Diamond locking couplings, also called back-end reamer

Diamond locking couplings, also called back-end reamer

 

Roschen spiral full hole back-end reamer

One or more solid rings of diamonds baked onto the locking coupling, like the standard reaming shell. This unit is wear-resistant and will last longer than the other types. It provides real hole stabilization, but it should be borne in mind that the diamonds-embedded sections are cutting elements and in rare cases might actually increase hole deviation. Water flow is more restricted as compared with other coupling, especially if the adaptor coupling, outer tube and reaming shell are also full hole type. Care should be taken in loose ground, as it is very easy to get this equipment stuck in the hole.
 

Lately, a variation of this type of coupling has become popular: a diamond LC with full hole body, usually with spiral water channels. The diamond sections protect the full hole body from wear, and the full hole body minimises the sideways cutting tendency of the diamond sections mentioned above. The full hole diamond coupling offers the optimum combination for hole stabilisation where ground conditions permit. This is the most expensive coupling.