Abstract: Apparatus providing an adjustable height work surface. A work table is cantilevered from posts supported for vertical motion inside columns from a base. A drive connected between the work table and the base changes the height of the work table and is located between the columns and posts. Each post carries a rack that engages with a pinion supported by a column for rotation about a common axis. A rigid shaft interconnects two pinions and prevents relative pinion rotation. A stabilizing structure in each column interacts with the post to maintain engagement between the rack and pinion structure and maintains the work table in a horizontal position during adjustment and use.