Steam valve disk assembly with internal bypass valve

Claim 1

A VALVE DISK ASSEMBLY COMPRISING A MAIN VALVE DISK MEMBER HAVING AN AXIAL BORE THERETHROUGH, A VALVE STEM PROJECTING INTO ONE END OF SAID BORE AND HAVING AN END PORTION PROJECTING FROM THE OTHER END OF THE BORE, THE VALVE STEM BEING DISPOSED FOR LIMITED AXIAL SLIDING MOTION IN SAID BORE, A CAP MEMBER SECURED TO SAID MAIN DISK MEMBER AND FORMING WITH THE MAIN DISK MEMBER A FIRST CENTRAL RECESS SURROUNDING THE PROJECTING END PORTION OF THE VALVE STEM, THE MAIN DISK MEMBER HAVING A PORTION FORMING A SECOND CENTRAL RECESS INCLUDING AN ANNULAR BYPASS VALVE SEAT DEFINING AN ANNULAR PASSAGE WITH THE VALVE STEM, AND A CYLINDRICAL BYPASS VALVE MEMBER DISPOSED IN SAID FIRST RECESS AND HAVING A THIRD CENTRAL RECESS RECEIVING THE EXTREME END PORTION OF THE VALVE STEM, SAID PROJECTING END PORTION OF THE VALVE STEM AND SAID THIRD CENTRAL RECESS FORMING COARSE INTERENGAGING HELICAL THREADS DEFINING A FIRST AXIAL CLEARANCE SPACE THEREBETWEEN WHEN THE BYPASS VALVE MEMBER IS IN CLOSED POSITION ABUTTING SAID BYPASS VALVE SEAT, THE EXTREME END SURFACE OF THE VALVE STEM FORMING A SECOND AXIAL CLEARANCE SPACE SMALLER THAN SAID FIRST CLEARANCE SPACE WITH AN ADJACENT ABUTMENT SURFACE OF SAID THIRD CENTRAL RECESS, WHEREBY AXIAL MOVEMENT OF THE VALVE STEM FIRST CAUSES THE SECOND CLEARANCE SPACE TO CLOSE WHILE SAID FIRST AXIAL CLEARANCE SPACE PROVIDES CLEARANCE ON BOTH SIDES OF SAID INTERENGAGING THREADS, WHEREBY FORCE IS TRANSMITTED IN THE VALVE OPENING DIRECTION ENTIRELY THROUGH THE END SURFACE OF THE VALVE STEM TO THE ABUTTING SURFACE OF THE THIRD CENTRAL RECESS WITH NO LOAD ON THE THREADED PORTIONS.