A valve actuator is provided for use in conjunction with a drive motor and a valve. In one embodiment, the valve actuator includes a housing assembly, a first power screw rotatably mounted in the housing assembly and configured to be rotated by the drive motor, a first rack translatably mounted in the housing assembly, and a pinion rotatably mounted in the housing assembly and mechanically linked to the valve. The first rack is threadably coupled to the first power screw and is configured to move linearly as the first power screw rotates. The pinion engages the first rack and is configured to rotate as the first rack moves linearly to move the valve to a desired position.