# I am on the train, useless but without me the train cannot work, what am I? [closed]

I am on the train, useless, but without me the train does not work, what am I?

• Welcome to Puzzling SE! I think this riddle may be "too broad", accepting several different answers that all fit equally well. E.g. driver, wheels, engine, or anything else involved in the mechanism of running the train. Jun 4 '15 at 23:32
• @randal'thor Not disagreeing that this is a broad puzzle, but I don't see your suggestions as being correct, for instance, the driver, engine, and wheels, all serve a purpose on the train (not useless) Jun 4 '15 at 23:38
• @caesay But how useless can it be if without it the train does not work? Jun 4 '15 at 23:42
• @randal'thor actually I think the OP wording is just slightly off, there's an old riddle "On the train I'm useless, without me the train is useless. Who am I?" (the answer is cargo or passengers). This doesn't fit this puzzle but I think it is along that vein. Jun 4 '15 at 23:49
• @randal'thor That's why I'm curious about what the OP's answer might be. I hadn't heard of the riddle that JGreenwell posted above, but my first thoughts were cargo as well - the train will not work without some purpose (in this case to move cargo). Jun 4 '15 at 23:52

Maybe

The passengers or merchandise

Reason

They are useless to the operation of the train, but if there were no passengers (or merchandise), the train wouldn't need to work.

• @JLee Thanks, english is not mother tongue Jun 5 '15 at 11:16
• Not really, if the train needs to go back to its point of origin or pickup something, it will be empty and not useless. Jul 8 '16 at 14:50

I have a bit of a different answer...

Hem

I know, not what you expected. Here's why it makes sense:

On a train of a dress, without a hem, the train is going to disintegrate as it's pulled across the ground, as fraying edges get worse. But the hem doesn't really do anything, it just exists.

I'll take a stab at it.

A long shot, but

gravity

does seem to fit

Could it be

Steam

Generally useless but needed for certain engines.

• I'm not sure it's useless if it's needed to power the engine. Jun 5 '15 at 0:34