Step switch

In combination with a step transformer having a row of contacts including at least a first contact and an adjacent second contact, a step switch comprising:

• a threaded drive shaft extending along the row of transformer contacts;
• a support movable relative to the drive shaft along the row of transformer contacts and threaded on the drive shaft;
• a fixed contact fixed on the support and movable therewith along the row of transformer contacts to successively engage same;
• a buss conductor extending longitudinally along the row of transformer contacts;
• a vacuum switch connected between the fixed contact and having an output riding on the buss conductor;
• first means for rotating the shaft and slowly displacing the support in one direction along the row for displacement of the fixed contact from the first contact to the second contact and in the opposite direction along the row for displacement of the fixed contact slowly in the opposite direction from the second contact to the first contact;
• a slide movable relative to the drive shaft and to the support;
• a movable contact carried on the slide;
• a switch and a resistor connected between the movable contact and the buss conductor;
• second means including a spring-loaded force-storage unit braced between the slide and the support for, on movement of the fixed contact from the first contact to the second contact, rapidly displacing the movable contact from the first contact to the second contact once the fixed contact is moved fully to the second contact and on opposite movement of the support by the shaft for, on movement of the fixed contact from the second contact to the first contact, rapidly displacing the movable contact from the second contact to the first contact once the fixed contact is moved to the first contact.