DC vacuum relay device

A relay device, comprising a chamber;

• an electromagnetically driven armature assembly including a movable armature shaft extending into the chamber and having a terminal end portion;
• movable contact means within the chamber comprising a disc surrounding and rotatable about the armature shaft adjacent its terminal end portion;
• stationary contacts mounted in the chamber to be bridged by the movable contact means;
• means permitting the terminal end portion of the armature shaft to continue motion beyond the movable contact means after the motion of the movable contact means ceases upon making of the stationary contacts by the movable contact means;
• impact break means for accelerating the armature shaft and its terminal end portion from rest prior to breaking the stationary contacts to thereafter drive the movable contact means away from the stationary contacts upon break, said impact break means comprising the movable contact means being resiliently mounted on the armature shaft by a spring which surrounds the armature shaft and is captured between the movable contact means and a stop on the armature shaft, said spring having at least one unattached free floating end and said spring being compressed when the armature shaft and its terminal end portion extend beyond the movable contact means following making of the stationary contacts by the movable contact means;
• and, means for varying the portion of contact between the movable contact means and the stationary contacts during a plurality of making operations, including the said spring providing means to rotate the disc during making and breaking of the stationary contacts to vary the portion of contact between the movable contact means and the stationary contacts during the plurality of making operations.