AU703766B2 - Running tool with retraction system for retracting a latching mechanism of said tool - Google Patents

Description

2 RUNNING TOOL WITH RETRACTION SYSTEM FOR RETRACTING A LATCHING MECHANISM OF SAID

TOOL

The present invention relates to a running tool having a self-retracting latching mechanism and in particular, but not exclusively, to a running tool for use in a system for in situ replacement of cutting means of a ground drill.

A system for in situ replacement of cutting means of a ground drill is described in Applicant's International Application No. PCT/AU94/0032 2 (WO 94/29567) The system in WO 94/29567 comprises a drive sub which is adapted for connection to a lower end of a core barrel attached to a drill pipe; a tool for installing and retracting drill bit segments from the drive sub; and, a bit locking sleeve (or insert) for selectively locking the bit segments into seats provided about the inner circumferential surface of an end of the drive sub and, subsequently releasing the bit segments from those seats. The tool includes a main body portion and a sleeve slidably mounted thereon. Installation latch dogs provided in the tool extend from apertures or openings cut in the sleeve so as to engage the bit locking sleeve and force it into an installation Position in which it locks the bit segments in a cutting position about the drive sub.

A slidable cradle extends from a lower end of the tool for S 25 carrying the bit segments to and from the drive sub. When installing the bit segments, the cradle is extended from a :lower end or head of the tool against the bias of a spring.

S• Bit segments are held by rubber bands about the cradle with one end abutting a stop provided at one end of the cradle and an opposite end bearing against the head of the tool. When the tool is lowered into the ground drill (which comprises the combination of the drill tube, core barrel and drive sub) and reaches a predetermined position with the drive sub, that 3being the point of engagement of the installation latch dogs with lands formed on the bit locking sleeve, the main body of the tool slides relative to the sleeve which in turn releases a detent system holding the spring about the cradle in compression. This fires the cradle enabling the spring to expand thereby retracting the cradle into the main body of the tool which causes an upper end of the bit segments to slide along the head of the tool so as to extend laterally from the outer periphery of the tool. The locking sleeve is simultaneously pushed by the tool so as to catch the ends of, and move inside, the bit segments thereby expanding the drill bit segments to the inner diameter of the drive sub and locking the bit segments in the cutting position.

Trials of the above system have proved very successful.

Nevertheless, it is thought that the system can be improved by ensuring positive firing of the cradle at all times. In the above system firing of the cradle is dependent upon the installation latch dogs of the tool abutting lands on the bit locking sleeve causing a temporary stop to the motion of the tool so that the momentum of the main body portion allows it to slide relative to the sleeve thereby disengaging the detent system holding the spring of the cradle in compression. If the locking sleeve is for some reason, not disposed at the correct level within the drive sub, firing of the cradle may occur too early or too late. Also, it is critical that the bit locking sleeve resist downward movement to an extent so as to apply sufficient force to the tool to ensure firing. This requires high tolerance machining of the locking sleeve and drive sub as well as snap rings and other 30 locking mechanisms which may temporarily hold the locking sleeve in a particular position.

The present invention was developed with a view to ensuring more definite and positive firing of the tool. This development involved moving the initiating point for firing of the tool from the bit locking sleeve to the drive sub. As 4 the drive sub is a fixed tubular element the potential problems arising from using the locking sleeve to initiate firing are alleviated. However, the problem then arises as to how disengage the latch dogs of the tool from the drive sub after firing. To this end, the present invention in general terms comprises a running tool in which the latch dogs are self-retracting after the main body of the tool has slid relative to the sleeve of the tool by a predetermined distance.

More particularly, the present invention provides a running tool adapted for travel within a tubular member, said running tool comprising: an elongate main body portion; an elongate sleeve slidably mounted on said main body portion said sleeve provided with at least one opening in a peripheral wall thereof; at least one latching mechanism housed in said main body portion and coupled to both said sleeve and said main body portion, said latching mechanism biased away from a 20 longitudinal axis of said tool to protrude from said opening; and, a retraction system associated with said latching S. mechanism and one of said sleeve or said main body portion for at least partially retracting said latching mechanism towards said longitudinal axis against said bias when said main body portion slides a predetermined distance in one direction relative to said sleeve, whereby, in use, when said running tool travels down a tubular member and said latching mechanism strikes a seat formed in said tubular member, said 30 main body portion can slide relative to said sleeve and, upon sliding said predetermined distance, said retraction system operates to retract said latching mechanism towards said longitudinal axis thereby disengaging said latching mechanism from said seat so that said tool can continue to travel through said tubular member.

Preferably said retraction system comprises a cam surface formed on the associated one of said main body portion and said sleeve, and a cam follower formed on said latching mechanism, said cam surface and cam follower relatively disposed so as that said main body portion slides relative to said sleeve, said cam surface engages said cam follower causing said latching mechanism to retract towards said longitudinal axis.

Preferably said cam follower comprises a pin attached to said latching mechanism.

Preferably said pin threadingly engages said latching mechanism.

Alternatively, said pin is formed integrally with said latching mechanism.

15 Preferably said cam surface is formed on said main body portion and said latching mechanism is fixed against linear movement relative to said sleeve.

Preferably said cam surface comprises the surface of a cutout made in said main body portion into which said pin extends.

Preferably said latching mechanism is one of a pair of latching mechanisms coupled to a common pivot pin and biased to pivot in opposite directions and said cutout is one of a pair of cutouts formed in said main body portion where individual pins extend into individual cutouts, and said 25 opening is one of a pair of openings through which respective ones of said latching mechanisms can protrude.

An embodiment of the running tool will now be described by way of example only with reference to the accompanying drawings in which: 6 Figure 1 is a longitudinal section view of the running tool disposed within a drill tube at the junction with a core barrel passing through a landing ring; Figures 2A, 2B, 2C and 2D when joined end to end is a longitudinal section view of the running tool disposed within a drive sub at a location immediately prior to the tool firing; Figure 3 is a view of the running tool shown in Figure 1 shortly after firing of the running tool; Figure 4 is a longitudinal section view of the running tool shown in Figure 3 but in a plane parallel to and offset from that of Figure 3; Figure 5 is an isometric view of the main body portion of the running tool when in the position shown in Figure 2; and 15 Figure 6 is a isometric view of the main body portion of the running tool when in the position shown in Figures 3 and 4.

In the following description, an embodiment of the running tool in accordance with the present invention will be described in relation to a system for in situ replacement for cutting means of a ground drill. However, it is to be 5understood that the running tool is not limited only to use in such a system and may be used in unrelated fields.

Referring to the accompanying drawings, and in particular, Figures 2A to 2D and 3, a system 10 for the in situ replacement of cutting means for a ground drill comprises a number of separate but interactive components including a drive sub 12 which is adapted for connection to a lower end of a core barrel 14; a locking sleeve 16 which is retained within the drive sub 12; and a running tool 18 in accordance with an embodiment of this invention.

7 While the drive sub 12 and locking sleeve 16 do not form of the present invention, a brief description of their salient features is provided below to assist in the understanding of the operation of the running tool 18. A detailed description of the features and function of the drive sub 12 and locking sleeve 16 is set out in Applicant's corresponding International Application No. PCT/AU94/00322.

The drive sub 12 is provided on its inner circumferential surface 20 at its lowest end 22 with a series of seats 24 for seating drill bit fingers 26 which are transported on the tool 18. The seats 24 comprise a plurality of contiguous inclined and level surfaces 28-40 commencing from an annular stepped surface 42 inboard of the lowest end 22 and culminating in a series of recesses 44 spaced circumferentially about the inner peripheral surface 20 at the lowest end 22. Adjacent ones of the recesses 44 are separated by respective drive lugs 46. Intermediate the length of the driv6 sub 12 above the step surface 42 is a circumferential groove 45 formed in the inner circumferential surface 20. A resiliently radially extendable snap ring 46 sits in the groove 45. When in the relaxed state a portion of the snap ring 47 sits proud of the inner circumferential surface 20. Further above the groove 45 is a circumferential seat 48 formed in the inner circumferential surface 20. The seat 48 is formed by machining a length 50 of the wall of the drive sub 12 to have a greater inner diameter than a lower contiguous length 52 of the wall of the drive sub.

The locking sleeve 16 is in the form of a hollow cylindrical tube having a pair of opposing peaks 54 (only one shown) extending from an upper end. A pair of lands 56 separate the bases of the peaks 54. A pair of circumferential grooves 58 and 60 are formed about the outer surface of the locking sleeve 16. Below the lowest groove 60 is a pair of diametrically opposed longitudinally extending slots 62 and 64. The purpose of the locking sleeve 16 is to lock the bit 8 fingers 26 onto the drive sub 12 and to angularly orientate the tool 18 so that the bit fingers 26 are aligned with the seats 24.

The tool 18 comprises a main body portion 66 and an outer sleeve 68 slidably mounted on the main body 66. An upper end of the main body 66 is threadingly connected to a spear point assembly 70. The spear point assembly 70 is described in detail in the Applicant's co-pending application No.

PCT/AU96/00589 and facilitates coupling of the tool 18 to a running line or wire (not shown) The main body 66 is itself composed of a first portion 72 and a second portion or head 74 which are retractably coupled together. Housed within a cavity 76 of the main body 66 is a pair of latching mechanisms 78 commonly known as installation latch dogs. The installation latch dogs 78 essentially comprise a pair of arms 80 which are pivotally coupled together at one end by a pin 82 and biased by a spring 84 at an opposite end so as to extend away from the longitudinal axis of the tool 18. Opposite ends of the pin 82 pass through respective slots 86 formed in the main body 66 and into diametrically opposed slots (not shown) formed in the sleeve 68. This provides a slidable connection between the sleeve 68 and main body 66 as, when sleeve 68 moves longitudinally relative to the main body 66, the pin 82 is 25 able to slide within slots 86. Pin 82 is held in place by a snap ring 88 which is disposed within a circumferential recess 90 provided about the outer periphery of the sleeve 68. To assist in locating the snap ring 88, opposite ends of the pin 82 are provided with respective grooves 92 (refer Figures 5 and 6) within which the snap ring 88 can sit. Snap ring 88 is basically in the form of a metal ring which is resiliently expandable in the radial direction.

The end of arms 80 which extend from the cavity 76 are provided with substantially planer latching faces 94 for 9 engaging the seat 48 on the drive sub 12 and the lands 56 of the locking sleeve 16. A channel 95 is formed intermediate the length of an outer-most surface of each arm 80. The opposite sides 97 of each channel 95 slope away from each other in a direction away from the base of its respective channel. Each latch dog 78 is also provided with a pin 101 which extends perpendicular to the plane of each latch dog.

The pins 101 are screwed into the respective latch dogs.

A central part of spring 84 is wound about a stud or bolt 96 which is held at its opposite ends in diametrically opposed slots 98 formed in the main body 66.

A pair of second latching mechanism 100, commonly known as retrieval latch dogs, are also located within the cavity 76.

SThe retrieval latch dogs 100 comprise a pair of arms 102 15 which are disposed in the same plane as arms 80 but are orientated in the opposite direction. The arms 102 are pivotally coupled together at a lower end about a pin 104 which in turn threadingly engages and is wholly disposed within the main body 66.

An opposite end of each arm 102 is biased by spring 106 so as to move out of cavity 76 away from the longitudinal axis of the tool 18. A central part of spring 106 is wound about and retained by a stud or bolt 108. Opposite ends of the stud oo o 108 are held within diametrically opposed slots 110 formed in S" 25 the main body 66.

The end of each arm 102 opposite the pin 104 is provided with a latching face 112 for engaging respective slots 114 in the locking sleeve 16. Adjacent an end of the latching face 112, nearest the sleeve 68, is a bevelled surface 116 which slopes away from the longitudinal axis of the tool 18 in the direction toward pin 104. The bevelled face 116 leads to a straight face 118 on the outer side of each arm 102 which in 10 turn leads to a second bevelled face 120 sloping toward the longitudinal axis of the tool 18.

A removable threaded pin 122 is provided which can pass through the arms 102 to lock the retrieval latch dogs 100 in a substantially compressed state so as to be disposed within the confines of the main body 66. This pin is inserted when the tool 18 is used in an installation mode to install the bit segments 26 into the drive sub 12, and is removed when the tool 18 is in a retrieval mode for retrieving the bit segments 26 from the drive sub 12.

The lower end of the first portion 72 of the main body 66 is formed with a tubular extension 124 which receives a spigot 126 extending from an upper end of the second portion 74.

Pin 128 extends transversely through the tubular extension 124 and resides within opposing slots 130 formed in the spigot 126 intermediate the length of the tubular extension 124. A pair of diametrically opposed holes 132 is formed in the tubular extension 124 for seating respective balls 134.

There is a stepped increase in the internal diameter of the 20 lower end of the tubular extension 124 so as to form a cuplike structure 136.

pair of diametrically opposed elongate slots 138 is formed in the spigot 126 below the holes 132. The slots 138 receive S* the balls 134 but are of a width so as to allow only a 25 portion of the balls 134 to extend therethrough, preventing the balls 134 from falling out. The elongate slots 138 allow relative movement of the spigot 126 and tubular extension 124 to facilitate movement of the head 74 relative to the first portion 72.

An upper portion 140 of the head 74 is of a substantially cylindrical shape but has a plurality of peripheral longitudinal channels (not shown) provided along the side thereof for allowing the flow of liquid such as water and 11 drilling mud. Adjacent an upper portion 140 is an intermediate portion 142 of constant but reduced diameter.

Contiguous with the intermediate portion 142 is a bottom portion 144 of substantially frusto-conical shape which narrows in the downward direction. A plurality of ramps 146 are disposed circumferentially about the outer surface of the bottom portion 144 for seating an upper end 148 of the bit segments 26. Each ramp 146 is bound by opposing sidewalls 150 between which the upper ends 148 lie. Longitudinal channels (not shown) are also formed centrally of each ramp 146 to allow the flow of water and drilling mud. Similarly, channels (not shown) are formed between adjacent side walls 150 of adjacent ramps 146, for the purpose of allowing further flow of water and drilling mud.

15 A spring 152 is disposed about the spigot 126 and has an upper end seated in the cup-like structure 136 and a lower end bearing against an upper surface 154 of the upper portion 140 of the head 74. The spring 152 is biased so as to push the head 74 and the first portion 72 apart in the 20 longitudinal direction.

Lower end 156 of sleeve 68 has an internal diameter greater than that of an immediate preceding length 157 of the sleeve 68 so as to form a gap 159 between the inner surface of the sleeve 68 and outer surface of the tubular extension 124.

25 Lower end 156 of the sleeve 68 is also biased in a direction so as to contact the face 154. This bias is provided by a coil spring 158 disposed about an upper portion of the main body 66 between the spear point assembly 70 and an upper end 160 of the sleeve 68.

A cradle 162 passes through an axial hole 164 formed in the head 74 so that an upper portion of the cradle 162 is disposed within the spigot 126. The purpose of the cradle 162 is to hold the bit segments 26 during transport to, and from, the drive sub 12 and, when installing the bit segments 12 26, to expand the upper end 148 of the bit segments radially outwardly so that they can be collected by the locking sleeve 16.

A spring 166 surrounds an upper end of the cradle 162 disposed within the spigot 126. The spring 166 is retained on the cradle 162 by a washer 168 fixed to the cradle 162 by a bolt 170. When the tool 18 is being used to install bit segments 26 into the drive sub 12, the cradle 162 is extended from the head 74 so as to compress the spring 166. The spring 166 is held in compression by the balls 134 which engage an upper surface of the washer 168 through the longitudinal slots 138. Balls 134 are held in this position by the inner surface of length 157 of sleeve 68 pushing the balls 134 into slots 138.

15 A disc-like flange 172 lying in a plane transverse to the axis of the tool 18 is attached by a nut 174 to the lowest end of the cradle 162. The flange 172 acts as a stop preventing the bit segments 16 from sliding off the end of the cradle 162. The bit segments 26 are held 20 circumferentially about the cradle 162 by three elastic bands 176.

An upper end of tool 18 is provided with a locking system 178 (refer Figure 3) for selectively locking the sleeve 68 to the main body 66 preventing relative sliding motion. The locking 25 system 178 includes a pair of diametrically opposed holes 180 S- formed in the main body 66. The holes 180 are designed to capture locking members in the form of balls 182. Disposed within the main body 66 is a biasing system 184 for urging the balls 182 radially outwards. The biasing system 184 comprises a pair of cups 186 which are dimensioned so as to able to slide within holes 180 and which between them retain a spring 188. A channel 190 extends from each hole 180 longitudinally about the outer surface of the main body 66.

The channels 190 provide a race within which the balls 182 13 may travel when they are able to escape from their respective holes 180.

The locking system 178 also includes a pair of diametrically opposed openings 192 of a diameter less than the maximum diameter of the balls 182 and formed at an upper end of the sleeve 68.

Below the openings 192 the sleeve 68 is provided with a pair of opposed longitudinal slots or openings 194 through which the arms 80 of the installation latch dogs 78 can extend by virtue of action of the spring 84.

Referring to Figure i, it can be seen that an upper end of the tool 18 is shrouded in a transport sleeve 196. The a **transport sleeve 196 is in the form of a hollow cylindrical atube having a pair of opposed longitudinal slots 198 formed 15 near and inboard of a lower end 200. The lowest edge 202 of each slot is bevelled at a complementary angle to the slope of the side surfaces 97 of grooves 95 formed in the latch dog arms The transport sleeve 196 is used for a dual purpose.

Firstly, the transport sleeve 196 holds the installation latch dogs 78 in a relatively compressed state to ensure that the tool 18 can pass through a standard landing ring 204 which is incorporated as a standard item in core drills.

Landing ring 204 is retained between the upper end of the "25 core barrel 14 and lower end of drill tube 206. The other function of the transport sleeve is to retain the balls 182 in holes 180 against the bias of spring 188 thereby locking the sleeve 68 to the main body portion 66 to prevent premature firing of the tool 18.

The transport sleeve 196 has an outer diameter greater than the inner diameter of the landing ring 204. Thus, as the tool 18 is being lowered through the drill tube 206 and to 14 the core barrel 14, eventually the lower end 200 of the transport sleeve 196 will abut the landing ring 204. At this time, because of the momentum of the tool 18, the pivotal nature of the installation latch dogs 78, and the complementary surfaces 202 and 97 the latch dogs 78 pivot further inwardly as surfaces 97 slide down surfaces 202 thereby allowing the tool 18 to continue in its journey down the core barrel 14. The transport sleeve 196 is held in the drill tube 206 above the landing ring 204. Also, the spring 188 now pushes the balls 182 outwardly so that they can run along the channels 190 so that the tool 18 can be fired.

Eventually the latch dogs 78 will contact peaks 54 of the locking sleeve 16 causing the tool 18 to rotate about its longitudinal axis. This orientates the tool 18 so that the 15 bit fingers 26 will be properly aligned with the seats 24.

Upon further downward travel of the tool 18 the latching face 94 of installation latch dogs 78 will abut the seat 48 formed in the drive sub. This generally coincides with the latching faces 94 also striking the lands 56 of the locking sleeve 16.

Because the latch dogs 78 are fixed to the sleeve 68 via the pin 82, the main body portion 66 is able to continue moving downwardly, slide relative to the sleeve 68 for a distance at least equal to the length of the slots 86 and the main body portion 66 in which the pin 82 resides. However, 25 in order to ensure that the tool 18 does not jam or otherwise stop at this point, it is necessary to retract the latch dogs 78 from the seat 48.

S

This is achieved by way of a retraction system 208 (refer to Figures 5 and 6) which comprises in combination, the pins 101 formed on the latch dogs 78 as well as the surface of each of a pair of cutouts 210 made in the main body portion 66. As seen most clearly each cutout 210 has a shape of a lower and upper substantially rectangular U's 212 and 214 respectively, which have the same longitudinal axis and face each other but with the upper 214 of a smaller width, and two planer but 15 inclined surfaces 216 and 218 joining adjacent ends of the U's 212 and 214. The surface 220 of each cutout 210 forms a cam surface of the retraction system 208. Each pin 101 acts as a cam follower and extends into a respective one of the cutouts 210.

As shown in Figures 2 and 5, prior to the latch dogs 78 striking the seat 48, the pins 101 are disposed within the lower U 212 and spaced from contact with the surface 220.

However, when the latching faces 94 strike the seat 48, and the main body portion 66 slides relative to the sleeve 68, the cutout 210 also moves downwardly so that the pins 101 come into contact with the peripheral surface 220 at the sloping sides 216 or 218 (depending on which of the latch dogs 78 is concerned). As the latch dogs 78 are able to 15 pivot about pin 82, this contact of the pins 101 with the peripheral surface 220 causes the latch dogs 78 to pivot inwardly toward the longitudinal axis of the tool 18 thereby retracting the latch dogs 78 and latching surfaces 94 from the seat 48 (refer Figures 5 and When this has occurred, the tool 18 is free to continue its downward journey. The retraction of the latch dogs is to an extent so as to release the latch dogs from the seat 48 only. At all times, the latching faces 94 maintain contact with the lands 56 of the locking sleeve 16.

C

The relative sliding motion of the main body portion 66 and sleeve 68 at the time of contact of the latch dogs 78 with the seat 48, also causes firing of the cradle 162. This happens because the relative sliding motion results in the end of the sleeve 156 being located over the balls 134. As the end 156 has a larger inner diameter than the immediately preceding portion 157 of the sleeve 68, the balls 134 can now be pushed out of holes 138 into gap 159 by the force of the spring 166 against the washer 168. This causes the cradle 162 to retract into the head 74 so that the flange 172 pushes on the bit fingers 26 causing the ends 148 to slide along the 16 ramps 146 so that they extend laterally beyond the outer periphery of the head 74 and can be collected by the locking sleeve 16. As the tool 18 continues its downward motion it forces the locking sleeve 16 downward expanding the bit fingers 26 outwardly against the bias of elastic bands 176 and into respective ones of the seats 24. The bit fingers 26 are prevented from falling from the end of the drive sub 12 by virtue of engagement of a barb or step 222 formed at ends 148 which engage the step surface 42.

The downward travel of the tool 18 stops when the head 74 of the tool 18 abuts the upper ends 148 of the bit fingers 26 after engagement with the stepped surface 42. However, due to the retractable coupling between the head 74 and first portion 72, the first portion 72 is able to continue moving 15 forward a short distance against the bias of spring 152 until the cup-like structure 136 abuts the upper surface 154 of upper portion 140. The effect of this is that the first portion 72 pushes the locking sleeve 18 further down the drive sub 12 by a distance equal to the length of retraction of head 74 into first portion 72. This positively locks the locking sleeve 16 in place.

The bit fingers 26 are now locked in place and in combination form a core drill bit.

The tool 18 can now be withdrawn from the drill pipe in a 25 conventional manner and the drill pipe rotated in order to :commence core drilling.

When it is desired or necessary to change the bit fingers 26, the tool 18 is again lowered through the drill and in particular the core barrel 14 and drive sub 12. Prior to lowering the tool 18, the cradle 162 is extended from the head 74 and the pin 122 removed from the retrieval latch dogs 100. The cradle 162 is locked in an extended position by inserting the removable pin 122 through the hole 224 formed 17 through the head 74 and the cradle 162. The transport sleeve 196 is again placed over an upper portion of the tool 18 to partially compress the installation latch dogs 78. Upon lowering the tool 18 through the drill tube 206, the transport sleeve 196 will again abut the landing ring 204.

In an identical manner to that described above when installing the bit segments 26, upon contact of the transport sleeve 196 with the landing ring 204, the tool 18 will pass through the landing ring while the transport sleeve 196 will be retained above the landing ring 204. Upon further downward travel of the tool 18, the latch faces 94 will engage the seat 48. Accordingly, the main body portion 66 will slide relative to the sleeve 68 so that surface 220 of the cutout 210 will contact the pins 101 on the installation latch dogs 78 causing them to pivot inwardly and thereby .release the latching dogs from the seat 48. Once the tool 18 has reached the bottom of its travel, it is pulled upwardly. As the retrieval latch dogs 100 are now free to pivot outwardly by virtue of the bias of spring 106, the 20 latching faces 112 will engage the slots 92 and 94 respectively of locking sleeve 16. Upon further upward motion of the tool 18 pulls the locking sleeve 16 upwards and away from the bit fingers 26 thereby releasing the bit fingers 26 so as to collapse back on to the extended cradle 25 162. The retrieval latch dogs 100 are then disengaged from the locking sleeve 16 (which is retained within the drive sub 12) and the tool 18 withdrawn from the drill pipe together with the bit segments 26.

Now that an embodiment of the invention has been described in detail it will be apparent to those skilled in the relevant arts that numerous modifications and variations may be made without departing from the basic inventive concepts. Most notably, the retraction system 208 is illustrated as comprising the surface 220 of a cutout 210 formed in the main body portion 66. As the surface 220 merely acts as a camming surface for the pins 101, this surface may be provided in 18 other ways such as for example providing a shaped flange protruding from the inside peripheral surface of the main body portion 66, or a cam surface recessed or machined into the inside peripheral surface of the main body portion.

Further, the retraction means operates by virtue of the relative sliding motion of the sleeve 68 and main body portion 66. Accordingly, if desired, the camming surface can be formed on the sleeve 68 rather than the main body portion 66. Also, the pins 101 and camming surface 220 can be switched so as to be provided on the main body portion 66 or sleeve 68; and, the installation latch dogs 78 respectively.

All such modifications and variations are deemed to be within the scope of the present invention the nature of which is to be determined from the foregoing description and the appended claims.

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19 THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:- 1. A running tool adapted for travel within a tubular member, said running tool comprising: an elongate main body portion; an elongate sleeve slidably mounted on said main body portion said sleeve provided with at least one opening in a peripheral wall thereof; at least one latching mechanism housed in said main body portion and coupled-to both said sleeve and said main body portion, said latching mechanism biased away from a longitudinal axis of said tool to protrude from said opening; and, a retraction system associated with said latching mechanism and one of said sleeve or said main body portion for at least partially retracting said latching mechanism towards said longitudinal axis against said bias when said main body portion slides a predetermined distance in one direction relative to said sleeve, whereby, in use, when said running tool travels down a tubular member and said latching mechanism strikes a seat formed in said tubular member, said main body portion can slide relative to said sleeve and, upon sliding said predetermined distance, said retraction system operates to retract said latching mechanism towards said longitudinal axis thereby disengaging said latching mechanism from said seat so that said tool can continue to travel through said tubular member.

2. A running tool according to claim 1, wherein said retraction system comprises a cam surface formed on the associated one of said main body portion and said sleeve, and a cam follower formed on said latching mechanism, said cam surface and cam follower relatively disposed so as that said main body portion slides relative to said sleeve, said cam surface engages said cam follower causing said latching mechanism to retract towards said longitudinal axis.

Claims (9)

1. 3. A running tool according to claim 2, wherein said cam follower comprises a pin attached to said latching mechanism.
2. 4. A running tool according to claim 3, wherein said pin threadingly engages said latching mechanism. A running tool according to claim 3, wherein said pin is formed integrally with said latching mechanism.
3. 6. A running tool according to any one of claims 2 to wherein said cam surface is formed on said main body portion and said latching mechanism is fixed against linear movement relative to said sleeve.
4. 7. A running tool according to any one of claims 3 to 6, wherein said cam surface comprises the surface of a cutout o o made in said main body portion into which said pin extends. *99*9 15 8. A running tool according to claim 7, wherein said latching mechanism is one of a pair of latching mechanisms 4 to. coupled to a common pivot pin and biased to pivot in opposite directions and said cutout is one of a pair of cutouts formed in said main body portion where individual pins extend into 20 individual cutouts, and said opening is one of a pair of openings through which respective ones of said latching mechanisms can protrude. 9*9999
5. 9. A running tool according to any one of claims 2 to 6, wherein said cam surface is formed on an inside peripheral surface of said main body portion. A running tool according to claim 9, wherein said cam surface protrudes from said inside peripheral surface of said main body portion. 21
6. 11. A running tool according to claim 9, wherein said cam surface is recesses or machined into said inside peripheral surface of said main body portion.
7. 12. A running tool according to any one of claims 2 to 5, wherein said cam surface is formed on said sleeve and said latching mechanism is fixed against linear movement relative to said main body portion.
8. 13. A running tool according to claim i, wherein said retraction system comprises a cam surface formed on said latching mechanism and a cam follower formed on the associated one of said main body portion and said sleeve, said cam surface and cam follower relatively disposed so as that said main body portion slides relative to said sleeve, said cam surface engages said cam follower causing said o 15 latching mechanism to retract towards said longitudinal axis. oooo DO
9. 14. A running tool substantially as herein described 5 Swith reference to and as illustrated in the accompanying S°"drawings. Dated this 21st day of November 1996 ooSe° S. o s. 20 DOWN HOLE TECHNOLOGIES PTY LTD By its Patent Attorneys GRIFFITH HACK 0 Fellows Institute of Patent Attorneys of Australia S.. oe *06 22 ABSTRACT Down hole running tool 18 comprises a main body portion 66 on which is slidably mounted an outer sleeve 68. Latch dogs 78 are housed within the cavity 76 of the main body 66. Latch dogs 78 comprise a pair of arms 80 which are pivotally coupled together at one end by a pin 82 and biased by a spring 84 at an opposite end to extend through slots formed in the main body 66 and sleeve 68. The arms 80 so extended can contact a seat 48 formed in the internal circumferential surface of a drive sub 12. To allow further passage of the tool retraction system 208 is provided to retract the arms inwardly. Retraction system 208 includes a pair of cutouts 210 made in the main body portion 66 and a pair of pins 101 attached to each arm 80. Each pin 101 acts as a cam follower and extends into a respective cutout 210 which acts as a cam .surface. When sleeve 68 slides relative to the body 66, cam Cfollowers 101 follow the cam surfaces 210 causing the arms to pivot inwardly thereby disengaging the arms from the seat 48 and allowing the tool 18 to continue travelling in the 20 downward direction. "t *4 4. *o .e 4~r