, and means providing an air supply passage communicating witi said airduct.

2. In a furnace, the combination with an endless traveling grate, of a movably-moiiritedmetal closure or gate located above the rear end of the-grate, and com risin`fa girder provided in one of its side aces with a, longitudinal channel, a plurality of'metal' protecting bars su ported upon the girderand arranged side by side transversely over 9g the channeled side of the same, said girder and the protectin bars forming between them a longitudina air duct; said bars being ada ted for the outward passage of air from air duet between their side faces, and means providin an air su ply passage cornmunicating witg said air uct at'the end of the gate. 3. In a furnace, the combination with a'.' endless traveling grate, of a movably mount 100 ed metal closure or gate located over thefrear end of the grate, and comprisinga metal girder provided at its ends with supporting extensions, and a, plurality of metal protecting bars su ported upon and a'rran ed side) by'si e transversely of said ir er, said girder and the protecting bars ing constructed to rovide between them a longitudinal air uct, said bars beingV adapted for the outward assage "of air from said air duct between t eir side fa.Ces,y and at least one of said supporting extensions being provided with an air supply communicatin with said air duct.

4. In a urnace, the combination with an 1115 endless traveling grate, of a movably mount.- ed metalclosure or gate located over the rear end of the ate and comprising a girder provided at its ends with support-ing extensions, and a luralit of metal protecting bars supported) on an arran ed side by side transversely of the said gir er; said girder and the protectin bars being constructed to provide between t ein a longitudinal ai'duct and at least one 'of said supporting exten- 125 sions being provided with an air inlet passage communicating with the exterior of the furnace and with the air duct formed by the girder and protecting bars.

5. In a furnace, the combination with an 1 80 lower edges andp'rovided at its ends with.

.endless traveling gra-te, of a movably mountlongitudinal air inletpassage communicat-y ing with the exterior of the furnaceand.

with said air duct, and t-hesaid bars having in their side faces transverse notches for the. passage ofair from said air ductbetween` said bars, the notches in opposite sides of the bars being arranged in alternate or staggered relation.

6. In a furnace, the combination with an endless traveling grate, of a movabl y mounted metal closure or gate located vabove the rear end of the grate, and comprising a girder provided at its ends with supporting extensions, a plurality of metal protecting bars arranged side by side and .extending transversely over one of the side faces of the girder,` said bars being provided'V at theirupper ends with arms adapted to en age the upper edge4 of said girder, and sai girder and the protecting bars being constructed-to,4

provide between them a loi1gitudinal`aii` duct, and at least one of said supporting ex--` tensions beingprovided with an air-supply passalge communicating with said air duct.

7. n a furnace, the combinzftion with an endlessA traveling grate, of a movably mounted metal closure or gate located over the' rear end of the ing longitudinal tianges at its upper and supporting extensions, and a plurality of metal protecting bars arranged side by side Atransversely of the front face of the girder and resting against the said flanges; said 'bars being rovided at their upper ends with arms whic extend over and embrace thc top edge of the girder, and at least oneof said supporting extensions being provided with an air supply passage communicating with the space between thc web of the girder and said protecting bars.

8. In a furnace, the combination with an endlesstraveling grate, ota movably mounted metal closure or gate located over the rear end-of the grate, and comprising a metal girder provided at its ends with supporting extensions, and a plurality of metal protecting bars' supported upon and arranged side by side transversely of said girder, said girder and the protecting bars being constructed to provide between them a longitudinal air duct, and the girder being provided at its ends with inwardly facing rate, and comprising a girderhaving a we portion and forwardly extendshoulders forming stops against which rest.

.the protecting bars at the ends ot the girder and at least one of said longitudinal extensions being provided with an air inlet passage communicating withfsaid air duet.

. i 9. In a-furnace, the combination with an endless traveling grate, of a movably mounted metal closure or gate located over the rear `,end of the grate, and comprising a girder, provided witha longitudinal channel in its side face and with trunnions at its ends, and a plurality 4of metal bars supported on and arranged side by 'sidetransversely over the channeled-side of saidvgirdcr-and forming with the girder a longitudinal air duct; said girder being-providcd at its ends with inwardly facing shoulders arranged in thc same planes with the end faces of the girder, and farming stopsto hold the protecting bars at the ends of.the..girdcr with .their outer side faccsitlushwith said -end faces of the girder, and atleast one of said trunnions bcingnladcof tubular form to provide an air. inlet passage communicating with .the p f10. In ya. furnace, theiannbination with an endlesstraveling-gratc, yand a bridge wall providedavith apart overhanginggr the rear cnd-0f said-grate, a, movably mounted metal closure or gate located above the. rear end of the grate and beneath the-overhanging part ofsaid bridge wull,.said n'ate comprising a longitudinally flanged girder provided at its ends withv supporting extensions, and a plurality of protecting bars arranged side by sido and extending transversely over one ot' the side faces of the girder and forming with the girder a longitudinal air duct, said bars being vprovided at their upper ends with armsv adaptedl to engage the upper edge of said girder, said arms being upwardly curved to form an air space'between the same and the top surface of the girder, and at least one of said longitudinal extensions being provided with an4 air supply passage.

communicatingv with said air duct.

11. In a furnace, the combination with an endless traveling grate, of a metal closureor gate located abovefthe rear Vfend of the grate 'and con'iprising a girder provided at its ends with trunnions by which it' is pivotally sup )o1-ted, and a )lurality of metal pro; tecting ars supporte upon and extending transversely of said girder, said girder and protecting bars being constructed to provide between them an air duct., and at least one of said trunnions Abeing provided with an air inlet passage in communication with said air duct.

'12. In a furnace, the combination with an endless traveling grate, of a metal closure or gate located above the, rear end of the grate, and comprising a girder provided in one of its side faces with a longitudinal channel and at its ends with trunnions, and a plurality range 10 `ported metal closure or gate located .over

f the rear end of the ate, and comprising A'a girder and a plura ity of protecting bars `arranged side by side transversely o the front face of the girder, said bars being hung 1'5at their upper ends on 'the girder, and the alternate bars having loose connection with the girder, permitting swinging movement of their'lower ends relatively to the girder and the intermediate bars.

14. In a furnace, the combination, with an endless traveling grate, of a pivotally supported metal closure or gate located over 'the reanend of the grate, and comprising a girder and a plurality of protecting bars arside b side transversely of the front "s'ltdelofthe girder; said bars being hung at their upper ends on the girder, by loose coufnections affording limited vswinging movethe alternate bars than in the lower ends of the bars intermediate thereto.

15. 1n a furnace, the combination .with the masonry side Walls thereof and an endless traveling grate, of a metal closure or gate located above therear end of the grate, comprising a girder provided at its ends with trunnions by which it is pivotallyy supported, and a' lurality .of metal protecting 4o ars supporte upon and extending transverselyl of said girder, said girder and protecting bars being constructed to provide between them an air duct, and at least one of .said trunnions being provided with an air inletpassage in connection With said air duct, and metal bearing blocks' for said trunnions, mounted in said side walls 'at a distance i outwardly 'from the inner vfaces thereof.

16. In a furnace, the combination with an endless traveling grate, of a metal closure or gate pivotally mounted over the rear end of the grate and comprising a girder and a plurality of metal protecting bars, said, gil-der and bars being constructed to'provide between them a longitudinal air duct.

In testimony, that I claim the foregoing as my invention I affix my signature in the presence of two witnesses, this 9th day of 60 May A. D. 1911. t ment of the lower endsof all orf the bars e30 .relatively to the girder, and a greater extent of swinging movement in the lower ends of JOSEPH HARRINGTN.

Witnesses C. CLARENCE POOLE, GEORGE R. WILKINS.

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