On-load tap changer for interrupted switching over between winding taps (n, n+1) of a tapped transformer, comprising - a selector for power-free preselection of the winding tap (n, n+1), which is to be switched over to and - a load changeover switch for the actual load changeover from the previous winding tap (n) to the preselected winding tap (n+1), Wherein - the load changeover switch has two main current branches and two auxiliary current branches, - the first main current branch electrically connects the first winding tap (n) to a load shunt by way of a vacuum switching tube (MVSa), - the second main load branch electrically connects the second winding tap (n+1) to the load shunt by way of a further vacuum switching tube (MSCb), - the first auxiliary current branch connects the first winding tap (n) to the load shunt by way of a series connection of a further vacuum switching tube (TTVa) and at least one switch-over resistance (Ra), - the second auxiliary current branch connects the second winding tap (n+1) to the load shunt by way of a series connection of a further vacuum switching tube (TTVb) and at least one further switch-over resistance (Rb), characterised in that - a further, separately actuable mechanical contact (MDCa, MDCb, TDCa, TDCb) is so provided in each of the two main current branches and each of the two auxiliary current branches between the respective winding tap (n, n+1) and the respective vacuum switching tube (MSVa, MSVb, TTVa, TTVb) in this branch that the vacuum switching tubes (MSVa or MSVb) in the main current branch and the vacuum switching tubes (TTVa or TTVb) in the auxiliary current branch of the unconnected winding tap (n or n+1) are electrically separable from this tap. - a selector for power-free preselection of the winding tap (n, n+1), which is to be switched over to and - a load changeover switch for the actual load changeover from the previous winding tap (n) to the preselected winding tap (n+1), - the load changeover switch has two main current branches and two auxiliary current branches, - the first main current branch electrically connects the first winding tap (n) to a load shunt by way of a vacuum switching tube (MVSa), - the second main load branch electrically connects the second winding tap (n+1) to the load shunt by way of a further vacuum switching tube (MSCb), - the first auxiliary current branch connects the first winding tap (n) to the load shunt by way of a series connection of a further vacuum switching tube (TTVa) and at least one switch-over resistance (Ra), - the second auxiliary current branch connects the second winding tap (n+1) to the load shunt by way of a series connection of a further vacuum switching tube (TTVb) and at least one further switch-over resistance (Rb), - a further, separately actuable mechanical contact (MDCa, MDCb, TDCa, TDCb) is so provided in each of the two main current branches and each of the two auxiliary current branches between the respective winding tap (n, n+1) and the respective vacuum switching tube (MSVa, MSVb, TTVa, TTVb) in this branch that the vacuum switching tubes (MSVa or MSVb) in the main current branch and the vacuum switching tubes (TTVa or TTVb) in the auxiliary current branch of the unconnected winding tap (n or n+1) are electrically separable from this tap.