AU2016100037A4 - Dolly - Google Patents

Abstract

- 28 The disclosure relates generally to drive assemblies for rock bolts and more specifically, but not exclusively, to a dolly for imparting thrust and rotation to a rock bolt and a tensioning device for tensioning a rock bolt. (NJ

Description

- 1 DOLLY TECHNICAL FIELD The present disclosure relates generally to drive assemblies for rock bolts and more specifically, but not exclusively, to a dolly for imparting rotation to and for tensioning of a 5 rock bolt. 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 prevent the possibility of collapse. Rock bolts, such as rigid shaft rock bolts and cable bolts are widely used for 0 consolidating the rock strata. In conventional strata support systems, a bore is drilled into the rock by a drill rod, which is then removed and a rock bolt is then installed in the drilled hole and secured in place typically using a resin or cement based grout. The rock bolt is tensioned which allows consolidation of the adjacent strata by placing that strata in compression. 5 To allow the rock bolt to be tensioned, the 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. Alternatively, a combination of mechanical anchoring and resin bonding can be employed by using both an expansion 20 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 plastic cartridge having one component containing a curable resin composition and another component containing a 25 curing agent (catalyst). The two component resin cartridge is inserted into the blind end of the bore hole and the rock bolt is inserted into the bore hole such that the end of the rock bolt ruptures the two component resin cartridge. Upon rotation of the 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 -2 and the shaft of the rock bolt. The mixed resin cures and binds the rock bolt to the surrounding rock. Tension and drive assemblies have been proposed to provide tension along rock bolts, for example, which in turn provides a compressive force on the substrate, usually a mine shaft 5 roof substrate, about the bolt. One such assembly is disclosed in the Applicant's co-pending patent application AU 2010291865. In this application, a dolly is operative to alternate between a 'cable drive mode', whereby rotation of the dolly rotates a shaft of the rock bolt within a bore hole to break a mix the resin cartridge for point anchoring, and 'tensioning mode', whereby rotation of the dolly rotates a tensioning device to tension the bolt. In this 0 tension and drive assembly, the drive assembly remains in contact with the bolt during insertion and tensioning of the rock bolt. The above references to the background art do not constitute an admission that the art forms part of the common general knowledge of a person of ordinary skill in the art. The above references are also not intended to limit the application of the dolly as disclosed herein. 5 SUMMARY In a first aspect, disclosed herein a dolly for imparting drive to a rock bolt having a shaft and a tensioning device mounted to the bolt shaft. The dolly may comprise a body having a first engagement portion adapted to connect to the tensioning device, and a drive mounted to the -0 body and operative to rotate the body upon rotation of the drive about a longitudinal axis of the body, the drive having a drive shaft and a second engagement portion adapted to connect to the bolt shaft, the body being able to translate axially relative to the drive between a tensioning position wherein the body projects from the drive such that the first engagement portion is positioned to connect to the tensioning device to allow rotation of the tensioning 25 device in response to rotation of the drive, and a shaft drive position wherein the body is retracted on the drive such that the second engagement portion is positioned to connect to the bolt shaft to allow rotation of the bolt shaft in response to rotation of the drive. In a second aspect, disclosed herein is a drive assembly for a rock bolt having a shaft. The 30 drive assembly may comprise a tensioning device and a dolly. The tensioning device may comprise a coupler that is adapted to be coupled to the dolly, and a base member adapted to -3 be fixed to the shaft of the rock bolt. The dolly may comprise a body having a first engagement portion adapted to connect to the coupler of the tensioning device, a drive mounted to the body, the drive having a second engagement portion adapted to connect to the shaft, the drive being operative to rotate the body upon rotation of the drive about a 5 longitudinal axis of the body, and the drive being able to translate axially relative to the body between a tensioning position wherein the first engagement portion is positioned to connect to the coupler of the tensioning device to allow rotation of the tensioning device in response to rotation of the drive, and a shaft drive position wherein the second engagement portion is positioned to connect to the shaft to allow rotation of the shaft in response to rotation of the 0 drive, and biasing means operative to bias the drive into the tensioning position. In a third aspect, disclosed herein is a method of installing a rock bolt in a bore formed in rock strata, the rock bolt comprising a bolt having a shaft and a tensioning device mounted to the bolt shaft. The method may comprise providing a dolly having a drive and a body 5 disposed over the drive, connecting the drive to the bolt shaft, rotating the drive to rotate the rock bolt within the bore, introducing fluid to a fluid passage extending through the drive to flush the rock bolt, disconnecting the drive from the bolt shaft; connecting the body to the tensioning device, and rotating the drive to rotate the tensioning device through the body to tension the rock bolt. 0 BRIEF DESCRIPTION OF THE DRAWINGS Embodiments will now be described by way of example only, with reference to the accompanying drawings in which Fig. 1 shows a side view of a tensioning device; 25 Fig. 2 shows a cross sectional view of the tensioning device of Fig. 1; Fig. 3 shows an exploded view of the bearer member and the base member of the tensioning device of Fig. 1; Fig. 4 shows a side view of a dolly for use with the tensioning device of Fig. 1; Fig. 5 shows a perspective view of the shaft in the dolly of Fig. 4; 30 Fig. 6 shows alternate bolt retention devices that can be used with the shaft of Fig. 5; -4 Figs. 7a-b show cross sectional views through the dolly of Fig. 4 in the tensioning position; Fig. 8 shows an exploded view of the dolly of Fig. 4; Figs. 9a-b show cross sectional views through the dolly shown in Fig. 4 in the 5 tensioning position (a) and the shaft drive position (b); Figs. 10a-b show cross sectional views through the dolly shown in Fig. 4 in the shaft drive position (a) and in the locked position (b); Fig. 11 shows a side view of the dolly of Fig. 4 disconnected from the tensioning device of Fig 1; 0 Figs. 12a-b show side views of the dolly of Fig. 4 connected to a rock bolt that is connected to the tensioning device of Fig. 1; Fig. 13 shows a cross sectional view of the dolly of Fig. 4 connected to the rock bolt that is connected to the tensioning device of Fig. 1, whereby the rock bolt is inserted into the rock strata; 5 Fig. 14 shows a side view of the dolly of Fig. 4 connected to the rock bolt that is connected to the tensioning device of Fig. 1, whereby the rock bolt is inserted into the rock strata; Fig. 15 shows a cross sectional view of the dolly of Fig. 4 in the locked position being rotated to rotate the rock bolt in a bore hole within the rock strata; 20 Fig. 16 shows a cross sectional view of the dolly of Fig. 4 in the shaft drive position before the dolly is biased towards the tensioning position; Fig. 17 shows a cross sectional view of the dolly of Fig. 4 in the tensioning position whilst connected to the tensioning device of Fig. 1; Fig. 18 shows a cross-sectional view of the dolly of Fig. 4 and tensioning device of 25 Fig. 1 following tensioning of the rock bolt.; and Fig. 19 shows a cross-sectional view of another embodiment of the dolly that includes a water flush passage in the bolt retention device.

-5 DETAILED DESCRIPTION In the following detailed description, reference is made to accompanying drawings which form a part of the detailed description. The illustrative embodiments described in the detailed 5 description, depicted in the drawings and defined in the claims, are not intended to be limiting. Other embodiments may be utilised and other changes may be made without departing from the spirit or scope of the subject matter presented. It will be readily understood that the aspects of the present disclosure, as generally described herein and illustrated in the drawings can be arranged, substituted, combined, separated and designed in 0 a wide variety of different configurations, all of which are contemplated in this disclosure. Disclosed herein a dolly for imparting drive to a rock bolt having a shaft and a tensioning device mounted to the bolt shaft. The dolly may comprise a body having a first engagement portion adapted to connect to the tensioning device, a drive mounted to the body and operative to rotate the body upon rotation of the drive about a longitudinal axis of the body, 5 the drive having a drive shaft and a second engagement portion adapted to connect to the bolt shaft, the body being able to translate axially relative to the drive between a tensioning position wherein the body projects from the drive such that the first engagement portion is positioned to connect to the tensioning device to allow rotation of the tensioning device in response to rotation of the drive, and a shaft drive position wherein the body is retracted on 0 the drive such that the second engagement portion is positioned to connect to the bolt shaft to allow rotation of the bolt shaft in response to rotation of the drive. In some forms, the dolly may comprise a biasing means operative to bias the body into the tensioning position. 25 In some forms, the drive and second engagement portion each include corresponding fluid passages formed therein that allow for fluid to be introduced to an internal passage of the rock bolt. 30 In some forms, in the shaft drive position, the first engagement portion is spaced from the tensioning device.

-6 In some forms, the second engagement portion comprises a recess able to receive an end of the shaft therein and inhibit relative rotation therebetween such that in the shaft drive position rotation of the drive causes rotation of the shaft. 5 In some forms, the body comprises an internal cavity, the drive being adapted to translate within the internal cavity. In some forms, the dolly further comprises a locking arrangement adapted to lock the drive in the shaft drive position. Advantageously, this allows for the shaft to be inhibited from moving 0 in response to the biasing means. In some forms, the body comprises opposing driven and engagement ends, the first engagement portion of the body being disposed at the engagement end of the body. This allows for the dolly to be coupled to a separate tensioning device, which is in turn coupled to 5 a separate rock bolt. In some forms, the second engagement portion comprises a recess able to receive an end of the shaft therein and inhibit relative rotation therebetween. This provides for a simple connection and disconnection means between the second engagement portion and the shaft of 0 the rock bolt. In some forms, in the shaft drive position the second engagement portion is disposed adjacent the engagement end of the body such that the second engagement portion is able to receive the end of the rock bolt therein. This enables the second engagement portion to couple with 25 the end of the rock bolt such that rotation of the second engagement portion can cause a corresponding rotation of the rock bolt. In some forms, in the tensioning position the second engagement portion is disposed adjacent the driven end of the body such that the second engagement portion is able to be spaced from 30 the end of the rock bolt. Advantageously, this provides enables the second engagement portion and the rock bolt to be decoupled. The spacing formed between the second engagement portion and the end of the rock bolt provides a tensioning gap, thereby simplifying installation of the rock bolt.

-7 In some forms, the internal cavity of the body comprises an internal wall disposed radially about the longitudinal axis. In some forms, the drive further comprises at least one projection extending laterally 5 therefrom. This allows for the drive to be guided between the shaft drive and tensioning positions in use. In some forms, the proj ection is one of a pair of radially spaced proj ections that each proj ect laterally from an outer surface of the drive. This provides for a secure guide arrangement for 0 the drive when it is translated between the shaft drive and tensioning positions in use. In some forms, the internal wall comprises a pair of longitudinally extending grooves formed therein, the pair of longitudinally extending grooves being adapted to receive the pair of projections to thereby guide the drive upon axial translation of the drive relative to the body. 5 In some forms, the locking arrangement comprises a pair of laterally extending grooves formed in the internal wall of the body, the laterally extending grooves being substantially perpendicular to the longitudinally extending grooves and adapted to receive the projections upon rotation of the drive relative to the body in the shaft drive position. This allows for a 0 simple locking mechanism, whereby the shaft or body can be rotated in use to lock the shaft in the shaft drive position. In an alternate embodiment, the body and shaft can include co operating portions of a detent, or any other locking mechanism, that allows for the shaft to be locked in the shaft drive position 25 In some forms, the projections of the drive are disposed in the laterally extending grooves in a locked position, the wherein the drive is inhibited from axial translation relative to the body in the locked position. Advantageously, this arrangement inhibits or prevents axial translation of the shaft by the biasing means in the shaft drive position. As such, the operator does not need to apply a constant axial force to the shaft when driving the rock bolt in the shaft drive 30 position. In some forms, the laterally extending grooves are substantially perpendicular to the longitudinally extending grooves (i.e. an angle that allows for the shaft and body to be locked in the shaft drive position without the requirement of a constant rotational force to be applied to maintain the shaft drive position).

-8 In some forms, the drive includes a head and a drive shaft and wherein the head is captured within the internal cavity of the body. In some forms, the head of the drive is enlarged as compared to the drive shaft. 5 In some forms, the drive further comprises an end fitting that is releaseably secured to the drive shaft, the end fitting incorporating the second engagement portion. Advantageously, this provides the dolly with flexibility to be used with many different types of rock bolt. In some forms, the end fitting and drive shaft each include corresponding fluid passages 0 formed therein that allow for water to be introduced to an internal passage of the rock bolt. In some forms, the biasing means is in the form of a compression spring. In other embodiments, the biasing means can include any material that provides elastic deformation such that the drive can be biased toward the tensioning position in use. Advantageously, the 5 biasing means also ensures that the tensioning device and the dolly remain in engaged during tensioning of the rock bolt (i.e. the biasing means biases the dolly towards the tensioning device during tensioning of the rock bolt). In some forms, the compression spring is disposed about the drive and is adapted to compress 0 between the head of the drive and the body upon axial translation of the drive from the tensioning position towards the shaft drive position. In some forms, when the drive is located in the tensioning position, the second engagement portion of the drive is arranged to be spaced from the rock bolt, the space defining a 25 tensioning gap that allows for the rock bolt to move towards the drive during tensioning of the rock bolt. Advantageously, the spacing between the rock bolt and the second engagement portion provides for a simplified use of the dolly (i.e. the dolly does not need to be moved away from a tensioning device during tensioning of the rock bolt). 30 Also disclosed herein is a drive assembly for a rock bolt having a shaft. The drive assembly may comprise a tensioning device and a dolly. The tensioning device may comprise a coupler that is adapted to be coupled to the dolly, and a base member adapted to be fixed to the shaft of the rock bolt. The dolly may comprise a body having a first engagement portion adapted to connect to the coupler of the tensioning device, a drive mounted to the body, the drive having -9 a second engagement portion adapted to connect to the shaft, the drive being operative to rotate the body upon rotation of the drive about a longitudinal axis of the body, and the drive being able to translate axially relative to the body between a tensioning position wherein the first engagement portion is positioned to connect to the coupler of the tensioning device to 5 allow rotation of the tensioning device in response to rotation of the drive, and a shaft drive position wherein the second engagement portion is positioned to connect to the shaft to allow rotation of the shaft in response to rotation of the drive, and biasing means operative to bias the drive into the tensioning position. 0 In some forms, the tensioning device further comprises a torque transfer arrangement that is arranged to allow a threshold torque to be applied to the shaft through the coupler without inducing relative rotation between the coupler and the shaft. Advantageously, the provision of the torque transfer arrangement means that in the shaft drive position, the drive does not need to directly engage the end of the rock bolt (i.e. rotational drive is transferred to the rock bolt 5 via the tensioning device, which is in turn inhibited from rotating relative to the shaft of the rock bolt). Also disclosed herein is a method of installing a rock bolt in a bore formed in rock strata, the rock bolt comprising a bolt having a shaft and a tensioning device mounted to the bolt shaft. 0 The method may comprise providing a dolly having a drive and a body disposed over the drive, connecting the drive to the bolt shaft, rotating the drive to rotate the rock bolt within the bore, introducing fluid to a fluid passage extending through the drive to flush the rock bolt, disconnecting the drive from the bolt shaft; connecting the body to the tensioning device, and rotating the drive to rotate the tensioning device through the body to tension the 25 rock bolt. In some forms, the method further comprises rotating the dolly in the first or second direction to release a torque transfer arrangement. In alternate embodiments, this step is not required (i.e. the tensioning device does not include a torque transfer arrangement and the drive is able 30 to directly engage the rock bolt). In some forms, the first direction of rotation is opposite to the second direction of rotation. This advantageously provides for simple operation during installation of a rock bolt.

- 10 In some forms, the method further comprises introducing water to a fluid passage extending through the drive to flush the rock bolt. This allows for the rock bolt to be flushed of debris and resin prior to filling the rock bolt with grout. 5 Rock Bolts Rock bolts are often used to reinforce walls and roofs of tunnels in mining operations to prevent the possibility of collapse. Rock bolts include both rigid shaft rock bolts and flexible cable bolts. Cable bolts provide advantages when used in confined spaces, as they can be fed into a bore hole within the rock substrate at an angle. This allows an extended length of cable 0 to be inserted into the rock substrate without the requirement of extensive excavation. Numerous cable bolts are available to reinforce walls and roofs of tunnels. One such cable bolt is manufactured from high strength flexible steel wire strands that are wound to form a single flexible strand. Another cable bolt is also manufactured from high strength flexible steel wire strands that are wound to form a single flexible strand but also includes a corrosion 5 protected flexible central steel hollow tube for grout injection. In the following description reference is made to a rock bolt 101 that includes a shaft 103 formed of multiple steel strands 102 that are wound around each other to form a solid structure, or alternatively, would around a hollow tube 104 to form a hollow structure. The tube 106 of the cable bolt includes a fitting 104 disposed at a proximal end 105 of the rock bolt 101 which is arranged to receive a bolt 0 retention device of on a dolly, as will be described in more detail below. Tensioning Device Tensioning devices are used to tension rock bolts to provide a compressive force on the substrate. Figs. 1 and 2 show a side view and sectional view respectively of a tensioning device 100 which in the illustrated form is connected to the rock bolt 101 adjacent its 25 proximal end 105. The tensioning device in the illustrated form comprises four primary components; a coupler, in the form of a rotatable outer sheath 112, a base member 114 that is adapted to be fixed to the shaft 103 of the rock bolt 101, a bearer member 118 which is movable relative to the base member 114 and which is arranged to abut either directly or indirectly the rock strata, and, optionally, a torque transfer arrangement 116 that is arranged 30 to allow a threshold torque to be applied to the shaft 103 of the rock bolt 101 through the outer sheath 112 without inducing relative rotation between the outer sheath 112 and the shaft 103.

- 11 The base member 114 as illustrated comprises a first part that forms a barrel 120, a second part that forms a stem 124, and tension wedges 122 which are located within the barrel 120 which in use secure the base member 114 with respect to the rock bolt 101. The tension wedges 122 receive the bolt shaft 103 in use and fix the bolt 101 to the base member 114. 5 The tension wedges 122 are forced into engagement with the rock bolt under loading of the barrel. Further the barrel 120 and wedges 122 have sufficient strength to prevent shear stress failure to ensure that the rock bolt 101 is held in place by the tension wedges 122 within the barrel 120 under this loading. The stem 124 of the base member 114 extends from the barrel 120 and along the rock bolt 0 101. The stem 124 is cylindrical and merges with the barrel to form an annular shoulder 126. An interior passage is provided through the barrel 120 and stem 124 to allow the rock bolt shaft 103 to be inserted through the stem. An external surface of the stem 124 includes a key section (such as a flat) so as to prevent relative rotation between the stem 124 and the bearer member 118 whilst allowing relative axial movement. This is described in more detail below. 5 In the illustrated embodiment, the torque transfer arrangement is in the form of a shear pin 116 that extends between the sheath 112 and the base member 114. It is understood that the torque transfer arrangement may also be in the form of a stop, or an adhesive (e.g., adhesive sold under the trade name LOCTITE), or any other suitable form of arrangement which prevents relative rotation between the outer sheath 112 and the shaft up to a threshold 0 loading. The torque transfer arrangement is able to break out when torque is applied to the outer sheath that exceeds that threshold torque such that the outer sheath is able to rotate relative to the shaft of the rock bolt. The bearer member 118 is mounted on, and moveable with respect to, the stem 124. The bearer member 118 comprises an externally threaded body 128 and a dome head 130 at one 25 end of the body. Fig. 3 shows an exploded view of the bearer member 118 and the base member 114. The body 128 has an internal cavity 140, the walls 142 of which are complementary to the exterior walls 144 of the stem 124 and include internal keyed sections 146. The internal keyed sections 146are located within the cavity such that when the bearer member 118 locates over the base member 114 (such that stem 124 extends into the cavity in 30 bearer member 118), the external keyed sections on the stem 124 engage with the internal keyed sections 146 on the bearer member 118 thereby inhibiting the rotation of the bearer member 118 with respect to the base member 114 about the longitudinal axis of the rock bolt - 12 101. However, the bearer member 118 is movable along the stem 124 in the direction of the axis of the rock bolt. The bearer member 118 is arranged so that the dome head 130 engages directly or indirectly with the rock surface into which the rock bolt extends. The head 130 which incorporates an 5 opening to allow passage of the rock bolt shaft 103 through the bearer member, may be shaped other than a dome (for example being flattened to form a plate like appearance) so that it is engageable directly with the rock surface. However, in the illustrated forms, the dome head 130 is arranged to engage a separate rock bolt bearer plate (e.g. abutment plate 401 shown in Figs. 10 to 16) which in use is positioned between the rock surface and the o bearer member 118. The dome head 130 is hemispherical and engages with an inner edge of the plate. This direct contact is arranged to provide sufficient frictional resistance so that in tensioning of the device 100 the engagement between the plate and the head 130 inhibits rotation of the head relative to the plate. Further the use of a generally hemispherical head 130 allows the head to 5 remain engaged (and thereby provide the rotational resistance) with the plate when the bearer member 118 is tilted at an angle with respect to the bearing plate, allowing for the axis of the rock bolt to be tilted with respect to the bearing plate, which may occur in use. The inhibiting of the rotation of the bearer member assists in preventing twisting of the rock bolt during tensioning. 0 The outer sheath 112 is arranged to receive the body 128 of the bearer member 118 and extend at least partially over the base member 114. The outer sheath 112 is internally threaded 137 so as to engage with the externally threaded body 128 of the bearer member 118 and includes a shoulder 132 which is adapted to engage with the shoulder 126 formed on the base member 114 at the junction between the barrel part 153 and the stem 124. In this way, 25 the sheath 112 engages both the base member 114 (through abutment of the shoulders 132 and 126) and the bearer member 118 (through engagement of the cooperating threads on those members). Rotation of the outer sheath 112 in one direction allows for both rotation of the bolt (when the shear pin is intact) by the sheath and base member rotating together, and tensioning of the 30 rock bolt (after the shear pin has failed) by causing relative rotation between the outer sheath and the base member. The outer sheath 112 is adapted to engage with a dolly that imparts this rotation so as to transmit that rotational force. This may be by making an external - 13 surface of the outer sheath 112 non-circular (such as a hexagonal or other polygonal profile) so that it can engage a dolly that incorporates a complementary shape and which locates over the outer sheath 112. In the following illustrated embodiments, the engagement is via teeth 11 formed on along an edge of the outer sheath 112 of the tensioning device 100. 5 Dolly Figs. 4 illustrates a drive dolly 200 which is suitable for use with the tensioning device 100 described above. It is to be appreciated that the drive dolly may be advantageously used with the tensioning device 100, but is not limited to that use and may be adapted (with for example 0 different drive ends) to be used in other applications where rotational drive is required to be imparted to a device. The dolly may also be used with rigid and flexible bolts. The dolly 200 comprises two primary components; a body, in the form of a casing 205, and a drive, in the form of shaft 203 that is mounted to the casing 205 and is operative to translate along a longitudinal axis A of the casing 205. The casing 205 has a first engagement portion, 5 in the form of teeth 207 at its engagement end 209 that connect to the tensioning device 100 (which in the illustrated embodiment is via the complementary teeth 115 formed on the outer sheath 112 of the tensioning device 100) to impart rotation to the sheath 112. Fig. 5 shows a perspective view of the shaft 203. The shaft 203 includes an enlarged head 211 which is designed to be captured within the casing 205. The shaft 203 includes a first (or -0 connecting) end 213 and a second (driven) end 215. The driven end 215 is adapted to fit into the chuck of a drilling rig to allow drive to be imparted to the shaft 203 from a drilling rig. The shaft head 211 is disposed at the connecting end 213 of the shaft. The shaft head 211 has an increased diameter relative to the body 212 of the shaft. In use, in addition to being able to impart rotation to the casing 205, the shaft 203 is designed 25 to be captured within the casing 205 and movable in an axial direction of the dolly 200 between first and shaft drive positions. The shaft head 211 includes projections, in the form of lugs 214, on its outer surface 216 that are configured to guide the shaft head 211 within the casing 205. The shaft head 211 includes an internally threaded recess 218 that is configured to allow the 30 head 211 to connect to a rock bolt. Figs. 6a-c show perspective views of different connectors, - 14 in the form of bolt retention devices 300a-c that can be coupled to the shaft head 211 to form part of (i.e. an extension of) the shaft head 211. In the illustrated embodiments, each of the bolt retention devices 300a-c includes a second engagement portion, in the form of an internal rock bolt receiving recess 30 1a-c that is configured to receive the rock bolt. For 5 example, bolt retention device 300a is configured to capture a hollow core bolt, bolt retention device 300b is configured to capture a core cable bolt, and bolt retention device 300c is configured to capture a solid hexagonally shaped rigid bolt. The internal recess 30 1a-c of each bolt retention device compliments the outer profile of a rock bolt such that rotation of the bolt retention device 300a-c imparted by rotation of the drive shaft 203 is able to 0 rotationally drive the rock bolt when connected. In other words, the internal recess 30 1a-c of each bolt retention device is arranged to allow insertion of the end 105 of a complimentarily rock bolt, and once received, to inhibit relative rotation of the end 105 of the rock bolt relative to the shaft 203. The bolt retention device includes a threaded projection 303 that is able to be coupled with the internally threaded recess 218 of the shaft head 211. 5 Advantageously, this provides the dolly with flexibility to be used with many different types of rock bolt. However, it is to be appreciated that the dolly 200 may be provided with a permanently fitted end fitting if desired (i.e. the bolt retention device 300, and therefore the second engagement portion, can be integral with the shaft head 211). Figs. 7a and 7b show cross sectional views through the dolly shown in Fig. 4. The cross 0 sectional view through the dolly shown in Fig. 7a is perpendicular to the cross sectional view shown in Fig. 7b. Longitudinally extending grooves 217 are formed in an inner wall 219 of the casing 205 to both limit and guide movement of the shaft head 211 in the casing 205. The longitudinally extending grooves are parallel to the longitudinal axis A of the dolly. In use, the lugs 214 of the head 211 are received and guided by the grooves 217. In the illustrated 25 embodiment, the dolly comprises two longitudinally extending grooves 217 radially spaced on either side of the casing 205 and two guide lugs 214 radially spaced on either side of the shaft head 211. Opposing first 221 and second 223 walls are formed in the internal wall 219 of the casing 205. The first 221 and second 223 walls are disposed at opposing ends of each longitudinally 30 extending groove 217 to limit the axial movement of the enlarged head 211 within the casing 205. The walls 221 and 223 also prevent removal of the enlarged head 211 from the casing 205.

- 15 Laterally extending grooves 225 are also formed in the internal wall 219 of the casing 205 to allow the lugs 214, and therefore the shaft head 211, to rotate relative to the casing 205 when the lugs 214 are aligned with the grooves 225. The laterally extending grooves are substantially perpendicular to the longitudinal axis A of the dolly. The laterally extending 5 grooves 225 also includes end walls 232, 234 formed in the inner wall 219 to limit rotation of the lug 214 relative to the casing 205. In the illustrated embodiment, the laterally extending grooves 225 are shorter than the longitudinally extending grooves 217 and is disposed between the engagement end 209 and the driven end 231 of the casing 205. In the illustrated embodiment, the dolly comprises two laterally extending grooves 225 radially spaced on 0 either side of the casing 205. The laterally extending grooves 225 each include an aperture, in the form of visual inspection hole 228, that is disposed adjacent the end wall 232 of the grooves 225 and extends between the inner 219 and outer 230 surfaces of the casing 205. This allows for the location of the shaft head 211, and in particular the lugs 214, to be inspected by an operator. 5 A biasing arrangement, which in the illustrated form comprises a compression spring 227, is disposed within the casing 205 and locates around the shaft 203 proximate the connecting end 213. The spring 227 bears against the enlarged head 211 and a retaining collar 229 that is fitted within the casing 205 (typically by a circlip, although any other suitable fastening arrangement may be used). In an alternate embodiment, the retaining collar is integral with 0 the casing 205. The compression spring 227 biases the casing 205 such that it slides over the shaft 203 and away from the driven end 215 of the of the drive shaft 203. For illustrative purposes, Fig. 8 shows an exploded view of all of the main components of the dolly 200 described with reference to Figs. 4 to 7. Operation of the Dolly 25 The operation of the dolly 200 will be described in detail with reference to Figs. 9 and 10. Figs. 9a and 9b show a cross sectional views through the dolly of Fig. 4. The shaft 203 is operative to translate along the longitudinal axis A of the casing 205 between a tensioning position (shown in Fig. 9a) and a shaft drive position (shown in Fig. 9b). In the tensioning position, the shaft 203 is operative to rotate the casing about the longitudinal axis A upon 30 rotation of the shaft 203. The lugs 214 engage the side walls 233 of the longitudinally - 16 extending recesses 217 such that clockwise or anticlockwise rotation of the shaft 203 imparts rotary drive to the casing 205. In the shaft drive position, the shaft connector 300 is positioned adjacent the engagement end of the dolly such that it is able to connect to the rock bolt. In the illustrated embodiment, the 5 lugs 214 align with the lateral grooves 225 of the body in the shaft drive position. As shown in Figs. 10a-b, the shaft 203 is able to be locked in the shaft drive position. Rotating the drive (clockwise in the illustrated embodiment as represented by arrow E) relative to the casing 205 about the longitudinal axis A forces the shaft 203 into a locked position whereby the shaft 203 is inhibited from being able to axially translate relative to the 0 casing 205. Figs 10a and l0b show the clockwise rotation of the shaft 203 relative to the casing 205 to form a locked position. In the locked position, the lugs 214 engages the end wall 232 of the laterally extending grooves 225 such that further clockwise rotation of the shaft 203 will impart a corresponding rotation onto the casing 205, while rotation of the shaft 203 in the opposite direction (in the illustrated embodiment this is anti-clockwise rotation of 5 the shaft 203, or clockwise rotation of the casing 205) will rotate the shaft 203 relative to the casing 205 towards the unlocked position, whereby the shaft is again able to axially translate relative to the casing 205. In use, to form the locked position, the casing 205 of the dolly is pulled back against the internal compression spring 227 such that the casing 203 slides over the drive shaft 203. The 0 two lugs 214 on the side of the enlarged head 211 are guided by the "L" shaped groove (longitudinal and lateral grooves 217 and 225) cut inside the casing 205. When the lugs 214 reach the top corner of the "L" groove (i.e. the intersection between the longitudinal and lateral grooves 217 and 225), the casing 205 is rotated to lock the lugs into the lateral groove 225. 25 The compression spring 227 biases the casing 205 towards the tensioning position, whereby the shaft head 211 is disposed proximal the driven end 231 of the casing 205. In the shaft drive position, the shaft head 211 is forced against the compressing spring 227 and the bolt retention device 300 of the shaft 203 is positioned proximal the engagement end 209 of the casing 205. Rotation of the shaft 203 whilst in the shaft drive position forces the lug 214 into 30 the lateral recess 225 (i.e. into the lock position) such that the spring 227 can remain compressed without the requirement of the application of constant axial thrust on the shaft 203.

- 17 Operation of the Dolly and Tensioning Device Operation of the dolly 200 and tensioning device 100 will be described in detail with reference to Figs. 11 to 18. In a first step, the dolly 200 is forced into the locked position whereby the bolt retention 5 device 300 of the shaft 203 is positioned proximal the engagement end 209 of the casing 205 (i.e. the position shown in Figs. 7b and 8b). As shown in Fig. 11, the tensioning device 100 is brought into contact with the end 105 of the cable bolt 100 (which has previously been placed in rock strata 400 together with a resin cartridge). The dolly 200 is attached to end 105 of the rock bolt 101. 0 As shown in Figs. 12 to 14, the teeth 207 on the dolly are spaced from the teeth 115 on the tensioning device when the dolly is attached to the end 105 of rock bolt 101. The standoff distance B ensures that only the rock bolt 101 is rotated during installation (i.e. no direct force is applied to sheath 112 of the tensioning device). This negates any issues associated with premature failure of the shear pin 116 that secures the sheath 112 to the base member 5 114 of the tensioning device. When in this position, a mining drilling rig (not shown) is attached to the driven end 215 of the dolly 200. The mining drilling rig is able to impart thrust to insert the cable bolt fully in the rock strata 400 and rotation to install the bolt. Under the trust of the drilling rig, the bolt is moved from a position as shown in Fig. 10a to the position as shown in Figs. 11 and 12 -0 where the tension device is located against an abutment plate 401 mounted on the rock bolt shaft 101 and disposed against the rock strata 400. In this position, the resin cartridge that was previously inserted in the bore 403 of the strata 400 is forced against the blind end of the bore 403 by the rock bolt 101 and caused to burst. When inserted into the rock strata 400 as shown in Fig. 12, the shaft 203 is rotated (under operation of the drill rig) to spin the rock 25 bolt 101 in the bore hole to mix the resin. After adequate mixing time, the rotation of the bolt then stops. No rotation or thrust is applied to the rock bolt 101 for a period of time that is sufficient to allow the resin to set, thereby anchoring the rock bolt 100 within the bore hole. As shown in Fig. 15, the drill motor is rotated in the opposite direction (as represented by arrow C) to force the two lugs 214 back along the laterally extending grooves 225 towards 30 the shaft drive position. As shown in Fig. 16, in the shaft drive position, the compression stored in the internal compression spring 227 biases the casing 205 such that it translates - 18 towards the tensioning position, whereby the bolt retention device 300 disengages the end 105 of the rock bolt 101. The outer casing 205 translates towards the tensioning device 100 such that the complementary teeth 115 and 207 of the dolly and tensioning device engage with one another. This position (whereby the dolly 200 is in the tensioning position) is shown 5 in Fig. 15. This retracting movement of the shaft creates the space "S" between the bolt retention device 300 and the rock bolt end 105 such that the bolt can be tensioned by further rotation of the drive shaft 203 once the resin has set. Figs. 17 and 18 show the tensioning of the rock bolt 101. When the dolly 200 is in the tensioning position, the driven end 215 of the shaft 203 is rotated by the drill rig (not shown). 0 This rotation of the shaft 203 imparts rotation to the casing 205 of the dolly by forcing the lugs 214 against the walls of the longitudinally extending grooves 217 in the casing 205. The applied torque exceeds the threshold torque of the shear pin to cause break-out the shear pin 116. Breaking the shear pin allows the outer sheath 112 to then rotate relative to the base member 114, bearer 113 and rock bolt 101 such that engagement between the shoulders 126 5 and 132 (see Fig. 2) forces the base member 114, and with it the end 105 of the rock bolt 101 captured within the base member 114, to move down the bearer 118 and away from the rock strata. The space "S" between the shaft 103 and the end of the rock bolt 105 allows the rock bolt to move towards the shaft during tensioning of the rock bolt. With the space, the shaft (and 0 therefore the drilling rig) does not need to move axially (relative to the shaft axis) during tensioning to allow for the extension of the rock bolt. In the described embodiment, the space "S" (or stand-off distance) is typically 45mm in the tensioning position. This distance has been found to be adequate for the thread extension 405 of the rock bolt 101 that occurs during tensioning of the rock bolt. However, depending on the application, this distance can be 25 varied. Fig. 16 shows the tensioning device 100 in the tensioned configuration with the head of the bearing member spaced from the end of the outer sheath. After tensioning of the rock bolt 101, the dolly 200 is released from the tensioning device 100. In an alternate embodiment, the teeth 207 of the dolly 200 connect with the teeth 115 of the tensioning device (i.e. there is no stand-off distance B) in the shaft drive position. In this 30 alternate embodiment, the tensioning device 100 includes a torque transfer arrangement. The torque transfer arrangement is in the form of a shear pin 116 that extends between the sheath 112 and the base member 114. In this embodiment, the bolt retention device 300 does not - 19 need to contact the rock bolt in the shaft drive position. Instead, the connection between the teeth 207 and 115 and the torque transfer arrangement ensure that rotation of the dolly 200 imparts rotary drive to the rock bock. When the rock bolt is anchored within the bore of the rock strata, further rotation of the dolly causes the threshold torque to be exceeded such that 5 the shear pin is caused to break out. This then allows for outer sheath 112 of the tensioning device to rotate relative to the rock bolt to tension the rock bolt. Another alternate embodiment of the dolly is shown in Fig. 19. In this embodiment, the dolly 500 and the rock bolt 700 each include aligned fluid passages that allow for water to be introduced into the rock bolt 700 via the dolly 500. The shaft 701 of the rock bolt 700 0 includes a passage 703 formed therein that allows for the rock bolt 700 to be flushed with water before the rock bolt is tensioned. The shaft 503 of the drive and the bolt retention device 300a (see also Fig. 6) include fluid passages (505 and 305 respectively) that, when aligned, allow for the flow of water from the driven end 515 of the drive shaft 503 into the shaft 701 of the rock bolt 700. Water, or any suitable flushing fluid, can be introduced into 5 the rock bolt 700 when the dolly is in the shaft drive position (i.e. the bolt retention device 300a engages the end 705 of the rock bolt 700). As was the case with the previously described embodiments, the bolt retention device 300a is able to drive the rock bolt 700 upon rotation of the drive shaft 503. The internal recess of the bolt retention device 300a compliments the outer profile of a coupling 707 disposed at the end 705 of the rock bolt 700 0 such that rotation of the bolt retention device 300a imparted by rotation of the drive shaft 503 is able to rotationally drive the rock bolt when connected. Flushing the rock bolt 700 with fluid clears a hollow rock bolt of resin or debris that may have infiltrated the rock bolt when it is inserted and rotated in the rock strata. Such debris can impede subsequent grouting of the rock bolt. Advantageously, the drive shaft 503 of the dolly 500 can be locked in the shaft 25 drive position (also the flushing position) such that there is no requirement for the application of constant axial thrust on the shaft 503 when flushing the rock bolt 700. In the claims and in the preceding summary except where the context requires otherwise due to express language or necessary implication, the word "comprising" is used in the sense of "including", that is, the features as above may be associated with further features in various 30 embodiments. Variations and modifications may be made to the parts previously described without departing from the spirit or ambit of the disclosure.

- 20 Alternative Statements of Invention Alternative statements of invention are recited in the following numbered clauses. 1. A dolly for imparting drive to a rock bolt having a shaft and a tensioning device mounted to the bolt shaft, the dolly comprising; 5 a body having a first engagement portion adapted to connect to the tensioning device; and a drive mounted to the body and operative to rotate the body upon rotation of the drive about a longitudinal axis of the body, the drive having a drive shaft and a second engagement portion adapted to connect to the bolt shaft, the body being able to translate 0 axially relative to the drive between a tensioning position wherein the body projects from the drive such that the first engagement portion is positioned to connect to the tensioning device to allow rotation of the tensioning device in response to rotation of the drive, and a shaft drive position wherein the body is retracted on the drive such that the second engagement portion is positioned to connect to the bolt shaft to allow rotation of the bolt shaft in response to 5 rotation of the drive. 2. A dolly according to clause 1, further comprising a biasing means operative to bias the body into the tensioning position. 0 3. A dolly according to clause 1 or 2, further comprising a locking arrangement adapted to lock the drive in the shaft drive position. 4. A dolly according to any one of the preceding clauses, wherein the drive shaft includes a fluid passage arranged to allow for fluid to be introduced to an internal passage of the 25 rock bolt when the second engagement portion is connected to the shaft. 5. A dolly according to any preceding clause, wherein the body comprises an internal cavity in which the drive extends, and wherein the drive includes a head that extends from the drive shaft and wherein the head is captured within the internal cavity of the body but 30 allows for translation of the body over the head to enable movement of the body between the shaft drive position and the tensioning position.

- 21 6. A dolly according to any preceding clause, wherein the body comprises an internal cavity, the drive being adapted to translate within the internal cavity. 5 7. A dolly according to any preceding clause, further comprising a locking arrangement adapted to lock the drive in the shaft drive position. 8. A dolly according to any one of the preceding clauses, wherein the body comprises opposing driven and engagement ends, the first engagement portion of the body being 0 disposed at the engagement end of the body. 9. A dolly according to any one of the preceding clauses, wherein the second engagement portion comprises a recess able to receive an end of the shaft therein and inhibit relative rotation therebetween. 5 10. A dolly according to clause 9, wherein in the shaft drive position the second engagement portion is disposed adjacent the engagement end of the body such that the second engagement portion is able to receive the end of the rock bolt therein. 0 11. A dolly according to clause 9 or 10, wherein in the tensioning position the second engagement portion is disposed adjacent the driven end of the body such that the second engagement portion is able to be spaced from the end of the rock bolt. 12. A dolly according to any one of the preceding clauses, when dependent on clause 3, 25 wherein the internal cavity of the body comprises an internal wall disposed radially about the longitudinal axis. 13. A dolly according to any one of the preceding clauses, wherein the drive further comprises at least one projection extending laterally therefrom. 30 14. A dolly according to clause 13, wherein the projection is one of a pair of radially spaced projections that each project laterally from an outer surface of the drive.

- 22 15. A dolly according to clause 14, wherein the internal wall comprises a pair of longitudinally extending grooves formed therein, the pair of longitudinally extending grooves being adapted to receive the pair of projections to thereby guide the drive upon axial 5 translation of the drive relative to the body. 16. A dolly according to clause 14 or 15, when dependent on clause 7, wherein the locking arrangement comprises a pair of laterally extending grooves formed in the internal wall of the body, the laterally extending grooves being substantially perpendicular to the 0 longitudinally extending grooves and adapted to receive the projections upon rotation of the drive relative to the body in the shaft drive position. 17. A dolly according to clause 16, wherein the projections of the drive are disposed in the laterally extending grooves in a locked position, the wherein the drive is inhibited from 5 axial translation relative to the body in the locked position. 18. A dolly according to any one of clauses 7 to 17, when dependent on clause 6, wherein the drive includes a head and a drive shaft and wherein the head is captured within the internal cavity of the body. 0 19. A dolly according to clause 18, wherein the head of the drive is enlarged as compared to the drive shaft. 20. A dolly according to clause 18 or 19, wherein the drive further comprises an end 25 fitting that is releaseably secured to the drive shaft, the end fitting incorporating the second engagement portion. 21. A dolly according to any preceding clause, wherein the biasing means is in the form of a compression spring. 30 22. A dolly according to clause 21, when dependent on clause 18, wherein the compression spring is disposed about the drive and is adapted to compress between the head of the drive and the body upon axial translation of the drive from the tensioning position towards the shaft drive position.

- 23 23. A dolly according to any one clauses 7 to 22, when dependent on clause 6, wherein when the drive is located in the tensioning position, the second engagement portion of the drive is arranged to be spaced from the rock bolt, the space defining a tensioning gap that 5 allows for the rock bolt to move towards the drive during tensioning of the rock bolt. 24. A drive assembly for a rock bolt having a shaft, the drive assembly comprising: a tensioning device and a dolly; the tensioning device comprising a coupler that is adapted to be coupled to the dolly, 0 and a base member adapted to be fixed to the shaft of the rock bolt; the dolly comprising; a body having a first engagement portion adapted to connect to the coupler of the tensioning device; a drive mounted to the body, the drive having a second engagement portion 5 adapted to connect to the shaft, the drive being operative to rotate the body upon rotation of the drive about a longitudinal axis of the body, and the drive being able to translate axially relative to the body between a tensioning position wherein the first engagement portion is positioned to connect to the coupler of the tensioning device to allow rotation of the tensioning device in response to rotation of the drive, and a shaft 0 drive position wherein the second engagement portion is positioned to connect to the shaft to allow rotation of the shaft in response to rotation of the drive; and biasing means operative to bias the drive into the tensioning position. 25. A drive assembly in accordance with clause 24, wherein the tensioning device further 25 comprises a torque transfer arrangement that is arranged to allow a threshold torque to be applied to the shaft through the coupler without inducing relative rotation between the coupler and the shaft 26. A drive assembly in accordance with clause 24 or 25 wherein the dolly is as defined 30 in any one of clause I to 23.

- 24 27. A method of installing a rock bolt in a bore formed in rock strata, the rock bolt comprising a bolt having a shaft and a tensioning device mounted to the bolt shaft, the method comprising: providing a dolly having a drive and a body disposed over the drive; 5 connecting the drive to the bolt shaft, rotating the drive to rotate the rock bolt within the bore; introducing fluid to a fluid passage extending through the drive to flush the rock bolt; disconnecting the drive from the bolt shaft; connecting the body to the tensioning device; and 0 rotating the drive to rotate the tensioning device through the body to tension the rock bolt. 28. A method of installing a rock bolt according to clause 27, wherein the drive and body together form a dolly. 5 29. A method of installing a rock bolt according to clause 27 or 28, further comprising rotating the dolly in the first or second direction to release a torque transfer arrangement. 30. A method of installing a rock bolt according to any one of clauses 27 to 29, wherein 0 the first direction of rotation is opposite to the second direction of rotation. 31. A method of installing a rock bolt according to any one of clauses 27 to 30, further comprising introducing water to a fluid passage extending through the drive to flush the rock bolt. 25 32. A method in accordance with any one of clauses 27 to 31 wherein the dolly is as defined in any one of clauses I to 23. 33. A dolly for imparting drive to a rock bolt having a shaft and a tensioning device 30 mounted to the shaft, the dolly comprising; a body having a first engagement portion adapted to connect to the tensioning device; a drive mounted to the body, the drive having a second engagement portion adapted to connect to the shaft, the drive being operative to rotate the body upon rotation of the drive - 25 about a longitudinal axis of the body, and the drive being able to translate axially relative to the body between a tensioning position wherein the first engagement portion is positioned to connect to the tensioning device to allow rotation of the tensioning device in response to rotation of the drive, and a shaft drive position wherein the second engagement portion is 5 positioned to connect to the shaft to allow rotation of the shaft in response to rotation of the drive; and biasing means operative to bias the drive into the tensioning position. 34. A method of installing a rock bolt into a bore formed in rock strata comprising: 0 translating a drive along a longitudinal axis of a body from a tensioning position to a shaft drive position, the translation being against the bias of a biasing means mounted within the body; rotating the drive in a first direction to lock the drive to the body such that the drive is inhibited from axially translating relative to the body; 5 rotating the drive in the first direction to rotate the rock bolt within the bore; rotating the drive in a second direction to unlock the drive from the outer body such that the drive is biased towards the tensioning position; and rotating the drive in the first or second direction to tension the rock bolt. 0

Claims (5)

1. A dolly for imparting drive to a rock bolt having a bolt shaft and a tensioning device mounted to the bolt shaft, the dolly comprising; a body having a first engagement portion adapted to connect to the tensioning 5 device; and a drive mounted to the body and operative to rotate the body upon rotation of the drive about a longitudinal axis of the body, the drive having a drive shaft and a second engagement portion adapted to connect to the bolt shaft, the body being able to translate axially relative to the drive between a tensioning position wherein the body projects 10 from the drive such that the first engagement portion is positioned to connect to the tensioning device to allow rotation of the tensioning device in response to rotation of the drive, and a shaft drive position wherein the body is retracted on the drive such that the second engagement portion is positioned to connect to the bolt shaft to allow rotation of the bolt shaft in response to rotation of the drive. 15

2. A dolly according to claim 1, further comprising a biasing means operative to bias the body into the tensioning position.

3. A dolly according to claim 1 or 2, further comprising a locking arrangement adapted 20 to lock the drive in the shaft drive position.

4. A dolly according to any one of claims I to 3, wherein the drive shaft includes a fluid passage arranged to allow for fluid to be introduced to an internal passage of the rock bolt when the second engagement portion is connected to the shaft. 25

5. A method of installing a rock bolt in a bore formed in rock strata, the rock bolt comprising a bolt having a shaft and a tensioning device mounted to the bolt shaft, the method comprising: providing a dolly having a drive and a body disposed over the drive; 30 connecting the drive to the bolt shaft; rotating the drive to rotate the rock bolt within the bore; - 27 introducing fluid to a fluid passage extending through the drive to flush the rock bolt; disconnecting the drive from the bolt shaft; connecting the body to the tensioning device; and 5 rotating the drive to rotate the tensioning device through the body to tension the rock bolt.