Snap ringed bit retainer ring

Abstract

A bit retainer system includes a bit having a head and a shank, a driver sub disposed around the shank of the bit and adapted to engage a hammer case, a bit retainer disposed around the shank of the bit and abutting an upper end of the driver sub, wherein the bit retainer includes a split ring with a circumferential groove, and a secondary retainer disposed around the bit retainer, wherein the secondary retainer includes a snap ring configured to engage the circumferential groove.

1 . A bit retainer system comprising:
 a bit having a head and a shank;   a driver sub disposed around the shank of the bit and adapted to engage a hammer case;   a bit retainer disposed around the shank of the bit and abutting an upper end of the driver sub, wherein the bit retainer comprises a split ring with a circumferential groove; and   a secondary retainer disposed around the bit retainer, wherein the secondary retainer comprises a snap ring configured to engage the circumferential groove.   
   
   
       2 . The bit retainer system of  claim 1 , wherein the snap ring is metal. 
   
   
       3 . The bit retainer system of  claim 1 , wherein the snap ring is magnetic. 
   
   
       4 . The bit retainer system of  claim 1 , wherein the snap ring is elastically expandable. 
   
   
       5 . A bit retainer system comprising:
 a bit having a head and a shank;   a driver sub disposed around the shank of the bit and adapted to engage a hammer case;   a bit retainer disposed around the shank of the bit and abutting an upper end of the driver sub, wherein the bit retainer comprises a split ring with a circumferential groove; and   a secondary retainer disposed around the bit retainer, wherein the secondary retainer comprises a plurality of preformed tabs disposed at selected portions along the retainer.   
   
   
       6 . The bit retainer system of  claim 5 , wherein the secondary retainer is configured to elastically expand, thereby allowing the preformed tabs to engage the circumferential groove of the split rings. 
   
   
       7 . The bit retainer system of  claim 5 , wherein the split rings comprise a chamfer on at least one edge of the circumferential groove. 
   
   
       8 . A bit retainer system comprising:
 a bit having a head and a shank;   a driver sub disposed around the shank of the bit and adapted to engage a hammer case;   a bit retainer disposed around the shank of the bit and abutting an upper end of the driver sub, wherein the bit retainer comprises a split ring with a circumferential groove; and   a secondary retainer disposed around the bit retainer, wherein the secondary retainer comprises a plurality of preformed webs disposed at selected locations along the retainer.   
   
   
       9 . The bit retainer system of  claim 8 , wherein the secondary retainer is configured to elastically expand, thereby allowing the plurality of preformed webs to engage the circumferential groove of the split rings. 
   
   
       10 . The bit retainer system of  claim 8 , wherein the split ring comprises a chamfer on at least one edge of the circumferential groove. 
   
   
       11 . A bit retainer system comprising:
 a bit having a head and a shank;   a driver sub disposed around the shank of the bit and adapted to engage a hammer case;   a bit retainer disposed around the shank of the bit and abutting an upper end of the driver sub, wherein the bit retainer comprises a split ring with a circumferential groove; and   a secondary retainer disposed around the bit retainer in the circumferential groove, wherein the secondary retainer comprises a band having a plurality of elastically expandable buckles disposed on a first end and at least one protrusion disposed on a second end of the band.   
   
   
       12 . The bit retainer system of  claim 11 , wherein the protrusions are configured to engage the buckles and secure the band around the bit retainer.