Mechanical jar having an adjustable tripping load

Claim 2

A well jar apparatus comprising: inner and outer members telescopically related and having impact surfaces that can be engaged by telescoping motion to deliver a jarring blow to an object that is stuck in a well bore; tripping means disposed on said members and including latch means and releasable locking means for preventing release of said latch means, said locking means being positioned for release of said latch means by longitudinal movement; resilient means capable of being foreshortened by said longitudinal movement and reacting between one of said members and said latch means for resisting said longitudinal movement with a reaction force that is a function of the amount of said longitudinal movement; and selectively adjustable means cooperable with said resilient means for adjusting the amount that said resilient means must be foreshortened before said locking means is in position to release said latch means, thereby adjusting the tripping load for said jar apparatus.

Claim 3

The well jar apparatus of claim 1 wherein said selectively adjustable means includes structure movable longitudinally along said one member for adjusting the longitudinal position of said resilient means with respect to said one member.

Claim 4

The well jar apparatus of claim 2 wherein said structure includes a jack mandrel having threaded engagement with said one member whereby rotation of said jack mandrel will feed said jack mandrel along said one member.

Claim 5

The well jar apparatus of claim 3 further including means providing access to said jack mandrel from the exterior of said members to facilitate rotational adjustment thereof.

Claim 6

A well jar apparatus comprising: inner and outer members telescopically related and having impact surfaces that can be engaged by telescoping motion to deliver a jarring blow to an object that is stuck in a welL bore; tripping means disposed between said members including laterally movable latch means having gripping engagement with said inner member, and releasable locking means movable with said outer member for normally preventing lateral movement of said latch means, said locking means being positioned for release of said latch means by longitudinal movement with respect thereto; resilient means capable of being foreshortened by said longitudinal movement and reacting between said outer member and said latch means for opposing said longitudinal movement with a reaction force that is a function of the amount of said longitudinal movement; and selectively adjustable means for adjusting the position of said resilient means within said outer member to change the amount that said resilient means must be foreshortened before said locking means is in position to release said latch means and enable lateral movement thereof, thereby to adjust the tripping load for said jar apparatus.

Claim 7

A well jar apparatus comprising: inner and outer members telescopically related and having impact surfaces that can be engaged by telescoping motion to deliver a jarring blow to an object that is stuck in a welL bore; tripping means disposed between said members including laterally movable latch means having gripping engagement with said inner member, and releasable locking means movable with said outer member for normally preventing lateral movement of said latch means, said locking means being positioned for release of said latch means by longitudinal movement with respect thereto; resilient means capable of being foreshortened by said longitudinal movement and reacting between said outer member and said latch means for opposing said longitudinal movement with a reaction force that is a function of the amount of said longitudinal movement; and selectively adjustable means for adjusting the position of said resilient means within said outer member to change the amount that said resilient means must be foreshortened before said locking means is in position to release said latch means and enable lateral movement thereof, thereby to adjust the tripping load for said jar apparatus.

Claim 8

The well jar apparatus of claim 5 wherein said selectively adjustable means includes a mandrel movable longitudinally along said outer member, and axial cam means responsive to rotation of said mandrel for feeding said mandrel along said outer member in either direction, depending upon the direction of rotation thereof.

Claim 9

The well jar apparatus of claim 6 further including means for fixing said mandrel against rotation in a selected longitudinal position thereof.

Claim 10

The well jar apparatus of claim 7 further including means extending through the wall of said outer member for providing access to mandrel to facilitate rotational adjustment thereof.