A - Human Necessities – 47 – C
Patent
A - Human Necessities
47
C
155/50
A47C 7/46 (2006.01) A47C 7/40 (2006.01)
Patent
CA 1232832
HEIGHT ADJUSTMENT MECHANISM FOR CHAIR BACKREST Abstract of the Disclosure An adjustment mechanism is provided for manually posi- tioning and releasably locking a chair backrest in a desired vertical position relative to the chair seat. The mechanism comprises a guide rigidly secured to an upright backrest support frame of a chair and a channel rigidly secured to the backrest. The channel is mounted for vertical sliding movement on the guide. The channel comprises a slot having a plurality of ver- tically arranged notches along one vertical edge of the slot, an inclined surface sloping downwardly from the lowest notch at the bottom end of the slot, and a cam surface, partially straight and partially curved, extending upwardly along the other ver- tical edge of the slot from the lower end of the inclined sur- face to the highest notch. A latch bar is pivotally mounted on a pivot pin on the guide and has a latch pin extending into the slot. A two-legged torsion spring mounted on the guide between the guide and channel biases the latch bar in a latched position wherein the latch pin releasably engages a notch to maintain the backrest at a selected height. Manually raising the backrest slightly above its highest latched position (lowest notch) engages the inclined surface with the latch pin to pivot the latch bar overcenter to spring-biased unlatched position. Then, manually lowering the backrest to its lowest position (highest notch ) while the latch pin engages the curved portion of the cam surface pivots the latch bar from overcenter unlatched position back to a latched position wherein the latch pin engages the highest notch to maintain the backrest in its lowest position. From there, the backrest can be lifted one notch at a time to raised positions.
516595
Donovan Kyle P.
Milsco Manufacturing Company
Smart & Biggar
LandOfFree
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