SPEAR Russian patent published in 2009 - IPC E21B31/20 

FIELD: mechanics.

SUBSTANCE: proposed device comprises a hollow housing with inner tapered surface in its lower part, a bushing rigidly connected with the said hollow housing, both arranged aligned in aforesaid housing and sharing a common axial channel. The spear comprises also an outer and inner gripping elements arranged to move axially, a spacer sleeve fitted on the said outer gripping element, a tapered piston fitted on the rod and resting upon the said spacer sleeve. The rod top part is locked by nut relative to the housing, while its central part represents an annular piston with radial inclined holes made above it to form, between the latter and circular space tapered piston, a space communicating with the common axial channel. The outer gripping element is fitted on the housing inner tapered surface and represents a split sleeve with ribbed inner surface and tapered outer surface. The outer gripping element is fitted on the central rod between the tapered piston and centering cone to axially move relative to the outer gripping element and represents a split sleeve with ribbed outer surface and inner surface representing converging top and bottom cones. The top cone surface makes an outer cone mating surface of the tapered piston, while that of the lower cone makes an outer cone mating surface of the centering cone.

EFFECT: higher reliability.

1 dwg