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, wherein the cooling device comprises: a heat transmitter comprising a distal arm or member and a proximal base or member, the distal arm or member being mounted by a spring loadable interconnection or engagement to or with the proximal base or member, the distal arm or member being comprised of a thermally conductive material having a distal end surface for engaging the clamp plate (80, 80a) under a spring load, the actuator comprising a housing body (12, 12a) that is thermally conductive and mounted in thermal communication with the manifold, the proximal base or member being mounted to the housing body of the actuator in an arrangement wherein the distal end surface of the distal arm or member is movable through the spring loadable interconnection toward and away from the actuator, the distal arm or member having a proximal surface adapted to be disposed in sliding contact with a complementary surface (12ls, 12as) of the actuator for transmitting heat from the proximal surface to the distal end surface, the clamp plate, the mold, the manifold, the actuator and the heat transmitter being assemblage together in an arrangement wherein the proximal surface slides along the complementary surface (12ls, 12as) and the spring loadable interconnection is loaded urging the distal end surface of the movable rod or arm into compressed engagement with the clamp plate (80, 80a) at least when the manifold is heated to an elevated operating temperature, characterized in that: the spring or spring loadable interconnection has engagement surfaces that engage against complementary opposing engagement surfaces (504us, 502us) of proximal and distal members having a selected area of engagement that renders spring substantially non-heat conductive between the proximal and distal arms or members. a heat transmitter comprising a distal arm or member and a proximal base or member, the distal arm or member being mounted by a spring loadable interconnection or engagement to or with the proximal base or member, the distal arm or member being comprised of a thermally conductive material having a distal end surface for engaging the clamp plate (80, 80a) under a spring load, the actuator comprising a housing body (12, 12a) that is thermally conductive and mounted in thermal communication with the manifold, the proximal base or member being mounted to the housing body of the actuator in an arrangement wherein the distal end surface of the distal arm or member is movable through the spring loadable interconnection toward and away from the actuator, the distal arm or member having a proximal surface adapted to be disposed in sliding contact with a complementary surface (12ls, 12as) of the actuator for transmitting heat from the proximal surface to the distal end surface, the clamp plate, the mold, the manifold, the actuator and the heat transmitter being assemblage together in an arrangement wherein the proximal surface slides along the complementary surface (12ls, 12as) and the spring loadable interconnection is loaded urging the distal end surface of the movable rod or arm into compressed engagement with the clamp plate (80, 80a) at least when the manifold is heated to an elevated operating temperature, characterized in that: the spring or spring loadable interconnection has engagement surfaces that engage against complementary opposing engagement surfaces (504us, 502us) of proximal and distal members having a selected area of engagement that renders spring substantially non-heat conductive between the proximal and distal arms or members.