Drive train with a hydrodynamic retarder that can be decoupled and has a displacement sensor

The invention relates to a drive train having: a hydrodynamic retarder, which comprises a bladed rotor rotating about an axis of rotation and a bladed stator, which, together with the rotor, forms a working chamber for the hydrodynamic transfer of power from the rotor to the stator; a power input for feeding drive power to the hydrodynamic retarder; a disconnect clutch in a drive connection between the power input and the rotor of the hydrodynamic retarder, wherein: the disconnect clutch is designed as a synchronised clutch having two clutch halves, friction elements that can be brought into contact with each other and mechanical blocking elements; the friction elements are designed to equalise the rotational speed between the clutch halves, and the blocking elements are designed to lock the two clutch halves to each other in an interlocking manner; and the disconnect clutch comprises an actuator that can be displaced along a displacement path and can be displaced over a first initial displacement section, in order to bring the friction elements into mutual contact, and can be displaced over a second displacement section adjoining the first displacement section, in order to synchronise the two friction elements and thus the rotational speed of the clutch halves and to lock same together with the blocking elements. The drive train according to the invention is characterised in that at least one displacement sensor is provided, which directly or indirectly senses the displacement travelled by the actuator and / or the position of the actuator on the displacement path.