Continuously adjustable lifting devices

Claim 1

A continuously adjustable lifting device for table tops, chair seats or the like, comprising a tubular casing containing a gas and/or liquid filling, a rod plunger means sealed in and protruding from an end of said casing, a blocking device operable from outside said casing and being arranged at the other end of said casing for locking said rod plunger means relative to said casing in an adjustable position, said blocking device provided in an overflow opening for the filling of the casing connecting the casing space before the plunger to the casing space behind the plunger, the blocking device (22,23,29,31) comprising a release pin (22) arranged on the longitudinal axis of the casing (11), said pin being axially displaceable from outside the casing and having at its inner end a head (23) controlling an axial bore (31) of said blocking device, said pin thereof being guided in two base portions (19,20) which include a deflector chamber (21) between them, said base portions bounding the corresponding end of the casing, (11) said casing consisting of two concentrically telescoped steel tubes (12,13) forming a by-pass chamber (34), the deflector chamber (21), by the release pin (22,23), being brought into communication through said axial bore (31) with a casing space (28) ahead of the plunger means (16) and being connectable through at least one axial opening in one of said base portions (36) to the by-pass chamber (34), and the latter being connectable through radial bores (43) and an annular chamber (41) of a plug in the first mentioned end of the casing to the casing space (42) behind the plunger means (16).