US2021203A - Coal stoker - Google Patents

Coal stoker Download PDF


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US2021203A US689869A US68986933A US2021203A US 2021203 A US2021203 A US 2021203A US 689869 A US689869 A US 689869A US 68986933 A US68986933 A US 68986933A US 2021203 A US2021203 A US 2021203A
United States
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Oscar W Savage
Savage Stanley
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Oscar W Savage
Savage Stanley
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    • F23K3/00Feeding or distributing of lump or pulverulent fuel to combustion apparatus
    • F23K3/10Under-feed arrangements
    • Y10T74/00Machine element or mechanism
    • Y10T74/21Elements
    • Y10T74/2142Pitmans and connecting rods
    • Y10T74/2151Longitudinally adjustable


Nov. 19, 1935.
O. W. SAVAGE El AL COAL STQKER Filed Sept. 18, 1955 2 sheets-sheet 1 arn/v.4 E Y 5414465 SQ ATTORN N 1935- o. w. SAVAGE El AL COAL STOKER I 2 Sheets-Sheet 2 Filed Sept. 18, 1933 lllilll I Patented Nov. 19, 1935 COAL STOKER Oscar W. Savageand Stanley Savage, Seattle, Wash.
Application September 18, 1933, Serial No. 689,869
' 2 Claims. (01. 110-109) This invention relates to improvements in coal stokers, and it has reference more particularly to stokers especially designed for use in combination with furnaces of the common types employed for residence heating, although it is to be understood that they are not limited to this particular use since they may be employed with entire satisfaction for other and various power and heating purposes.
It is the principal object of the present invention to provide a comparatively inexpensive stoker of a durable, efiicient and satisfactory character; that is simple in construction; easily accessible for adjustment, cleaning or repair, and
so designed that it may be readily installed in furnaces of the ordinary types without requiring any material alteration in the structure of the furnace to receive and accommodate the stoker grates.
It is also an object of this invention to provide a coal stoker of the character above stated, whereby fine coal is forced, under definite control, from a supply hopper and through a tube leading to the stoker grates, by the reciprocal action of a feed plunger operating in conjunction with a movable plate forming the bottom wall of the tube, which plate is reciprocally actuated by the plunger in a manner whereby clogging of the tube is avoided and the coal fed easily to the grates even when the finest of coal is used.
It is also an object of the invention to provide for a controlled feeding of coal by definitely regulating the effective reciprocal stroke of the plunger.
Another object of the invention resides in the provision of means for automatic delivery of ashes from the furnace to a position for easy removal.
Still another object is to provide a controlled,
forced delivery of air to the fire box through the stoker tube in a manner to effect complete and satisfactory combustion of fuel.
Other objects of the invention reside in the details of construction of the various parts; in
their combination and mode of operation as will hereinafter be fully described.
In accomplishing these objects of the invention, we have provided the improved details of construction, the preferred forms of which are illustrated in the accompanying drawings,
wherein Fig. 1 is a longitudinal, sectional view taken in a vertical plane, of a coal stoker embodying the present invention.
Fig. 2 is a diagrammatic sectional detail illustrating an alternative construction asapplied to the ash removing parts.
Fig. 3 is a top, or plan view of the stoker; the hopper and motor being removed and the stoker tube being shown in horizontal section for pur- 5 pose of better illustration.
Fig. 4 is a view, with parts omitted showing the plunger operating mechanism and means for effecting adjustment in the efiective length of the plunger stroke." 10
Fig. 5 is a side view of the stoker as applied to a furnace.
Fig. 6 is a cross section of the stoker tube as seen on line 6-- 6 in Fig. 3.
Fig. 7 is a diagrammatic outer end elevation of 15 the stoker.
Referring more in detail to the drawings- The present stoker, as herein illustrated, is designed especially for use in combination with the usual types of residence heating furnaces 20 such as that designated by reference character i in Fig. 5, which has the usual ash door opening 2 located below the usual firing door 3, making it possible to install the stoker simply by removing the usual coal grates from within the 25 furnace, and the door from the ash opening, then projecting the grate casting at the end of the stoker tube into the furnace through the ash door opening as clearly shown in Figs. 1 and 5.
The stoker embodied by this invention, briefly 80 described, consists of a cast metal housing 5 fastened securely to the outer end of the stoker tube 6, which tube in turn is fastened securely to the stoker grate housing I. A coal supply hopper 8 is mounted on the tube and feeds coal, by 35 gravity fiow, to the tube and the coal is advanced in the tube onto the grate bars within the grate housing 1.
As will be readily seen by reference to Figs. 1 and 6 of the drawings, the coal delivery tube 6, 40 or what has previously been referred to as the stoker tube, is divided by a horizontal partition plate i0 into upper and lower longitudinal passages; the top passage I i being for the passage of coal from the hopper to the stoker grates and 45 the lower passage I! being for feeding of air to aid combustion. The plate in is supported for reciprocal movement in the tube by bars, or strips I3-i3' fixed to opposite side walls of tube 6, and at its inner end it slidingly overlaps a horizontal partition wall 13 within the grate bar housing land at its outer end it rests slidingly upon a transverse, vertical wall I4 that closes the outer end of the air delivery passage as seen in Fig. l. 55
Reciprocally contained in the outer end portion of the tube 6, within the coal delivery passage H, is a coal feeding plunger 15 having-an outwardly extending shank l6 passing through an opening IS in a wall of housing 5 and connected with a cross head l1 that is reciprocally slidable between guide rails 18-18 formed on a cross plate l9 fixed within the housing 5.
Revolubly mounted in vertically alinecl bearings 20-20 formed in the bottom wall of the housing 5 and on the plate 19, respectively, is a shaft 22 which has a worm gear wheel 23 fixed thereon between the bearings. A worm shaft 24 is mounted horizontally in bearings 25 in thev housing 5, as seen in Fig. 3, and has a worm 26 in driving mesh with the worm gear 23. The shaft 24 has one end extended to the outerside of housing 5 and is equipped with a belt pulley 21. An electric motor 30 is fixed upon the housing 5 and this is equipped with a belt pulley 3| with a belt 32 operatingthereover and about pulley 21 to drive the shaft 24.
Fixed on the upper end of shaft 22, just above .plate 19, is a wheel 35 and mounted on the wheel by an eccentrically located stud 36 is a roller 31. This roller is disposed between the cross head 11 and a cooperatively arranged cross head 38 that is reciprocally mounted by the guide rails l8-l8 and is connected with the cross head i1 by an adjusting screw 40.
As will be observed best by reference to Figs. 1 and 4, the screw 40 is rotatably mounted in cross head 38 but is held against longitudinal movement relative thereto by a hand wheel M at its outer end and a collar 12 engaging the opposits side of the cross head. The inner end portion of the screw is threaded through the cross head i1. Therefore, it is apparent that by turning this screw, the cross heads i1 and 38 may be adjusted toward or from each other.
Should it be desired to obtain the maximum stroke of the plunger for feeding coal to the furnace, the screw 40 is manipulated to draw the two cross heads closely against opposite sides of the roller 31. Then, as the wheel 35 rotates, the rotary motion of the eccentric roller is translated. to reciprocal movement of the plunger. Should it be desired to lessen the effective stroke of the plunger, the cross head 38 is moved away from cross head l1, as seen in Fig. 1, to permit a certain amount of lost motion in the driving action of the roller. The outward movement of the plunger will thereby be lessened in accordance with the increase of space between the roller 31 and the cross head 38, at the completion of the inward stroke. By reason of the fact that there is no relative adjustment between cross head I1 and the plunger I5, the inward limit if movement of the plunger will always be at the same place, but its outward stroke will depend on the closeness with which the cross head 38 is adjusted to cross head 11.
When the plunger is reciprocally actuated inwardly to its limit of travel by roller 31 acting on cross head 11, its forward surface will be flush with the inner edge of the hopper opening. When the plunger is retracted by roller I1 acting against cross head 38, the coal feeds downwardly from the hopper to fill in the space vacated by the plunger. Then on its forward action, the plunger pushes the coal forwardly along the passage I l to the grates. It is apparent that the rate of feeding of coal may be very accurately and definitely determined by the setting of. the cross head 38 relative to cross head" thereby to regulate the extent of the stroke of the plunger in its outward travel.
Heretofore, it has been observed that coal stokers employing reciprocating plungers for feeding fine coal through a tube to the stoker grates, 5 were unsatisfactory because of the tendency of the coal to pack in the tube. Apparently, the plunger had a pulverizlng action on the coal that was detrimental to easy feeding. Therefore, in the present instance we have provided the mov 10 ably mounted bottom plate I0 for the passage II and we effect a reciprocal action of this plate in accordance with forwarding action of the plunger so that the coal in the passage is bodily moved along the entire length of the passage and 15 is thereby relieved of that pulverizing pressure of the plunger that would tend to pack it. To effect this movement of the plate 10, a cross piece 50 is fixed on the plate near its outer end, and this has a vertical flange 5| extending into a re- 20 cess 52 formed in the under edge of the shank iii of the plunger. The length of the recess is such that it provides a lost motion connection whereby the movement of the plate 10 is of lesser extent than the plunger movement. How- 25 ever, on every outward movement of the plunger, the inner end of the recess engages the flange 51 to pull the plate outwardly, and on each inward movement of the plunger the outer end of the recess engages the flange to push the plate 30 inwardly. The combined actions of the plunger and plate provides a very easy feeding of coal and thereby makes possible use of a motor of lesser power than otherwise would be necessary.
The grate housing 1 consists of a casting 35 formed with opposite side walls 10-10, a top wall 1| covering its outer end portion, a lower wall 12 and the previously mentioned horizontal partition wall 13 extending from the outer end of the casting a short distance inwardly. The 40 hopper tube 6 is joined with the outer end of this casting so that the coal passage ll registers with the open space between the side walls 10-10 and the top and partition walls 1| and 18. The
inner end of plate 10 flatly overlies the wall 13. 45
the opposite side walls 10-10 of the casting, 55
and, as it burns, it is pushed successively from one grate bar to the next lower one and finally the ashes are pushed over the end of the grate into the lower part of the housing for removal, as presently described.
The grate bars ID are transversely corrugated and are arranged in overlapped relation and in a manner whereby the corrugations cooperate to provide air spaces between the bars for delivery of air through the grate to the top side as an aid to combustion. Also, there are air passages 18 leading upwardly at opposite sides of the casting from the air space below the grates and these open at their upper ends into horizontally directed channels 19, in the under surface of the 7 top wall 1 I.
Air is delivered forcibly into the air channel I! at the outer end of the stokertube I by menu a blower fan ofatandard entirety at I.
from and is coaxial of the motor 30, as seen in Fig. 7, and has its shaft driven directly by the motor and an air delivery tube 82 from the fan housing leads into the air channel H through a side opening 83 of the latter as seen in Fig. 1. Thus air supplied under pressure by the fan is forcibly delivered along the channel l2 and through the grate bars and through the passages 18-19 to the fire to effect completeand satisfactory combustion. The amount of air admitted is regulated by opening or closing a damper plate 85 overlying the air intake opening 86 of the fan housing 80 and thus the rate of burning may be retarded or quickened as desired.
Attached to the under side of the grate bar housing is a forwardly directed tube 90, the bottom wall of which is extended to the inner end of the casting l to catch the ashes which fall from the grates. An end gate 9| is disposed across the inner end of the casting I, pivotally suspended by a cross rod 92 and connected pivotally at its lower edge, as at 93, to a link 9 which extends forwardly and is pivotally connected at its outer end by a pin or bolt 95 to a crank arm 96 fixed on the lower end of the driven shaft 22. Thus, with each rotation of shaft 22, the gate 9| is swung rearwardly and then forwardly and pushes the ashes forwardly along the tube 90 to the outer end for delivery into a pan or pit at the outside of the furnace. In this arrangement the reciprocal and also oscillating action of the link in the tube keeps the ashes loosened or agitated so that packing in the tube does not occur.
As a detail of construction, the outer end of the stoker is supported by a two piece adjustable leg 98 as seen in Fig. 7, bolted to the casting 5. This has a roller 99 at its lower end to facilitate shifting the stoker into or from the furnace.
In Fig. 2 we have shown an alternative construction as applied to the ash tube. In this arrangement, a plate I is reciprocally movable on the bottom wall of the tube and is connected pivotally at IM with the link 94. At its inner end the plate has an operating connection at I03 with the gate 9|.
With the stoker constructed and installed as described, it is quite apparent that the coal will feed by gravity into the stoker tube and that it will be advanced by the combined reciprocal action of the plunger and plate It, and fed in regulated amounts dependent upon the adjustment of cross head 38 with respect to cross head l1; the rate of coal delivery being governed by the efl'ective stroke of the plunger.
Such devices are relatively inexpensive; are
easy to install; may be accurately regulated and will deliver the ashes to the outside of the furnace.
As a feature of construction, the ash removing means is so connected with the drive shaft 22 that its operating stroke will alternate with the coal forwarding stroke of the plunger, thus to avoid any overload on the motor and make possible use of a motor of less power.
Another feature of this construction is to be found in the lost motion connection between the coal feeding plunger l5 and the feed plate It. It is apparent by reference to Fig. 1 that when the plunger l5 starts on its outward movement, coal will be admitted from the hopper to fill in the space vacated by the plunger. This space is filled to a certain extent before the plate It starts on its outward movement. This is important for the reason that should the plate It start to move rearwardly with the plunger, it would be apt to carry coal in the tube 6 rearwardly and there would not be a desired downward feeding action from the hopper.
Stokers of this character are satisfactory for various heating and power producing purposes other than general residence heating, and while it is believed to contain various novel features in general construction, its most important features reside in the combination of reciprocating plunger and feed plate I0 whereby easy feeding of coal is made possible by the plunger and plate action.
Having thus described our invention, what we claim as new therein and desire to secure by Letters Patent is- 1. A coal stoker comprising a. grate housing, a feed tube comprising air and coal delivery pas- 86 sages leading into the grate housing, said passages being separated by a horizontal feed plate adapted to support the coal in the coal passage, a hopper arranged to feed coal by gravity flow into the coal passage, means for effecting a forced delivery of air into the air passage, 2. plunger reciprocally movable in the coal passage to control admittance thereto of coal from the hopper and to effect its advancement within the tube to the grate housing, and means for eflecting reciprocal action of the plunger and of the plate to cooperate in the advancement of coal along the passage.
2. A device as in claim 11 wherein the plunger has a longitudinal slot, and an abutment is fixed to the plate and extended into theslot in the plunger thereby providing a lost motion connection and delayed movements of the plate with respect to those of the plunger.
US689869A 1933-09-18 1933-09-18 Coal stoker Expired - Lifetime US2021203A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2495084A (en) * 1944-08-01 1950-01-17 Boston Safe Deposit An Company Variable stroke press

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2495084A (en) * 1944-08-01 1950-01-17 Boston Safe Deposit An Company Variable stroke press

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