Screw thread cutting apparatus with yieldable clutch drive means

Claim 1

A SCREW THREAD CUTTING APPARATUS COMPRISING A ROTATABLE DRIVEN PART FOR HOLDING A TOOL, A ROTATABLE DRIVING PART ROTATABLE COAXIALLY WITH SAID DRIVEN PART AND ALIGNED AXIALLY THEREWITH, A SLEEVE MOUNTED COAXIALLY ON SAID PARTS FOR LIMITED AXIAL MOVEMENT INDEPENDENTLY THEREOF, A FIRST COUPLING MEMBER AXIALLY SLIDABLE IN SAID SLEEVE AND CONNECTED TO SAID DRIVING PART FOR ROTATION THEREBY AND FOR AXIAL MOVEMENT RELATIVE THERETO, A SECOND COUPLING MEMBER SECURED TO SAID SLEEVE FOR AXIAL MOVEMENT THEREWITH AND CONNECTED TO SAID DRIVEN PART FOR ROTATION THEREWITH AND FOR AXIAL MOVEMENT RELATIVE THERETO, MEANS IN SAID SLEEVE AND INTERPOSED AXIALLY BETWEEN SAID SLEEVE AND SAID FIRST COUPLING MEMBER TO YIELD AXIALLY BUT TO URGE SAID COUPLING MEMBERS RESILIENTLY AXIALLY TOWARD AND INTO DRIVING ENGAGEMENT WITH ONE ANOTHER, NORMALLY TO TRANSMIT THE ROTATION OF SAID DRIVING PART TO SAID DRIVEN PART, AND OPERATIVE, WHEN THE TORQUE TRANSMITTED FROM SAID DRIVING TO SAID DRIVEN PART EXCEEDS A PREDETERMINED VALUE, TO PERMIT SAID COUPLING MEMBERS TO SHIFT AXIALLY AWAY FROM ONE ANOTHER, AND RELATIVE TO SAID DRIVING AND DRIVEN PARTS, TO DISENGAGE SAID COUPLING MEMBERS AND DISCONNECT THE DRIVE BETWEEN SAID PARTS.