Hanna Stoker on CB&Q 2-10-2 Class M3 6306

The CB&Q Class M-3 2-10-2 locomotives were built by Alco - Brooks Works in January 1919 to USRA design, and were delivered with the Hanna Stoker. Description as follows from 1914, by Brotherhood of Locomotive Firemen and Enginemen Magazine:

1. Introductory. - The Hanna mechanical stoker, same as the Street and Standard stokers, is of the overfeed, or scatter, type. In its original form it did not meet with the requirements of the Stoker Committee of the Master Mechanics' Association in that there was no mechanical means employed for conveying the coal from the tender to the hopper, from whence it was finally injected into the firebox. Instead of that there was a hopper located in the middle of the deck immediately back of the firedoor, into which it was necessary to shovel the coal, and as the screw conveyor located within the hopper could only handle lumps of a definite size, it was necessary when run of mine coal was provided to crack the lumps to a size that would permit of the screw conveyor handling them.

 

In the first type of Hanna stoker the curved pipe leading up from the screw conveyor was projected into about the center of the firedoor; in fact, it was necessary that a special firedoor be provided to which the curved pipe could be attached. Insufficient provision was also made to enable one to note the condition of the fire; in fact when it was necessary to look at or rake the fire the top of the curved pipe had to be disconnected, and when necessary to resort to hand-firing, the upper portion of the conveyor pipe, as well as the upper portion of the hopper had to be removed, and as the lower portion of the hopper still remained rigidly attached to the deck it made it a very awkward proposition for the fireman to fire the engine by hand.

 

As the original type of Hanna stoker has been considerably improved, and this improved type is gradually being adopted, we will treat of the same only in this paper.

 

While the Hanna stoker differs somewhat in general form and construction from the Street and the Standard, yet the principle involved is practically the same in that the coal after being conveyed to a point within the firebox is blown by means of steam jets and scattered over the fire as desired.

 

2. Description of the Improved Type of Stoker. - A hopper is provided in front end of the coal space in the tender, which is covered with a series of movable plates, this hopper being circular in form. The plates are made movable so that the quantity of coal fed to the hopper can be regulated by increasing or decreasing the opening over the hopper. The coal after dropping into the hopper falls into a trough in which is located a screw conveyor, this conveyor being operated by a small, double-acting, reversible steam engine, bolted to the frames on the left side. The screw conveyor carries the coal forward to a hopper located at the bottom of a curved pipe through which by means of another screw conveyor the coal is forced upward and discharged through the firebox door opening. When the stoker is in use the firebox door original to the locomotive is removed or swung to one side, and a sheet-iron plate, readily removable, is substituted. Fig. 1 shows clearly the hopper in the bottom of the tender as well as the curved pipe which serves as a conveyor to carry the coal into the firebox. As the coal is forced through this curved pipe it falls down on top of a cast-iron ridge plate, located just inside of the firedoor opening. On either side of this ridge plate there are two inclined cast-iron wings, which are hinged at the back and arranged so that they can automatically travel from the top to the bottom of this ridge plate. These wings form a trough for directing the stream of coal, which then slides down in front of the steam jets.

 

3. The Steam Jets. - Immediately below this ridge plate are two sets of steam jets, the upper group consisting of a series of fingers about three inches long and arranged in the form of an arc; in fact exactly the same as would be the extended fingers of your hand with the fingers spread out. Immediately below these fingers in a very thin flat opening from which issues a thin fan-shaped jet of steam, covering practically the whole area of the firebox.

 

As the coal drops down from the ridge plate in front of these jets, the larger pieces strike the fingers and are caught by the jets and blown to that part of the firebox served by the particular jets pointing in that direction. At the same time the finer and lighter particles of coal, passing between the fingers, are caught by the fan-shaped jet below.

 

Each set of steam jets is served by a separate steam pipe, and on each pipe there is located a small steam gauge so that the pressure in each pipe can be regulated as desired. This pressure must be regulated to conform the the length of the firebox and also to the quality of the fuel furnished.

 

The upper jets, that is, the finger jets, being used to blow the heavier particles of coal toward the front of the firebox necessarily must have a higher steam pressure than that of the lower or fan-shaped jet; therefore the finer particles of coal falling in front of the fan-shaped jet are blown into the firebox with less force and consequently the greater portion of the fine coal is deposited further back in the firebox.

 

There is another reason also for locating the finger jets above the fan jet in that it enables the heavier coal to be blown over the finer coal, thus forming a blanket over the dust and serving to prevent the escape of the same unconsumed into the flues, and also to burn a considerable amount of the dust while in suspension and thoroughly mixed with the larger and heavier coal.

 

Immediately below the carting carrying the jets is a cast-iron table plate, grooved out on both sides, in such a form that a certain portion of the coal is carried by means of these grooves into the back corners and immediately behind the door. This table is capable of a limited adjustment, in and out, to suit the conditions; that is, if it is desired to deposit more coal immediately under the door and into the back corners, this plate is moved backward, and vice versa.

 

The steam jets in the Hanna stoker, unlike those in the Street and Standard, operate continuously, although of course it is possible by means of globe valves located in the steam pipes to close either one or both of the jets as may be desired, or to vary the force of the jet at will, as the condition of the fire may require. The operation of the wings on the ridge plate gives the direction that the stream of coal shall take. Each of these wings is rigidly secured to a shaft which is continued through a universal joint to a point on either side of the firebox door and over the inlet pipe, and their movement can be controlled independently of each other. At the upper ends of these shafts are short cranks having a ball on the outer end and over the balls is slipped a spring latch, forming the end of the operating gear coming from the control arrangement on the left side. This arrangement is made so that it can be easily and quickly disconnected if desired.

 

4. The Operating Gear. - The rods connecting to the operating gear are secured to the top of a slotted block that is hinged at the bottom to a short crank arm operated by the handles on the quadrant shown at the left of the stoker. Fig. 2, which is a view of the stoker with the coal supply pipe disconnected for hand firing, gives a better view of the cab arrangement and shows clearly the two quadrants referred to, as well as the operating levers. In the slot in this block is a pin from the vertical arm of the rocker which is oscillated by an eccentric connection from the small stoker engine. The throw of this arm is capable of adjustment. Each of the wings in the stoker has a separate connection, consequently either can be adjusted as to its movement. If the control lever is so located that the pointed end of the block is at the bottom the slot will then be vertical in a center position and the wings of the stoker will have their maximum travel. Turning the operating lever so that the pin connection is at one side, the pin on the rocker will then simply slide back and forth in the slot and the wing casting controlled by the particular gear will have no movement, remaining stationary in a position at the top or bottom of its stroke, depending upon which way the control lever is swung. Therefore and position of the control handles between these two extremes will give either wing a motion from the bottom part way up its stroke or from the top, part way down and return in a regular cycle.

 

By throwing both operating levers to the top, the two wing castings will remain stationary and form a trough in the center and all the coal will be thrown underneath the flue sheet and on the forward end of the grate. If the handles are both placed at the bottom of the quadrants, the wing castings will remain at the bottom of their stroke and the coal will practically all be discharged into the back corners of the firebox; if one handle is placed at the top and one at the bottom, all the coal will then be fed along one side of the firebox, being scattered from front to back. If one is placed at the top of the quadrant, and the other is placed to give full stroke, a cycle of firing will occur through one-half of the firebox only.

 

From this it can be seen that the coal can readily be placed over any desired part of the grate area by the proper adjustment of the control handles. If it is desired to put a large amount of coal into the back corners or underneath the door quickly, it can be done by placing both control handles at the bottom of the quadrant, shutting off the blast, and allowing the coal to pile up on the deadplate, then with a quick blast through the fingers it will be discharged immediately under the door and into the back corners almost entirely.

 

5. The Stoker Capacity. - The amount of coal fed to the firebox will naturally be governed by the hopper opening in the tender and the speed of the small engine driving the worm. The steam jets will take care of practically all the coal that is placed in front of them, therefore the capacity of the machine is practically limited only by the speed of the small stoker engine.

 

6. Getting Engine Ready for the Road. - In getting an engine equipped with a Hanna stoker ready for the road, that is, firing it up in the roundhouse, that portion of the curved feed pipe immediately above the fire door, together with the auxiliary door used in stoker firing, is disconnected and the engine is fired up by hand in the usual manner. After the fire has been built up and the steam pressure raised to a point where the coal can be handled by the steam jets, the pipe is connected up again, the firedoor original to the engine is swung to one side, the auxiliary firedoor is mounted in place, and the fire thereafter maintained by the stoker. If it is desired to examine the fire or to rake down the banks, the lower half of the auxiliary door which is used in connection with the stoker, can be swung open so that a full view of the fire can be obtained or the hook inserted.

 

7. Inspection and regulation of Fire. - It is advisable in firing an engine equipped with this stoker, same as with any type of stoker, to occasionally look into the firebox to see that the proper distribution of coal is being obtained by the steam jets, as otherwise banks are liable to form which may make it necessary to use the hook in leveling them down. As a rule, however, after the engine has made a few mile with the stoker working, the intensity of the blasts, as well as the travel of the wing plates, can be so regulated as to avoid the necessity of any further regulation on the trip.

 

8. Performance of Stoker vs. Hand Firing. - So far there have not been enough of the improved type of stoker placed in service to develop its weak features, if any, consequently we cannot at the present time treat on its troubles and their remedies.

 

While there are other stokers in the course of development, none of them have yet reached the stage that would warrant their adoption, and consequently this paper must necessarily be incomplete. There is one fact in connection with all types of stokers, and that is that so far the best performance of any of them has not excelled the best hand-firing; what is meant by this is that a skilled fireman can deliver more pounds of tractive power at the rear of the tender per pound of fuel used, up to a certain limit, that has yet to be delivered by any type of mechanical stoker. However, as a fireman cannot keep up his best performant from one end of the division to the other, the stokers have in many instances shown an economy over hand firing, especially when applied on suck locomotives as consume a considerable amount of fuel.

 

It can also be seen from the foregoing that no stoker can handle successfully every kind of fuel that may be placed on the tender, as, for instance, with the overfeed or scatter type, the coal must necessarily consist of lumps no larger than can be readily handled by the conveyors or blown into the firebox where desired by the steam jets, while with the underfeed type of stoker mine run, or coal containing moderately large percentage of lumps, is best adapted, as where straight slack of fine coal has been used, considerable difficulty was encountered in trying to keep the coal from blocking in the conveyor troughs or from banking after it was forced into the firebox.

 

The mechanical stoker has, however, this advantage over hand-firing, in that its capacity being practically unlimited, and the fact that it does not become tired when near the end of a long, hard trip, coal of a lower fuel value can be used, and the coal of a low fuel value is naturally cheaper than the better grades, the mechanical stoker can readily show an economy in pound of tractive power delivered per unit of cost over that of the best hand-firing. At any rate the stoker is here and here to stay, as the demands for fuel necessary to develop the full capacity of the modern type of locomotive that are now being constructed is far beyond the capacity of any fireman, and for that reason we can look forward to the time, and it is not that far distant, when practically all freight locomotives, and perhaps the heavier type of passenger locomotives, will be fitted with some type of mechanical stoker.

Done