How did these steam engines provide electrical power to the train behind them?
Some sort of electrical steam generator? If so, how did the power get to the cars?
I’m talking of course of passenger cars. Was the power AC or DC? Did each passenger car have it’s own generator of some sort?
I know the very old cars had gas lanterns. Or did they?
Yours (Very Nostalgic), Jake
It’s complicated. Have a look at Head-end power - Wikipedia
This photo explains the arrangement on UK steam-hauled trains very clearly.
http://shovelling-white-steam.co.uk/wp-content/uploads/201212_carriage_dynamo.jpg
Very informative, I’ve always wondered that myself! 
For most of the lifetime of steam trains, there wasn’t any electricity provided to the cars. The old cars had kerosene lamps (later gas ones), heat was provided by stoves in each car, etc. Nothing in the cars that needed electricity until toward the end of the steam era.
I’ve ridden on some steam train excursions and these days they run a generator car right behind the tender. Got to have our air conditioning you know.
As explained in the Wikipedia article, this is just not the case.
Cars began to be electrified for lighting and other uses around the turn of the 20th century and in some countries, most notably China and India but also others, steam locomotives lasted well into the 1970s and 80s.
The system in the link provided by JBDivmstr is exactly what I remember from historical railway carriages here in Oz. In my youth we used to travel on historical train trips, pulled by steam, and in original rolling stock. There was a wide range of carriages, some were turn of last century German (WW1 reparations) complete with lovely inlaid woodwork depicting German forests. Other carriages were locally made. All pretty mediocre condition at that time.
The electrical system only provided light. It also dimmed when the train stopped. Probably due to lack of upkeep of the storage batteries. Heat was often by drums filled with hot water placed along the carriage. Cooling was by opening a window.
I’m pretty sure they went electric, early on, to reduce the risk of fire.
Interestingly, you can also get air conditioning through a steam supply. No, really. Santa Fe was probably the most prominent user of steam air-conditioning. It worked kind of like a swamp cooler with a steam jet producing a partial vacuum over a basin of water. The lower pressure induced evaporation and thus evaporative cooling. The chilled water was then pumped through a heat exchanger to cool the car’s interior air. It wasn’t terribly efficient and required a fair amount of maintenance. Santa Fe brass later admitted regret to not switching to more reliable mechanical AC earlier than they did.
Going off at a tangent, a bit; but a little regular use of steam locomotives still goes on in China – including, if I’m right, a couple of venues with regular passenger services. Steam locos also still see regular use at industrial locations in a few other parts of the world.
Thanks all, for the replies!
eburacum45, do you have the home computer address of the picture?
I do not understand this question. What do you mean? The address appears in your browser bar when you are viewing the photo in your browser.
http://shovelling-white-steam.co.uk/wp-content/uploads/201212_carriage_dynamo.jpg
In Northern Calif. before updating in the 1980’s. The cars were made in the 1920’s and 30’s. The lights were powered by batteries and generators connected to the car’s wheels. The cars with good batteries the lights did not dim. But the lights on the ones with weak batteries would dim or go out at every stop.
They also had steam heat. The engines had waste heat boilers on the engine’s exhaust. At night the main station had stationary boilers. On cold nights the boilers were light off to keep the cars worm. But if the stationary boilers were not fired up on a cold night the cars were really cold for the first run of the day.
I’m speaking to North American (US and Canada) practice, elsewhere YMMV.
From around WW 1 to the 1980s when head end power became prevalent, everything ran off a steam line under the passenger cars. The steam provided heat in the winter, air conditioning in the summer, and powered a DC generator to charge the previously mentioned batteries.
Some cars were occasionally built with an internal combustion generator or retrofitted if they went into branchline and mixed train service where the steam line was not available because freight cars were also handled.
Axle generators were not generally used on passenger equipment, but were common on cabooses. These were high maintenance items and a real PITA to maintain.
Head end power today is an electrical distribution line that runs under the passenger cars. Amtrak requires it on any car they haul, I’m not sure about VIA up north.
sailor, I enjoy pictures of steam engines with trains. I’m sorry I didn’t make myself clear in my post. I would like to know where you got the picture of the generator system so I can see more pictures of steam engines and railroads that were operating back in the forties and fifties. 
Have a look
http://shovelling-white-steam.co.uk/index.php/tag/railway-carriages/
http://shovelling-white-steam.co.uk/index.php/category/branch/
http://shovelling-white-steam.co.uk/index.php/category/excursion/
There’s plenty more just searching with Google
I’ve never heard of that system, but there are propane and natural gas fired refrigeration units, I wonder if one if those could run on steam? Steam can have quite high temperatures if the pressure is high.
In the US, steam engines were used at least into the 60’s for freight!