Well, the focal length is a distance to the point in which all of the rays of a parallel beam cross. Since a parallel beam reflected by the mirror is still parallel and does not converge, no matter how far from the mirror it travels, the focal distance of a mirror is
f = -∞
minus sign denotes that the image in the mirror is imaginary
You could attach the pulley to a secure object on the top of the ramp, and crank the pulley to bring the wagon up said ramp into a loading bay perhaps, or a track.
