Mud throttling valve

Claim 1

IN A FLUID THROTTLING VALVE, THE COMBINATION OF AN ELONGATED HOUSING ADAPTED FOR PASSAGE OF FLUID LONGITUDINALLY THERETHROUGH AND HAVING AN INLET AND AN OUTLET END, A FIXED ABUTMENT MEMBER MOUNTED IN FIXED POSITION OF THE INLET END PORTION OF SAID HOUSING AND PROVIDED WITH A CENTRAL PORT, A TUBULAR VALVE MEMBER OF RESILIENT MATERIAL POSITIONED IN THE HOUSING AND HAVING THE INLET END THEREOF SECURED TO SAID FIXED ABUTMENT MEMBER, SAID VALVE MEMBER BEING PROVIDED WITH A CENTRAL FLUID PASSAGE IN COMMUNICATION WITH SAID PORT OF THE FIXED ABUTMENT MEMBER, A SLIDABLE ABUTMENT MEMBER AT THE OUTLET END OF SAID VALVE MEMBER AND PROVIDED WITH A CENTRAL PORT IN REGISTER WITH SAID FLUID PASSAGE OF THE VALVE MEMBER, SAID RESILIENT VALVE MEMBER BEING AXIALLY COMPRESSIBLE AND RADIALLY INWARDLY EXPANSIBLE WHEREBY THE CROSS-SECTION OF SAID FLUID PASSAGE MAY BE REDUCED AS A FUNCTION OF AXIAL THRUST APPLIED TO SAID SLIDABLE ABUTMENT MEMBER IN THE DIRECTION OF THE FIXED ABUTMENT MEMBER FOR COMPRESSING THE RESILIENT RESILIENT VALVE MEMBER THERETHROUGH, AND MEANS FOR APPLYING AXIAL THRUST TO SAID SLIDABLE ABUTMENT MEMBER, TOGETHER WITH A TUBULAR LINER OF WEAR RESISTANT MATERIAL AXIALLY JUXTAPOSED TO SAID RESILIENT VALVE MEMBER.