The RIGGER ENGINEERING mechanical releasing assembly consists of a releasing nut, a finger ring, and a loc ring, pictured here assembled to the kelly bar. The case hardened releasing nut has a coarse 2-pitch square thread that is designed to fit the liner. In this way the liner diameter is unrestricted. The thread is left hand to allow the operator to set the hanger with right hand rotation. This will prevent the operator from accidentally unscrewing from the liner should the releasing nut become jammed. The finger ring has steel fingers that lay in grooves in the liner hanger. These fingers in tum butt up against the spring loaded slips, holding them in the down or unset position. The loc ring screws onto the top of the nut to back up the finger ring and hold it onto the nut. There is clearance between the finger and loc ring to allow the finger ring to remain in position as the nut is unscrewed. As the nut is unscrewed it carries the finger ring up, which in turn allows the slips to come up and engage the casing.

Another option available with the mechanical releasing assembly is the off bottom tool. This tool is screwed onto the assembly in place of the loc nut and allows the liner to be hung without setting it on bottom. For more information see off bottom tool.