Electromagnetic relay with an interchangeable contact mechanism

Claim 1

AN ELECTRIC RELAY ADAPTABLE TO EITHER A COMBINED NORMALLY OPEN AND A NORMALLY CLOSED CONTACT ARRANGEMENT OR A NORMALLY OPEN CONTACT ARRANGEMENT ONLY, SAID RELAY COMPRISING A SINGLE COIL, AN ARC CHAMBER, A FIRST MEMBER ADAPTED TO BE DETACHABLY SECURED TO SAID CHAMBER, A FIRST SET OF CONTACTS FIXED ON SAID CHAMBER, A SECOND SET OF CONTACT CARRIER FOR MOVING SAID THIRD SET OF CONTACTS, A CONTACT CARRIED FOR MOVING SAID THIRD SET OF CONTACTS BETWEEN SAID FIRST AND SECOND SETS OF CONTACTS, SAID FIRST MEMBER COOPERATING WITH SAID COIL TO IMPOSE A FIRST PREDETERMINED LOAD ON SAID CARRIER IN SUCH COMBINED OPEN AND CLOSED ARRANGEMENT BETWEEN SAID FIRST, SECOND AND THIRD SETS OF CONTACTS AND A SECOND MEMBER DETACHABLY SECURED TO SAID CHAMBER SAID SECOND MEMBER COOPERATING WITH SAID COIL TO IMPOSE A SECOND PREDETEMINED LOAD ON SAID CARRIER CORRESPONDING TO SAID FIRST LOAD IN SUCH OPEN CONTACT ARRANGEMENT ONLY BETWEEN SAID FIRST AND THIRD SETS OF CONTACTS WHEN SAID SECOND MEMBER IS SUBSTITUTED FOR SAID FIRST MEMBER ON SAID CHAMBER.