On-load tap changer for uninterrupted switching over between different winding taps of a tapped transformer, comprising - a selector contact unit (7.1, 7.2, 8.3) which comprises a respective plurality of fixed selector contacts (8.1, 8.2, 8.3, 8.4, 8.5), which are respectively electrically connected with the individual winding taps, and two longitudinally displaceable movable selector contacts (11.1, 11.2) by which by the fixed selector contacts (8.1... 8.6) are contactable; - two vacuum interrupters (19.1, 19.2, 19.3, 19.4, 19.5, 19.6) for each phase for uninterrupted switching over; - a motor drive for introducing a drive movement into the on-load tap changer; and - a threaded spindle; characterised in that - the entire load changeover switch is arranged by means of a transmission module at the underside of a transformer cover; - the on-load lap changer has three selector contact units (7.1... 7.3); - each selector contact unit (7.1... 7.3) has a slide carriage (12.1... 12.3) and a contact carrier (10.1... 10.3); - a rotational movement generated by the motor drive is transmissible by means of the transmission module to the threaded spindle, which is engaged with a spindle nut provided at a centre slide carriage (12.2), so that a longitudinal displacement of the centre slide carriage (12.2) along guide rods (14.1, 14.2) can thereby be produced; and - the remaining slide carriages (12.1, 12.3) are operatively connected with the centre slide carriage (12.2) by way of a similarly longitudinally displaceable guide link, which is mechanically coupled with the centre slide carriage (12.2), so that the remaining slide carriages (12.1, 12.3) in turn are so mechanically coupled with the centre slide carriage (12.2) by way of the guide link that not only the selector contact units (7.1... 7.3), but also the vacuum interrupters (19.1... 19.6) are thereby simultaneously actuable. - a selector contact unit (7.1, 7.2, 8.3) which comprises a respective plurality of fixed selector contacts (8.1, 8.2, 8.3, 8.4, 8.5), which are respectively electrically connected with the individual winding taps, and two longitudinally displaceable movable selector contacts (11.1, 11.2) by which by the fixed selector contacts (8.1... 8.6) are contactable; - two vacuum interrupters (19.1, 19.2, 19.3, 19.4, 19.5, 19.6) for each phase for uninterrupted switching over; - a motor drive for introducing a drive movement into the on-load tap changer; and - a threaded spindle; - the entire load changeover switch is arranged by means of a transmission module at the underside of a transformer cover; - the on-load lap changer has three selector contact units (7.1... 7.3); - each selector contact unit (7.1... 7.3) has a slide carriage (12.1... 12.3) and a contact carrier (10.1... 10.3); - a rotational movement generated by the motor drive is transmissible by means of the transmission module to the threaded spindle, which is engaged with a spindle nut provided at a centre slide carriage (12.2), so that a longitudinal displacement of the centre slide carriage (12.2) along guide rods (14.1, 14.2) can thereby be produced; and - the remaining slide carriages (12.1, 12.3) are operatively connected with the centre slide carriage (12.2) by way of a similarly longitudinally displaceable guide link, which is mechanically coupled with the centre slide carriage (12.2), so that the remaining slide carriages (12.1, 12.3) in turn are so mechanically coupled with the centre slide carriage (12.2) by way of the guide link that not only the selector contact units (7.1... 7.3), but also the vacuum interrupters (19.1... 19.6) are thereby simultaneously actuable.