How to trains run?

Question

How to trains run?

Answer 1

Good question.

Trains ride on the rails and are kept on the rails by a flange on the inside of the rail.  The equipment is coupled together by the "draft gear", which includes the coupler, draw bar and center sill.  Some cars are equipped with either "sliding" sills or end of car cushioning device to help eliminate the shock from "slack action".

Locomotives that power the train are most usually diesel electric, where the diesel "prime mover" turns an alternator for electricity to power the traction motors, which are mounted on the axle.  Older DC locomotives had to have "rectifiers" to turn AC power output into DC to power the motors.  Newer units have traction motors that run on AC, and the rectifiers are not needed.  Overall, AC is a much better way to go, but it is relatively new technology.

Other locomotives are strictly electric, getting their electricity from wires suspended overhead by a "catenary", or from one or two electrified rails, usually referred two as the "third rail".  Voltage in the US is near 11,000 volts for catenary, and 600 in the UK.  I don't know about the voltage of US third rail electrification.

In other parts of the world, steam engines are still used.  There are many different types and are usually fueled by coal, oil, or wood, though the latter is relegated primarily to "tourist" railroads.  Simply put, the boiler produces steam which is then fed into two or more cylinders.

Most are used to seeing the "reciprocating" steam engine with the side rod and valve gear.  These can be "single expansion" or "compound engines", where the steam is expanded twice, once in the low pressure cylinders and again in the high pressure cylinders.  These fall into two types as the "Mallet" or "Vauclain" compound engines.

There are others that the cylinders drive gears mounted on trucks, which include the "Shay", "Heisler" and "Climax".  These are geared quite low as they were designed for logging operations.

Finally, there is the "condenser" type engines, which recapture exausted steam and condense it back into water before boiling it again to make more steam.  These are usually found on the African continent where, in many areas, water is in short supply.

And there ya go.

Answer 2

mostly on electricity these days.

Answer 3

i dont get your answer. did you mean, how do trains run? if you did then i have no idea.