Support column with gravity dependent retention means
US4640484A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 6, 1985 |
| Grant date | Feb 3, 1987 |
| Priority date | — |
| Expiry date | May 6, 2005 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA47C3/30
- WIPO fieldFurniture, games
- WIPO sectorOther fields
Abstract
A support column unit for an adjustable-height chair and the like comprises upper and lower telescoping tubular members, a piston-and-cylinder type pneumatic spring located coaxially within the tubular members and having its cylinder member secured to the lower tubular member, and a gravity dependent locking mechanism for locking the piston rod member of the pneumatic spring to the upper tubular member when the support column is upright and for releasing the piston rod member when the support column is inverted. The locking mechanism comprises a lock body retained within the upper tubular member and having a bore sized and positioned to permit sliding axial movement of the piston rod member therein. The lock body has one or more cavities, each one in communication with the bore and containing a locking member. The cavities and the locking members are sized and shaped such that when the support column is upright, each locking member falls to a position in which a portion thereof protrudes into the bore, and when the column is inverted, each locking member falls to a position in which it is fully retracted from the bore. The piston rod member has an annular retaining groove shaped to…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.