Stoker Engines

[The Old Dessauer]

Wow, thanks for the in-depth information.

[Dr D]

Checking the New York Central Firemans course of study gives general operating instructions and description of common design of locomotive stokers.  An explanation of basic parts - DISTRIBUTION TABLE, ELEVATOR PIPE, INTERMEDIATE UNIT, STOKER ENGINE, and CONVEYOR SCREW, etc.  Following this is an overview and general explanation of the commercial stoker systems.

These firebox stoker systems used on the New York Central are as follows.

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STANDARD HT STOKER - The stoker engine unit can be mounted on the locomotive or tender.  The stoker engine can be controlled with a steam throttle valve to adjust the amount of coal delivered.  Pulsations on the steam indicator gauge gave an indication of the running speed of the stoker.  Directional control of the stoker engine allows it to be reversed to clear obstructions that enter the stoker.  Steam supply to the stoker was through the stoker throttle or also through an additional steam supply with a booster valve which increased the stoker engine power to clear exceptionally large clumps of coal.

STANDARD BK STOKER - This unit is similar to the STANDARD HT STOKER with the exception of the coal distribution table in the firebox door.  The stoker engine may be located in either the locomotive or tender.  This unit has no coal delivery elevator conveyor screw in its design. 

STANDARD B STOKER - This stoker unit varies from the STANDARD HT AND BK STOKER in the design of the coal distribution table.

STANDARD MODIFIED B STOKER - This stoker is called the MB and New York Central Railroad includes a discription the same as STANDARD B STOKER.

THE DUPLEX STOKER - This unit has two coal elevator screw delivery systems one for each side of the locomotive firebox.  There is a central firebox door and a right and left stoker feed - one on each side of the locomotive backhead.  These two stoker elevator conveyor screws can be operated independently.  A door on the locomotive cab floor can be opened to clear obstructions of the coal delvery.  A booster valve is also provided to clear lumps of coal.  Failure of the DUPLEX STOKER allows the engine to be manualy fired because the stoker distribution tables are not in the way of the firebox door.

STANDARD LT-1 AND LT-2 STOKER - This system combines the features of the DUPLEX AND HT STOKERS.  These stoker systems combine the drive and the engine systems of the DUPLEX STOKER design with the coal distribution table system of the STANDARD HT STOKER design.

HANNA SF TYPE STOKER - This system uses similar coal delivery screws and crusher as others, but features two small cone shaped elevator screws that are found within the firebox door coal distribution table of the stoker.  This coal distribution plate has two chanels to send coal to the back corners of the firebox.

HANNA STOKER H4 TYPE - This is similar to the HANNA SF STOKER but uses a different firedoor coal distribution table.  The HANNA H4 STOKER does not use the small twin cone screws of the HANNA SF STOKER but uses instead two coal deflector gates in the firebox door coal distribution table.

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Hope this helps understand a variety of locomotive stoker systems.

Doc

[NDG]

 

Thank You.

 

[gmpullman]

I'm familiar with a 1918 USRA Mikado with the Duplex stoker engine mounted below the cab. There was a square drive shaft going to a gearbox under the tender coal hopper to drive the main auger that brought the coal forward to the dividing plate where the two elevator screws would lift the coal to the distributor plate.

The exhaust was piped along the left side running board then curved up the smokebox and exited just behind the stack.

I have seen the Reading T-1s running and I know the stoker exhaust was similarly piped just behind the stack, too. I believe these engines had a Simplex stoker.

A good reference for the study of steam locomotives are the International Correspondence School books. 

Have Fun, Ed

[The Old Dessauer]

Thank you for the insight. I appreciate the reply.

[Wizlish]

The Old Dessauer

Depending on the model and railroad, were some mounted under the cab while others mounted in the tender?

Yes.  It depended on the manufacturer of the stoker (and no little on which patents might need to be worked around).  Most if not all modern ('20s-'40s) models were available with either 'engine' or 'tender' motor drive as a specification option.  I don't know the precise motorand driveline locations for different manufacturers, but there are some here who will.

There are different advantages to having the stoker engine on the locomotive or in the tender: how the steam gets to and from the engine; how accessible the engine is for maintenance or 'unblocking' of the worms;  that the steam lines have solid or flexible connections.  A principal one that is not obvious, to quote one manual:

"The tender application is particularly adaptable when the weight on the trailing truck journals has reached the permissible limit ...."

this becoming very important as grate area and firebox size increased, plate spec became heavier to accommodate higher boiler pressure, and heavy syphons or circulators were installed inside the firebox and chamber, all the while attempting to keep the trailing truck at a mazimum of two axles...

I personally think some of the tendency 'not' to fit boosters on later large road power was related to this weight issue.  While much of the booster's mass was not taken on the 'journals' of the trailing truck, it would show up in the net axle or wheel loading, and in things like calculations for bridge Cooper rating.

[The Old Dessauer]

I'm doing some research about stoker motors on steam locomotives.  Depending on the model and railroad, were some mounted under the cab while others mounted in the tender?  Where would you see the exhaust steam when they were working?