Abstract: A releasable locking device for a vehicle steering column adjustable in the longitudinal direction is disclosed which has a postionally fixed steering column part and a steering column section displaceable relative to the latter. A steering wheel is provided at the end of the steering column. The fixing of the steering column can be influenced by a hydraulic system which can be controlled by a mechanical actuating member. A locking device is provided which has a sealed hydraulic piston-cylinder unit which is arranged axially parallel to the steering column and is coupled between the positionally fixed steering column part and the displaceable steering column section with the cylinder chamber subjected to pressure in the case of an impact on the steering wheel being completely filled.