A Motor comprising: - a housing containing a liquid and a working mixture comprising at least vapour from the liquid , the housing comprising at least one cooling wall and at least one heating wall ; - a cold source configured to cool the at least one cooling wall and wherein the working mixture , the cold source and the working mixture are suitable for being disposed on either side of the at least one cooling wall ; - a hot source configured to heat the liquid or at least one heating wall , wherein the hot source and the liquid are disposed on either side of the at least one heating wall ; - a movable means , arranged inside the housing , movable between a first position and a second position , the motor being configured in such a way that • the heat exchange between the working mixture and the at least one cooling wall in the second position is greater than the heat exchange between the working mixture and the at least one cooling wall in the first position; • the movable means allows contact between the liquid and the working mixture in the first position and the movable means is interposed between the liquid and the working mixture in the second position ; - an actuator capable of moving the movable means from the first position to the second position and vice versa; - at least one cylinder comprising at least one piston , the said piston being different from the movable means and the actuator , a chamber of the said cylinder being fluidly connected to the housing , so as to be in contact with the working mixture characterized in that the motor is configured so that the temperature and pressure conditions applied to the liquid during the operation of the said motor remain below the temperature and pressure conditions so that the liquid does not boil. - a housing containing a liquid and a working mixture comprising at least vapour from the liquid , the housing comprising at least one cooling wall and at least one heating wall ; - a cold source configured to cool the at least one cooling wall and wherein the working mixture , the cold source and the working mixture are suitable for being disposed on either side of the at least one cooling wall ; - a hot source configured to heat the liquid or at least one heating wall , wherein the hot source and the liquid are disposed on either side of the at least one heating wall ; - a movable means , arranged inside the housing , movable between a first position and a second position , the motor being configured in such a way that • the heat exchange between the working mixture and the at least one cooling wall in the second position is greater than the heat exchange between the working mixture and the at least one cooling wall in the first position; • the movable means allows contact between the liquid and the working mixture in the first position and the movable means is interposed between the liquid and the working mixture in the second position ; • the heat exchange between the working mixture and the at least one cooling wall in the second position is greater than the heat exchange between the working mixture and the at least one cooling wall in the first position; • the movable means allows contact between the liquid and the working mixture in the first position and the movable means is interposed between the liquid and the working mixture in the second position ; - an actuator capable of moving the movable means from the first position to the second position and vice versa; - at least one cylinder comprising at least one piston , the said piston being different from the movable means and the actuator , a chamber of the said cylinder being fluidly connected to the housing , so as to be in contact with the working mixture characterized in that the motor is configured so that the temperature and pressure conditions applied to the liquid during the operation of the said motor remain below the temperature and pressure conditions so that the liquid does not boil. <EOS>