AU2014101221A4 - Tension assembly - Google Patents

Abstract

A tensioning assembly 10 for a cable bolt 11 comprises a clamping device (14, 16) adapted for fastening to the bolt and an outer member 18 adapted for interacting with 5 the clamping device. The outer member 18 is able to undergo relative movement to the clamping device in the direction of the bolt's axis, and under such movement, the clamping device is caused to fasten to the bolt. Furthermore, the outer member may be adapted for interacting with the bolt 11 whereby, during such relative movement, twisting of the bolt 11 with respect to the outer member 18 is restrained. 2,S c/(. 2 54n 32 19h t6c Section AA

Description

- 1 TENSION ASSEMBLY Technical Field 5 A tension assembly is disclosed for cable bolts that are suitable for use in mining and tunnelling to provide rock and wall support. The assembly is suitable for use in hard rock applications as well as in softer strata, such as that often found in coal mines. Thus, the term "rock" as used in the specification is to be given a broad meaning to cover all such applications. 10 Background Art Roof and wall support is vital in mining and tunnelling operations. Mine and tunnel walls and roofs consist of rock strata, which must be reinforced to reduce the 15 possibility of collapse. Rock bolts, such as rigid shaft rock bolts and flexible cable bolts, are widely used for consolidating the rock strata. In strata support systems, a bore is drilled into the rock by a drill rod, which is removed and a rock bolt is then installed in the drilled hole and secured in place, either mechanically or by using a resin or cement based grout. The rock bolt is tensioned 20 which allows consolidation of the adjacent strata by placing that strata in compression. To allow the rock bolt to be tensioned, an inserted end of the bolt may be anchored mechanically to the rock formation by engagement of an expansion assembly on the end of bolt with the rock formation. Alternatively, the bolt may be adhesively bonded to the rock formation with a resin bonding material inserted into the bore hole. 25 Alternatively, a combination of mechanical anchoring and resin bonding can be employed by using both an expansion assembly and resin bonding material. When resin bonding material is used, it penetrates the surrounding rock formation to adhesively unite the rock strata and to hold firmly the rock bolt within the bore hole. Resin is typically inserted into the bore hole in the form of a two component 30 plastic cartridge having one component containing a curable resin composition and another component containing a curing agent (catalyst). The two component resin cartridge is inserted into the blind end of the bore hole and the mine rock bolt is then -2 inserted into the bore hole such that the end of the mine rock bolt ruptures the two component resin cartridge. With rotation of the mine rock bolt about its longitudinal axis, the compartments within the resin cartridge are shredded and the components are mixed. The resin mixture fills the annular area between the bore hole wall and the shaft 5 of the mine rock bolt. The mixed resin cures and binds the mine rock bolt to the surrounding rock. Tension assemblies have been proposed to provide tension along cable bolts, for example, which in turn provides a compressive force on the substrate surrounding the anchored bolt, usually a mine shaft roof substrate. Such tension assemblies often 10 involve hydraulic means for installation and require the installer to lift the means above chest height to be placed on the cable end exposed from the bore hole. This can lead to safety issues, depending on the mine shaft roof height. In one such assembly, with the resin cured about the cable portion in the bore hole, a nut is placed onto a thread cut into a portion of the outer wires of the cable bolt 15 remaining outside the bore hole. The nut is then rotated on the cable bolt toward and to abut the substrate about the bore hole either directly or through a bearer plate disposed on the shaft between the substrate and the nut. Rotation of the nut is continued for a predetermined number of turns to provide tension along the cable. This method has been found to be unreliable in practice, with failures occurring between the nut and 20 cable. In another assembly, a threaded rod is coupled onto a distal end of the cable using an external coupling. The coupling is disposed within the bore and the threaded rod is arranged to project from the bore. A plate is then disposed on the rod and a nut threadably engaged with the rod to capture the plate. The nut is rotated on the rod such 25 that the plate is forced onto the substrate about the bore hole. This assembly requires a portion of the bore hole, adjacent the bore hole opening, to be widened to accommodate the external coupling. This is disadvantageous in that it requires two drilling events when forming the bore hole. Alternatively, if the bore hole is drilled to have one diameter large enough to accommodate the fitting, a larger space is created between the 30 bore hole wall and the cable bolt, requiring more resin to fix the cable bolt in the bore. This has been shown to reduce bond strength between the cable, resin and bore hole wall.

-3 In a further assembly, a clamping device is mounted onto a distal end of the cable bolt outside the bore. An outer barrel is then located over to engage with the clamping device, whereby the barrel can be moved axially with respect to the cable bolt along the clamping device. This movement can cause a plate that is disposed on the rod 5 to be forced by the outer barrel onto the substrate about the bore hole. Such known assemblies do not, however, prevent the cable bolt from twisting during tensioning. After a time, the cable bolt can twist back whereby bolt tension is progressively lost. A reference herein to prior art is not an admission that the prior art forms part 10 of the common general knowledge of a person of ordinary skill in the art in Australia or elsewhere. Summary of the Disclosure 15 According to a first aspect there is provided a tensioning assembly for a cable bolt, the assembly comprising: - a clamping device adapted for fastening to the bolt; - a carrier member; and - an outer member adapted for location on the carrier member whereby 20 an end of the carrier member projects beyond the outer member, with the end being adapted for engagement by a drive apparatus to cause a relative movement of the carrier member away from the outer member in the direction of the bolt's axis, which movement causes the clamping device to fasten to the bolt. When the clamping device is caused to fasten to the bolt it can allow the 25 assembly to apply tension thereto. Further, such an assembly can allow tension to be provided to the bolt via the carrier member. When, for example, the carrier member is rotatable relative to the clamping member, such an assembly can allow for bolt tensioning and clamping without requiring or imparting bolt twisting or rotation. . Thus, the cable bolt can better retain tension therewithin over time, thereby providing for more 30 secure rock strata support over time. Further, in contrast to prior tensioning assemblies, cable bolt tensioning can occur without inducing or requiring bolt rotation. The outer member can be further adapted for interacting with rock strata into -4 which the cable bolt is to be anchored in use. Whilst an end of the outer member could be adapted for directly abutting rock strata, the assembly can further comprise a plate-like member (e.g. a bearing/bearer plate) which is employed to face and urge against the rock strata in use. The plate-like member can be positioned with respect to 5 the cable bolt (e.g. slid along the bolt via an aperture therethrough) such that, during bolt tensioning, an end of the outer member, which is preferably domed, can be brought into abutment with the plate-like member to urge it against the rock strata in use. This abutment can retain and support the adjacent rock strata. In one form the carrier member includes a hollow shank for receipt of the cable 10 bolt therethrough that extends from the carrier member head, with the shank being externally threaded for engagement with a corresponding internal thread defined at an interior surface of the outer member. The relative movement of the outer member away from the clamping device may, in this case, arise from the carrier member being unscrewed from the outer member. 15 In one form the clamping device can comprise a barrel and wedge assembly that interact with each other to enable clamping of the assembly to the cable bolt. In this regard the barrel can be located for rotation relative to the carrier member, whereby the carrier member is thus still free to rotate, relative to the clamping device, after clamping of the assembly to the cable bolt. To provide for easier rotation of the carrier member 20 with respect to barrel and wedge assembly during the application of tension to the cable bolt, an anti-friction washer or a thrust bearing can be located between the carrier member and the clamping device. The wedges can be positioned in the barrel so that the barrel surrounds the wedges whereby, during the relative movement (e.g. by unscrewing of the carrier 25 member from the outer member), the barrel is urged against the wedges to force them against the cable bolt, thereby fastening the clamping device (and thus the assembly) to the bolt. In an embodiment of this form the barrel can comprise a tapered inner surface and each of the wedges can comprise a corresponding and oppositely tapered outer 30 surface. During the relative movement the barrel tapered inner surface can be urged against each wedge's oppositely tapered outer surface. Also, the carrier member head is shaped for engagement by a drive apparatus -5 (e.g. a dolly spanner connected to the drive of a drill rig) to cause the carrier member to move away (e.g. unscrew) from the outer member. For example, the head can be provided with a hexagonal profile. In addition, the outer member can be further adapted for interacting with the 5 cable bolt whereby, during such relative movement, twisting of the bolt with respect to the outer member is restrained. Brief Description of the Drawings 10 Notwithstanding any other forms which may fall within the scope of the tension assembly and method as set forth in the Summary, a number of specific embodiments of the tension assembly will now be described, by way of example only, with reference to the accompanying drawings in which: Figures 1A to IC respectively show plan, part-sectional side, and part-sectional 15 underside plan (taken on the line AA of Figure 1B) views of a cable bolt tensioning assembly in accordance with a first embodiment; Figure 2 shows a part-sectional side view of a cable bolt tensioning assembly in accordance with a second embodiment; Figure 3 shows a part-sectional side view of the cable bolt tensioning assembly 20 of Figure 2 in use with a cable bolt in a first non-tensioned configuration; Figure 4 shows a part-sectional side view of the cable bolt tensioning assembly of Figure 2 in use with a cable bolt in a second tensioned configuration; Figures 5A to C show a perspective view from below, a view from below and a side view of a bearing plate of a cable bolt tensioning assembly; 25 Figures 6A, B and C show a perspective view from below, a view from below and a sectional view of an outer housing of a cable bolt tensioning assembly in; Figures 7A and B illustrate operation of the outer housing of Figure 6 with the bearing plate of Figure 5; Figures 8A, B and C show a perspective view from below, a view from below 30 and a side view of a bearing plate for a cable bolt tensioning assembly in accordance with a further embodiment; -6 Figures 9A, B and C show a perspective view from below, a view from below, and a sectional view of an outer housing for a cable bolt tensioning assembly in accordance with a further embodiment; Figures 10A and B illustrate operation of the outer housing of Figure 9 with the 5 bearing plate of Figure 8; Figures 11 A and B show a view from above and a side view of an outer housing for a cable bolt tensioning assembly in accordance with yet a further embodiment of the invention; Figures 12A and B show a view from the side and a view from below of a 10 bearing plate for use with the outer housing of Figures 11 A and B; Figures 13A and B show a view from above and a side view of an outer housing for a cable bolt tensioning assembly in accordance with yet a further embodiment; and Figures 14A and B show a side view and a view from below of a bearing plate 15 for use with the outer housing of Figures 13A and B. Detailed Description of Specific Embodiments Referring to the Figures, a tensioning assembly 10 is shown for use with a 20 cable bolt 11 (Figures 3 and 4) for supporting walls and/or roofs of mining shafts and the like. The assembly 10 is configured for use with cable bolts which typically comprise several cabled steel wire strands 12 wound together to form a cable bolt that has a degree of flexibility, however the bolt may be made from other suitable materials, depending on its application. For example, the bolt may be manufactured from other 25 hard or hardened metals or polymeric materials. The bolt is typically 15-28mm in diameter, although the cable diameter used may vary with the material used to form the bolt or the type of substrate in which the bolt is to be located. The length of the bolt is typically in the range of about 4m to 10m, depending on the application and user requirements. 30 The tensioning assembly 10 comprises a clamping device in the form of an internally tapered hollow barrel 14 and a corresponding, opposing externally tapered -7 hollow wedges 16 configured to mount to the cable bolt 11. The respective angles of tapering are about 7' with respect to the cable bolt longitudinal axis. The assembly 10 may include two or more, in this case three, wedges 16a, 16b and 16c which are configured to be clamped about and against the cable bolt 11 as 5 illustrated in Figures 3 and 4. The wedges 16a, 16b and 16c are placed upon the cable bolt 11 and held together at the bolt by an O-ring (or steel spring ring) that is located in an exposed groove 17, prior to the barrel 14 being located around the wedges. The tensioning assembly 10 further comprises an outer member in the form of outer housing 18 and a carrier member in the form of inner housing 19. Outer housing 10 18 is provided with an internal thread 20 for complementary threaded engagement with an outer thread 21 located on a shank 22 of the inner housing 19 (the threads being most clearly depicted in Figure 4). As also illustrated by Figures 3 and 4, the inner housing 19 is arranged to be unscrewed from the outer housing 18 in the direction of a longitudinal axis of the cable bolt to thereby tension the cable bolt (as described 15 hereafter). The inner housing 19 further comprises a hexagonal drive head 23 at the end of the shank 22 that is configured to be driven by an appropriate drill rig (e.g. via a dolly spanner). The drive head may alternatively comprises slots, similar to a standard or Phillip's head screw, to receive a complementary drive mechanism. 20 A recess 24 is defined to extend into the inner housing 19 from head 23 and part way into the shank 22, thereby defining a shoulder 25 within the recess. In the tensioning assembly embodiment of Figure 1A it will be seen that the barrel 14 is received in recess 24 to oppose shoulder 25. In the tensioning assembly embodiment of Figure 1 an anti-friction washer 44 is disposed between the barrel 14 and the shoulder 25 25, whereas in Figure 2 it will be seen that a thrust bearing 26 is located between the barrel 14 and the shoulder 25. In either case, the recess and barrel are sized such that the inner housing 19 can rotate with respect to the barrel 14. The washer 44 or thrust bearing 26 aid such rotation as the cable bolt is progressively placed under increasing tension by the tensioning assembly. Also, as described hereafter, when the inner 30 housing 19 is unscrewed from the outer housing 18 in the direction of a longitudinal axis of the cable bolt the shoulder 25 acts on the barrel 14 which in turn acts on the three wedges 16a, 16b and 16c, causing them to clamp about and against the cable bolt.

-8 A rounded, tapering "bull-nosed" (alternatively frustoconical) end 28 of the outer housing 18 has a passage 30 therethrough for the cable bolt. A hollow insert 32 is positionable for fastening in a recess defined in the end 28 to surround the passage 30 (with fastening occurring e.g. via a weld 34). The insert 32 comprises a number of 5 elongate inwardly projecting protrusions in the form of ridges 36 that are adapted to extend interferingly into grooves defined between adjacent strands 12 of the cable bolt 11 (Figures 3 and 4). In this regard the ridges 36 can "bite" into the cable bolt external surface. This arrangement locks the cable bolt against twisting/rotation with respect to the outer housing 18. 10 The insert can be readily/easily fastened onto the cable bolt at a suitable location prior to locating the outer housing thereon (e.g. by sliding it along and then crimping it into place on the cable bolt). Alternatively, the insert and outer housing together can be fastened onto the cable bolt at a suitable location by being forcibly slid along the cable bolt and into place. In the form shown in Figures 1 and 2, the insert 32 15 is formed separately to the outer housing. In an alternative form, the outer housing may be machined to include the inwardly directed protrusions, extending into the passage thereby obviating the need for the separate insert 32. As illustrated in Figures 3 and 4, the tensioning assembly 10 can further comprise a bearing plate 40 for slidable location on the cable bolt 11. In use, the plate 20 40 can be retained between the rounded end 28 of the outer housing 18 and a substrate in the form of a mine shaft roof R. The plate 40 is configured to abut the surface S surrounding a bore B in the roof R within which a portion of the cable bolt 11 has been inserted and anchored. In this regard, the plate 40 is provided with a central boss 42 for receiving there-against the rounded end 28 of the outer housing 18 when the assembly is 25 used to tension the cable bolt. In use, the cable bolt extends through an aperture defined by the central boss, so that the plate is slid along the anchored cable and into position against the surface S. In a variation, the plate can be formed integrally with the outer housing, or the outer housing end 28 may even be shaped to simulate a plate-like bearer. As described hereafter, during tensioning of the cable bolt, the interaction of 30 the rounded end 28 with the central boss 42 may be such as to prevent the outer housing 18 from rotating about its longitudinal axis. This, together with the locking at insert 32 of the cable bolt against twisting/rotation with respect to the outer housing 18, -9 effectively restrains or prevents the cable bolt from twisting/rotation with respect to the bore B in the mine shaft roof R during cable bolt tensioning. The interaction of the rounded end 28 with the central boss 42 is such as to also promote an axial alignment of the plate 40 and outer housing 18, thereby avoiding lateral shear stresses between the 5 bolt 11 and the assembly 10. The configuration of the tensioning assembly 10 is such as to allow the assembly 10 to be located on the cable bolt 11, either prior to or after anchoring the cable bolt 11 in the bore B. If the assembly 10 is to be preassembled on the cable bolt, the components may 10 be positioned on the cable bolt and the barrel 14 and wedges 16a, 16b, and 16c are pretensioned so as to be caused to clamp onto the cable bolt. The outer and inner housing can then overlay the pretensioned barrel and wedge and may be held in place for transport by a plastic film or a settable polymeric or mastic wrap or through use of mechanical fasteners such as ties or grub screws or the like or by a combination of the 15 foregoing. Alternatively, the assembly 10 can be slid onto the end of the cable bolt after the bolt has been installed. Once in position the barrel 14 and wedges 16a-16c may then be caused to clamp the cable by inducing relative movement between the barrel and wedges. 20 Once the cable bolt 11 is point anchored in the bore B of mine shaft roof R and the tension assembly 10 is in place on the cable bolt 11, the assembly is ready for tensioning, as illustrated in Figure 3. A drilling rig is moved into proximity of the assembly 10, and a dolly spanner loaded into the chuck of that rig is coupled to the hexagonal drive head 23. The rig 25 drive is activated and a torque of typically 100-400 Nm is applied to the hexagonal drive head 23 to cause the inner housing 19 to start to rotate within and unscrew from the outer housing 18. The initial rotation (unscrewing) of the inner housing 19 causes it to move away from the outer housing 18 in the direction of the cable bolt axis (i.e. downwardly 30 in Figure 3), whereby the shoulder 25 drives the barrel 14 (optionally via the washer 44 or thrust bearing 26) against the wedges 16a-c. The wedges are thus caused to further clamp against the cable bolt 11 and fasten the assembly to the bolt.

- 10 Throughout rotation of inner housing 19, the inner housing rotates on and around the barrel 14. In the assembly embodiment of Figure 1, the shoulder 25 directly abuts the washer 44 and thus there is a continuing frictional resistance that must be overcome by the rig drive. In the assembly embodiment of Figure 2, the thrust bearing 5 26 is located between the shoulder 25 and the barrel 14, whereby such frictional resistance is substantially reduced. Such an arrangement can allow for bolt tensioning and clamping without requiring or imparting bolt twisting or rotation. With the wedges now clamped against the bolt, continued rotation (unscrewing) of the inner housing 19 now forces the outer housing 18 against the plate 10 40 (i.e. upwardly in Figure 4). Because the plate abuts the roof surface S it can only move up to a very limited extent (if at all) and so the downwardly moving inner housing 19 induces a tensile force in the cable bolt 11. Continued rotation (unscrewing) of the inner housing progressively increases this tensile force. This in turn provides a compressive force on the rock substrate S of the mine shaft roof R about the bore B. 15 In addition, with continued rotation of inner housing 19, the rounded end 28 of the outer housing 18 is driven into the boss 42 with a high degree of frictional engagement, thus preventing the outer housing 18 from rotating. Further, because the rounded end 28 is fastened to the cable bolt via the insert 32 to prevent the bolt from twisting with respect to the outer housing, the cable bolt is thus prevented from twisting 20 with respect to the rock substrate S at the bore B. Preventing twisting of the bolt means the tensile force that is induced in the cable bolt 11 will be retained therein over time (i.e. the bolt does not untwist over time to release the tension therein). Once a desired cable bolt tensile force is reached (usually determined by the rig drive motor, which will eventually stall), the drilling rig is then removed from the 25 hexagonal drive head 23, leaving the cable bolt 11 and tensioning assembly 10 in place on the mine shaft roof R. As will be understood, the same process can be performed in various locations on the mine shaft roof using a plurality of cable bolts 11 with respective tensioning assemblies 10 attached thereto. As clearly shown in Figures 3 and 4, the tensioning assembly 10 is located on 30 the cable bolt 11 outside the bore B and, after tensioning, remains located outside the bore B. This means that the bore B can be sized just to accommodate the cable bolt 11, and need not be enlarged over all or part of its length to accommodate any part of the - 11 assembly. Thus, the bore can be formed in one drill pass, and also strong cable bolt anchoring with less resin can be achieved. It should be noted that the thread between the inner and outer housings can be made left- or right-handed to suit a preferred direction of inner housing rotation 5 (e.g. depending on the drive, application, user requirements etc). In the above described embodiments, the outer housing 18 may be prevented from rotating by frictional contact with the boss 42 of the bearing plate 40 (which, in turn, is prevented from motion by being forced against the substrate surface S). Figures 5 through 14 illustrate further arrangements showing various different ways in 10 which the outer housing 18 and bearing plate 40 may interact to facilitate prevention of rotation of the outer housing 18. Figures 5 through 7 illustrate an embodiment where the outer housing 18a is provided with a key projection 100 which is arranged to interact with a corresponding slot 101 in the boss 42a of bearing plate 40a. 15 In operation the key projection 100 fits within the slot 101 and relative rotation between the bearing plate 40a and outer housing 18a is prevented. In the illustrated embodiment, the key projection 100 extends from the top of the "bull-nose" end 28 to the main body of the housing 18a. This allows for the key projection 100 to still engage with the slot 101 when the housing 18a is tilted at an angle 20 with respect to the central boss 42a of the bearing plate 48, allowing for the axis of the cable bolt to be tilted with respect to the bearing plate 40a, which may occur in use. Figures 7A and B illustrate how the outer housing 18a interacts with the bearing plate 40a in operation, with the key 100 fitting into the slot 101. Note, that in the drawings, only the dome end 28a of the outer housing 18a is 25 shown. In Figure 6C the presence of the rest of the outer housing is indicated by ghost lines 110. Figures 8 through 10 show an alternative embodiment, in which a slot 120 is provided in the domed end 28b of the outer housing 18b and a complimentary key projection 121 is mounted in the boss 42b of the bearing plate 40b. Operation of the 30 embodiment of Figures 8 through 10 is similar to the operation of the embodiment of Figures 5 through 7, except the key 121 is provided in the bearing plate 40b and the slot 120 is provided in the outer housing 18b.

- 12 Figures 11 and 12 illustrate yet a further way in which the outer housing may engage with the bearing plate. In this embodiment, the domed end 28c of the outer housing 18c is provided with a plurality of key surfaces 150. The key surfaces 150 have edges 151 that define boundaries between each key surface 150. Complimentary 5 receiving key surfaces 152 with edges 153 are provided in the receiving boss 42c of the bearing plate 40c. In operation the key surfaces 150 of the outer housing 18c engage with complimentary key surfaces 152 of the boss 42c, preventing relative rotation between the outer housing 18c and the bearing plate 40c. 10 Figures 13 and 14 show yet a further embodiment which utilises key surfaces 160 and edges 161 on the outer housing 18d. These key surfaces 160 are similar in operation to the key surfaces of Figure 11, but there are less of them. Complimentary key surfaces are provided on the boss 42c of the bearing plate 40c. They comprise complimentary surfaces 163 and edges 164. 15 As well as the above embodiments, there may be other arrangements which facilitate engagement of the domed end 28 of the outer housing with the bearing plate so that the outer housing does not rotate, and the cable is not twisted. For example, the embodiments of Figures 5 through 10 show only one key in slot arrangement. There may be two key in slot arrangements on opposite sides of the domed surface/bearing 20 plate boss, or more than two. Arrangements causing interference between the domed end 28 and bearing plate 40 could even be used in cable bolt tensioning assemblies that vary from the embodiments described with reference to Figures 1 to 4. In fact, any cable bolt tensioning assembly which requires interaction between a domed end of a tensioning 25 component and a bearing plate may utilise any of these arrangements. While the tensioning assembly and method for cable bolt tensioning has been described with reference to specific embodiments, it is to be understood that variations may be made to the without departing from the scope as defined herein. In addition, it should be understood that the tensioning assembly and method 30 are not limited to mining applications. Also, whilst the tensioning assembly and method have been described with reference to a roof, it will be understood that they can equally be applied to a sidewall or base/floor.

- 13 In the claims which follow and in the preceding description, except where the context requires otherwise due to express language or necessary implication, the word "comprise" and variations such as "comprises" or "comprising" are used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence 5 or addition of further features in various embodiments of the tensioning assembly and method.

Claims (5)

1. A tensioning assembly for a cable bolt, the assembly comprising: 5 - a clamping device adapted for fastening to the bolt; - a carrier member; and - an outer member adapted for location on the carrier member whereby an end of the carrier member projects beyond the outer member, with the end being adapted for engagement by a drive apparatus to cause a relative movement of the carrier 10 member away from the outer member in the direction of the bolt's axis, which movement causes the clamping device to fasten to the bolt.

2. An assembly as claimed in Claim 1, wherein the clamping device comprises a barrel and wedge assembly, the barrel surrounding the wedges whereby, during the 15 relative movement, the barrel is urged against the wedges to force them against the cable bolt, thereby fastening the clamping device to the bolt.

3. An assembly as claimed in Claim 1 or 2, further comprising a thrust bearing or anti-friction washer that is located between the clamping device and the carrier member. 20

4. An assembly as claimed in any preceding Claim, wherein the carrier member includes a hollow shank that extends from the carrier member end for receipt of the cable bolt therethrough, with the shank being externally threaded for engagement with a corresponding internal thread defined at an interior surface of the outer member and 25 wherein the relative movement arises from the carrier member being unscrewed from the outer member.

5. An assembly as claimed in any preceding Claim, wherein the outer member has a domed end that is arranged to be brought into abutment with a plate-like member for 30 facing and urging against rock strata into which the cable bolt is to be anchored in use.