US2874784A

US2874784A - Tubing anchor

Info

Publication number: US2874784A
Application number: US540732A
Authority: US
Inventors: John R Baker; Jr Earnest H Clark
Original assignee: Baker Oil Tools Inc
Current assignee: Baker Hughes Oilfield Operations LLC
Priority date: 1955-10-17
Filing date: 1955-10-17
Publication date: 1959-02-24
Anticipated expiration: 1976-02-24

Description

Feb. 24, 1959 Filed Oct. 17. 19

J. R. BAKER ET AL TUBING ANCHOR 3 Sheets-Sheet 1 Feb. 24, 1959 Filed oct. 17,l 1955 J. R. BAKER ET Al.

TUBING ANCHOR 3 Sheets-Sheet 2 KNK INVENTORS.

Feb. 24, 1959 J. R. BAKER x-:TAL 2,874,784

TUBING ANCHOR Filed Oct. 17. 1955 -3 Sheets-Sheet 3 E 6 ajraif e. @l 2 .J 4 w 5MM UnitedStates Patent O TUBING ANCHOR Jolln R. Baker, Pasadena, and Earnest H. Clark, Jr., Downey, Calif., assignors to Baker Gil Tools, Inc., Los Angeles, Calif., :a corporation of California Application October 17, 1955, Serial No. 540,732

-15 Claims. (Cl. 166-212) hydraulically actuatable retrievable apparatus for securingva tubular string to a well casing, or the like, against upward movement therein, in which the hydraulic pressure developed as a resultl of runningthe apparatus through the lluid in the well casing is prevented from expanding the slips or gripping members of the apparatus into engagement with the wall of the well casing. Accordingly, the slips are not dulled during lowering of the apparatus in the well casing and are eiective to anchor the apparatus to the casing against upward movement therein, when the anchoring location in the casing has been-reached, and to withstand high pressures tending to force the apparatus up the well casing.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of a form in which it'may be embodied. This form is ,shown in the drawings accompanying and forming part of the present specication. It will now be described in detail, for the purpose of illustrating -the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best dened by the appended claims.

Referring to the drawings:

Fig. l is a longitudinal section through a tubing anchor, with its parts in retracted position;

Fig. 2 is a view similar to Fig. l, on an enlarged scale, disclosing the apparatus anchored against the well .casm8;

Fig. 3 is an enlarged cross-section taken along the line 3--3 on Fig. l;

Fig. `4 is an enlarged fragmentary longitudinal section through the latching portion of the apparatus, with the parts disposed in the position shown in Fig. l;

Fig. 5 is a view similar to Fig. 4, with the parts disposed in the position illustrated in Fig. 2;

Fig. 6` is a view similar to Fig. l, illustrating the apparatus 'being elevated in the Well casing;

Fig. 7 is an enlarged fragmentary section taken along the line 7-7 on Fig. 6;

Fig. 8 is an enlarged fragmentary section taken along the line 8--8 on Fig. 6.

The tubing anchor A disclosed in the drawings is adapted to be secured to a well casing B, well liner, or the like, against upward movement therein, despite the presence of comparatively high pressure therebelow. The apparatus A is lowered in the well casing by means of a tubular string C, which can be formed of tubing or drill v pipe. The lower end of the apparatus can be secured to a lower tool D, such as a retrievable packer, that is adapted to be anchored in packed-off condition inthe well casing against downward movement therewithin. Inasmuch as the retrievable packer D forms no part of fi Ice 2,874,784

f 2 the present invention, only'its upper tubular body portion is disclosed.

The tubing anchor A includes a body 10 consistmg of an upper tubular body section 11, the lower end of which n is threadedly secured within la lower body section 12. This latter section, in turn, has a lower threaded pin 13 adapted to be threadedly secured to the upper box 'end 14 of the body D of the lower tool. Spaced about the body of the tool are a plurality of slips 15, or corresponding gripping members, which can shift laterally between retracted and expanded positions. The lower ends of the slips are disposed within radial slots 16 in the upper portion of the lower body section 12, the slips being guided in their radial movement by pins 17 `secured to their lower portions, each pin projecting in opposite directions from the side faces of a slip and into opposed grooves 18 on opposite sides of the body slot 16. The disposition of the pins into these grooves 18 permits the slips 15 to slide radially relative to the body section 12, while preventing any substantial longitudinal movement of the slips with respect to this body section.

The slips 15 extend upwardly from the lower body section, being received within circumferentially spaced grooves 19 provided in an expander member 20. The

base 21 Vof each groove is inclined in a downward and inward direction, coacting with a companion inclined ,slidable connection between the expander and the slips.

The expander l20 is shifted Adownwardly within the slips 15, to force the slips into anchoring engagement with the wall of the well casing, by virtue of uid under pressure Within the tubular string C and the body 10 of the tool. The fluid under pressure will pass through. upper and lower sets of

ports

26, 27 through the upper body section 11 into a cylinder space 28 defined between an upper.

annular piston`29 integral with and extending outwardly from the body section above the ports 26 and the upper portion 30 of the expander which may be considered to be the head of the hydraulic cylinder, and also dened between the periphery of the body 11 and a cylinder sleeve or housing 31, the lower end of which is threadedly securedY to the expander head 30, and which extends upwardly along and above the piston 29 to a substantial extent.

The upper end of the cylinder sleeve 31 is threadedly secured onto a head 32 that is slidable along a tubular mandrel 33, the lower portion 34 of which is telescoped over the upper body section 11 above the piston 29, and the upper end of which is formed as a threaded pin 35 threadedly secured to aI coupling 36 that is, in turn, threaded onto the lower end of the tubular string C. It may be desirable to transmit the turning effort of the tubular string C and mandrel 33 to the lower tool D secured to the lower. body section 12. For that purpose, the mandrel 33 may be provided with a longitudinally extending groove or keyway 37 receiving a key or pin 33 secured to the upper head 32. Turning eifort imposed on the mandrel 33 will be transmitted through the key 38 to the upper head 32,and from the latter, through the cylinder sleeve 31, expander 20 and slips 15 to the lower body section 12, from where the turning motion is transferred to the lower packer body D.

Fluid is prevented from leaking from the cylinderV spacey Patented Feb. 24, 1959 gsvgrefi' ably" andse'alingly engaging the inner wall ofthe` c'ylilldel:`

sleeve,3 1. Fluid is prevented from leakingmina down-A ward direction between the cylinder. head 30 end upper body section `11 by providing an internal seal ring 42, such as' a rubber orA rubber-like 0 ring, in an'internal groove 43'in the cylinder head, whichslidably seals against the periphery of the upper bodyrsection. A thread seal 44 may be provided in a groove `45 in the cylinder head 30, engaging the wall of the cylinder sleeve'31' to prevent leakage through theV threaded connectioirbetween the sleeve and the cylinde'rhead or expander 20. Likewise; fluid is prevented from passing between the `rriandrelr.33 andthe body .portion111 .aboyev the piston 29 lby a suit-v ablelseal ring 46, such asa rubberor rubber-like O ring A located in an vinternal'groove 47 in" the lower head 34 of the` mandrehwhich slidably andisealingly engages the periphery ofthe body 11a above thepiston. v

In'the operation ofv the'fapparatusl A so far described, it is yrun in the well casingB by the tubular string C, with its lower body section 12 attached to the body D of the lower tool, and withits expander 20 disposed in an upward position withrespect to the slips 15, which are held ina retracted position. As assurance against the dropping of the expander 20 by gravity along the slips 15, a helical-compression spring 50 may. be disposed in the annular space 51 between the mandrel 33 and the cylinder sleeve '31, withv its lower endV bearing against the lower mandrel head 34 and its upper endagainst the upper cylinde'rhead 3 2. V`This spring will tend to maintain the expander 20 in 'its elevated'position. The apparatus is lowered through the uid in the well casing until the location is reached at which it is to be anchored to the latter. When such location is reached, the tubing string C is suitably manipulated to anchor the lower packer D in packedot condition within the well casing. Thereafter, pressure mayY be imposed onthe uid in the tubular string C, ma'ndrel 33 andbody 10 of the tool, such uid under pressure passing through the

ports

26, 27 and into the cylinder space 28, to act in a downward direction on the cylinder head 30 and shift the expander 20 downwardly within the slips 15, expanding the latter outwardlyinto anchoring engagement withthe wallof the well casing.

It is to be noted thatfthe wickers or teeth 23 on the slips 15 face in anupwarddirection, so as to anchor the slips -to the casing aganstupward movement vwith respect thereto. Upward movement of the lower packer D, as a result of pressure in the casing .therebelow, is preventedin view of the anchoring of the slips against the well casing. Such pressure is also present within the body 10, and is acting in a downward direction on the expanderhead 30 to hold the expander 20 wedged behind'the slips 15, preventing their retraction from the well casing.

When the apparatus- A is to be released from the well casing B, the pressure is relieved and an upward pull taken on the tubular string C, which will be transmitted to the mandrel 33, shifting the latter upwardly alongv the body 10 and the cylinder sleeve 31. The mandrel is provided with an upwardly facingshoulder 52, which will engage the lower end of the upper cylinder headA 32,-\

whereupon further upward movement of the mandrel 33 is transmittedthrough the head 32 and cylinderk sleeve 31 to the expander 20; to raise the latter with respect to the `slips 1S and effect a shifting of the slips to their retracted position. During upward movement of the apparatus A in the well casing B, the expander 20 will be heldin its upper position relativeto theslips 15, to insure that thelatter will remain in their retracted position. If it is desired to againanchor the slips to the casing, it is merely necessary to relowenthe mandrel 33 valong the body 1( t o reengage therilownhead 314 withl the .pistonm 29, and then provide pressure in the tubular string C,

relative to the body 10 against the forceof the spring 50,

to engage the slips 15 with the wall of the well casing. With the slips engaging the wall of the well casing, downward movement of the apparatus will slide the wickers 23 along the casing, which might result in their being dulledwhen the location in the4 well casing is reached at which the apparatus is to be anchored. Accordingly, the slips 15 may be unable to withstand any substantial upwardly directed forces or pressure imposed thereon.

The present invention seeks to overcome the aforenoted ditiiculty by preventing the expander 20 from being shifted downwardly within the slips 15 yuntil s uch action is desired. A latching device is incorporated between the expander 20 and thev body 10 of the toch-which is effective to hold the expander inan upward position and which must be subjected to substantial pressures bel fore its release can occur. The latching device consistsy of a split, inherently contractile ringy 53 placed around' the body 10 between the expander 20 and the piston 29. This ring'has a lower surface 5 4 inclined at a substantial angle'in a downwardv and outward direction, and this holding surface 54 is adaptedto engagea companion holding surface or shoulder 55 provided on the,l body,V sectionl 11, 'preferably immediately below the upperl set-of ports 26. @The ring S3 is contained within an internalv groove 56 formed between a coupling or retainer ring 57 and the upper end of the expander or cylinder head 30. Thus, Vthe coupling ring 57 is made of two halves, with its periphery 58 engaging the inner wall of the cylinf der sleeve31. This ring has a lower, inwardly directed flange 59 received within an external groovev60 in the cylinder head, and an upward inwardly directed ilange 61 spaced abovethe upper end of the cylinder head 30 and also extending across the upper end of the latch ring 53.

The intermediate web portion 62 of the coupling ring be- At this time, the expander 20 is in its uppermost position;`

within the slip/s `.15, .with the upperVV end of the vcoupling ring`57 disposed adjacent the body piston 29. The inherent, contractileforce of the latch ring 53 and the angle of inclinationvof the body shoulder 55 are such as to require a substantial downward force by the upper flange 61 on the latch ring to expand the ring outwardly free of the holding shoulder 55. As an example, the force required to free the latch yring from the shoulder may correspond to a pressure differential of 250 to 350 p. s. i. within the annular cylinder space 28.

During lowering of the apparatus in the well casing,' pressure differential will be developed in the body 10, but the total force of such pressure acting in the cylinder space 28 Vin a downward direction on the expander 20 will neverreach the unit pressure that is necessary to release the latch ring 53 from the holding shoulder 55. The downward force of the pressure von thehead 30 will cause 'the'upper ring flange 61 to engage the ring mentv withthe wall' of the well casing, the lower packer H D is set and suicient pressure differential is developed Within the packer body to overcome the holding force of the latch ring 53. Such pressure will act in a downward direction on the cylinder head 30, being exerted through the upper flange 61 on the ring 53. Because of the inclined coaction between the lower end 54 ofthe ring and shoulder 55, the pressure will eventually cause the ring 53 to be expanded outwardly ot the shoulder 55, whereupon the

cylinder

31, 30 is shifted downwardly relative to the body 10, to shift the expander within the slips and expand the latter outwardly into anchoring engagement with the wall of the well casing B. During downward movement of the

cylinder

30, 31 the ring 53 will also slide downwardly along the body 11.

It is preferred that the body have a relatively steep tapered periphery 70 that inclines in a downward and inward direction from the holding shoulder 55 and along which a companion tapered surface 71 of the ring 53 can slide, to permit the ring to retract to some extent. The coaction between this relatively steep body surface 70 andthe ring surface 71 will then cause the ring 53 to support the body 10 of the tool, and the apparatus D secured therebelow from the expander and the anchored slips 15, and will prevent the force of gravity, or

other relatively light forces, as well as the force of theV compression spring 50, from inadvertently shifting the parts back to a retracted position, in the event the pressure within the body 10 of the tool is relieved, or is reduced to any substantial extent.

When it is desired to retract the slips 15 from the well casing, the pressure is relieved and an upward pull is taken on the tubing string C and mandrel 33. The man-v drel shoulder 52 moves upwardly against the force of the compression spring 51, which exerts a comparatively light force, until the mandrel shoulder engages the upper cylinder head 32. An upward pull can now be taken on the cylinder 31 and the expander 20, to shift the latter upwardly relative to the slips 15 and the body 10 of the tool. The latch ring 53 will not offer very great resistance to such upward movement, in view of the relatively steep taper or inclination of the coacting surfaces 71, 70 on the ring 53 and the body 10. When the expander 20 has been shifted upwardly to its fullest extent, the slips s 15 will be completely retracted and the latch ring 53 can again snap back into its position above the holdingl shoulder 55, to again preclude inadvertent downward movement of the expander 20 within the slips 15. The apparatus can now be elevated to a new location in the well casing or removed entirely therefrom; or, if desired, it can be lowered to another setting position within the well casing. During such lowering movement, any fluid pressure differential within the body 10 of the tool cannot eiect a downward shifting of the expander 20 within the slips 15.

It is to be noted that longitudinally spaced sets of ports ment of the

cylinder

31, 30 along the body 10, prevent-` ing relative upward movement of the cylinder along the body. Any such particles can be forced out of thecylinder space 28 through the upper sets of ports 26 when the cylinder 31, expander 20 and latch Vring 53 are elevated along the body to effect reshifting of the slips to their retracted position. The upper set of ports`26 precludes theV presence of any dead pockets or spaces intoY which sand particles or the like can pack.

It is, accordingly, apparent that a tubing' anchor-has been provided which is actuatable hydraulically to expand the slips into anchoring engagement with the wall of the well casing, and in which hydraulic forces incident to the lowering of the apparatus through the diuid in the well casing are incapable of anchoring the slips against the well casing. Thus, the slips are prevented from being inadvertently expanded against the wall of the well casing during descent ofthe apparatus in the latter, preventing dulling of the teeth or wickers of the slips, andY insuring that they will be in appropriate condition for anchoring the apparatus to the well casing securely, and with a capability to withstand comparatively high pressure that might be imposed on the anchor A and tending to elevate it in the well casing.

The inventors claim:

1. In a well tool: a body; expander means on said body; slips cooperable with and shiftable with respect to said expander means for anchoring the tool to the wall of a well casing; uid actuated means for moving said slips and expander means in one direction relative to each other to shift said` slips to casing anchoring position; said slips having casing engaging wickers facing in the same direction'as said slipsare movable relative to said expander means; latch means operatively connected to said expander means for preventing relative movement between said slips and said expander means and releasable in response to a predetermined pressure imposed upon said expander means to permit relative movement between said slips and expander means; and means for shifting said fluid actuated means to relatively move said slips and expander means in the opposite direction to reset said latch means.

2. In a well tool: a body; van expander on said body and having an expander surface inclined downwardly and inwardly; slips engageable with said surface and shiftable relative to said expander for anchoring said tool to the wall of a well casing; uid actuated means for relatively moving said expander downwardly within said slips to expand said slips against the wall of the well casing; said 'slips having upwardlyfacing wickers on their exterior surfaces; latch means operatively connected to said expander for preventing downward movement of said expander relative to said slips and releasable in response to a predetermined pressure imposed upon said expander to permit downward movement of said expander relative to-said slips; and means for elevating said fluid actuated means with respect to said body to reset said latch means in its condition preventing downward movement of said expander relative to said slips.

3. In a well tool: a bodyg'an expander on said body and having an expander surface inclined downwardly and inwardly; slips engageable with said surface for anchoring said tool to the wall of a well casing; iluid actuated means for relatively moving said expander downwardly within said slips to expand said slips against the Wall of the well casing; said ,slips having upwardly facing wickers on their exterior surfaces; releasable latch means engageable with said body and expander to prevent downward movement of said expander relative to said slips, said latch means being releasable in response to a predetermined fluid pressure imposed on said expander and urging it downwardly of said body; and means for elevating said lluid actuated means with respect to said body to reset said latch means in its condition preventing downward movement of said expander relative to said slips.

4. In a well tool: a tubular body; an expander slidable longitudinally on said body and having an expander surface inclined downwardly and inwardly; slips carried by said body and coacting with said expander to be shifted outwardly into anchoring engagement with the wall of the well casing; means responsive to fluid pressure in said body for shifting said expander downwardly of said body to expand said slips outwardly; latch means engageable with said body and shifting means and releasable in response to a predetermined force exerted on said latch means by said shifting means for resisting downward movement of said expander along said body; and means for elevating said shifting means with respect to said body to re-engage saidrlatch meanswithsaid bodytoY vagain resist downward movement of saidexpanderalong said body.

5. In a well tool: a tubular body; an expander slidable longitudinally on said body and. having an expander surface inclined downwardly and inwardly; slips carried by said body and coacting wim said expander to be shifted outwardly into anchoring engagement with the wall of a well casing;rmeans responsive to fluid pressure in said fbody for shifting said expander downwardly of said body to expand said slips outwardly; latch means carried by said shifting means and engageable with said body for resisting downward movement of said expander along said body, said latch means being releasable from said body in response to a predetermined force exerted on said latch meansby saidshifting means; and means for elevating said shifting means with respect to `said body to re-engage said latch means with said body to again resist downward movement of said expander along said body.

6. In a well tool: a tubular body having a piston and a port below said piston; an expander slidable longitudinally onv said body below said piston and having an expanderV surface inclined downwardly and inwardly; slips coacting with saidexpander to be shifted outwardly into anchoring engagement with the wall of a wellcasing; means coupling said slips to said body to prevent relative longitudinal movement between said slips and body; a cylinder secured to said expander and extending upwardly therefrom along said piston; lluid under pressure being adaptedto pass through said port into said cylinder to shift said expander downwardly of said body to expand said slips outwardly; and latch means carried by said cylinde'r and engageable with said body to resist downward movement of said expander along said body, said latch means being releasable in response to a predetermined force imposed thereon by said cylinder.

7. In a well tool: a tubular body havinga piston and upper and lower ports below said piston; an expander slidable longitudinally on said body below said piston and having an expander surface inclined downwardly and inwardly; slips carried by said body and coacting with said expander to be shifted outwardly into anchoring` engagement'with the wall of a well casing; a cylinder secured to said expander and extending upwardly therefrom along said piston; fluid under pressure -being adapted to pass through said ports into said cylinderto shift said expander downwardly of said body to expand said slips outwardly; and latch means carried by said cylinder and engageable with said body adjacent said upper port to resist downward movement of said expander along said body, said latch means being releasable in response to a predetermined force imposed thereon .by said cylinder.

8. In a well tool: a tubular body having a piston and a port below said piston; an expander slidable longitudinally on said body below said piston and having an` expander surface inclined downwardly and inwardly; slips carried by said body and coactingwith said expander to be shifted outwardly into anchoring engagement with the wall of a well casing; a cylinder secured to said expander and extending upwardly therefrom alongv said piston; fluid under pressure being adapted to pass through said port into said cylinder to shift said expander downwardly of said body to expand said slips outwardly; and a split, inherently contractible latch ring carried by said cylinder and engageable with an upwardly facing shoulder on said l 9. In a well tool: a tubular body having a piston and A upper and lower ports below said piston; an expander slidable longitudinally on said body below said piston and having an expander surface inclined downwardlyv and inwardly; slips carried by said body'and coacting with said expander to be shifted voutwardly into anchoring engagement withthe walljof avwell casing; a cylinder securedl to saidrexpander and,e xtending upwardly therefrom along -a port below said piston; an expander slidable longitudinally on said body below said piston and having an expander surface inclined downwardly and inwardly; slips carried bysaid body and coacting with said expander to be shifted outwardly into anchoring engagement with the ,wall ofa well casing; a cylinder secured to said expander and extending upwardly therefrom along said piston; fluid under pressure lbeing adapted to pass through said port into said cylinder to shift said expander downwardly of said body to expand said slips outwardly; and a split, inherently contractible latch ring carried by said cylinder and engageable with an upwardly facing shoulder on said body lto resist downward movement of said expander along said body, said latch ring being releasable from said shoulder in response to a predetermined downward force imposed thereon by said cylinder; said body having a downwardly converging surface engaged by said latch ring upon its release from said shoulder to resist upward movement of said expander along said body.

' 1l. In a well tool: a tubular body having a piston and a port below said piston; an expander slidable longitudinally on said body below said piston and having an expander surface inclined downwardly and inwardly; slips carried by said body coactingwith said expander to be shifted outwardly into anchoring engagement with the wall of a well casing; a cylinder secured to said expander and extending upwardly therefrom along said piston; lluid under pressure being adapted to pass through said port into said cylinder to shift said expander downwardly of said body to expand said slips outwardly; latch means carried by said cylinder and engageable with said body to Aresist downward movement of said expander along said body, said latch means being releasable in response to a predetermined force imposed thereon by said cylinder; and a mandrel telescoped over said body above said piston and engageable with said cylinder to elevate said expander along said body.

l2. In a well tool: a tubular body having a piston and a port below said piston; an expander slidable longitudinally on said body below said piston and having an expander surface inclined downwardly and inwardly; slips v response to a predetermined force imposed thereon` by said cylinder; a mandrel telescoped over said body above said piston and engageable with said cylinder to elevate saidexpander along said body; and spring means between` said mandrel and cylindery tending to elevate said cylinder 'and expander with respect to said mandrel and body.

13. In a Well tool: a tubular body having apistonand a port below. said piston; an expander slidable longitudinally on said. body below said piston and having an ex-I pander surfaceinclined downwardly and inwardly; slips carried -by said body and coacting with said expander to be shifted outwardly into anchoring engagement with the wall of a well casing; a cylinder secured to said expander and extending upwardly therefrom along said piston; fluid under pressure being adapted to pass through said port into said cylinder to shift said expander'downwardly of said body to expand said slips outwardly; a split, inherently contractible latch ring carried by said cylinder and engageable with an upwardly facing shoulder on said body to resist downward movement of said expander along said body, said latch ring being releasable from said shoulder in response to a predetermined downward force imposed thereon Iby said cylinder; and a tubular mandrel telescoped over said body above said piston and engageable with said cylinder to elevate said cylinder and expander with respect to said body.

14. In a well tool: la tubular body having a piston and a port -below said piston; an expander slidable longitudinally on said body below said piston and having an expander surface inclined downwardly and inwardly; slips carried by said body and coacting with said expander to be shifted outwardly into anchoring engagement' with the wall of a well casing; a cylinder secured to said expander and extending upwardly therefrom along said piston; uid under pressure being adapted to pass through said port into said cylinder to shift said expander downwardly of said body to expand said slips outwardly; and a split, inherently contractible latch ring carried by said cylinder and engageable with an upwardly facing shoulder on said body, said latch ring being releasable from said shoulder in response to a predetermined downward force imposed thereon by said cylinder; said body having a downwardly converging surface engaged by said latch' ring upon its release from said shoulder to resist upward movement of said expander along said body; and a tubular mandrel telescoped over said body above said piston and engageable with said cylinder to elevate said cylinder and expander along said body to relocate said latch ring in a position engaging said body shoulder.

15. In a well tool: a tubular body having a piston and a port below said piston; an expander slidable longitudinally on said body below said piston and having an expander surface inclined downwardly and inwardly; slips carried by said body and coacting with said expander to be shifted outwardly into anchoring engagement with the wall of a well casing; a cylinder secured to said expander and extending upwardly therefrom along said piston; iluid under pressure being adapted to pass through said port into said cylinder to shift said expander downwardly of said body to expand said slips outwardly; latch means carried by said cylinder and engageable with said body to resist downward movement of said expander along said body, said latch means being releasable in response to a predetermined force imposed thereon by said cylinder; and means for elevating said cylinder along said body to re-engage said latch means with said body to again resist downward movement of said expander along said body.

References Cited in the le of this patent UNITED STATES PATENTS 2,435,899 Page Feb. 10, 1948 2,609,879 Webber Sept. 9, 1952 2,735,497 Brumleu et al Feb. 21, 1956 2,737,247 Baker et al Mar. 6, 1956