An on-load tap changer is provided having a vacuum interrupter that is actuated by a shaft of an actuation assembly. A damper dampens the movement of the shaft. The damper provides more dampening when the shaft is closing the vacuum interrupter than when the shaft is opening the vacuum interrupter. The damper includes a housing at least partially defining an interior chamber into which the shaft extends. A piston with openings extending therethrough is disposed in the interior chamber and is secured to the shaft so as to be movable therewith. A blocking structure is operable to block the openings in the piston when the shaft is closing the vacuum interrupter and to un-block the openings in the piston when the shaft is opening the vacuum interrupter.