What are the mechanics behind the wheel and axle simple machine?

[gearhead]

I have a question about the simple machine: the wheel and axle. I know already that mechanical advantage through a wheel and axle system is achieved by force being applied through the wheel to turn the axle. This mechanical advantage would be in the form of you applying less force, but over a greater distance. But, if you do the opposite and apply the force through the axle to turn the wheel, then you would have to apply much more force, but over a shorter distance right?

 

[Phrak]

That's right. You can look at it another way too. You get more distance for the applied force.

 

[Naty1]

You can also think about the motion of the wheel and the axle circumference: one revolution of each is involved regardless of the source of the force...the circumference of the wheel is many times that of the axle...the wheel circumference always moves a much longer distance than the axle circumference...assuming they are rigidly connected.

 

[Naty1]

And by the way, wheels usually turn on axles...that is they are not rigidly connected so maybe thinking of different size gears might eliminate any confusion...Remember in the old cowboy movies when the wagon wheels were removed and grease applied between the wheel and axle??