In general, where were the air comp and elec gen located on a typical steam locomotive? I would guess that steam was the source of motion rather than axle connections, etc. that produced air and electricity. If so, could you all briefly describe the mechanism. I was around steam locos till they were phased out but never got past the obvious componnents, boiler, firebox, drivers, rods, cylinders, etc. Were there any batteries to store electricity or was it produced by the generator on a continious basis? I sound dumb but all you gurus can help on that. Thanks
Steam powered reciprocating air pumps provided air pressure to the reservoirs for the brakes and other air powered appliances. Steam driven turbines called turbo-generators provided electricity. No steam locomotive that I am aware of carried batteries. When the turbo was shut down, the lights go out.
Forgive the childish arrows, twas all I could find on the Photobucket photo editor.
The tubine driven electric generator is usually on top of the locomotive attached to the appliance dome (along with whistles, relief valves and such) at the back of the boiler. Our generators make 32 V DC which powers the lights and a voltage converter for the radio. The air compressor is normally too tall to be atop the locomotive so it is on the side or front of the boiler (being on the side makes cleaning out the smoke box easier). The compressor is usually a two stage compressor with an output pressure of 120 to 150 psig. After the air is compressed it has absorbed the heat of compression so it is hot. The grid of pipes along the side of the boiler is for cooling the high pressure air before it is stored in the locotive’s reservior. Most locomotives have two reservior tanks with a check valve between them and relief valves on one or both.
The generator usually starts with about 50 psig steam pressure. The air compressor usally takes full steam pressure (200 psig) to get it going but will compress enough to charge the train with air at 120 or so psig steam pressure. The problem you run into with too little steam pressure is that the air compressor won’t keep the reserviors charged up and you cannot run the brake system. Once the brake reserviors get down to 75 psig of air, you have to stop the train as there is not enough pressure to assure that the braking system will work. This depends on your fireman: he/she has to keep the water level up so the firebox crown sheet doesn’t soften and rupture and has to keep the steam pressure high enough to keep the air compressor going and the injectors going so you can add water to the boiler. A fun job once you get used to how the engineer and the track profile affect your need for steam.
Thanks much for the info. I see now that steam was the power source of all important accessories needed to safely run the loco and in addition provide some measure of comfort.
“In the winter, maybe. In the summer things can get pretty warm in the cab.” If you were lucky and had a cab with a back and doors. Otherwise in the winter your backside froze and your frontside roasted. In the summer…
Note that the radiator, or cooling coil, for the compressed air is located in-line between the tanks and the pump to encourage moisture in the warmed air to condense against the cool metal tubing. The accumulation of water condensate is collected at a low point in the apparatus and drained periodically. You don’t want moisture-laden air working through the brake pipes and system because it could/would freeze in cold weather.
