On-off tool for sucker rod string
An on-off tool for latching a sucker rod to a plunger rod has a housing, a pawl, guide pines, and a key. One end of the housing is connected to the sucker rod, and an interior of the housing defines a key slot terminating at a seat inside the interior. The pawl is disposed in the interior of the housing and is biased longitudinally preferably by disc springs. Bearings in the form of elongate pins are engaged between the pawl and the housing and dispose longitudinally in slots to guiding longitudinal movement of the pawl in the interior and preventing rotation of the pawl. The key has a head at its distal end that is passable through the key slot, interlockable with the pawl, and seatable on the seat. The key's head preferably defines a waist thereabout to provide the head with greater load bearing surface to engage the housing's seat.
1. A tool for latching a sucker rod to a plunger, the tool comprising:
a housing having first and seconds ends and defining an interior, the interior defining at least one longitudinal slot, the first end connecting to the sucker rod, the interior defining a key slot at the second end of the housing, the key slot terminating at a seat inside the interior;
a pawl disposed in the interior of the housing and biased longitudinally therein away from the first end toward the seat, the pawl defining a longitudinal side pocket;
at least one bearing being an elongate pin and being engaged between the longitudinal side pocket of the pawl and longitudinal slot of the housing, the at least one pin guiding longitudinal movement of the pawl in the interior and preventing rotation of the pawl in the interior; and
a key having distal and proximal ends, the proximal end connecting to the plunger, the distal end having a head extending on a stem from the proximal end, the head passable through the key slot, interlockable with the pawl, and seatable on the seat.
2. The tool of claim 1 , wherein the housing comprises at least one biasing element disposed in the interior and basing the pawl longitudinally therein away from the first end.
3. The tool of claim 2 , wherein the at least one biasing element comprises a plurality of disc springs.
4. The tool of claim 2 , further comprising a lug disposed in the interior and engageable between the first end of the housing and the pawl, the lug limiting the longitudinal movement of the pawl in the housing toward the first end.
5. The tool of claim 1 , wherein the pawl defines opposing ones of the longitudinal side pocket, wherein the housing defines opposing ones of the longitudinal slot in the interior, and wherein the at least one bearing comprises at least two of the elongate pins being disposed in the opposing side pockets of the pawl and in the longitudinal slots of the interior.
6. The tool of claim 1 , wherein the pawl comprises forks on both sides of the pocket, the forks defining edges slanted in opposing directions and engageable with the head.
7. The tool of claim 1 , wherein the housing defines an inner shoulder; and wherein the pawl defines an outer shoulder, the inner shoulder engageable with the outer shoulder and limiting the longitudinal movement of the pawl toward the second end of the housing.
8. The tool of claim 1 , wherein the key comprises a shoulder disposed about the stem, and wherein the second end of the housing is engageable with the shoulder.
9. The tool of claim 1 , wherein the head of the key defines a first outer dimension greater than a second outer dimension of the stem, and wherein the head comprises a waist with a third outer dimension greater than the first outer dimension of the head.
10. The tool of claim 9 , wherein the third outer dimension of the waist is rectangular with long sides and short sides, the short sides curved according to a circular profile.
11. The tool of claim 10 , wherein the key slot defines a keyway defining a profile approximate to the third outer dimension of the waist.
12. The tool of claim 9 , wherein the waist defines a lower contact area of a lower bearing surface of the key to engage on the seat in the housing.
13. The tool of claim 9 , wherein the head toward the distal end defines a tip beyond the waist, the tip having the first outer dimension with thinned sides to engage in the pocket of the pawl.
14. The tool of claim 13 , wherein the head defines an upper contact area between the first dimension of the tip and the third dimension of the waist and defines a lower contact area between the third dimension of the waist and the second dimension of the stem.
15. The tool of claim 14 , wherein the key slot of the housing defines a headway in which the head positions, the headway having the seat as a lower shoulder engageable with the lower contact area of the head, the headway having an upper shoulder engageable with the upper contact area of the head.
16. The tool of claim 15 , wherein the headway defines a circular dimension in the interior of the housing.
17. A tool for latching a sucker rod to a plunger, the tool comprising:
a housing having first and seconds ends and defining an interior, the first end connecting to the sucker rod, the interior defining a key slot at the second end of the housing, the key slot terminating at a seat inside the interior;
a pawl disposed in the interior of the housing and biased longitudinally therein away from the first end toward the seat;
at least one bearing engaged between the pawl and the housing, the at least one bearing guiding longitudinal movement of the pawl in the interior and preventing rotation of the pawl in the interior; and
a key having distal and proximal ends, the proximal end connecting to the plunger, the distal end having a head extending on a stem from the proximal end, the head passable through the key slot and interlockable with the pawl, the head having a waist seatable on the seat, wherein the head of the key defines a first outer dimension greater than a second outer dimension of the stem, and wherein the waist of the head has a third outer dimension greater than the first outer dimension of the head.
18. The tool of claim 17 , wherein the waist with the third outer dimension provides a seating area seatable on the seat greater than the first outer dimension of the head.
19. The tool of claim 17 , further comprising a plurality of disc springs disposed in the interior and biasing the pawl longitudinally therein away from the first end.
20. The tool of claim 19 , further comprising a lug disposed in the interior through the plurality of disc springs and engageable between the first end of the housing and the pawl, the lug limiting the longitudinal movement of the pawl in the housing toward the first end.
21. The tool of claim 17 , wherein the third outer dimension of the waist is rectangular with long sides and short sides, the short sides curved according to a circular profile.
22. The tool of claim 17 , wherein the head toward the distal end defines a tip beyond the waist, the tip having the first outer dimension with thinned sides to engage in the pocket of the pawl.
23. The tool of claim 17 , wherein the waist defines an upper contact area between the first dimension of the head and the third dimension of the waist and defines a lower contact area between the third dimension of the waist and the second dimension of the stem.
24. The tool of claim 23 , wherein the key slot of the housing defines a headway in which the head positions, the headway having the seat as a lower shoulder engageable with the lower contact area of the waist, the headway having an upper shoulder engageable with the upper contact area of the waist.
25. The tool of claim 24 , wherein the headway defines a circular dimension in the interior of the housing.