Column unit

摘要

According to an illustrative example of the invention, a chair column comprises a base tube with a support plate. A gas spring is accommodated within the base tube. The piston rod of the gas spring is supported on the base tube by a ball bearing. The cylinder of the gas spring is guided at the upper end of the base tube by a guiding sleeve. The guiding sleeve is telescopical with respect to the base tube in response to outward and inward movement of the cylinder with respect to the base tube such that a full satisfactory guiding function is maintained between the cylinder and the base tube, even when the cylinder is in its uppermost position.