Lockable elevating mechanism for the continuous adjustment of chair seats

Claim 1

A lockable elevating mechanism for the continuous adjustment of chair seats comprising a guide tube (1) to be connected with a pedestal (4) and having a bottom plate (5) a longitudinally adjustable, lockable gas spring (8), which has a central longitudinal axis (6) and a piston rod (10), which in a direction of said axis (6) is tightly, but releasably connected with said bottom plate (5) of said guide tube (1), and which gas spring (8) has a housing (9), which is guided in said guide tube (1) and which in the direction of said axis (6) is tightly connectable with a chair seat (31) at an end opposite to said piston rod (10), and which housing (9) is displaceably guided in the direction of said common longitudinal axis (6) and is guided in said guide tube (1) without substantial play radially to the direction of said common longitudinal axis (6), wherein a first guide bush (27) is arranged between said housing (9) and an additional tube (20), so that said housing (9) is supported for displacement relative to said additional tube (20) in the direction of said longitudinal axis (6), wherein a second guide bush (22) is arranged between said additional tube (20) and said guide tube (1) and is arrested in relation to said guide tube (1) in the direction of said longitudinal axis (6) so that said additional tube (20) is in turn displaceable while axially guided in relation to said guide tube (1), and wherein a mechanical helical compression spring (26, 26a) is provided between said additional tube (20) and said guide tube (1) and acts upon said additional tube (20) in a direction away from said bottom plate (5) of said guide tube (1) to said housing (9).