A motion retarding system includes a linear array of permanent magnets for providing a magnetic flux along with a diamagnetic member for engaging the magnetic flux and producing eddy currents in the diamagnetic member which results in the braking force between the linear array of permanent magnets and the diamagnetic member. A mechanism is provided for causing reciprocating movement of the diamagnetic member within the magnetic flux and coupling apparatus disposed in an operative relationship with the mechanism is provided for engaging a vehicle moving with respect to the mechanism, in order to reciprocate the diamagnetic member within the magnetic field and retard the motion of the vehicle past the mechanism.