US2389711A

US2389711A - Well jar

Info

Publication number: US2389711A
Application number: US406646A
Authority: US
Inventors: Arthur L Armentrout
Original assignee: Individual
Current assignee: Individual
Priority date: 1941-08-13
Filing date: 1941-08-13
Publication date: 1945-11-27
Anticipated expiration: 1962-11-27

Description

NOV. 27, 1945. A ARMENTRQUT f 2,389,711

WELL J' AR Filed Aug. 13, 1941 3 Sheets-Sheet 2 @3H/yay l Nov. 27, 1945. A. L.. ARMENTROUT r W ,m /N W W WELL JAR Filed Aug. 13 1941 Patented Nov. 27, 1945 UNITED STATES FATENT OFFICE WELL .ma Arthur'LfArm'entrout, Long Beach, Cali-f. Application Angustia, 1941, serial No. 406,646:

(ci. 25a-27) Claims.

This invention relates to Well tools and relates more particularly to jars or jaring tools useful in removing objects from wells. Al general object of this invention is to provide a practical effective jarring tool capable of producing very heavy jarring effects forfreeing objects caught in wells.

Rotary jars of various types have been introduced but all have certain limitations of use or have certain disadvantages accompanying their operation. One type of'jar now employed embodies av jarring hammer actuated by a spring. The spring is compressed to store up energy for the operation of the hammer, thisrcompression either being vaccomplished by a pull'on the lishing string or by'a cam mechanism actuated by rotation of the string.v The size and space limitations of a well tool, such as a jar, prevent the use of a heavy 'strong spring and, for this reason, the spring-hammer type jar is incapable of producing jarring'blows of any substantial maghitude. Another general type of jar that has been introduced utilizes the stretch or resiliency of the fishing string to provide a jarring action, ythe string being put lunder heavy tensile strains in order to obtain the required stretchv This subjects the string to excessive and dangerous strains and subjects the hoisting .cables, etc. to excessive wear. Furthermore, it is impossible Jto-strike the jarring blow while maintaining-the tensile strain on the string because the sudden release of the tool momentarily relieves the string of its tension and the blow-is struck during this -interval of rio-tension. A third general type of jar has been proposed which contemplates the use of the hydrostatic pressure in the deep Well as the actuating force for the hammer, The hydraulic Well pressure is very slow inits action and cannot develop sucient dynamic inertia in Ehe hammer to produce an effective jarring acion.

Another object of this invention is to provide a well jar operable to produce a jarring action of great intensity. The tool of the present invention is operable to produce a jarring action of much greater intensity than previously introduced well jars.

Another object of this invention is to provide a Well jar operable to provide a heavy strong jarring action Without subjecting theI fishing string to excessive or dangerous tensile strains. |Ifne tool of the present invention is operable to provide a jarring action o f any desired or required magnitude without Vputting theY string undertension, it being optional with the operator whether theAV string is to be maintainedunder tensionV andthe tension, if applied, may' beef selected or the required degree Without varying the intensity of the jarring blows. In employing the tool of the. present invention it is unnecessary to subject the flshing string to a stretch in order lto obtainV the jarring action and vthere is little or no dangerof breaking the string during the 'shing'operations and the hoist lines, etc. are ntsubjected to excessive Wear.

Another object of this invention is to provide a jarring tool of the character referred to in which jarring blows of great intensity may be imparted tothe string and iishwhile maintaining an uninterrupted and unvarying pull or tension on the string. No relaxationin thegtensile strain on the fishing string is requiredin the operation of the tool and a constant uniform or varied tension may be maintained on the fishingstring without interruption to utilize (the jarring action to Ythe'best advantage in freeing the fish.

Another object-of this invention is'to'provide a Well jar of the character referred togwhich is fully operable by simple rotation of the fishing string in either direction.

Another object of this invention is -to provide a jarring tool of the character mentioned in; which the hammer element is driven or movedatV further increase the'pressure Yon the `gas and is thenreleased to be driven against the anvil at a high velocity by the sudden expansion 'of the gas.

Another and importantobject of this invention is'to vprovide a jarring tool of the character just mentioned in `which the hammer-piston Aelement may have along stroke or a stroke of any required extent. If the tool is constructedso that the: hammer element has a long stroke the contained body of gas may be put undery greatly increased pressure'to operate the hammer with great speed and force. On the other hand`,if the tool is constructed so that the hammer has a shorter `stroke the gas is subjected to less compression and ythe hammeris actuated with less speed and force.

In my copending application entitled Jarring tools, filed August 12, 1941, Serial No. 406,465, I have disclosed a jarring tool in which a hammer is forced against a body of gas under pressure by a cam means and is released to be driven against the anvil by the expanding gas upon the release or disengagement of the cam means. Certain prior jarring tools employ broken threads or cams for advancing a hammer against a spring and for providing relative longitudinal movement between the jar body parts. The cams employed in such tools can only provide a very short hammer stroke or a very short relative movement between the jar body parts, as the case may be, and the resultant jarring action is accordingly relatively weak. The tool of the present invention may be constructed to give the hammer or relatively movable parts a stroke of great length or of sufcient length to produce a very heavy jarring action.

Another object of this invention is to provide a well jar embodying novel hammer operating and controlling means capable of full operation by simple rotation of the fishing string in either direction.

Another object of this invention is to provide a jarring tool that may be easily prepared or set to produce a jarring action of any selected or re,

quired intensity or, if desired, may be conditioned to employ the high hydrostatic pressures in the well to increase the magnitude of the jar blows without a reduction in the velocity of movement of the hammer element.

A further object of this invention is to provide a jarring tool that is operable to produce a succession or series of heavy jarring blows by simple rotation of the operating string with or without tension on the string and which may be operated continuously or intermittently for a long period without a diminutionV in the magnitude of the jarring blows.l

The various objects and features of my invention will be fully understood from the following detailed description of typical preferred forms and applications of the invention, throughout which description reference is made to the accompanying drawings, in which:

Fig. 1 is a central longitudinal detailed sectional view of one form of a jarring tool 'of the invention showing the hammer element latched in the retracted position. Fig. 2 is a fragmentary longitudinal detailed sectional view of the tool illustrated in Fig. 1 showing the latches released with the hammer element striking the anvil. Fig. 3 is a transverse detailed sectional view taken as indicated by line 3-3 on Fig. l. Fig. 4 is a central longitudinal detailed sectional View of another form of the invention. Fig. 5 is a side elevation of the upper portion of the hammer element removed from the tool illustrating the latch slot. Fig. 6 is a side elevation of the travelling nut of the tool illustrated in Fig. 4 removed from the other elements. Figs. 'I and 8 are transverse detailed sectional views taken as indicated by line 'I-1 and 8 8, respectively, on Fig. 4. Fig. 9 is a fragmentary longitudinal detailed sectional view showing the hammer element approaching the lower end of its downward stroke. Fig. l is a central longitudinal detailed sectional View of still another form of the invention. Fig. 11 is a fragmentary vertical detailed sectional view taken substantially as indicated by line |I-| I on Fig. l0. Fig. 12 is a fragmentary longitudinal detailed sectional view of the tool shown in Fig. Withthe travelling nut atthe lower end of its stroke and Fig. 13 is a transverse detailed sectional view taken as indicated by line |3-I3 on Fig. 12.

The jarring tool of the invention illustrated in Figs. l to 3, inclusive, may be said to comprise, generally, a body I0, a cylinder II in the body I0, a movable or reciprocable hammer I2 in the cylinder I I, means I3 for providing and maintaining a body of gas under pressure under the hammer element I2, latch means I4 for releasably latching the hammer I2 in a position where it maintains the gas under increased pressure and means |5 for moving the hammer I2 to said position and for thereafter releasing the latch means |4.

The body I0 is an elongate hollow or tubular member to be interposed in a fishing string of drill pipe, or the like. In the particular case illustrated, the body Ill comprises an elongate tubular main section I6 having a cap I1 threaded in its upper end and a sub I 8 threaded in its lower end, it being understood that the body may be varied considerably without departing from the invention. An internal annular ange I9 is provided on the cap II adjacent its upper end. A connecting member 20 having a suitable connection with the fishing string, Ynot shown, has a reduced stem 2| extending downwardly through the ange I9 with suitable clearance. A nut or collar 22 is threaded or otherwise xed on the stem 2| below the flange I9. Rows of anti-friction elements or balls 23 are engaged between th'e collar 22 and the lower side of the iiange I9 and between the upper side of the flange I9 and a shoulder 24 on the member 20. The balls 23 operate in suitable races in the ilange I 9, the collar 22 and the shoulder 24. The nut or collar 22 turnably fits in the member I1 and carries packing 25 for sealing with the interior of the member. The structure just described constitutes a swivel connection` between the member 20 on the fishing string and the body I 0. The body I Il is in the nature of a shell and serves to conduct the circulation fluid downwardly around the cylinder I I. A passage 26 having communication with the fishing string extends downwardly through the member 20 to lateral ports 21 in the stem 2|. The ports 2'I in turn communicate with lateral ports 28 in the collar 22 which discharge into the interior of the body IU. A central longitudinal passage 29 is provided in the sub I8 and leads to the lower portion of the string or sh, not shown. One or more lateral ports 30 is provided in the sub I8 to place the interior of the body I0 in communication with the passage 29.

The cylinder defines or provides the chamber 3| for containing the gas under pressure and for housing the reciprocable hammer I2. The cylinder I I is supported in the body I 0 for limited longitudinal movement and slidably or shiftably engages on a mandrel 32 depending from the stem 2| of the connecting member 20. The cylinder may be varied considerably and, in the typical case illustrated, is an elongate tubular member provided at its upper end with a cap or head 33. The head 33 is preferably quite heavy and is threaded into the upper end of the cylinder to provide a downwardly facing annular shoulder 34 in the cylinder. The upper end of the head 33 is flat and is adapted to bear or engage upwardly against the lower side of the collar 22 and the shoulder 35 of the stem 2| which lies in the same plane as the lower end of the collar. A central vertical opening 36 in the head 33 slidably passes the mandrel 32. Packing 3l is provided in the opening SStotightly seal with the mandrel 32. The body of the cylinder II preferablyhas a rather heavy or thick wall. The .cylinder as, just described, is centrally or coaxially arranged in the body I0 and is, proportioned to leave an annular clearance space or passage between its periphery and the interior of the body II] for conducting they circulation fluid.

The lower end of the cylinder II has packed sliding engagement with the sub I3.v A boss 38 of reduced diameter is provided on the upper end of the sub I8 and is slidably received in the lower portion of the tubular cylinder The means for slidably sealing between the cylinder II and the boss 38 may comprise packing 39 of the chevron type set in a recess in the cylinder I I to slidably seal with the boss 38. The packing 39 preferably faces in both directions to prevent leakage from and into the cylinder. Means is provided for keying the cylinder II to the boss 38 and to limit longitudinal movement of the cylinder relative to the body I0. A keyway or groove di) is formed in the interior of the cylinder above the packing 39 and receives a key or pin 4| projecting from the boss 38. The keyway 43 is located and proportioned to allow the cylinder II to move upwardly until its head 33 engages the under side of the collar 22 and the lshoulder 35. Fig. 1 of the drawings shows the cylinder II in its lowermost position where the upper end of the keyway 40 engages the pin II` to stop the downward travel of the cylinder.

The hammer element I2 is movable or shiftable vertically in the cylinder II, being operable in one direction by the means I5 and being moved or driven in the other direction with great force and speed by expansion of the confined gas under pressure contained in the lower portion of the cylinder. rIhe hammer I2 is a weight element preferably formed and proportioned to have substantial weightV and is a piston element being operable in the cylinder to further compress the gas under pressure when moved in one direction and being operable in the other direction by the sudden expansion of the gas.

In the preferred construction, the hammer I2 is an elongate block-like part of cylindrical configuration having opposite end portions which slidably nt the cylinder II. It is preferred to provide means on the hammer I2 for slidably sealing with the interior of the cylinder to definitely separate the portions of the chamber 3| above and below the hammer. In the structure illustrated chevron type packing 42 is engaged on a reduced lower end portion of the hammer I2 and is actuated or compressed by a threaded-on nut or gland 43 to effectively seal with the internal surface of the cylinder II. A central longitudinal opening or socket ill enters the hammer I2 from its upper end and freely receives the mandrel 32. The socket 44 is of sufficient depth to entirely receive the mandrel 32. This allows the upper end of thehammer to directly strike against the shoulder 34.

The weight of the hammer I2 and the length of the hammer stroke are two important factors in determining the intensity of the jarring action produced by the tool. It is an important feature of the present invention that the stroke of the hammer I2 may be as long as required or desiredi the means I5 being operable by simple rotationof the fishing string to feed the hammer I2 downwardly any required distance to give the hammer the necessary stroke. The cylinder ||k may be proportioned to provide for the selected or required hammer stroke with additional length for (lll the length of the hammer I2 and fcr that por-fv tion of the cylinder chamber 3| below the ham mer which contains the air or gas under pressure when the hammer is in its lowermost position. By increasing or decreasing the length of the hammer I2, its weight may be regulated or provided as desired and where the cylinder I| may be of any selected length it will be seen that the hammer I2 may be given as great a weight as will be necessary under any conditions of opera tion.

The means I3 provides and maintains a body of air or other gas under pressure in the cylinder chamber 3| below the hammer I2 under super-atmospheric pressure. It is an impo-rtant feature of the invention-that the gas thus held under super-atmospheric pressure is operable to develop a greater hammer velocity and to impart a greater driving force to the hammer than any means employed in the jarring tools heretofore introduced. In accordance with the invention the hammer actuating gas is initially under substantial super-atmospheric pressure and this pressure is greatly increased or multiplied when the hammer I2 is forced down by the means I5 so that the gas is under a very high pressure at the time of release of the latch means I4 to throw the hammer I2 upwardly at a tremendous speed and with great force. It is preferred t0 construct the means I3 so that the gas pressure initially provided in the cylinder chamber 3| under the hammer I2 may be varied or changed to adapt the tool for any given operation and so that the high hydrostatic' pressures in the well may be utilized to boost or increase the initial pressure on the gas. That portionfof the cylinder chamber 3| below the hammer I2 constitutes the gas chamber, it being noted that the packing 39 seals off the lower end of this chamber by sealing between the cylinder and the boss 38 and that -the packing I2 seals oif the upper end of the gas chamber by packing between the wall of the cylinder I and the hammer I2.

This .sealed or packed olf lower portion of the cylinder chamber 3| is pre-loaded or pre-charged with air or other gas under super-atmospheric pressure prior to running the tool into the well. The initial gas pressure provided in the lower portion of the cylinder chamber 3|, that the gas pressure in the lower part of the cylinder with the hammer I2 in its uppermost position is one of the important factors in determining the intensity of the jarring blow produced by the device. The initial gas pressure may range from a few pounds per square inch to several thousand 1 pounds per square inch depending upon the intensity of the jarring action desired and depending upon the length of stroke of the hammer I2. In general it may be said that when the hammer I2 is given a long stroke the initial gas pressure provided in the chamber 3| under the hammer I2 may be less than when the hammer is given a shorter stroke.

The means I3 preferably includes a ported valve structure for admitting air or gas under pressure to the-cylinder chamber 3| and for bleeding or removing such pressure from the chamber. It is to be understood that the invention contemplates permanently sealing a body of gas under pressure in the chamber 3l under the hammer I2, in which case the valved means for admitting the gas to the chamber may notl be required. In the construction illustrated a port 15 leads upwardly from the exterior of the sub I8 and through the boss 38 to communicate with the chamber 3|. A spring loaded' check Valve 431s provided inthe mouth portion of the port 45 and is arranged to close outwardly to retain the gas pressure in the cylinder chamber. The port 45 is equipped or formed to receive the nozzle or threading tting of a pressure supply means, not shown. In the simple case illustrated, the outer end of the port 45 is threaded. A plug 41 is removably threaded in this outer portion of the port 45 to exclude the high hydrostatic pressure present in the well bore and to exclude the mud ladened well uid. A second port is provided in the sub I8 to facilitate the leading or relieving of gas pressure from the cylinder chamber 3|. In practice, this second port 48 may be a branch of the port 45. The port 48 is equipped with a normally closed valve 49 adapted to be opened or removed to permit bleeding of the chamber 3| or to relieve excess pressure from the chamber. The valve 43 may be in the nature of a needle valve carried by or actuated by a plug D threaded in the outer end of the port 48. It is to be understood that the valve 43 is normally closed and that the plug 50 is normally threaded in the port 48 so that gas cannot pass outwardly through the port and so that well uidsare excluded.l

In conditioning or charging the lower portion of the cylinder chamber 3| the plug 41 is removed and the threaded tting of a pump line or air pressure supply line is threaded in the port 45 to deliver the air or gas under pressure to the chamber 3 I. During this operation it is preferred to have the hammer I2 in its uppermost position to be later described. When selected gas or air pressure has been provided in the chamber 3| under the hammer I2 the plug 41 is returned to the port so that well fluids cannot leak into the well and so that the high external pressures that may be encountered in the well will not change the initial pressure provided in the chamber 3|. In the event that it is desired to utilize the high hydrostatic pressures in the well to boost or increase the initial gas pressure provided in the chamber 3|, under the hammer I2, the plug 41 is removed or left out of the port 45. In this case the valve 46 remains closed against the entrance of well fluids and pressures until the tool has reached a depth in the well where the hydrostatic pressures are greater than the initial gas pressure provided in the chamber 3|, at which time the valve I6 opens inwardly to admit the well pressure to the lower end of the chamber 3|. It is to be understood that the gas remains under high pressure in the cylinder chamber 3| under the hammer I2 and the liquid from the well occupies or enters only the lowermost part of the cylinder chamber.- 'Ihe use of the hydrostatic pressures to increase the initial gas pressure in the chamber 3| is not essential in every case and, in many uses of the tool, the plug 41 is left in the port 45 to exclude the well pressures from the chamber 3|. The portion of the chamber 3| above the hammer I2 is sealed or closed by the previously described structure and when the hammer I2 is forced downwardly a reduced pressure is created above the hammer. This reduced pressure materially assists the expanding gas under pressure below the hammer I2 in driving the hammer upwardly with great velocity and force, as will be more fully described.

It may be desired to incorporate a spring 5| in the jar to assist the gas under pressure in driving the hammer I2 upwardly, it being understood that the spring is'not essential to the tool or its operation and may be omitted if desired. In

the drawings I have shown a coiled spring 5| arranged under compression between the lower end of the hammer I2 and the sub boss 38. A boss 52 on the lower end of the hammer I2 and a socket 53 formed in the boss 38 centralize and retain the spring 5| Where the spring 5| is employed it is preferred to construct it to be under compression when the hammer I2 is in its uppermost position in striking engagement with the collar 22 and to be under materially increased compression when the hammer I2 is in its lowermost position.

The latch means I4 is operable to hold the hammer I2 in its lowermost position, against the gas pressure and spring .pressure which act upwardly against the hammer, and the latch means is released by the means I5 to allow the hammer I2 to be forcibly driven upwardly by the expanding gas and spring 5|. The means I4 is such that it is automatically made operative or latched when the hammer I2 is moved to the lower end of its stroke by the means I5. The releasable latch means Is includes one or more latches 54 carried by the hammer I2 for latching or cooperating with the mandrel 32. In the particular structure illustrated there are latches 54 arranged in two diametrieally opposite slots 55 in the upper portion of the hammer I2. The latches 54 are Y alike, independent elements each pivoted on a transverse or horizontal pivot pin 56. The slots 55 extend longitudinally of the hammer |2 and have communication with the socket 44 throughout their lengths and extend outwardly to the exterior of they hammer I2 at their upper portions only. Each latch has a lower nose 51 and an upper nose 58. The lower noses 51 of the latches 54 are engageable with the lower end of the mandrel 32.to latch the hammer I2 against upward movement with respect to the mandrel body I Il, etc. The lower end of the mandrel 32 may be provided with a downwardly proj'ecting marginal lip 59 and the latch noses 51 are constructed to hook under this lip 59. Springs 60 are arranged under compression between the walls of the slots 55 and the lower portions of the latches 54 to urge the latch noses 51 inwardly for automatic cooperation with the lower end of the mandrel 32.

The upper noses 58 of the latches 54 project outwardly through the upper .portions of the slots 55 to extend into longitudinal keyways or grooves 6| formed in the wall of the cylinder I I. The latch noses 58 engaged in the grooves 5| may key the hammer I2 against turning but it is preferred to provide keys 62 on the body of the hammer I2 to operate in the grooves 6| for this purpose. The lower ends of the keyways or grooves 6I terminate in abrupt upwardly facing shoulders 63 and the parts are proportioned so that these shoulders 63. occur immediately below or a very short distance below the noses 5B of the latches 54 when the cylinder II and the hammer I2 are both in their lowermost positions. Thus, as illustrated in Fig. 1 of the drawings. where the pin 4I is supporting the cylinder in its lowermost position and where the latch noses 53 are engaged with the lower end of the mandrel 32 to hold the hammer I2 in its lowermost position the shoulders 63 are adjacent and below the latch noses 58. The outer ends of the latch noses 58 have upwardly and outwardly inclined surfaces 64 cooperable with the shoulders 63. As will be later described, the means I5 is operable to shift the cylinder I Iupwardly slightly subsequent to latching of the hammer I2 so that the shoulders 63 are made to cooperate with the surfaces 64 and pivot the latches 54 to 'release their noses 51 from the mandrel 32. Upon the release ofthe latch means I4 the hammer I2 is forcibly driven upwardly by the expanding gas and as the hammer travels upwardly the latches 54 remainin retracted positions' such as illustrated in Fig.v 2. The latches 54 also remain fully retracted during the downward or return movementof the hammer I2, the engagement'of the faces of the noses 51 with the mandrel 32 holding the latches Ain the released position.

The means I5 serves to move the hammer I2 downwardly to its lowermost p'ositionwhere the latches 54 latch with the 'end of 'the'mandrel 32 and where the gas is put under the maximum increased pressure and is operable thereafter to shift the cylinder II to cause the releaseof the latches 54' so that the hammer I2 may be driven upwardly by the rapidly expanding gas under super-atmospheric pressure. rhev means I5 is operable by simple rotation of the shing string in either direction without regard to the vertical forces on the string, that is, the means I5 is fully and effectively operative with great or little tension on the string as'desired. It is an important feature of the invention that the means I5 may be constructed tov give the hammer I2'as long or as short a stroke as desired, thus distinguishing the present invention over prior jarring tools employing cam means operable by rotation of the string and capable of producing only a very short hammer stroke. The meansV I5 may force the hammer I2Y against the contained gas under pressure for a substantial distance to greatly increase'or multiply the 'gas pressure.

YThe means I5 is a thread means or` screw means comprising a thread or groove in the mandrel 32 and a` travelling nut 65 'cooperating' with the thread or groove. vThe thread'of the 'mandrel 32 will be' considered as a groove and, as illustrated, comprises two oppositely pitched portions A and' B connected or joined at their ends lto constitute a single continuous groove.

The groove portions Av and B may be termed the' right and lefthand portions, respectively, of the thread or groove' having' right and' left "hand pitches. The threador grooveportionsA and B are of'edual 'pitch orleadand'are ofe'qual uniform width and depth throughout their lengths.

Itis preferred to give 'the groove portions A and B a substantial pitch, as illustrated, to assure rapid travel of the nut 65. vThe grooveportions A and B aresquare or rectangular in cross section having hat upper and lower walls'and'beirig 'of substantially the same width at their mouths and at their bases or inner walls. [The portionsA and B being'pitched in opposite directions cross or intersect one anothereach 180' at the points or intersections C'.

The right and left hand portions A and B of the continuous spiral groove or thread'are joined at their upper and lower `ends by what I will term reversing or connecting portions D' formed to reverse the direction-of -travel ofthe nut 65. The reversingportions D have smoothly rounded or' curved walls joining the 'oppositely pitched walls of the right and left hand groove portions A andl B. Fig. 1 of the* drawings clearly illustrate themanner in whichY thev groove portions D connect" the right and' left -handfgroove portions A and B. The curvatureof the groove walls in the portions D is such thatthe' groove is slightly'- wider atv these Ipoints for the purpose Ato be later-described. The'length of the above de' scribed thread'or groove comprisedof the oppositely pitched portions Aand'B determines the length of `ltravel of the nut' 55 and, therefore, determines the stroke of the hammer I2. It is important to note that the thread or groove A-B may beof any length required to give the hammer I2 the desired or necessary stroke. In the case illustrated, the groove A-B extends' a substantial distance along the mandrel 32, it being understood Athat it may be made longer or shorter than illustrated.

`The nut 65 is an annular or tubular member having -ai, central opening slidably receiving the mandrel 32. The nut'65 is received in the chamber 3| with substantial clearance, being spaced a considerable distance from the internal wall of the cylinder. Means is provided for holding the nut 65 against rotation. A lug or ear 66 projects from vthenut 65 and cooperates with one of the grooves' 6I to holdthe nut against turning. 'A recess l is provided in the under side of the 'cylinder head 33 to receive the nut 65 when the nut is in its uppermost position and the recess B'I'has anextension or notch 68 for receiving theI ear 86.

The nut`65 carries a follower for 'cooperating With the thread or groove'A-B to produce up and down' movement of the nut as the mandrel 32 rotates. A radialopening 69 is provided in the wall of the nut 65 to carry a block'or rocker 10. The outer end of the opening 69 is' closed by a plug'II `to prevent loss or displacement of the rocker 1G. A lug or key 'I2 is provided on the inner end of theA rocker 'I0 to cooperate with the groove A--B. The key 'I2 has flat upper and lower sides and is of such'height or thickness that its sides readily ride on the upper and lower Walls of the groove portions A and B. The Width of the key I2 is substantial, being greater than the intersections C, that is, greater than the width of the spaces occurring where the portions A and B cross. This is important as it assures the continued movement of the key I2 through a given groove portion A or B and prevents the key from catching at an intersection C and from switching from one groove portion to the other at an intersection. However, the width of the key 12 is not so great that the key cannot be directed from one groove portion to the other at the reversing groove parts D. The curvatures of the groove'walls at the 'reversing parts D are designed toV direct the key 'I2 from one groove portion to the other. This" direction or transference of the key 12 from one groove portion A or B to the other is accompanied by slight oscillation or turning of the rocker 1li?. It will be seen that with the'V grove and nutstructure just described simple continued rotation of the mandrel 32 in a selected direction`causes up and down movement of the nut 55 along the mandrel for a stroke or distance equal"to' the 'length of the groove In the operation of the tool illustrated in Figs. 1 to 3, inclusive, it will be assumed that the tool is to be Aemployed in jarring an object or sh caught in a deep well,"such as an oil well or gas well. Prior to lowering the tool into the well air or other Vgas is supplied to the lower portion of the cylinder chamber 3l under the selected pressure. The threaded valved port 45 provides for the convenient delivery ofthe air under pressure to the lower portion of the'cylinder chamber 3|. The pressure employed'mayvary greatly and depends upon the nature of the jarring action, the capacity of the cylinderv chamber 3l, the Vstroke of the hammer I2, etc. In most instances the plug 41 will be threaded in the port 45 following the delivery of the gas under pressure to the valve 3|. The valve 49 remains closed. The jarring tool is connected in the fishing string, not shown, above the selected fishing tool and the string is run into the well to engage the fishing tool with the lost object or sh, all being in accordance with the usual practice. With the lower portion of the shing string coupled with the object or sh by the fishing tool the equipment is in condition for jarring. In many instances it will be preferred or necessary to apply an up-pull or tension to the fishing string. It is a feature of the present invention that this tension may be continuously maintained throughout the jarring operations, may be of any selected intensity or may be varied and interrupted, if desired.

The tool is actuated to produce the jarring action by merely rotating the shing string. This rotation may be continuous so long as the jarring action is required and may be as rapid or as slow as selected. Rotation of the shing string causes up and down movement of the travelling nut B5. Assuming that the iishing string is rotated to the right the engagement of the key 12 in the left hand groove portion B causes downward travel of the nut 65. Further, assuming that the hammer I2 and the nut 65 are in their uppermost positions shown in Fig. 2 of the drawings the downward travel of the nut, just mentioned, results in downward movement of the hammer, the nut forcing the hammer down. The lug or key 12 engaged in the left hand groove portion B causes the nut 65 to move downwardly the full length of the groove A-B and the nut in turn forces the hammer I2 downwardly ahead of it. The downwardly travelling hammer I2 compresses the gas in the lower portion of the chamber 3 I. This gas is initially supplied to the chamber 3| under a super-atmospheric pressure and the downward travel of the hammer I2 greatly increases the pressure on the gas. The increase in pressure on the gas under the hammer I2 depends upon the length or volume of the cylinder chamber 3l and the stroke of the hammer I2. The downward movement of the hammer I2 also results in the creation of a vacuum or reduced pressure condition above the hammer. Accordingly, a very high gas pressure may exist below the hammer element I 2 and a substantial negative pressure may exist above the hammer I2 by the time the hammer has reached the end of its downward movement. When the nut 65 approaches the lower end of its downward travel, that is, when the key 12 enters the lower reversing groove portion D the noses 51 of the latches 54 suddenly snap under the lower end of the mandrel 32 to assume positions such as illustrated in Fig. l.. This positively latches the hammer I2 in the down position where a greatly increased gas pressure condition exists under the hammer and a substantial negative pressure condition exists above the hammer.

The engagement of the key 'I2 in the lower reversing groove portion D causes the rocker to turn slightly and directs the key 12 upwardly into the groove portion A. The engagement of the key 12 in thegroove portion A of the rotating mandrel 32 causes the nut 65 to travel up on the mandrel. The nut travels upwardly on the mandrel until its upper end cooperates with the upper wall of the recess 61. This occurs before the key 12 is reversed or turned in the upper reversing groove portion D. Engagement of the upwardly CJI travelling nut 65 with the wall of the recess B'I produces upward movement of the cylinder II. This brings the shoulders 63 upwardly against the surfaces 64 and releases the latches 54 from the lower end of the mandrel 32. The release of the latches 54 just described occurs at a time when the nut 65 has raised the cylinder I I to th'e position where the upper end of its head 33 is in engagement with the collar 22 and anvil shoulder 35 and at a time when the key 12 is in or entering the upper reversing portion D of the groove. When the latches 54 are released the hammer I2 is suddenly driven upwardly with great force by the instantaneous expansion of the high compressed gas under the hammer aided by the negative pressure above the hammer. The hammer I2 is forcibly driven upwardly at a high velocity and its upper end strikes the shoulder 34 with great force. The resultant impact or upward action is directly transmitted from the cylinder head 33 to the collar 22 and shoulder 35 in turn is transmitted to the string and the sh engaged by the shing string.

The jarring impact generated depends upon several factors such as the weight of the hammer I2, the maximum pressure created under the the down or left hand portion B of the thread or hammer and the length of the hammer stroke. As pointed out above, the construction of the present invention permits the employment of a hammer l2 of any selected Weight and makes it possible to give the hammer I2 a, very long stroke or a shorter stroke, as desired.

As the rotation of the fishing string and man- Y drel 32 continue the key 12 travels through the upper reversing portion D of the groove to enter groove. The engagement of the key 12 in the groove portion B causes the nut 65 to travel down on the mandrel 32 and the nut forces the hammer l2 downwardly against the gas under pressure in the lower portion of the chamber 3I to further compress the gas. The nut and hammer move downwardly until the latches 54 again engage with the lower end of the mandrel 32 and the operations above described are repeated. It is important to note that the simple rotation of the operating string in either direction with any selected tension on the string will produce a series of heavy upward jarring blows so long as the rotation is continued, it being unnecessary to manipulate the fishing string in any way to provide for the repeated jarring actions. During the upward and downward travel of the hammer I2 the latches 54 remain in the retracted positions illustrated in Fig. 2. The inner sides of the latch noses 51 engage against the surface of the mandrel 32 to hold the latches in the retracted positions. Those portions of the noses 51 which contact the mandrel 32 are of such width or vertical extent that they cannot engage in the groove A-B.

The embodiment of the invention illustrated in Figs. 4 to 9, inclusive, may be said to comprise, generally, a body 15 having or providing a chamber 16, a hammer 11 operable in the chamber 16, means 18 for supplying and maintaining air or other gas under pressure in the lower portion of the chamber 16 and means 19 for forcing the hammer 11 against the gas under pressure contained in the chamber 16 and thereafter releasing the hammer to be driven against an end of the chamber by the expanding gas.

The body 15 is adapted to be interposed in a fishing string such as a string of Well drill pipe and serves to house and carry the other elements of the tool. As illustrated, the body 15 is an elongate hollow structure or tubular member provided at its opposite ends with means for facilitating its connection in the iishing string. In the case illustrated, a sub 80 is threaded in the lower end of the body I and may be considered as connected with the lower portion of the shing string, not shown. A fluid passage 8| extends downwardly through the sub 89 to communicate with the lower part of the string. A connecting member 82 is threadedly connected with the upper end of the body 15. An internal annular flange 83 is provided in the connecting member 82 at a point between its ends. A member or sub 84 of the shing string has a stem 85 which passes downwardly through the annular ange 83 with clearance. A nut or collar 86 is threaded or otherwise xed to the stem 85 below the iiange 83. Series of balls 8l are arranged in opposing races in the under side of the fiange 83 and the upper side of the collar 8S and in the'upper side of the ange 83 and a downwardly facing shoulder 88 on the sub- 84. Packing 89 on the collar 86 seals with the interior of the member 82 below the flange 83 and similar packing 99 seals between the sub 84 and the member 82 above the ange 83. The structure just described constitutes a packed swivel connection between the jar body and the fishing string.

In accordance with this form of the invention a mandrel 9| extends downwardly from the stem 85 and may pass completely through the body 15 to the sub 89. The mandrel 9| serves to carry certain elements of the means 19 and further serves to conduct the circulation iluid downwardly through the tool. The lower portion of the mandrel 9| is received in the passage 8| of the sub 80. A passage 92 extends downwardly through the sub 84 from the well string and continues down through the stem 85 and the mandrel 9! to discharge directly into the passage 8| of the sub 80. The mandrel 9| is preferably of uniform external diameter.

The hammer 11 is arranged in the body chamber 16 to travel longitudinally therein. The hammer is in the nature of a piston operable to compress the gas under pressure when moved in one direction and adapted to be operated or driven in the other direction by the expanding gas and is in the nature of a hammer or weight element having substantial dynamic inertia for striking a part of the body when thus driven or actuated by the expanding gas. The hammer 'l1 is an elongate member received in the body chamber 16 with suitable clearance and is chambered or provided with an enlarged opening |09 between its ends to have its major portion entirely clear of the mandrel 9|. A tubular head or plug 93 is threaded in the lower end of the hammer to slidably ride on the mandrel 9|. The hammer is provided with a heavy or thickened upper wall portion 94 which likewise slidably rides on the mandrel 9|. The upper end of the hammer is flat and extensive and is adapted to strike upward-ly against the face presented by the lower end of the collar 86 and the lower end of the stem 85, which face I will term the anvil 95. The hammer just described, is of substantial length to house or contain various elements of the means 19. The weight of the hammer may be varied to suit the tool for diierent operations. The weight of the hammer 11 is one of the elements or factors which governs the intensity of the jarring effect and this factor may be changed as conditions may require.

The means 18 provides for the supplying of air or other gas under pressure to the body chamber 'l5 below the hammer and for maintaining a charge or body of gas under pressure in the chamber. In accordance with the invention the portion of the body chamber 78 below the hammer 'l1 is pre-charged or pre-loaded with gas or ,pressure prior to introducing the tool into the well. While the charge of gas under pressure Amay be permanently sealedin the chamber i6 it is preferred to construct the means "i8 so' that the tool may be supplied witha charge of air or gas under a selected pressure before running the tool into the well and so that the .pressure on the gas may be increased or decreased as operating conditions may require. The means 18 includes a port 99 leading from the exterior of the sub` 89 and eX- tending upwardly to communicate with the lower end of the body chamber 78. The port 99 has a spring loaded check valve 9'? which closes outwardly to prevent the discharge of the gas under pressure and which may be opened inwardly to admit fluid under pressure. The mouth of the port 96 is prepared to receive the fitting of a press-ure supply means such as an air hose tting or the tting on\a pump. A plug 98 is threadedin the outer portion or mouth of the port 99 and under most operating conditions is retained in the port to prevent the entrance of the well fluids to the port.

The means 'i8 further provides for the bleeding or discharge of gas under pressure from the body chamber Ti. The port 99 may have a branch port 99 leading to the exteriorof the sub 89. A valve, say a needle valve, |99 sets inwardly to close the port 99. The needle valve |99 is carried or actuated by a 4plug lll! threaded in the mouth of the port 99. The valve B93 is readily opened to permit the discharge of gas from the body chamber l for the purpose of reducing the pressure within the chamber and for the purpose of bleeding well liquid from the chamber if this becomes necessary.

The means 18 embodies packing structures for sealing oii the opposite ends of the chamber 16 to prevent the escape of the air or gas under pressure therefrom. A socket is provided in the top of the sub 8|) and contains packing |92 sealing about the mandrel. The packing |92 may be chevron type 4packing arranged to face in both directions and actuated or compressed by a follower |93 to effectively prevent the leakage of fluid in both directions. It will be observed that there is no relative longitudinal movement between the mandrel 9| and the sub 89 but that there is relative rotation between these parts and the packing |92 may be of a type which eectively seals between relatively rotatin members. The means for packing up between the hammer Tl and the body 'I5 may comprise a body of chevron type packing |84 surrounding the plug 93 to seal with the wall of the chamber 18 and actuated by a threaded follower |95. The lower end of the plug 93 is relieved or reces-sed to carry packing |96 for sealing with the mandrel 9|. packing |86 may be of the chevron type and may be actuated by a threaded follower |91.

It will be observed that the cylinder chamber 'I6 is completely sealed at both ends and that the hammer forms a closed piston sealing with the walls of the chamber 'IS and with the mandrel 9| to partition or completely separate the upper and lower portions of the chamber. The lower portion of the chamber 'i6 contains the air or gas under pressure admitted by the means '18 and- The operation of the hammer 11 produces a negative or reduced pressure condition in the upper portion of the chamber during certain phases of the operation. The'lower portion of the chamber 16 is charged with the selected initial gas pressure, while the hammer 11 is in the uppermost position illustrated in Fig. 4. Upon downward movement of the hammer 11 the .pressure below the hammer is greatly increased and a reduced pressure or negative pressure condition is created above the hammer.

If desired, a spring S may be provided to assist the expanding gas in driving the hammer 11 upwardly against the anvil 95. The spring S is arranged in the lower portion of the chamber 16 and is under compression between the sub 80 and the under side of the plug 93. The spring S is in surrounding relation to the mandrel 9| to be held against displacement thereby.

The hammer operating and controlling means 19 is a feature of the invention. The 'means 19 is operable by simple rotation of the fishing string in either direction to force the hammer 11 downwardly in the chamber 16 to increase the gas pressure below the hammer and to create a reduced pressure above the hammer and the means 19 then operates to release the hammer so that it is driven upwardly with great force and speed to strike against the anvil 95. The means 19 repeats these operations to provide a succession of heavy jarring blows so long as rotation of the shing string and mandrel 9| continues.

The means 19 includes a travelling nut |08. The nut |08 is an elongate tubular member freely sliding on the mandrel 9| and received in the opening |09 of the hammer 11 with clearance. The means 19 further includes threads or spiral grooves in the mandrel 9| and parts on the nut |08 cooperating with the grooves. In the form of the invention being described there are two like double spiral grooves formed in the mandrel 9| and spaced a short distance apart to be entirely independent of one another. Each of these grooves includes a right hand groove portion F helically pitched or spiralled in the right hand direction, a left hand portion G spiralled in the left hand direction and connecting portions H connecting or joining the corresponding ends of the groove portions F and G. The oppositely pitched groove portions F and G cross at intersections J. The groove portions F and G are of uniform pitch and of equal width and depth throughout their lengths and connecting portions H join the corresponding ends of the right and left hand portions so that the grooves are continuous or without ends. The portions H are smoothly or gradually curved and may lbe slightly wider than the other parts of the grooves. The grooves F-G are formed so that the connecting portions H of one groove are at the opposite side of the mandrel 9| from the connecting portions H of the other grooveF-G. The grooves are preferably square or rectangular in cross section having substantially flat upper and lower walls and have a steep or substantial lead. The length of the grooves F-G determines the stroke of the hammer 11. The length of the hammer stroke is one of the factors determining the intensity of the jarring action obtained and, in accordance with the invention, the length of the grooves F--G may be great or small, as desired, to give the hammer 11 the required stroke for the jarring action desired. This is a marked advantage over prior jarring tools employing cam means for actuating the hammers in which the hammer strokes are deflnitely limited.

In this form of the invention the hammer 11 carries a key part for cooperating with each of the two grooves F-G. Cylindrical pins or rockers l0 are turnably supported in radial openings in the wall of the tubular hammer |08. The rockers ||0 are held against displacement by the wall of the hammer opening |09 and the surface of the mandrel 9 The inner ends of the rockers ||0 have lugs or keys ||2 for cooperating with the grooves F-G. The keys ||2 are diametric of the longitudinal axes of the respective rockers ||0 and are elongate in transverse cross section having flat upper and lower sides of the substantial extent for cooperating with the upper and lower walls of the groove F--G. The width of the keys ||2 is greater than the width of the intersections J so that the keys readily bridge or pass through the intersections J without being caught and without taking the wrong course. However, the keys ||2 are not of such excessive Width that they cannot move through the connecting portions H of the grooves and the substantial width of the keys is the reason for making the grooves H of slightly greater width than the other portions of the grooves F and G. When the keys ||2 reach the connecting groove portions H they are directed by the portions H in such a way that their rockers |I0 turn on their longitudinal axes and the grooveportions H guide or direct the keys from one groove portion F or G to the other so that the keys may travel through, say the groove portions F and then plane but occupy vertically spaced horizontal planes so that one key ||2 cooperates with the upper groove and the other key cooperates with the lower groove. The vertical spacing of the keys l2 is such that they cooperate with corresponding parts of the two grooves, that is, both keys may cooperate with the upper portions of the two grooves F-G when the parts are in the position shown in Fig. 4 and the spacing of the keys remains constant. The pins or rockers ||0 are provided in the upper and lower portions of the nut |08 so that the nut is Well balanced and will not bind on the mandrel 9|. Further, it will be understood that the loads are equally divided between the two keys ||2 relieving the individual keys to excessive loading. Upon rotation of the fishing string and mandrel 9| the keys 2 travel through the grooves F-G from their upper ends to their lower ends and then back to the upper ends and the downward movement of the nut |08 is transmitted to the hammer 11 by the releasable latch means to be presently described. The nut |08 has splines or keys ||3 engaged in grooves ||4a in the hammer 11 to be held against rotation relative to the hammer and the hammer 11 in turn is keyed to the body 15 by the latch means to be described below.

The hammer actuating means 19 further includes latch mechanisms for releasably connecting the nut |08 with the hammer 11 to transmit downward movement to the hammer and for releasing the hammer for free upward movement at the completion of the down stroke. The latch means includes one or more longitudinal slots H4 in the wall of the hammer 11. In the presides.

ferred arrangement illustrated, there are two diametrically opposite slots H4. The slots H4 are straight and are of uniform width and configuration except at their upper ends where they are provided with enlargements or openings H5. The slot enlargements or openings H5 provide upwardly facing shoulders H6 at the upper ends of the slots I I4,

The nut |08 carries latches H1 for transmitting downward movement from the nut to the hammer 11. The latches H1 are set in radial sockets I I8 in the hammer |08 and are urged outwardly by springs H9 arranged under compression between the inner sides of the latches and the bottoms of the sockets. The latches H1 are preferably located substantiially midway between the opposite ends of the nut |08. The lower portions of the latches H1 cooperate with the wall of the hammer opening |09 to limit the outward travel of the latches. The latches H1 are considerably wider than the slots H4 and cannot enter the slots. The upper portions of the latches H1 have noses or lugs |20 extending outwardly and adapted to enter the openings H5. The latches I|`| may be cylindrical and the lugs |20 may be semi-cylindrical to have flat lower When the latch lugs 20 are received in the openings H5 their at lower sides are engageable downwardly against the shoulders H6. The sturdy latch lugs |20 cooperable with the nat shoulders H6 at opposite sides of the nut |08 are operable to dependably transmit the downward forces from the travelling nut |08 to the hammer 11.

Cam means is provided for releasing the latches I1 from the hammer 11 when the nut |08 approaches the lower end of its downward stroke. The cam means includes internal projections or cam parts |2| on the body 1'5. The cam parts I2I extend into the slots H4 of the hammer 11. The upper sides of the cam parts |2| present downwardly and inwardly pitched surfaces |22 engageable by the under sides of the latch lugs |20. The parts are proportioned and related so that the under sides of the latch lugs |20 cooperate with the surfaces |22 to retract the latches, and thus disengage the lugs from the openings H5, shortly before the keys I I2 reach the lower ends of their respective grooves ITL-G, thus providing for over-travel of the nut |08 following the release of the hammer 11. This completely relieves the keys H2 of hammer-pushing forces when the keys are being directed by or passed by the groove portions H. Further, the parts are related and proportioned so that the nut |08 over-travels or begins its downward stroke before it starts to transmit downward movement to the hammer 11. Assuming the hammer 11 to be at its uppermost position against the anvil 95 and assuming that the nut |08 has reached the upper end of its stroke and the rotation of the mandrel 9| is continuing the keys H2 will travel through the upper connecting portions H of the grooves to be directed thereby to the right or left hand portions F or G, as the case may be, and will begin moving down through said groove portions before the latches H1 become effective in transmitting downward movement from the nut |08 to the hammer 11. When the nut reaches the upper end of its stroke or slightly before, the latch lugs |20 move out into the openings I5. The openings H are of greater vertical extent than the lugs and when the keys H2 pass through the upper connecting portions H of the grooves and start to travel down the spiral groove portions F or G the latch lugs |20 move down in the openings H5, The latch lugs |20 move down through the openings H5 a short distance before their lower ends strike the shoulders H6. This allows the keys I I2 to fully enter the main groove portions F or G before assuming the transmission of downward forces from the nut to the hammer 1l.

In operating the tool illustrated in Figs. 4 to 9, inclusive, the portion of the chamber 16 under the hammer is charged with air or other gas under the selected pressure prior to introducing the tool into the well. This may be readily done by removing the plug 98 and securing a pressure hose in the mouth of the port 96 to deliver the gas under pressure to the chamber 16. pressure initially provided in the chamber 'I6 may be varied to adapt the tool for the particular requirements of the operation. In most instances, the plug 08 will be replaced prior to introducing the tool into the well. The fishing string, not shown, in which the jarring tool is connected is run into the well and is connected with the fish or lost object by a shing tool, not shown, in the usual manner- When this has been done a selected up strain is put on the string and the string is rotated either to the right or the left. It is to be understood that the tensile strain applied to the string may be constant throughout the jarring operations and may be of selected intensity or, if desired, may be varied in intensity.

Assuming that the hammer 11 is at the upper end of its stroke and that the shing string is ro tated to the right the keys I 2 start down the left hand portions G of the spiral groove .and as they begin their downward travel the latch lugs |20 move down in the openings H5. As the downward travel of the nut I8 continues the under side of the lugs engage the shoulders I I 6 for the transmission of downward movement from the nut to the hammer 11. The hammer 'I1 is forced downwardly against the. gas under pressure in the lower portion of the chamber 16 to greatly increase the pressure. As the hammer moves downwardly a reduced pressure or negative pressure is produced above the hammer. In practice, the down stroke of the hammer may be of such length that the gas pressure under the hammer is greatly multiplied before the hammer reaches the lower end of its stroke and so that a substantial negative pressure is developed above the hammer. Shortly before the nut |08 reaches the lower end of its downward travel the latch lugs |20 come into engagement with the cam surfaces |22 and the surfaces retract the lugs from the openings H5. Upon disengagement of the latch lugs |20 from the openings H5 the hammer 11 is released from the nut |08 and is suddenly driven upwardly with great force and at a high velocity by the `expanding gas held at a very high pressure under the hammer. The negative pressure condition existing above the hammer 11 and the spring S,

where used, assist in driving the hammer upwardp ly. The hammer moving upwardly at a high ve-- locity and with great force strikes against the anvil 05 to impart a heavy upward blow to the body 15. The nut |08 may continue its downward travel while the hammer 'I1 is being driven upwardly and the keys H2 nally move through the lower groove portions H into the right hand groove portions F.

As rotation of the mandrel 9| is continued the keys H2 travel upwardly through the groove por- Thel tions F until the nut |08 reaches the end of its upward stroke. During this interval the hammer 11 is held against thek anvil 95 by the spring S and they gas under pressure in the chamber 16. The keys I 2 move through the groove portions H at the upper ends of the grooves and start back down through the groove portions G. During or prior to movement of the keys through the upper groove portions H the latch lugs |20 move out into the openings ||5. When the nut |08 starts to move downwardly the latch lugs |20 move down in the openings I5. This downward movement of the latch lugs |20 in the openings |5 allows vthe keys ||2 to fully engage in the groove portions F before the lugs engage the shoulders IB for the transmission of downward force to the hammer 11.

So long as rotation of the shing string and mandrel 9| continue, the above described operations are repeated, the hammer 11 being repeatedly driven upwardly against the mandrel 9| with great force to impart heavy jarring blows to the body 15. It is to be observed that in this form of the invention the hammer 11 moves downwardly with the nut when the nut approaches the end of its downward stroke and there is no delay or time interval during which the gas, put under increased pressure by downward movement of the hammer, may leak upwardly past the hammer into the upper portion of the chamber 16. This provides for more efficient operation of the tool.

If desired, the plug 98 may be left out of the port 98 when running the tool into the wall. In this case the valve 91 remains closed until the hydrostatic pressure in the well is greater than the gas pressure in the chamber 1B. When the tool has reached a position where these conditions eX- ist hydrostatic pressure is admitted from the well to boost or increase the gas pressure in the chamber 16 to provide for a heavier jarring action. It is to be noted that in this embodiment of the invention the nut |08 is balanced by the engagement of the vertically spaced oppositely directed keys ||2 in the two spiralled grooves F-G and that the strains and wear are equally divided between the two keys.

Figs. to 13, of the drawings, illustrate a modiication of the general construction 'of Figs. 4 to 9, inclusive, in which the nut |08a carries two keys for cooperating with a single double endless spiral groove in the mandrel 9|.v The body 15, the mandrel 9| and the means 18 may be the same as above described and the hammer 11a may be substantially the same and corresponding reference numerals are applied toY corresponding parts in the two forms of the invention.

The nut |083L is substantially the same as the nut |08, being a tubular member freely slidable on the mandrel 9|. The nut |08a is keyed with the hammer 11a, as at 200, and carries the latches ||1 having lugs |20 cooperable with the openings ||5 in the hammer 11a and released by the cams |2| projecting into the grooves 4, all as above described. A single lcontinuous double spiralled groove R-L is provided in the mandrel 9|. 'I'he groove is comprised of the right and left hand portions R and L, respectively, joined at their opposite ends by connecting portionsM, The right and left hand groove portions R and L intersect at intersections N. The groove R-L may be substantially the same as the groove A-B described above, and may be of the selected length. The connecting portions M may be slightly wider than the other parts of the groove.

AThe nut 08* carries two tumbler blocks or rock. ers |30* and |30*, turnably carried inradial openings |3|Yi'n the Wall of the nut |08a. In accordance'with the-invention the rockers |30* and |30* are provided in diametrically opposite sides of the nut |08* but for reasons which will later become apparent the rockers are offset vertically a distance equal to one-half the lead of the threads or double groove R-L. Keys |32* and |32y similar to the keys ||2 described above are provided on the inner ends of the rockers 30* and |30* to cooperate with the groove R-L. The vertical offsetting of the rockers |30* and |30* relates the keys |32* and |32* so that the two keys may simultaneously cooperate with the same groove portion R or L.

Assuming that the string and mandrel 9| are being turned to'lthe right and that the nut |08a is approaching the upper end of its upward stroke the key |32* will move `upwardly from the groove p ortionR and through the connecting portion M to the left hand groove portion L to start the hammer on its downward movement. When the key |32* is moving through the reversing portion M-of the groove the pin |35* is engaging with the upper end of the slot |34* and this engagement turns or pivots the rocker 30* in a direction to align the key |32* withthe left hand groove portion L. The intersection N in which the key |32* turns may be slightly widened to permit this turning. Thus, when the key |32* starts down the "groove portion L the key |32* is conditioned to likewise move down the groove portion L.

When the nut |08'l approaches the lower end of its downward movement with the mandrel 9| being turned to the right the key |32* will move from the groove portionrL into the lower connecting grooveportion M and the groove portion AM will direct it in to the groove portion R. During the guiding or directing of the key |32* through the lower groove portion M the pin |35* 1s engaged with thelower wall of the slot |34x and the slight downward movement of the nut |08'is such that this Vengagement causes the rocker |30* to turn. This turning of the rocker |30* turns its key |32* in the lower intersection N bringing the key in alignment with the groove portion R. The lower intersection N may be slightly'widened to permit this turning of the key. ''When the nut |08a starts upwardly through The slots cooperation with the key |32y with the groove portion R the key |32X is likewise engaged in the groove R so that the loads or forces are equally divided between the two keys.

The tool illustrated in Figs. 10 to 13 operates in substantially the same manner as the tool shown in Figs. 4 to 9, inclusive. With the tool in operative position in the well the shing string is rotated while under a selected tensile strain. The engagement of the keys |32* and |325 in the groove R-L feeds the nut |08a up and down on the mandrel and the latch lugs |20 cooperating with the openings IE drive the hammer 11 down during down strokes of the nut and the cams I2| release the latches ||1 at the completion of the down strokes so that the hammer is forcibly driven upwardly at high speed and with great force to strike against the anvil 95.

While I have herein illustrated and described the several jarring tools of this invention as employed to create upward jarring actions it is to be understood that the invention contemplates inverting the tools to produce downward jarring actions. When downward jarring actions are desired the tool is connected in the shing string in an inverted position from that shown in the drawings. The tool is operated substantially the same as above described, that is, the fishing string is rotated to produce a succession of jarring blows which, in this case, will be downwardly directed.

Having described typical preferred forms and applications of my invention, I do not wish to be limited or restricted to the specic details herein set forth, but wish to reserve to myself any variations or modifications that may appear to those skilled in the art or fall within the scope of the following claims:

Having described my invention, I claim:

1. In a well tool, two sections connected for relative turning and adapted to be interposed in a well string, one section having a longitudinal cylinder with a shoulder therein, a hammer shiftable in the cylinder, means maintaining a fluidtight seal between the hammer and cylinder, the portion of the cylinder at one side of the hammer containincr gas under pressure, and means operable by relative turning of the sections for moving the hammer against the gas under pressure to increase the pressure thereon and for then releasing the hammer to move in the other direction under the action of the expanding gas to strike against the shoulder.

2. In a well tool, two sections connected for relative turning and adapted to be interposed in a well string, one section having a longitudinal cylinder with a shoulder therein, a hammer shiftable in the cylinder, means maintaining a fluidtight seal between the hammer and cylinder, means for introducing gas under pressure to the cylinder below the hammer, and means operable by relative turning of the sections for moving the hammer longitudinally against the gas under pressure to increase said pressure and produce a low pressure condition at the other side of the hammer and releasable by said relative turning following a given movement of the hammer to allow the hammer to move in the other direction under the action of the expanding gas and reduced pressure condition so that it strikes a jarring blow against the shoulder.

3. In a well tool, two sections connected for relative turning and adapted to be interposed in a well String, one section having a longitudinal cylinder with a shoulder therein, a hammer shiftable in the cylinder, means maintaining a fluidtight seal between the hammer and cylinder, means for introducing gas under pressure to the cylinder below the hammer, means operable by relative turning of the sections-for moving the hammer longitudinally against the gas under pressure to increase said pressure and produce a low pressure condition at the other side of the hammer and releasable by said relative turning following a given movement of the hammer to allow the hammer to move in the other direction under the action of the expanding gas and reduced pressure condition so that it strikes a jarring blow against the shoulder, and means for relieving the pressure at the first named side of the hammer.

4. In e, well tool, twov sections related for relative movement, one section having a sealed longitudinal cylinder with a shoulder therein, a hammer member slidable in the chamber, means maintaining a sealing connection betweenthe hammer and thewall of the chamber, there being an initial charge yof gas under pressure in the lower end portion of the cylinder, a spring in said lower end portion of the cylinder, and means operable by relative turning of the sections for moving the hammer member relative to a section to compress the gas and spring and for then releasing the hammer member to be forcibly driven against the shoulder by the expanding gas and spring.

5. In a well tool, two sections connected for relative turning and adapted to be interposed in a well string, one section having a longitudinal cylinder with a shoulder therein, a hammer shiftable in the cylinder, means maintaining a uidtight seal between the hammer and cylinder, the portion of the cylinder below the hammer normally containing gas under pressure, means for introducing gas under pressure to said side of the cylinder operable to exclude well pressure from the cylinder, and means operable by relative turning of the sections for moving the hammer against the gas under pressure to increase the pressure thereon and for then releasing the hammer to move in the other direction under the action of the expanding gas to strike against the shoulder.

6. In a well tool, two sections connected for relative turning and adapted to be interposed in a well string, one section having a longitudinal cylinder with a shoulder therein, a hammer shiftable in the cylinder, means maintaining a. fluidtight seal between the hammer and cylinder, the portion of the cylinder below the hammer normally containing gas under pressure, and means operable by relative turning of the sections while maintaining a, selected tension on the string and sections'for moving the hammer against the gas pressure to increase the same and operable by.

said turning to release the hammer to move Vin the other direction under the action of the expanding gas to strike against the shoulder while said tension is maintained.

7. In a well tool, two sections connected for relative turning and adapted to be interposed in a well string, one section having alongitudinal cylinder, a hammer shiftable in the cylinder, the portion of the cylinder at one side of the hammer containing gas under pressure, and means operable by a. plurality of relative revolutions between the sections for moving the hammer against the gas under pressure to increase the pressure thereon and for releasingthe hammer to move in the other direction under the action of the expanding gas to jar against the section having the chamber.

8. In a well tool, two sections connected for relative rotation, one section having a chamber, a mandrel on the other section, a hammer slidably sealing in the chamber, the portion of the chamber at one side of the hammer containing gas under superatmospheric pressure, a nut adapted to travel along the mandrel, thread means operable to move the nut back and forth on the mandrel upon relative rotation between the sections, and means for connecting the nut with the hammer to move the same against the gas to increase pressure thereon during movement of the nut in one direction and releasable to allow the hammer to be forcibly driven against a section by the expanding gas.

9. In a well tool, two sections connected for relative rotation, one section having a chamber, a, mandrel on the other section, a hammer slidably sealing in the chamber, the portion of the chamber at one side of the hammer containing gas under superatmospheric pressure, a nut adapted to travel along the mandrel, thread means operable to move the nut back and forth on the mandrel upon relative rotation between the sections, and means for connecting the nut with the hammer to move the same against the gas to increase pressure thereon during movement of the nut in one direction and releasable to allow the hammer to be forcibly driven against a section by the expanding gas, the last named means including a latch for releasably connecting the nut and hammer.

10. In a well tool, two sections connected for relative rotation, one section having a chamber, a mandrel on the other section, a hammer slidably sealing in the chamber, the portion of the chamber at one side of the hammer containing gas under superatmospheric pressure, a, nut adapted to travel along the mandrel, thread means operable to move the nut back and forth on the mandrel upon relative rotation between the sections, and means for connecting the nut with the hammer to move the same against the gas to increase pressure thereon during movement of the nut in one direction `and releasable to allow the hammer to be forcibly driven against a section by the expanding gas, the last named means including a latch forv releasably connecting the nut and hammer, and means for releasing the latch when the nut approaches the end of its travel in said direction.

11. In a well tool, two sections connected for relative rotation, one section having a chamber, a mandrel on the other section, a hammer slidably sealing in the chamber, the portion of the chamber at one side of the hammer containing gas under superatmospheric pressure, a nut adapted to travel along the mandrel, thread means operable to move the nut back and forth on the mandrel upon relative rotation between the sections, and means for connecting the nut with the hammer to move the same against the gas to increase pressure thereon during movement of the nut in one direction and releasable to allow the hammer to be forcibly driven against a section by the expanding gas, the last named means including a latch for releasably connecting the nut and hammer, and means for releasing the latch during movement of the nut in the other direction.

12. In a well tool, two sections connected for relative rotation, one section having a chamber, a mandrel on the other section, a hammer slidably sealing in the chamber, the portion of the chamber at one side of the hammer containing gas under superatmospheric pressure, a nut adapted to travel along the mandrel, thread means operable to move the nut back and forth on the mandrel upon relative rotation between the sections, and means for connecting the nut with the hammer to move the same against the gas to increase pressure thereon during movement of the nut in one direction and releasable to allow the hammer to be forcibly driven against a section by the expanding gas, the last named means including a latch on the nut cooperable with the hammer, and a part on the iirst named section for releasing the latch when the nut approaches the end of its travel in said direction.

13. In a well tool, two sections connected for relative rotation, one section having a chamber, a mandrel on the other section, a hammer slidably sealing in the chamber, the portion of the chamber `at one side of the hammer containing gas under superatmospheric pressure, a nut adapted to travel along the mandrel, a continuous groove in the mandrel having portions pitched in opposite directions and connected at their opposite ends, a part on the nut cooperable with the groove to cause the nut to travel back and forth on the mandrel upon relative rotation between the sections, and means operable by said back and forth movement of the nut for forcing the hammer against the gas to increase the pressure thereon and then releasing the hammer to be forcibly driven back against the end of the chamber by the expanding gas.

14. In a well tool, two sections connected for relative rotation, one section having a chamber, a mandrel on the other section, a hammer slidably sealing in the chamber, the portion of the chamber at one side of the hammer containing gas under superatmospheric pressure, a nut adapted to travel along the mandrel, a continuous groove in the mandrel having portions pitched in opposite directions and connected at their opposite ends, parts on the opposite sides of the nut cooperable with the groove to cause the nut to travel back and forth on the mandrel upon relative rotation between the sections, and means operable by said back and forth movement of the nut for forcing the hammer against the gas to increase the pressure thereon and then releasing the hammer to be forcibly driven back against the end of the chamberby the expanding gas.

15. In a well tool, two sections connected for relative rotation, one section having a chamber, a mandrel on the other section, a hammer slidably sealing in the chamber, the portion of the chamber at one side of the hammer containing gas under superatmospheric pressure, a mit adapted to travel along the mandrel, two separate continuous grooves in the mandrel each having portions spiralled in opposite directions with said portions joined at their corresponding ends, parts on the nut cooperable with said grooves to cause the nut to travel back and forth on the mandrel