Full-interlocking Kelly bar is composed of three weld-on ribs with continuous  concave and convex  keys  During the drilling process, the downward thrust is transmitted to drill bucket directly by rotation power of  Rotary head inner ribs and Kelly bar outer ribs at any time.
This type of Kelly bar is the best one of transferring pressure at present , especially for hard ground and frozen oil layer construction. In the drilling process , every continuous steps can form pressure point to reduce  wear and tear of local pressurization key lines, also to avoid the stick problem that Kelly pipe is deformation always in a part pressurization.
Our full locking kelly bar is one hot selling type for customers to choose.