The invention relates to a servo drive comprising an electromechanical energy converter, which has a rotatably mounted disc rotor for generating a torque and a stepping up mechanism that is connected downstream of the disc rotor, for coupling the disc rotor to an output element and for stepping up the torque that acts on the disc rotor and comprising a locking mechanism that locks a rotational displacement of the output element, when a torque is introduced on the output side. According to the invention, the locking mechanism comprises a coil spring which can be radially expanded and compressed and which extends around the outer periphery of the stepping up mechanism.