In a vehicle transmission, an electric linear machine is operable for controlling the position of a clutch actuator rod. A permanent magnet is housed in a cylinder (134) at one end of the linear machine. An output member from the machine extends through the cylinder and is coupled to the actuator rod. Magnetic material is carried on the section of output member within the cylinder. Movement of the output member influences a magnetic circuit between the magnetic material (180) and the permanent magnet material, to provide a non-powered contribution to movement of the output member, thereby reducing the load required to move the actuator rod (116).