Means for suppressing contact-separation at the end of a vacuum circuit-breaker closing operation

A vacuum-type circuit breaker comprising:

• (a) a plurality of vacuum circuit interrupters, each comprising:
• (i) an evacuated envelope,
• (ii) a pair of separable contacts within said envelope,
• (iii) a movable contact rod secured to one of said contacts for actuating said one contact and extending between the inside and outside of said envelope, and
• (iv) a bellows providing a seal between said movable contact rod and said envelope on which pressure external to said envelope acts to apply a bellows force to said contact rod in a direction to drive said one contact toward engagement with the other of said contacts,
• (b) motive means for developing a circuit-breaker closing force for application to the movable contact rods of all of said interrupters,
• (c) a common operating member through which said closing force is applied to the movable contact rods of all of said interrupters, said common operating member being the closest common operating member to said interrupters in the drive train to the interrupters if there is more than one common operating member,
• (d) a wipe mechanism for each of said interrupters comprising a wipe spring through which closing force is applied to the contact rod of the associated interrupter and a force-transmitting member for transmitting closing force to said wipe spring,
• (e) a plurality of linkages, one for each interrupter, each linkage being connected between said common operating member and said force-transmitting member in the wipe mechanism for the associated interrupter,
• (f) each of said linkages comprising a plurality of pin joints connected mechanically in series between said common operating member and said associated force-transmitting member, each of said pin joints comprising a pin and a bearing that rotates with respect to said pin during circuit-breaker closing, a preselected one of said pin joints in each linkage being located at the contact-end of the associated linkage for coupling said contact-rod end of the linkage to the associated force-transmitting member, said preselected pin joint being devoid of any lost motion usable to effect significant changes in stroke length of the associated interrupter, and
• (g) opening spring means effectively located at the movable contact-rod end of each of said linkages that comprises at least three of said series-connected pin joints for applying a bias to said associated three-or-more pin joint linkage that acts upon all of the pin joints in said associated linkage to eliminate from said acted-upon pin joints such clearance as allows reversal of the associated movable contact rod immediately following contact-engagement near the end of a closing operation while closing force is still being applied to said associated linkage by said motive means.