Why are some train engines run backwards?

Question

I have noticed that some trains have their engines run in both directions, this is not always the case, sometimes they are run pointing in the same direction.

Sorry I have yet to agree with the current answers that, convenience is the only reason for running them backwards. And sorry an electrical motor does know the difference between forward and backwards. Look into the new flashlights and portable radios, that you crank up to power them up, they are small electrical motors inside them that are turned backwards creating electricity.........

Answer 1

The only locomotive that needs to be facing forward is the leading one, and that is strictly for engineers visibility and signaling requirements.
Because locomotives are electric drive they operate exactly the same way in reverse as in forward. Mechanically they dont know the difference. Even deisel locomotives are technically electric, they only have a deisel engine to generate electricity.
So, they are put together any way they are facing, it is quicker than taking time to turn a locomotive when it really doesnt matter.
Sometimes they will placed "back to back" so that when a locomotive consist gets to the end of aline with no way to turn around they can simply change operating cabs and go back where they came from.
and to complicate matters even more, some railroads have equipped their locomotives with the controls on the "wrong side" so the long end is forward, even though it looks backward form the outside, and then there are a few locomotives with dual controls so from the outside you never know which way is facing.
Most RRs have a small white "F" stenciled ont he front near the boarding steps.

Answer 2

We don't turn our locomotives because there's just no need to. They run exactly the same in either direction, and you're wrong when you say that the motors know the difference. With the flip of a handle, you're pumping the electricy the other way. That's all there is to it.

As for reasons to run a locomotive in reverse, there are a few. One, the long hood provides more protection to the crew in the event of a collision. If there's a crew member sitting on either side of the cab, the lost visibility isn't dangerous. If you're running a switcher, it's much safer (and more comfortable) to run in reverse, since the long hood is in front of the cab.

Second reason. There are certain situations where the locomotive is best facing in a particular direction. For example, if one of the moves takes place in a heavily populated area, you might want the cab to be leading the long hood for maximum visibility. If that leg of the journey rules the direction of the engine (and if there's no convenient place to turn it), then the crew might have to run backwards elsewhere.

Third reason. Convenience! Like I said, it really doesn't matter. Desktop controls are a pain to run backwards, but if it's a conventional control console it's really no big deal; there are headlights, class lights and number boards on either end. I actually prefer reverse because the brake handles are easier to work when I'm sitting the other way. That's a matter of preference, though. Bottom line is, they work just fine in either direction, so why take the time to turn them?

Answer 3

Rango gave the perfect explaination... 10 points

There are ALSO some commuter-passenger operations that operate in a Push-Pull manner. For example: CalTrain (San Jose to San Francisco) trains have a loco that pushes from the rear on the Northbound and then pulls on the Southbound. The car at the end opposite from the locomotive is a "Cab-Car" and has a compartment for an engineer to sit in the "front" when heading Northbound.

This is done for the simple reason that it would be a waste of time and money to pull the loco off at each terminal and either turn it around or put a new loco on the "new front-end".

Answer 4

There is no reason for this. Sometimes when you see unit trains, like grain or coal, there is often 1 or 2 on the front, and one on the rear facing backwards, this is because this train operates between point A and B on a regular basis. It's a pain to have to assign another locomotive to the train because the first isn't pointing in the direction of travel. On other trains, it's just the way they're assigned. Obviously, on the newer models, the first one is pointing in the direction of travel, but the 2nd, 3rd, 4th, etc..etc are just they way they were facing when they were assigned. Also, if you wanted to know why there is often locomotives in the middle or rear, I believe it's to prevent coupler strain.

Answer 5

You are certainly entitled to disagree with the answers above. However, whether in agreement or not, you aren't going to change the immutable, universal laws of physics.

Diesel electric locomotive run in either direction without complaint. Only the polarity of electrical supply is reversed when changing directions. All weight is on the drivers, evenly distributed.

The only other electrical consideration is, when locomotives start to move, the traction motors are wired in parallel, then, between 18 and 23 mph, switch gear changes the wiring set up to series, in what is called "transition." Sort of like changing gears in your automobile.

When in dynamic braking, the entire process is switched such that the traction motors are now producing electricity, which provides retarding effort (a lot of it), also in either direction. the electricity produced is dissipated as heat through the DB grids, which are kept cool by fans which are powered by the same electricity. That is why the audible "pitch" of the whine changes as retarding effort increases or decreases.

Usually a consist has units facing opposite directions of the ends for convenience in that they may be operated in either direction without turning the consist.

I'm sure new radios and flashlights are very technically advanced, yet I can usually figure out how to operate one. But then again, they aren't handling much tonnage, now, are they?

Answer 6

In some cases the last coach has a driving cab built in from where the driver can remotely control the locomotive. This a) saves time in that the locomotive doesn't have to run around the train, b) saves space - the line to pass the locomotive along isn't required c) saves manpower - staff are not required to uncouple / couple the loco to the carriages d) reduces the requirement for spare locos to be available if a run around isn't possible and therefore also makes loco rostering easier too.

Answer 7

I know this post is mega old but to clear it up for you a litte easier to understand , electric motors work in either dirction with no difference. What they mean is if its spinning clockwise and you want to make it spin counter clockwise. To do this you switch the polarity neg. and pos. and this will make it go the other way. I think you were confusing it with the actuall direction of current. if you put power into an electric motor it will run, if you have something that can power or spin the electric motor ie. your crank on radio then it becomes a generator. Thats just that basics describing it simply

Answer 8

If it's known that a particular train of many cars will need to "backup" or travel in the opposite direction during the course of it's run, it will have two (diesel) locomotives facing opposite directions so that the one that is facing "backward" is the one that is used when the train needs to go backward in that direction.

Answer 9

train engines run

Answer 10

rango, highball, and hoghead have the best answers all together. I work for the former Illinois Central Rail Road now called CN. I must say that I agree with what they have said and found it quite well put.