As shown in the figure, the ideal mechanical advantage is calculated by dividing the radius of the wheel by the radius of the axle. Any crank-operated device is an example of a wheel and axle. Force applied to a wheel exerts a force on its axle.
The work you put into a machine -- the input force -- is the force you apply times the distance you apply it. The work done by the machine equals the resisting weight times the distance it moves when you perform the work.
