Constant strain jar

Claim 2

A jarring tool for removing a fish from a well bore, comprising: a mandrel adapted to be connected to a running-in string of pipe, anchor means on said mandrel for anchoring said mandrel with respect to said fish, and jarring means carried by said mandrel including impact means for applying a repetitive impact force to said fish responsive to rotation of said mandrel, said impact means comprising an annular hammer piston reciprocable on said mandrel, a cylinder sleeve disposed about said mandrel and defining with said mandrel an atmospheric chamber in which one end of said hammer piston is disposed, said piston having a portion projecting from said chamber and exposed to the hydrostatic pressure of fluid in the well bore, said cylinder sleeve including a portion engageable with said anchor means, and means for repetitively moving said piston away from said anchor means in said chamber.

Claim 3

A jarring tool as defined in claim 1, said means for repetitively moving said piston away from said anchor means in said chamber including ratchetting cam means on said piston and rotatable with said mandrel.

Claim 4

A jarring tool as defined in claim 1, said means for repetitively moving said piston away from said anchor means in said chamber including ratchetting cam means on said cylinder sleeve and said hammer piston, means for holding said cylinder sleeve against rotation with respect to said fish and means for affecting rotation of said hammer piston responsive to rotation of said mandrel, said ratchetting cam means including cam lugs extending about said cylinder sleeve and said hammer piston, said cam lugs having axially extended surfaces for allowing instantaneous movement of said hammer piston to effect a jarring force upon said rotation of said hammer piston.

Claim 5

A jarring tool as defined in claim 1, and including centering means on said mandrel for centerinG said hammer piston with respect to the well bore.

Claim 6

A jarring tool as defined in claim 1, wherein said anchor means includes anchor elements engageable with said fish, and cam means for forcing said anchor elements into engagement with said fish responsive to the application of an upward strain to said running in string.

Claim 7

A jarring tool as defined in claim 1, wherein said anchor means includes anchor elements engageable with said fish, cam means for forcing said anchor elements into engagement with said fish responsive to the application of an upward strain to said running-in string, and releasable means for normally latching said mandrel and said anchor means against operation.

Claim 8

A jarring tool for removing a fish from a well bore comprising: a mandrel adapted to be connected to a running-in string of pipe, anchor means on said mandrel engageable with the fish including slip elements carried by said mandrel, said mandrel having expander means thereon for actuating said slip elements into gripping engagement with said fish responsive to upward movement of said mandrel, a cylinder sleeve engaged with said expander means, said mandrel extending through said cylinder sleeve and having an annular Anvil slidable in said cylinder sleeve, an annular hammer piston axially shiftable on said body and having an end disposed in said cylinder sleeve, the other end of said hammer piston being exposed to the hydrostatic pressure of fluid in the well, and cam means on said mandrel and said hammer piston for repetitively forcing said hammer piston axially away from said anvil and allowing pressure-responsive hammer blows of said hammer piston on said anvil responsive to rotation of said mandrel relative to said hammer piston.

Claim 9

A jarring tool for removing a fish from a well bore comprising: a mandrel adapted to be connected to a running-in string of pipe, anchor means on said mandrel engageable with the fish including slip elements carried by said mandrel, said mandrel having expander means thereon for actuating said slip elements into gripping engagement with said fish responsive to upward movement of said mandrel, a cylinder sleeve engaged with said expander means, said mandrel extending through said cylinder sleeve and having an annular Anvil slidable in said cylinder sleeve, an annular hammer piston axially shiftable on said body and having an end disposed in said cylinder sleeve, the other end of said hammer piston being exposed to the hydrostatic pressure of fluid in the well, and cam means on said mandrel and said hammer piston for repetitively forcing said hammer piston axially away from said anvil and allowing pressure-responsive hammer blows of said hammer piston on said anvil responsive to rotation of said mandrel relative to said hammer piston.

Claim 10

A jarring tool for removing a fish from a well bore, comprising, in combination, anchor means adapted to be connected to a running-in string of pipe and engageable with said fish and including anchor elements expansible into engagement with said fish, expander means responsive to an upward strain on said running-in string to expand said anchor means, and hydrostatic fluid pressure-operated hammer means for applying a jarring force to said expander means upon rotation of said running-in string while said upward strain continues.

Claim 11

A jarring tool for removing a fish from a well bore, comprising, in combination, anchor means adapted to be connected to a running-in string of pipe and engageable with said fish and including anchor elements expansible into engagement with said fish, expander means responsive to an upward strain on said running-in string to expand said anchor means, and hydrostatic fluid pressure-operated hammer means for applying a jarring force to said expander means upon rotation of said running-in string while said upward strain continues.