DRILLING TOOL Russian patent published in 1994 - IPC

FIELD: drilling engineering. SUBSTANCE: tubular housing with bit is mounted at the bottom of movable casing string. Limiting movable sleeve and drill string with extension are mounted inside housing. Longitudinal external slots are made on extension and longitudinal grooves - in housing. Flat spring loaded bushings are positioned in housing grooves. With the drill string reciprocating and rotating, bushings engage longitudinal slots of extension when it lands on limiting movable sleeve. EFFECT: transfer of axial load and torque from drill string on housing provided. 2 dwg