US2163825A - Stoker - Google Patents

Description

June 27; 1939. 7 w. BROS 2,163,825

STOKER Filed July 29, 1935 a Sheets-Sheet 3 Arro'zNEYr BROS STOKER Fiied J 29' 1935 6 Sheets-s 4 I llrllll I.

c. 'w. BROS June 27, 1939.

' STOKER 6 Sheets-Sheet 5 Filed July 29, 1935 Patented June, 27, 1939 UNITED STATES PATENT OFFICE.

STOKER I Chester W.. Bros, Minneapolis, Minn., assi'gnor to Wm. Bros Boiler & Manufacturing Company, Minneapolis, Minn., a corporation of Minnesota Application July 29, 1935, Serial No. 33,153 7 Claims. (Cl. 110-115) in actual operation, primarily because of not beindependently of one another.

ing designed to withstand the hard usage to which such apparatus is subjected, particularlycommercial stokers. Commercial stokers are required to operate for long intervals without interruption, and may frequently be subjected to heavy loads in order to supply the demand for steam during'peak periods. Unless a stoker is properly designed, it may not becapable of meeting the demand placed upon it. This may result in loss of economy, or may result in breakage, necessitating that the plant be temporarily,

shut down. It is also desirable in a stoker,'that the operating parts thereof be so arranged and constructed that the stoker will be substantially noiseless in operation, as stokers are frequently operated in places where noise isextremely objectionable.

The novel sprinkler type-stoker herein disclosed, has been designed to remove the objectionable features present in ordinary stokers. To facilitate installation, the stoker, including the motor for driving the same, is assembled as a unit, whereby the entire stoker may readily be secured to the steel plate front of a boiler at comparatively small cost, and without danger of the operating parts thereof becoming disalined, as when the various parts thereof are assembled Sturdiness of construction is reflected throughout the entire design of the stoker. It is provided with various control means which present the utmost in flexbustion' field may readily be satisfied. The stoker is designed to provide at all times, the proper mixture of air and fuel for high efliciencies; suitable air ports being provided whereby air is drawn cline and adjustable with respect to the rotor,

ved for pivotal movement, whereby tramp iron ly quiet in operation, and is so constructed as to present the utmost in efliciencyand continuity of operation, and is extremely economical in operation. Y

A further object is to provide a sprinkler type 5 stoker, all of the parts of which are'assembled as a unit, including the motor and the driving mechanism for the stoker, whereby the stoker may be conveniently secured to the steel plate front of the boiler, as a single unit, and whereby the operating mechanism thereof is not likely to become disalined, when installing the stoker, or when the stoker is subsequently operated.

A further object is to provide a sprinkler type stoker comprising a rotor constructed of a pluv rality of Sections interchangeably secured together to form .a single unit, whereby sections having blades inclined to the axis thereof, may be substituted for other dissimilar sections, whereby the angle of inclination of the rotor blades may be varied to thereby cause the fuel being delivered into the furnace by the rotor to be spread over the'fire bed in a direction laterally with respect-to the rotor, and whereby the fuel may be evenly spread over the entire fire bed, even though the fire box is actually wider than the length of the rotor.

A further object is to provide a sprinkler type stoker comprising a feed plate disposed at an inwhereby the lengthof the fuel throw into the furnace may be varied to accommodate the particular type of furnace and coal with whichthe stoker is used.

A further object is to provide .a sprinkler type stoker having a pivoted gate cooperating with the feed plate and feed shoe to control the feeding of the fuel into the furnace, said shoe being constructed of a plurality of sections each mountand other foreign pbjects delivered into the stoker may pass therethrough without damaging the ibility, whereby any condition met in the com- .=,5 t0ker, or causing it to cease operations.

" Other object's;.;;reside in the unique construction of the rotor and the manner of mounting it space is provided to prevent direct conduction of heat from the rotor to the shaft; in the specific construction of the gate which comprises a pluality ofair ducts, whereby air may circulate t erethrough and into the furnace, directly over i' the rotor, where itis intermixed with the fuel stream to thereby/provide a highly combustible fuel mixture, and whereby combustion is reatly facilitated;--in the novel arrangement and conrotor;

struction of the feed shoe, which comprises a plurality of sections which may be operated simultaneously as a unit, or, if desired, independently of one another; and, in the simple and inexpensive construction of the control means, whereby the stoker is adapted for either manual or automatic operation, as may be desired.

Other objects of the invention will appear from the following description and accompanying drawings and .will be pointed out in the annexed claims.

In the accompanying drawings there has been disclosed a structure designed to carry out the various objects of the invention, but it is to be understood that the invention is not confined to the exact features shown as various changes may be made within the scope of the claims which follow..

In-the drawings:

Figure 1 is a vertical sectional view on the line l-I of Figure 2, showing the construction of the fuel feeding means;

Figure 2 is a vertical sectional view, substantially on the line 22 of Figure'l, with some of the parts shown in elevation;

Figure 3 is a plan view of the structure shown in Figure 1, partially broken away, and showing the rotor adapted for spreading the fuel laterally beyond the length of the rotor;

Figure 4 is a detail sectional view showing a rotor composed of sections which are all alike, whereby the fuel delivered into the furnace will not be spread laterally beyond the length of the Figure 5 is an enlarged detail sectional view showing the fuel feeding mechanism, including the feed plate and feed shoe, and also the feed gate mounted for pivotal movement whereby it may be tilted to permit tramp iron and other foreign objects to pass through the stoker;

Figure 6 is a detail sectional view substantially on the line 66 of Figure 5, showing the sectional construction of the feed shoe, and some of the parts being broken away to. more clearly illustrate the means for controlling the operation of the sections thereof;

Figure 7 is a vertical sectional view on the line 'l-l of Figure 2, showing the driving means for the feed shoe positioned for maximum stroke;

Figure 8 is a detail sectional view on the line 8-8 of Figure 9, looking in the direction of the arrow and showing the parts adjusted to reduce the stroke of the feed shoe;

Figure 9 is a sectional plan view on the line 93 of Figure '7;

Figure 10 is an enlarged detail sectional view on the line l0l0 of Figure 7, showing the feed control mechanism; and

Figure 11 is a detail sectional view on the line Il.ll of Figure 10.

Stoker frame In the selected embodiment of the invention here shown, there is illustrated in Figure 1, for purposes of disclosure, 2. portion of a conventional furnace, generally indicated by the numeral 2, and comprising a front wall 3 and a combustion chamber 4. The upper portion of the combustion chamber is shown defined by'an inclined wall 5 having an air duct 6 therein communicating with an air trunk 1, whereby air is delivered into the fuel adjacent the fuel opening 8 provided in the front wall 3.

The novel stoker herein disclosed, is constructed as a unitary structure, and is shown adapted to be secured to the front wall 3 of the furnace by suitable bolts 9 received in suitable apertures provided in the flange H of the main frame of the stoker, generally indicated by the numeral l2.

The supporting flange ll of the main frame of the stoker extends below the fuel opening 8, as best shown in Figure 1, and is 'provided with a hinged door l3, through which'access may be had to the interior of the furnace. The door 13 is normally held closed by a suitablelatch M. A cylindrical chamber I5 is provided in the main frame of the stoker adjacent to the fuel opening 8, and has a removable casing I 6, whereby access may be had to the interior thereof.

An, important feature of the novel stoker herein disclosed resides in the construction of the means for distributing the fuel over the fire bed. As best shown in Figure 1, such means consists of a rotor, generally indicated by the numeral l1, suitably secured to a shaft l8 mounted in suitable bearings, generally indicated by the numeral [9 in Figure 2. The rotor I! may be composed of a plurality of straight sections 2l-and angle sections 21 and 28; which are suitably secured together to provide a rigid structure, as illustrated in Figure 3. The sections -2l, are mo ted directly upon a tubular member 22, one end of which is fixedly secured to a flanged collar 23 which, in turn, is secured to theshaft l8, as best shown in Figure 2.

The opposite end of the tubular member 22 has a sleeve 24 fixedly secured thereto which is bored to receive the shaft I8. 'A suitable nut 25 is received in threaded engagement with the sleeve 24 and provides means for clamping the rotor sections 2| in position upon the tubular member 22, as will readily be understood by reference to Figure 2. A suitable spacing collar or sleeve 26 is provided intermediately of the ends of the tubular member 22 to retain the latter in axial alinement with the shaft I8. By thus supporting the rotor sections upon the shaft l8, a dead air space is provided between the shaft I8 and the tubular member 22 to thereby protect the shaft,

from the heat of the furnace.

In Figures 2 and 3, the rotor is shown provided at its ends with sections 21 and 2B which have their blades disposed at different inclines with respect to the axes of said sections, so that when said sections are secured in position upon the tubular member 22, the blades 29 formed by the rotor sections 2|, 21, and 28, will be shaped as best shown in Figure 3. By thus shaping the ends of the rotor blades, the fuel engaged thereby will be thrown outwardly to the sides'of the fire box, whereby the fuel may be spread over the entire fire bed. In Figure 4, the entire length of the rotor is shown composed of sections 2|,

whereby the blades 29 thereof will be parallel to the axis of the rotor their entire length. When thus arranged, the fuel delivered into the furnace Hopper and feed plate A suitable fuel hopper 3| is supported in a bracket 32 secured to the front side of the main frame I2 of the stoker by suitable bolts 33. The hopper 3| has the usual throat 34, the bottom of which is defined by an inclined feed plate slidably supported in the lower portion 36 of the bracket 32, and mounted for relative adjustment thereon by a suitable-adjusting screw 31, whereby the discharge end 36 of the 'feed plate may be varied with respect to the rotor 11, to thereby control the distance the fuel is delivered into the furnace. The adjusting screw 31 is'rotatably. mounted in 'a guide 39, preferably integrally formed with the lower portion 36 of the bracket 32. The guide 39 is shown provided with a cavity 4| adapted to receive a collar 42 suitably secured to the screw 31 by such means as a pin 43, whereby the screw cannot move axially with respect to the guide 39, but is free to rotate with respect thereto. The lower end of the screw 31 is received in a threaded engagement with a lug 44 suitably secured to the feed plate 35, whereby, when the screw is rotated, the feed plate will be relatively moved with respect thereto.

The opposite end of the adjusing screw 31 is shown having a suitable sleeve 45 loosely mounted thereon, which is supported between the guide 39 and a heacl'46 on the screw 31. is preferably square in cross-section, as shown in Figures 2 and 6; and is provided with suitable marks adapted to cooperate with an indicating member or pointer 41, secured to the outer end of the feed plate 35, to indicate the position of the inner edge 38 of the feed plate with respect to the rotor. From the foregoing, it will be noted that the feed plate may readily be adjusted from the front of the stoker by the simple manipulation of the head 46 of the screw 31, to-thereby control the distance the fuel is delivered into the furnace.

Feed shoe The means for feeding the fuel from the hopper into the furnace is shown comprising a feed shoe, generally indicated by'the numeral .48. This feed shoe has a plurality of substantially vertical walls 49 and 5|, arranged at different elevations and adapted to impinge against the fuel and shove it forwardly over the surface of the feed plate 35, as will readily be understood by reference to Figures 1 and 5. The feed shoe preferably comprises a plurality of similarly shaped sections 52, operatively'connected to a'rocker shaft 53 mounted in suitable bearings 54in the bracket 32, as best shown in Figure 2.

The sections 52 of the feed shoe are shown operatively connected to the shaft 53 by forked arms 55, loosely mounted upon the shaft, and having their upper ends pivotally connected to a pair of links 56, the opposite ends of which are pivotallypconnected to thesections 52, as best shown in Figures 1 and 5. Thus, when the arms 56 are oscillated, reciprocal movement will be imparted to the sections 52 of the feed shoe, to

thereby feed the fuel onto the rotor, as illustrated.

in Figure 1. The upper ends of the arms 55 are provided with curved bearing surfaces 51 adapted to be engaged by the lower edges of the flanges 58 provided upon the feed shoe sections 52, whereby a portion of the weight of said sections and the load carried thereby will be supported directly upon the arms 55, independently of the links 56.

The rearward ends of the feed shoe sections 52 are shown provided with suitable wearing plates 59, adapted to slide upon the upper surface of the feed plate 35, as clearly illustrated in Figure 5. The feed shoe sections are provided at their ends with upstanding flanges 6| which are guidingly supported in suitable guides 62 and 63 secured to the bracket 32, as best shown The sleeve 45 'in'Figure 2. The

side guides 62 may be suitably secured to the walls of the bracket 32 by suitable bolts 64, and the center guide 63 may be integrally formed with the bracket 32, as shown.

The feed shoe sections 52 are operatively conneeted to the rock shaft 53, whereby they are adapted for either independent or simultaneous operation. To thus connect the sections 52 to the rock shaft 53, the hub of each arm 55 is shown provided with a suitable lug 65 having a pin 66 slidably mounted therein, one end of which is adapted to be received in an aperture provided ina lug 61 secured to a-hub 68 which is suitably keyed or otherwise secured to the shaft, as shown, for example, at 69 in Figures 2 and 6. Suitable collars 11 are secured to the shaft 53 to prevent endwise movement of the arms 55.

Thus, it will be seen that the pins 66 operatively connect the arms 55 to the shaft 53 and, as hereinbefore stated, provide means whereby the shoesections 52 may be operated independently of one another or simultaneously. By thus constructing the shoe 48 of a plurality of sections, and providing means whereby said sections may be operated independently of one another, or simultaneously, a greater range of control is provided, in that if it is desired to feed the fuel to one side of the furnace for the pur-v tween' the. bottom of the hopper and the upper surfaces of the shoe sections 52, a suitable sealing member 12 is shown secured to the wall portion 13' of the bottom of the hopper, by suitable thumb screws 14, as best shown in Figure 5. The wall portion 13, in the present instance, is shown integrally-formed with the bracket 32.

A suitable door 15 is-pivotally supported upon a pivot casting 16, shown secured to the inclined wall 11 of the hopper, and normally c'onceals and protects the operating mechanism, above described. The pivot casting 16 is supported on a pivot 18 secured to the bracket 32. Thus, the hopper is pivotally supported at the front of the ,stoker, so that it may be tilted forwardly, as indicated by the dotted lines in Figure 1, whereby access may be had to the mechanism back of the hopper, which will subsequently be described.

Feed gate Another important feature of the invention resides in the construction of the means for varying the depth of the fuel fed over the feed plate 35 to therotor by the feed shoe 46. Such means is best shown in Figures 1, 2, and 5, and comprises a gate, generally indicated by the numeral 19. This gate comprises a plurality of sections 8| pivotally supported upon a tubular shaft 82 having its terminals supported on suitable blocks 83, adjustably supported upon threaded adjusting rods 84, rotatably-supported in suitable bearings 65 provided in the side members of the main frame l2. The sections 8| of the gate 19 are shaped as best shown in Figures 1 and 5, and

videsan abutment. for the sections 6! to thereby normally retain them in their-operative positions, as shown in'full lines in Figure 5. Each gate section 6| is shown provided with a plu-.

rality of air ducts 88, through which air is drawn into the furnace from the exterior thereof, as clearly illustrated by the arrows in Figure l.

The gate sections 8I are mounted for pivotal movement, whereby tramp iron and other foreign objects which may be entrained with the fuel, may pass through the stoker without dam- .aging the same, it being understood that when such foreign objects engage the upright wall portion 88 of any one or more of the gate sections 8|, said section or sections will swing outwardly, as indicated by the dotted lines in Figure 5, and thereby permit such objects to pass through the stoker without damaging the same.

The means provided for vertically adjusting the gate I9 is best shown in Figures 1 and 2, and comprises suitable sprocket wheels 89 and 9I secured to the upper ends of the adjusting rods 84 and operatively connected together by a suitable chain 92. The sprocket wheel M is shown provided with a ratchet wheel 93 adapted to be engaged by means, not shown, provided upon an operating handle 94, whereby the sprocket wheel 9I may be rotated in'either direction, to thereby rotate the screws 84; with the result that the gate is vertically adjusted.

' Driving mechanism 95, shown mounted directly upon the main bracket I2 of the stoker by a suitable bracket 98. The bracket 95 is shown secured to the main bracket I2 by suitable bolts 9], and to the gear casing by bolts 98, one of which is shown in Figure 3. The gear casing 95 is shown provided with a suitable cover 99 suitably secured thereto and whereby convenient access may be had to the interior thereof. A suitable filler cap I00 isprovided on the cover 99 for the introduction of a suitable lubricant into the casing 95.

A suitable coupling, generally indicated by the numeral I02, connects the rotor shaft I8 directly to one end of a suitable drive shaft IOI, mounted in the gear housing 95. The drive shaft IOI has a sheave or pulley I03 secured to -the opposite end thereof, exteriorlypf the casing 95, and a belt I04 operatively connects the sheave to a variable speed pulley I05 secured to the shaft of a suitable motor I08. The variable speed pulley I05 is of well-known construction, and it is therefore thought unnecessary to herein describe the same in detail.

The motor I06 is shown mounted upon a suitable base I0'I supported upon an arm I08, which has one end pivotally connected to a pair of lugs IIO,'shown provided upon the cover 99 of the casing 95. The opposite end of the arm I08 is forked to receive a flanged head I09 provided upon a member I II having an operating handle II2, whereby it may be conveniently rotated. The member III is received in threaded engagement with a threaded stem II8, the'lower end which is secured to a block II4 pivotally m unted upon the cover 99 of the casing 95, as indicated at II5. By rotating themember H2 in one direction, the arm I08 will be elevated,

whereby the motor is likewise elevated to tighten.

The rocker shaft I I8 is rotatably mounted I23 which is suitably secured thereto, as shown in Figure 7. A forked link I24 has one end pivotally connected to the arm I23 and a suitable pin I25 is mounted in the opposite end of the link with suitable collars I26 adaptedto slide between guides I21 and I28 provided in an oscillatable member I29, supported within the casing 95. The member has its upper end mounted upon a pivot pin I3 I secured in the casing 95, as best shown in Figure 9.

A slide I32 is mounted for reciprocal movement in guides I33 provided in the member I29, as best shown in Figure 8. The slide I32 is provided with oppositely disposed inclined stepped edges I34 adapted to be enga ed by a V-shaped block I35, mounted upon the pivot pin I25 sup-. ported in the forked link I24. The member I29 is oscillated by an eccentric I38 secured to a shaft I31 which is driven from the drive shaft IOI by a suitable train of gears, generally indicated by the numeral I38, whereby the eccentric shaft I3I will rotate at a relatively lower rate of speed than the drive shaft IOI.

- As a result of the geared connection between the drive. shaft IM and the shaft I31, the latter will rotate continually when the stoker is operating and will thereby continually oscillate the The rocker shaft H8 is I24, and is shown provided at its ends member I29, whereby an oscillating movement is I imparted to the forked arm I23, because of its connection with the link I24 of the member I29.

To vary the amount of fuel fed into the furnace for each stroke of the feed shoe, the degree of oscillation of the forked arm I23 is varied. In other words, when the maximum amount of fuel is fed into the furnace per stroke of the feed shoe, the forked arm I23 isoscillated its maximum stroke, and when less fuel is required, the stroke of the forked arm I23 is shortened which, of course, directly effects the reciprocal movement of the feed shoe because of its operative connection therewith through the coupling III.

To thus vary the degree ofoscillation of the forked arm I23 and therefore the stroke of the feed shoe 48, the slide I32 in the member is mounted for longitudinal adjustment,- whereby the inclined edges I34 thereof may be moved with respect to the V-shaped block I35. In Figure 7, the slide is shown adjusted to impart maximum movement to the forked arm I23, wherein it will be noted that the oppositely disposedv inclined edges of the V-shaped block I35 is engaged with both of the inclined edges I34 of the slide I32, whereby no lost motion is permitted between the block I35 and the inclined edges I34 of the slide. When ,the slide is thus positioned, the arm I23 will be operated at its maximum stroke. When it is desired to feed less fuel into the furnace, the slide I32 is relatively moved in the member I29 in a direction towards the pivot pin I3I, as best shown in Figure 8, whereby a lost motion is provided betweenthe inclined edges I34 of the slide and the V-shaped block I35, thereby reducing the stroke of the arm I 23 and therefore, the stroke of the feed shoe 48.

Control means The means provided for relatively adjusting the slide I32 in thememberis best illustrated 'in Figures 3, 7, 10, and 11, and comprises a rocker shaft 136 mounted in a suitable bearing I39 in a wall of the casing 95, as best shown in Figure 10. This rock shaft has at one end, a crank arm I to which is secured a block I42 slidably supported in an arcuate guide groove I43 provided in the slide I32, as best shown in Figure 8. The curvature of the guide groove I43 is in the formof an arc struck approximately from the axis of the pivotpin I3I so that the member I29 may oscillate without imparting any relative movement to the slide I32 thereof.

To the opposite end of the rock shaft I38, there is secured a lever I44 having a suitable opening I45 adjacent its upper end adapted to receive a quadrant bar I46, one end of which is pivotally connected to an arm I41, the lower end of which is loosely mounted upon the rock shaft I38. The bar I46 has a plurality 'of spaced notches I48 adapted to engage a suitable pin I49 traversing the lower portion of the opening I45 of the lever I44. A latch member I5I is pivotally mounted in the arm I41 and has its lower end I52 adapted to be received in a notch I53 provided in the upper edge of a plate I54, mounted for relative rotary movement upon the hub of the arm I41. The plate I54 has a link I55 connecting it to an .arm I56 secured to a shaft I51 mounted in suitable bearings which may be provided within or on the gear casing 95. One end of this shaft may be connected to a suitable automatic control, not shown in the drawings.

The upper end of the latch member I5I is shown provided with a suitable projection I59 adapted to be selectively received in aplurality of notches.

I59, I6I, and I62, provided in a portion of the bracket 96 which provides the connection between the main frame of the stoker and the gear casing 95, as shown in Figure 3. When the latch member I5I is engaged with one of the notches I59,

' I6I, or I62, as best shown in Figure 10, the con-' trol mechanism is adapted for manual operation.

When the latch I5I is positioned for manual. I32 is relatively adjusted in operation, the slide the member I29 by oscillating the lever I44, WhiGhI iS normally retained in adjusted position by the notched bar I46 engaging the pin I49 thereof.

When the adjusting lever I44 is positioned as shown in Figures 7 and 11, the slide I32 is positioned to impart maximum movement to the arm I23 of the rock shaft II6. To relatively adjust the slide I32 in the member I29, the adjusting lever I44 is moved in ,a direction towards the right, when viewed as shown in Figures? and 11, which may readily be accomplished when the notched bar I46 is moved upwardly to free the pin I4I therefrom. The notched bar I46 is shown pro-'- vided with a suitable hand grip I63, whereby it may be conveniently manipulated, as will readily be understood by reference to Figure '7.

When the latch member II is in the notch I59, the parts are positioned for maximum movement of the rock shaft 53 and may be adjusted from maximum within predetermined limits by I34 of the slide I32. In like manner, when the latch member I5I is moved into. locking engagement with the notch I62, minimum rocking move,- ment may be imparted to the shaft 53, whereby the feeding of the fuel into the furnace may be reduced to minimum. Thus, it will be seen that the above described mechanism provides means whereby the feeding of the fuel into the furnace may be controlled at will. The mechanism also is so arranged that it may be used for either manual or automatic operation, which is desirable in the operation of stokers, in that it is often desirable to control their operation automatically,

while at other times, it may be deemed more desirable to manually control their operation.

Operation .shoe. The spreading of the fuel over the fire bed is controlled by adjustment of the feed'plate 36 and the speed of the rotor. All of these adjustments may be conveniently made while the stoker is imoperation as they are readily accessible, as clearly illustrated in Figures 2 and 3. Because of the motor being supported directly upon the main frame of the stoker, it becomes, in effect, an integral part thereof, and provides a unitary structure which may readily be secured to the wall of a furnace without danger of any of the working parts of the stoker becoming disalined, thereby assuring that the stoker will always operate with minimum friction and substantially without vibration. Also, because of the operating mechanism of the stoker, including the gear train 38 and the member I29, and its associated parts, operating in a bath of oil withinthe gear case 95, these parts are substantially noiseless in operation, which is a very desirable feature in the operation of a stoker.

I claim as my invention:

1. In a stoker, a rotor, a fuel hopper, an inclined feed plate forming the bottom of the hopper having its discharge end positioned over the rotor,

, means mounted for reciprocating movement over to the stoker, and said gate being provided with openings permitting the circulation of air therethrough. a I

- 2. In a stoker, a rotor, a fuel hopper, a plate forming the bottom of the hopper and having its discharge end positioned over the rotor, a reciprocating feed shoe mounted over said plate to feed fuel from the hopper to the rotor, an air-cooled gate vertically adjustable to limit the amount of fuel delivered to the rotor per stroke of the feed shoe, and meanspivotally supporting the gate whereby the latter may yield, when engaged by tramp with the fuel, to thereby permit such foreign objects to pass through the stoker without damaging. thesame.

3. In a stoker, a rotor, a fuel hopper having a iron and other foreign objects entrained bottom wall whose discharge end is positioned over the rotor and is adjustable with respect thereto, a reciprocating feed shoe mounted over said bottom Wall to feed fuel from the hopper to the rotor, a vertically adjustable gate for controlling the amount of'fuel delivered to the rotor per stroke of the feed shoe, and means pivotally supporting the gate whereby the latter may swing in the direction of fuel travel, when engaged by tramp iron and other foreign objects, thereby to permit such foreign objects to pass throughthe stoker without damaging the same, said gate having a plurality of air ducts therein for the admission of air into the fuel adjacent the rotor to facilitate combustion.

4. In a stoker, a rotor, a fuel hopper having a bottom wall whose discharge edge is positioned over the rotor, means for feeding fuel from the hopper to the rotor, a horizontally pivoted gate having its lower edge spaced from said bottom wall to provide an elongated feed opening, means for verticallyadjusting said gate to vary the size of the feed opening and thereby control the amount of fuel fed from the hopper to the rotor by the fuel feeding means, and said gate comprising a plurality of sections independently movable to permit'tramp iron and other foreign objects to pass through the feed opening without damaging the stoker.

1 5. In a stoker, a rotor, a fuel hopper, an inclined feed plate forming the bottom of the hopper and having its discharge edge positioned over the rotor, means mounted for reciprocating movement over the feed plate for feeding fuel from the hopper to the rotor, a gate mounted for vertical adjustment with respect to the bottom wall and comprising a plurality of pivoted sections adapted to swing about a common horizontal axis, said gate limiting the amount of fuel delivered to the rotor per stroke of the feeding means, and said gate sections being adapted to yield independently of one another, thereby to permit foreign objects to pass through the stoker without damaging the same.

6. In an overfeed stoker, a rotor, a fuel hopper, an inclined feed plate forming the bottom of the hopper and having its discharge edge positioned over the rotor, means mounted for reciprocating movements over the feed plate for feeding fuel from the hopper to the rotor, a gate mounted for vertical adjustment with respect to said bottom wall and whereby the amount of fuel delivered to the rotor per stroke of the feeding means may be varied, means pivotally supporting the gate whereby it may yield when engaged by a foreign object entrained with the fuel, thereby to prevent damage to the stoker, and means for driving said feeding means, comprising a suitable mechanism operable within an oil tight housing.

7. In an overfeed stoker, a fuel hopper, a rotor, a shaft for the rotor, means for feeding fuel from the hopper to the rotor, the intermediate portion of said rotor beingcomposed of a plurality of sections each having a plurality of blades disposed in substantially parallel relation to the axis of the rotor, and the blades of said sections being alinedlengthwise of the rotor and cooperating to provide elongated unbroken blade portions extending a substantial length of the'rotor, and other rotor sections having blades disposed at an angle to their axes and constituting the end portions of the rotor, said end sections having their blades abuttingly engaged with the blades of said intermediate section, whereby the end portions of the effective blades of the rotor are rearwardly inclined to the direction of rotation, thereby to spread the fuel outwardly to the sides of the fuel bed.

CHESTER W. BROS.

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