Abstract: A linear motion device intended particularly as the elevating mechanism of a medical examination table consists of four parallel rack members on one relatively movable part each engaged by a respective pinion carried by the second relatively movable part. The pinions are mounted in pairs on two parallel shafts, the two adjacent pinions on the two shafts being adjacent the same support member mounting the shafts. Stabilizing means comprise two meshed pinions each of which meshes with a respective rack rigidly mounted on the second movable part as far as possible from the first-mentioned pinions. A pair of rollers spaced from the meshed rollers engage another rack member for stabilizing action at right angles to that provided by the meshed pinions.