An electromechanical strut using an inline motor coupled to an inline planetary gear that are both mounted in the lower housing. The motor-gear assembly drives a worm gear and nut screw in the upper housing, extending or retracting an extensible shaft. Additionally, a power spring mounted coaxially around the worm gear provides a mechanical counterbalance to the weight of a lift gate on the shaft. As the shaft extends, the power spring uncoils, assisting the motor-gear assembly in raising the lift gate. Retracting the shaft recoils the spring, storing potential energy. Thus, a lower torque motor-gear assembly can be used, reducing the diameter of the lower housing. Preferably, the power spring can also drive the power screw to extend the strut even when the motor-gear assembly is not engaged.