How is the rail road crossing bar considered a lever?

Question

I have to create a project using three simple machines. I am doing a toy train. My inclined plane is inside the coal car which is helped to load coal easier. My wheel and axle is the wheels that help the train move. And the lever is the rail road crossing bar. The fulcrum would be the point where the 2 peices of wood are attached correct? The load would be the force on it??? And what would be the effort?

Please help me as soon as possible for my project is due friday.

thanks.

Answer 1

For a railroad crosssing gate, it's a little tricky.  The fulcrum is obviously the pivot point. However a crossing gate is very close to balanced (note the very heavy weights on the end away from the road).  The effort point is actually inside the motor drive box, and not easily seen.

But this coal car will have an air brake syetem, and the most interesting part of that is levers! Here is the simplest example I could find, they get much crazier than this!  http://en.wikipedia.org/wiki/Image:Brake...

The dark green cylinder pushes on the brake linkage.  Note that many links don't have a fixed fulcrum, but have two loads - one in each direction!  Got enough levers for you? :)

Answer 2

No. The cross bucks marking a grade crossing is not a lever.  The boards are stationary and do not apply any leverage.  A lever is used to operate a railroad track switch.  The lever operates the manual switch machine to move the switch points back and forth to select the desired track.  Your example would be more correct on a pair of scissors.