Patent ID: 7905464

Claim:
A longitudinally adjustable intermediate piece with a unidirectionally acting displacement blocking mechanism, comprising: a first longitudinal element, provided with a thread; a second longitudinal element which interacts with the first longitudinal element in a longitudinally displaceable manner; and a spindle nut retained in the second longitudinal element in a rotatable and axially nondisplaceable manner relative to the second longitudinal element, the spindle nut interacting with the thread of the first longitudinal element, wherein the spindle nut rests via one of its two faces on a friction surface of the second longitudinal element while covering a large area or can be brought into contact therewith, if an axial compressive force takes effect on the first and second longitudinal elements, while between the other face of the spindle nut two faces and the second longitudinal element a friction-reducing axial bearing is provided, so that, when an axial tractive force is applied to the first and second longitudinal elements, the spindle nut can be rotated by the axial tractive force via the thread and the first and second longitudinal elements can be pulled apart, while, on application of an axial compressive force onto the first and second longitudinal elements, the rotation of the spindle nut is blocked by friction resistance between the spindle nut and the friction surface, thereby preventing the first and second longitudinal elements from being pushed together.