Abstract: In a puffer-type gas blast switch including a gas compression device composed of two components defining, respectively, a piston and a cylinder, one of the components being stationary and the other one of the components being movable for compressing a quenching gas in the chamber during switch opening, a nozzle mounted for directing the compressed quenching gas from the chamber against a switching arc, a first power contact fixed to the movable component of the gas compression device and movable between a switch closing position and a switch opening position, a second power contact arranged to be conductively connected to the first power contact when the latter is in its switch closing position and movable with the latter during at least the initial portion of its movement from the switch closing position, and spring means urging the second contact in a direction to break its connection with the first contact, the second contact is directly and releasably connected to the first contact when the first contact

Abstract: A combined tool for precision boring and burnishing a tubular workpiece includes a bore head and a burnishing head which are advanced by a feed tube into the interior of the tubular workpiece while the latter is rotated about its axis. In order to reduce the stresses on the three above-mentioned elements and to avoid markings on the finished surface, two of the three elements are connected by a coupling, which while transmitting torque between the two connected elements, permits limited deviations of the axes thereof.