This occurred to me watching Jeremy Clarkson on Top Gear, manually shovelling coal into the furnace of a steam train. The train must produce many horse powers, why can’t some of those drive a belt that takes coal from the pile behind the engine towards or into the furnace? A friend said it’d be too heavy but the carriages must be many times heavier than a belt. Surely scooping coal onto a belt which throws the coal into the furnace would be easier than manually transferring the coal from the coal carriage over to the furnace and putting it in?
There’s probably a very simple answer after many years of research, that manually putting the coal in is better. What that answer is, is what I’m curious about.
I think it would create a problem if the mechanism broke down, making it harder to manually shovel the coal, and you’d need to have a guy there to do that shoveling anyway just in case. In the days of coal powered trains labor was cheap and machinery expensive. I know there were coal feed screws in the early 20th century, don’t know how long they’d been used or if they were ever tried on trains.
I can see several engineering problems that would have to be overcome.
You’d need a belt and transport mechanism that can stand a raging fire without damage, then a cooling cycle. The fuel drop-off point would have to be fairly far inside the burner, and you would have to be able to adjust it for an even spread. You would also need a way to load the belt consistently. Perhaps a man with a shovel?
You’d need a way to control the speed of the belt so you don’t load too much or too little.
All of these engineering challenges are well met by a human named John Henry.
Some steam engines did have mechanical stokers. Belts didn’t work very well, but many used augers (big screws) to push the coal into the engine. The problem with augers is that they can jam. Men with shovels are more flexible when there’s a problem.
Augers were more common on larger steam engines where men with shovels had a hard time shoveling enough coal to feed the huge engine.
You mean something like this mechanical stoker?
As you can see, they have been around for many years. I didn’t see Jeremy Clarkson doing any shovelling, but I imagine the loco wasn’t as big as some that did use the mechanical stokers.
One thing to keep in mind is that 100+ years ago labor was cheap. Sure, you could install a mechanical system but in many cases it would be cheaper and more reliable to use a human. The extra human in the cab also provided some help in other tasks. Something a mechanical system couldn’t do. As things progressed, keeping the fireman in the cab became a major union issue. So you were going to have a fireman there anyway.
My first thought was that the coal is in a separate hopper car attached to the locomotive (at least wt was on my Lionel), and the conveyor could therefore not be rigid, it wold have to flex for a curve in the tracks.
As a boy, our household coal furnace had a stoker, with a thermostatically controlled electric screw drive that delivered the coal from the hopper to the furnace. But I still had to shovel coal from the coal bin into the stoker, that held about a 2-3 day supply of coal (and pull the clinkers out of the furnace with tongs and throw them out in the snow to cool – do railroad firemen have to do that?). But our basement never went around curves so the screw from the stoker to the furnace could be fixed.
I would have thought that for safety reasons, you would want two men in the cab. Modern trains have a “dead man’s handle” so the train will stop if the driver drops dead. Steam trains had no such device and would just keep going until they hit something or ran out of steam.
The hospital where I used to work which was built in the 1970s, had coal fired boilers. The coal, which had to be the correct size, was fed into the boiler with a screw mechanism.
You also need to be able to deliver the coal at the right rate. A human can look into the furnace and see how much is needed, but it’d be harder to build that feedback into a mechanical system. You could, I suppose, have a man there looking into the furnace and adjusting a knob on the automatic system, but if you’re going to have the man there anyway, why isn’t he holding a shovel?
The systems were not automated.
The screw delivered the coal to the front of the fire box. The fireman controlled the speed that the coal was delivered. And he controlled where the coal was delivered to the fire box by steam jets.
The bigger engines used this method because a man could not deliver enough coal to keep up a head of steam.
Clinkers were removed when the engine was taken off line daily. The engine was driven to a dumping location. The grates in the bottom of the fire box were opened and all the ash and clunkers dropped out. Then the engine is taken to the round house where the daily maintenance and water testing was done.
Because a man can not shovel fast enough. The feed rate can be set automatically by using boiler pressure when traveling on the road. The problem would be starting and stopping. With coal there is a delay in building a fire and also a delay when cutting back a fire.
British locomotives were small enough that a mechanical stoker was not needed. British Railways did build locomotives with mechanical stokers in the 60s, mainly to allow lower grade coal to be used (lower grade = more coal needed), but did not find it worthwhile. That wikipedia entry says: “The success of mechanical stoker on North American railroads was mainly because the locomotives were significantly larger (with a suitably greater demand for coal) and many routes required hours of supplying coal at a rate beyond the physical limit of a single fireman.”
The locomotive featured in Top Gear was the LNER Peppercorn Class A1 Tornado. For comparison, the Peppercorn A1 has a firebox fire grate area of 50 square ft. The American 4-8-4 locomotives typically had fire grate area of 100 square feet, and was only made possible by mechanical stokers. The Big Boy had a 150 sq ft grate.
Huh, this is the first I’ve learned that John Henry wasn’t an actual historical figure (he may have actually existed, but if so, there doesn’t seem to be any reliable account of him, which makes him non-historical). I mean, some aspects of the story are clearly legendary (like his reputed prowess with a hammer even as an infant), but I had previously thought that the main events were historical.
Just incorporate a centrifugal governor connected with a mechanical linkage to the throttle and the coal auger. If the throttle is increased, it would increase the speed of the coal auger. As the steam pressure rose, it would slow the coal auger to maintain the pressure required by the throttle setting.
The famous Flying Scotsman, which should not be confused with the engine with the same name, had specially made tenders with a passage through them for a relief crew.
The London to Edinburgh trip took the best part of nine hours, too much for a single crew.
This train still runs, with electric locomotion, but only from Edinburgh to London and not in the other direction.