An on-load tap changer is provided having a vacuum interrupter actuatable by a shaft. A movable shuttle is connected to an impact mass by springs such that the impact mass tends to follow the shuttle when the shuttle moves. A pawl assembly is operable to hold and then release the impact mass when the shuttle starts moving. The holding of the impact mass when the shuttle starts to move causes the springs to store both a compression force and a tension force, which are released when the impact mass is released.