Abstract: A thermally actuated motor which has a short piston stroke is provided with mechanism for converting the stroke to a selected longer stroke without prolonging the motor actuation time. The said mechanism comrises a base, means pivotally mounting the motor on the base, a crank arm pivotally mounted at one end on the base and having a fitting on its opposite end for connection to the object to be actuated by the motor; said crank arm being pivotally connected between its ends to the motor piston shaft. A limit switch is adjustably mounted on the base for contact by the crank arm. Coiled springs connected to the base and crank arm return the crank arm to normal position after it has been actuated by the motor shaft. In a thermal motor having an approximately 11/16 inch piston stroke, the mechanism converts the stroke to a selected longer stroke of approximately 3 inches.