Adjustable back rest support for chairs

Claim 1

Adjustment apparatus for use in association with a posture chair of the type having a back cushion and a seat cushion, in which the back cushion is mounted on column means and is adjustable both as to height and as to inclination relative to the seat cushion, said apparatus comprising; mounting bracket means for fastening to said chair; swingable support shoe means swingably mounted on said bracket means and adapted to slidably receive said back cushion column means and support the same; releaseable locking means engageable with said column means; adjustable telescopic strut means pivotally mounted at one of its ends to said bracket means and at its other end to said support shoe means; said strut means comprising sleeve means, forming one end of said strut means, and being open at one end, and hollow rod means forming the other end of said strut means and extending slidably into said sleeve means and snugly fitting the same, locking rib means formed on said hollow rod means, a locking arm member pivotally mounted transversely on said sleeve means and extending to one side thereof at a right angle thereto and releaseably interengageable with said locking rib means, handle means extending from said locking arm member for manual operation thereof, and spring means extending along said locking arm and engaging said sleeve means transversely and urging said locking arm member into engagement with said locking rib means, the ends of said strut means being pivotally fastened at points on said bracket means and said support shoe means spaced from said swingable mounting between said support shoe means and said bracket means, whereby the angular position of said support shoe means relative to said bracket means is controlled by the length of said strut means.