Stepping switch with vacuum switching tubes

A tap changer with vacuum-switching tubes for controlling a transformer having taps has a selector for power-free selection of a one of the taps to be switched and a load-changeover switch for actual switching over from the connected tap to a new, pre-selected one of the taps. A first cam disk is fixed against rotation on a rotatable switch shaft, and a rocker lever arrangement has a first roller for actuating the vacuum-switching tubes. A second cam disk is also rotationally fixed on the switch shaft, and there are two further arms of U-shaped construction on the rocker lever arrangement. A lever has a free end provided with a second roller that co-operates with the second cam disk. This lever is between the further arms and mounted to be rotatable about an axis. A compression spring is provided between the lever and the further arms.