Vertically adjustable support

Claim 1

In a vertically adjustable support assembly including an elongated tubular member having upper and lower ends with its lower end adapted to be supported on a base, an elongated support post member of solid cross-section having upper and lower ends with its upper end adapted to support a load, said post member being telescopically received in said tubular member and being vertically movable with respect thereto, said post member having a plurality of vertically aligned, generally horizontal, spaced holes therein, a locking mechanism including a horizontally extending pin and means for selectively rectilinearly moving said pin generally in parallelism with its axis horizontally between a locking position in which one end thereof is seated in a selected hole and an unlocked position in which said end is withdrawn therefrom thereby to hold said post member in a plurality of selected vertical positions, said one end having an end surface which inclines downwardly toward the other end of said pin, said mechanism including means yieldably urging said pin in a horizontal direction in which said one end normally engages said post member when it is not seated in one of said holes, the wall of each of said holes having a relatively narrow abutment extending downwardly, said one pin end having an upwardly facing notch engageable selectively by the abutment of the respective hole into which said pin is entered thereby resisting withdrawal from said hole, each said abutment comprising an annular, inwardly extending flange adjacent to the entrance of the respective hole, the inner surface of each flange being beveled, said pin having a distal end, said notch having a beveled surface on the side thereof toward said distal end which cooperates with the beveled surface of the respective flange to cam said post member upwardly in response to withdrawal movement of said pin in the absence of a load on said post member.