Abstract: A linear drive unit (52), comprising(a) a housing (54) in which a driving motor (58) is accommodated;(b) a driven rod (64) adapted to be driven in linear manner and having a hollow portion (104) which partly extends over the housing (54) and is supported on the outer circumference of the housing (54) in axially slidable manner;(c) a conversion drive (62) which is in driving connection with the motor (58) and the driven rod (64) and converts rotational movement into linear movement of the driven rod (64);(d) a drive body (92) which belongs to the conversion drive (62) and is adapted to be driven by the motor in rotating manner and which is provided on its outer circumference with a circumferential groove profile (160) and with teeth (162);(e) a pluralityy of axially extending revolving members (166) which are rotatable about their own axes and which each have a circumferential groove profile (172) as well as teeth (174);(f) engagement of the groove profiles (172) of the revolving members (166) at a radially in