Locking device for the control knobs of instruments

Claim 1

IN COMBINATION: AN APPARATUS COMPRISING A PAIR OF GENERALLY DISK-SHAPED MEMBERS, ONE OF SAID MEMBERS HAVING A PLURALITY OF RESILIENT FINGERS PROTRUDING FROM THE PLANE DEFINED BY SAID ONE MEMBER, AND THE OTHER OF SAID MEMBERS HAVING A CAM-SHAPED OUTER EDGE, SAID OTHER MEMBER BEING DISPOSED BETWEEN SAID FINGERS FOR ROTATION RELATIVE TO SAID ONE MEMBER IN A PLANE SUBSTANTIALLY PARALLEL TO SAID FIRST-MENTIONED PLANE, SAID CAM-SHAPED EDGE COMPRISING A SECTION OF INCREASING RADIUS, WHEREBY SAID CAM-SHAPED EDGE EXERTS A FORCE TILTING SAID FINGERS OUTWARD AT SOME ANGULAR POSITION OF SAID OTHER MEMBER AND RELEASES SAID FINGERS FROM SAID FORCE IN OTHER ANGULAR POSITIONS, EACH SUCH MEMBER BEING PROVIDED WITH A HOLE LOCATED SUBSTANTIALLY CENTRALLY WITHIN SAID MEMBER, SAID APPARATUS FURTHER COMPRISING A SHAFT TRAVERSING BOTH SAID HOLES, AND A BODY MOUNTED CONCENTRICALLY ON SAID SHAFT FOR ROTATION INTEGRALLY WITH SAID SHAFT, SAID BODY HAVING A SUBSTANTIALLY ROUND INTERNAL SURFACE, AND SAID FINGERS EXTENDING TOWARD SAID INTERNAL SURFACE AND COMING INTO LOCKING ENGAGEMENT WITH SAID BODY WHEN SPREAD APART BY SAID FORCE.