Mud throttling valve

Claim 1

A HYDRAULIC THROTTLING VALVE, COMPRISING IN COMBINATION, A TUBULAR HOUSING HAVING A FLUID INLET END AND A FLUID OUTLET END, AN ABUTMENT MEMBER FIXED IN THE FLUID INLET END PORTION OF SAID HOUSING AND PROVIDED WITH A CENTRAL PORT IN COMMUNICATION WITH THE FLUID INLET, A TUBULAR VALVE MEMBER OF RESILIENT MATERIAL POSITIONED IN THE HOUSING WITH ONE END THEREOF AGAINST SAID ABUTMENT MEMBER, SAID VALVE MEMBER HAVING A CENTRAL FLUID PASSAGE IN REGISTER WITH SAID CENTRAL PORT OF SAID ABUTMENT MEMBER, A PISTON SLIDABLE IN THE HOUSING AND ABUTTING THE OTHER END OF SAID VALVE MEMBER, SAID PISTON HAVING A CENTRAL PORT IN REGISTER WITH SAID FLUID PASSAGE OF THE VALVE MEMBER, A PARTITION SECURED IN SAID HOUSING IN SPACED RELATION BETWEEN SAID PISTON AND SAID OUTLET END OF THE HOUSING, THE PORTION OF THE HOUSING BETWEEN SAID PARTITION AND THE HOUSING OUTLET END DEFINING A FLUID OUTLET CHAMBER DISCHARGING THROUGH THE OUTLET END, A FLUID TRANSMITTING TUBE SECURED CENTRALLY TO SAID PISTON IN REGISTER WITH THE PISTON PORT, SAID TUBE EXTENDING SLIDABLY THROUGH SAID PARTITION AND HAVING AN OUTER END DISCHARGING INTO SAID FLUID OUTLET CHAMBER, A PORTION OF SAID HOUSING BETWEEN SAID PARTITION AND SAID PISTON DEFINING A PRESSURE CHAMBER SURROUNDING SAID TUBE BUT OUT OF COMMUNICATION WITH THE INTERIOR OF THE LATTER, SAID RESILIENT VALVE MEMBER BEING AXIALLY COMPRESSIBLE BY SAID PISTON AND RADIALLY INWARDLY EXPANSIBLE WHEREBY THE CROSS-SECTION OF SAID PASSAGE MAY BE REDUCED AS A FUNCTION OF AXIAL THRUST APPLIED TO THE VALVE MEMBER BY THE PISTON, AND MEANS FOR ADMITTING FLUID UNDER PRESSURE INTO SAID PRESSURE CHAMBER WHEREBY TO EFFECT APPLICATION OF AXIAL THRUST BY SAID PISTON TO SAID VALVE MEMBER.