Abstract: An overbed table is provided with a linear positioning mechanism for fixing the height of the table relative to the base. An upper outer column depends from the underside of the table, and a lower inner column is received within the upper outer column. In this manner, spillage of any liquids onto the support for the overbed table drips single fashion past the joint between the columns. The linear positioning mechanism incorporates a high lead screw which is rotatably mounted to the overbed table within the upper outer column. A fixed nut is attached to the upper end of the inner column, and receives the threads of the high lead screw. Up-down movement of the overbed table causes rotation of the high lead screw within the fixed nut. A spring clutch mechanism is provided for selectively preventing and allowing rotation of the high lead screw when a downward force is applied to the table. When rotation of the lead screw is prevented, downward movement of the overbed table is thus prevented.

Abstract: A support assembly (2) is provided for an overbed table (4). A lower pedestal column (6) is mounted on a base (8), and an upper pedestal column (12) is telescopically slideable within the lower column, and supports a table (4). A wedge and roller clutch (14) at the bottom of the upper column includes: wedges (16, 18) fixed to the upper column and extending downwardly from the lower end (20) thereof and having opposing camming surfaces (22, 24); a retainer (26) mounted to a release rod (28) and moveable up and down toward and away from the bottom end of the upper column; and rollers (32, 34) loosely received in the retainer and forced laterally horizontally outwardly against the inner walls (36, 38) of the lower column by the camming surfaces of the wedges to stop downward movement of the upper column and support the table.