Suction Port Lock Nut With Stub Buttress Threads

Abstract

A reciprocating pump assembly having a block body, a cylinder chamber in the block body, a plunger reciprocatingly disposed in the block body, an opening in the block body adjacent the cylinder chamber, and a cover plate in the opening. Threads on the outer periphery of the cover plate engage threads formed within the opening. The threaded outer periphery of the cover plate extends into the cylinder chamber and past the threaded portion of the opening so that the load on the cover plate transfers from fully formed threads on the cover plate to threads formed on the opening.

1 . A reciprocating pump assembly comprising:
 a block body;   a cylinder chamber in the block body;   a plunger reciprocatingly disposed in the block body;   an opening in the block body adjacent the cylinder chamber;   threads formed in the opening;   a cover plate in the opening; and   a threaded surface on the outer periphery of the cover plate engaging the threads formed within the opening and projecting within the block body past the threads on the opening.   
   
   
       2 . The reciprocating pump assembly of  claim 1 , wherein the threaded surface on the cover plate includes at least two unloaded threads that project within the block body past the threads in the opening. 
   
   
       3 . The reciprocating pump assembly of  claim 1 , wherein the threaded surfaces on the cover plate comprises a length of loaded threads that engage the threads in the opening, and a length of unloaded threads that project within the block body past the threads in the opening and the length of loaded threads is greater that the length of the unloaded threads. 
   
   
       4 . The reciprocating pump assembly of  claim 1 , wherein the threaded surface on the outer periphery of the cover plate includes threads having a root portion with a curved profile. 
   
   
       5 . The reciprocating pump assembly of  claim 1 , wherein the threaded surface on the outer periphery of the cover plate comprises a British Butt threads. 
   
   
       6 . The reciprocating pump assembly of  claim 1 , wherein the threaded surface on the outer periphery of the cover plate includes threads having a thread depth that is from about 60% to about 70% of the thread pitch. 
   
   
       7 . The reciprocating pump assembly of  claim 1 , wherein the threaded surface on the outer periphery of the cover plate includes threads having a truncated crest. 
   
   
       8 . The reciprocating pump assembly of  claim 3 , wherein at least some of the unloaded threads are substantially identical to the loaded threads. 
   
   
       9 . The reciprocating pump assembly of  claim 1 , wherein the threaded surface on the outer periphery of the cover plate includes threads having a rear flank disposed along a path oriented at an angle of about 45° with respect to the angle of the cover plate axis. 
   
   
       10 . A reciprocating pump assembly comprising:
 a cylinder block;   cylinder chambers formed in the block;   a plunger reciprocatingly disposed in each cylinder chamber;   circular openings in the block at an end of each chamber;   a thread formed in the openings;   cover plates, each having a thread formed on their outer circumference, at least a portion of the length of the thread being fully formed and at a maximum depth, the cover plates coaxially coupled into each opening so that the maximum depth portion of each cover plate thread engages the portion of each thread in the openings proximate the ends of each chamber; and   part of the maximum depth portion of each cover plate thread being out of engagement with and further inward from the thread in the opening.   
   
   
       11 . The reciprocating pump assembly of  claim 10 , wherein an axial length of the thread in the openings, relative to an axis of the opening, is less than an axial length of each cover plate thread. 
   
   
       12 . The reciprocating pump assembly of  claim 11 , wherein when in a secured position, an outer end of each cover plate thread is substantially flush with an outer end of the thread in the opening. 
   
   
       13 . The reciprocating pump assembly of  claim 10 , further comprising a smooth cylindrical portion in each opening joining an inner end of the thread in the opening and wherein part of maximum depth portion of each cover plate thread is located within the smooth cylindrical portion. 
   
   
       14 . The reciprocating pump assembly of  claim 10 , wherein the threaded surface on the outer periphery of the cover plate includes buttress threads having a truncated crest and rounded root. 
   
   
       15 . A pump assembly comprising:
 a block body;   a cylinder chamber in the block body;   a plunger reciprocatingly disposed in the block body;   an opening in the block body adjacent the cylinder chamber;   threads formed in the opening;   a cover plate in the opening;   a threaded surface on the outer periphery of the cover plate engaging the threads formed within the opening and having at least two unloaded threads projecting within the block body past the threads on the opening, and a length of loaded threads that exceeds the length of the unloaded threads.   
   
   
       16 . The pump assembly of  claim 15 , wherein the threads on the cover plate comprise British Butt threads. 
   
   
       17 . The pump assembly of  claim 15 , wherein the threads on the cover plate have a truncated crest.