An injection molding apparatus comprising a clamp plate, a heated manifold, an actuator, a mold and a cooling device that cools the actuator, wherein when assembled the clamp plate and the mold are interconnected and spaced apart from each other, the manifold is disposed between the clamp plate and the mold and the actuator is mounted in thermally conductive communication with the manifold, characterized in that the cooling device comprises: a heat transmitter comprising a distal arm or member comprised of a rod or tube and a proximal base or member comprising a portion of the housing body that is laterally spaced from an axis along which the valve pin is driven, the actuator comprising a housing body (12, 12a) that is termally conductive and mounted in thermal communication with the manifold, the rod or tube being slidably disposed within a complementary bore disposed within the laterally spaced portion of the housing body, the complementary bore and the rod or tube being configured such that the exterior surface of the rod or tube is slidable and engaged in thermally conductive contact against an interior surface (12si, 12asi) of the complementary bore, the rod or tube being comprised of thermally conductive material having a distal end surface for engaging the clamp plate (80, 80a) under a spring load exerted by a spring loadable interconnection disposed between the rod or tube and the laterally spaced portion of the housing body such that the spring loadable interconnection can exert a spring load between the laterally spaced portion of the housing body and the rod or tube, the clamp plate, the mold, the manifold, the actuator and the heat transmitter being assemblable together in an arrangement wherein the spring loadable interconnection is loaded urging the distal end surface of the movable rod or tube into compressed engagement with the clamp plate (80, 80a) at least when the manifold is heated to an elevated operating temperature. a heat transmitter comprising a distal arm or member comprised of a rod or tube and a proximal base or member comprising a portion of the housing body that is laterally spaced from an axis along which the valve pin is driven, the actuator comprising a housing body (12, 12a) that is termally conductive and mounted in thermal communication with the manifold, the rod or tube being slidably disposed within a complementary bore disposed within the laterally spaced portion of the housing body, the complementary bore and the rod or tube being configured such that the exterior surface of the rod or tube is slidable and engaged in thermally conductive contact against an interior surface (12si, 12asi) of the complementary bore, the rod or tube being comprised of thermally conductive material having a distal end surface for engaging the clamp plate (80, 80a) under a spring load exerted by a spring loadable interconnection disposed between the rod or tube and the laterally spaced portion of the housing body such that the spring loadable interconnection can exert a spring load between the laterally spaced portion of the housing body and the rod or tube, the clamp plate, the mold, the manifold, the actuator and the heat transmitter being assemblable together in an arrangement wherein the spring loadable interconnection is loaded urging the distal end surface of the movable rod or tube into compressed engagement with the clamp plate (80, 80a) at least when the manifold is heated to an elevated operating temperature.