Abstract: A fluid-operated actuating device of the type including an actuating cylinder member, an axially movable actuating piston rod member, and actuating fluid connection means for introducing actuating fluid to and removing actuating fluid from the actuating cylinder member so as to adjust the relative axial position of the actuating cylinder and piston members and including structure for damping the movement of the piston rod member with respect to the cylinder member.

Abstract: In the illustrative embodiments of the invention disclosed, the extension rce of a gas spring is controlled as a function of temperature by varying the volume of the working chamber entered by the piston rod, and thus the gas pressure within the working chamber, as a function of temperature.

Abstract: A gas spring for height adjustment of drawing-tables or the like includes an arrangement for hydraulically locking the gas spring against sudden collapse due to overloading or loss of internal gas pressure. The hydraulic locking mechanism includes a pressure responsive valve which operates, in response to an excess pressure differential between the gas spring cavity and the pressurized gas chamber, either to prevent flow of the hydraulic locking medium out of the cylinder cavity or to restrict such flow to a slow, safe rate.

Abstract: A column in which an inner elongated member of circular cross section is partly received in the polygonal bore of an outer, tubular member and secured against angular displacement about the common axis by guide elements secured against longitudinal movement in respective recesses of the inner member open toward the outer member and engaging the outer member in respective corners of its polygonal cross section. A manually controlled arresting mechanism permits the two column members to be arrested against relative longitudinal movement in a multiplicity of relative positions.