There is provided an electromechanical actuator for a parking brake system of a vehicle, including an electric motor, reduction gear train associated with the motor for transmitting motion from the motor to a single power transmission chain sprocket, one power transmission chain section drivable by the sprocket partly encircling one sheave, rotatably mounted on a free longitudinally movable pulley block, an end of the power transmission chain being attached to a first stationary anchor point, and a connector connecting the pulley block to the vehicle's parking brake system.