An injection molding system comprising an injection molding machine that injects a flow of injection fluid to a heated manifold that distributes the injection fluid to a flow channel that delivers the injection fluid to a gate of a mold cavity, the injection molding system comprising: an actuator comprised of a rotor having a drive axis and a driver (100, 200) interconnected to the rotor adapted to drive the rotor around the drive axis, the driver (100, 200) receiving electrical energy or power that generates drive heat, the actuator having a housing comprised of radial (20r, 20ri, 20ro, 20roa, 20rob, 20roc, 20rod) and axial walls (20a, 20ai, 20aue, 20ade) that form an enclosed chamber containing a heat conductive chamber fluid, the rotor and driver (250, 100, 200) being mounted within the chamber in intimate heat conductive contact with the heat conductive fluid, the rotor and driver being supported within the chamber by the radial and axial walls (20r, 20ro, 20ri, 20roa, 20rob, 20roc, 20rod, 20a, 20ai, 20aue, 20ade) in an arrangement such that the rotor and driver (100, 200) are drivably rotatable within the chamber, wherein one or more of the radial and axial walls (20r, 20ro, 20ri, 20roa, 20rob, 20roc, 20rod, 20a, 20ai, 20aue, 20ade) comprise a heat conductive material that has an inner surface disposed in heat conductive contact with the heat conductive fluid contained within the enclosed chamber, the one or more radial or axial walls (20r, 20ro, 20ri, 20roa, 20rob, 20roc, 20rod, 20a, 20ai, 20aue, 20ade) absorbing heat from the heat conductive fluid contained within the chamber, an actuator tube or channel surrounded by and in intimate heat conductive contact with the heat conductive material of one or more of the radial and axial walls (20r, 20ro, 20ri, 20roa, 20rob, 20roc, 20rod, 20a, 20ai, 20aue, 20ade), a source of heat absorptive fluid sealably interconnected to the tube or channel in an arrangement such that the heat absorptive fluid is routed through the tube or channel in a flow that absorbs heat from the one or heat conductive walls (20r, 20ro, 20ri, 20roa, 20rob, 20roc, 20rod, 20a, 20ai, 20aue, 20ade), a valve pin having a pin axis, the valve pin being interconnected to the rotor such that the valve pin is controllably drivable along a linear path of travel along the pin axis, characterised in that the housing of the actuator is mounted in heat conductive communication with the heated manifold such that manifold heat is absorbed by or communicated to the one or more radial and axial walls (20r, 20ro, 20ri, 20roa, 20rob, 20roc, 20rod, 20a, 20ai, 20aue, 20ade) of the housing, the heat absorptive fluid absorbing the manifold heat absorbed by or communicated to the one or more radial and axial walls (20r, 20ro, 20ri, 20roa, 20rob, 20roc, 20rod, 20a, 20ai, 20aue, 20ade) of the housing. an actuator comprised of a rotor having a drive axis and a driver (100, 200) interconnected to the rotor adapted to drive the rotor around the drive axis, the driver (100, 200) receiving electrical energy or power that generates drive heat, the actuator having a housing comprised of radial (20r, 20ri, 20ro, 20roa, 20rob, 20roc, 20rod) and axial walls (20a, 20ai, 20aue, 20ade) that form an enclosed chamber containing a heat conductive chamber fluid, the rotor and driver (250, 100, 200) being mounted within the chamber in intimate heat conductive contact with the heat conductive fluid, the rotor and driver being supported within the chamber by the radial and axial walls (20r, 20ro, 20ri, 20roa, 20rob, 20roc, 20rod, 20a, 20ai, 20aue, 20ade) in an arrangement such that the rotor and driver (100, 200) are drivably rotatable within the chamber, wherein one or more of the radial and axial walls (20r, 20ro, 20ri, 20roa, 20rob, 20roc, 20rod, 20a, 20ai, 20aue, 20ade) comprise a heat conductive material that has an inner surface disposed in heat conductive contact with the heat conductive fluid contained within the enclosed chamber, the one or more radial or axial walls (20r, 20ro, 20ri, 20roa, 20rob, 20roc, 20rod, 20a, 20ai, 20aue, 20ade) absorbing heat from the heat conductive fluid contained within the chamber, an actuator tube or channel surrounded by and in intimate heat conductive contact with the heat conductive material of one or more of the radial and axial walls (20r, 20ro, 20ri, 20roa, 20rob, 20roc, 20rod, 20a, 20ai, 20aue, 20ade), a source of heat absorptive fluid sealably interconnected to the tube or channel in an arrangement such that the heat absorptive fluid is routed through the tube or channel in a flow that absorbs heat from the one or heat conductive walls (20r, 20ro, 20ri, 20roa, 20rob, 20roc, 20rod, 20a, 20ai, 20aue, 20ade), a valve pin having a pin axis, the valve pin being interconnected to the rotor such that the valve pin is controllably drivable along a linear path of travel along the pin axis, characterised in that the housing of the actuator is mounted in heat conductive communication with the heated manifold such that manifold heat is absorbed by or communicated to the one or more radial and axial walls (20r, 20ro, 20ri, 20roa, 20rob, 20roc, 20rod, 20a, 20ai, 20aue, 20ade) of the housing, the heat absorptive fluid absorbing the manifold heat absorbed by or communicated to the one or more radial and axial walls (20r, 20ro, 20ri, 20roa, 20rob, 20roc, 20rod, 20a, 20ai, 20aue, 20ade) of the housing.