Abstract: A heat engine employing a memory alloy and a force field such as gravity for converting heat energy into mechanical work. Field effect elements are mounted on the distal ends of flexible spokes which in turn are mounted about a hub to form a rotating wheel. The memory alloy is in the form of a helix disposed about the circumference of the wheel and interconnecting the ends of adjacent spoke pairs. Heat is transferred to segments of the memory alloy on one side of the wheel so that the segments deform toward their memory shape and deflect the associated spokes toward each other. Heat is transferred away from the memory alloy segments on the opposite side so that the segments deform toward their trained shape and permit the spokes to flex apart. The concentration of field effect elements onthe first side of the wheel is greater than the concentration on the other side so that the resultant force created by a remote field acts as a torque for rotating the wheel.