AU2010212736B2

AU2010212736B2 - Method for using retainer, and retainer

Info

Publication number: AU2010212736B2
Application number: AU2010212736A
Authority: AU
Inventors: Sami Keranen; Juha Piipponen
Original assignee: Sandvik Mining and Construction Oy
Current assignee: Sandvik Mining and Construction Oy
Priority date: 2009-02-12
Filing date: 2010-02-11
Publication date: 2013-01-10
Anticipated expiration: 2030-02-11
Also published as: EP2396497B1; WO2010092237A1; FI20095134L; FI121894B; CA2734361C; EP2396497A4; FI20095134A0; JP2012504721A; CA2734361A1; CN102216555B; AU2010212736A1; EP2396497A1; CN102216555A; JP5487210B2

Abstract

The invention relates to a method for using a retainer, and to a retainer. The retainer(14) comprises a first clamping arm (18a) and a second clamping arm (18b) provided with clamping jaws (21a, 21b) for clamping a drill rod (9), a rock bolt or the like. The clamping arms are turned in relation to their pivot points (19a, 19b) by an actuator (20), whereby the clamping jaws move either towards or away from each other. On the portion between the pivot points of the clamping arms there are shape members that interconnect the movements of the clamping arms to make them interdependent and thus synchronize the movements of the clamping arms in both directions of movement of the clamping arms.

Description

- 1 METHOD FOR USING RETAINER, AND RETAINER BACKGROUND OF THE INVENTION The invention relates to a method for moving clamping arms of a retainer belonging to an excavation apparatus in 5 such a manner that clamping jaws provided in the clamping arms move simultaneously towards each other, clamping between them a drill rod, rock bolt or a similar excavation tool, which is located in the drilling centre of the rock drilling unit or another excavation apparatus. 10 Mechanical synchronization is provided between the clamping arms to render their movements interdependent. The invention further relates to a retainer adaptable to a feed beam of a rock drilling unit, bolting device or a similar excavation apparatus. The retainer comprises at 15 least two clamping jaws that are moved by means of one or more actuators. Between the clamping arms there is a synchronization mechanism to render their movements interdependent. The field of the invention is described in greater 20 detail in the preambles of the independent claims. Rock drilling is performed using a rock drilling unit provided with a rock drilling machine and a tool connected thereto to produce a drill hole into the material to be worked on. The tool may comprise a drill rod and a drill 25 bit connected to the distal end thereof or, if long drill holes are to be drilled, a plurality of successive drill rods connected one after the other into an extension rod arrangement. When drilling is started, the drill rod needs to be centred by guiding it with the clamping jaws of the 30 retainer in the drilling centre. Moreover, the retainer 2686388_1 (GHMatters) P86408.AU 3/06/11 - 2 may be used for locking the drill rod or other drilling tools to prevent them from rotating for example when drill rods are attached to each other, to the drilling machine or the drill bit. 5 Publication US 4 438 984 discloses a retainer in which the clamping arms of the retainer are interconnected by a rod transmitting the forces from one arm to another. The disclosed structure occupies a lot of space on the feed beam. 10 SUMMARY OF THE INVENTION In accordance with the present invention there is provided a method for using a retainer belonging to an excavation apparatus, the retainer comprising: a body, a first clamping arm and a second clamping arm, which are 15 pivoted to the body, clamping jaws at the distal ends of the clamping arms, and at least one actuator; and the method comprising the steps of turning with the actuator the clamping arms with respect to their pivot points, whereby the clamping jaws 20 move towards each other and, correspondingly, away from each other depending on the direction of movement of the actuator; clamping a tool in the centre of the excavation apparatus with the clamping jaws to centre and gripping it 25 while positioned in the centre; connecting the clamping arms with each other by separate mechanical synchronization means, the movements of the clamping arms being thus interdependent and the clamping jaws moving simultaneously and symmetrically, 30 and arranging shape members on the portion between the pivot points of the clamping arms and synchronizing the 2686388_1 (GHMatters) P86408.AU 3/06/11 - 3 movement between the first clamping arm and the second clamping arm with the shape members in both travel directions of the clamping arms; arranging at least one portion of both the first 5 clamping arm and the second clamping arm in an interleaved manner and arranging shape surfaces provided in the form of openings in the interleaved portions to coincide; and transmitting movement between the clamping arms by means of a connecting pin parallel with the centre, the 10 pin being in contact with the shape surfaces of the clamping arms. In accordance with the present invention there is further provided a retainer comprising a body allowing the retainer to be attached to a feed 15 beam of an excavation apparatus; a first clamping arm connected by a first pivot joint to the body and a second clamping arm connected by a second pivot joint to the body; clamping jaws arranged on the portions of the distal 20 ends of the clamping arms and facing each other; at least one actuator for moving the clamping arms in relation to the pivot joints, the clamping jaws being movable towards and away from each other; mechanical synchronization means separate from the 25 actuator for connecting the movement of the first clamping arm and that of the second clamping arm to be interdependent; and wherein the synchronization means of the retainer are arranged on the portion between the first and the 30 second pivot joint; and the synchronization means comprise shape members formed to the first and the second clamping arm and 2686388_1 (GHMatters) P86408.AU 3/06/11 arranged to transmit synchronization movements between the clamping arms in both travel directions of the clamping arms; wherein 5 the first clamping arm and the second clamping arm are interleaved at least on the portion of the shape surfaces; the shape surfaces defining a connecting channel; and a connecting pin arranged in the connecting channel, whereby the connecting pin transmits movement 10 between the shape surfaces of the clamping arms. An idea of the retainer described herein is that the retainer comprises synchronization means with which the movements of the clamping arms are made mutually dependent. The synchronization means are separate from one 15 or more actuators acting on the clamping arms and transmit the movements of the clamping arms in both travel directions thereof. The synchronization means are implemented by shape members arranged to the clamping arms and located on the portion between the pivot joints of the 20 clamping arms. An advantage of the invention is that since the synchronization means are arranged on the portion between the pivot joints, they do not add to the outer dimensions of the retainer in any way. A further advantage is that by 25 utilizing shape surfaces formed to the clamping arms, synchronization may be implemented using a simple mechanical structure and a small number of components. Due to this synchronization does not increase significantly the weight of the retainer. Moreover, the retainer 30 operates reliably. 2686388_1 (GHMatters) P86408.AU 3/06/11 -5 According to an embodiment the shape members on the portion between the pivot points are in constant contact with each other, and thereby at all times ready to synchronize the movements of the clamping arms in both 5 travel directions. According to an embodiment the synchronizing means comprise shape surfaces formed directly to the structure of the first and the second clamping arms, the surfaces being arranged against each other and transmitting 10 synchronization movements between the clamping arms through their contact surfaces that set against each other. According to an embodiment the first clamping arm and the second clamping arm are provided with mutually 15 compatible teeth arranged against each other, movement between the clamping arms being transmitted by direct tooth contact. The teeth may be made directly to the structure of the clamping arms. According to an embodiment the shape surfaces formed 20 to the first and the second clamping arms are in constant contact with each other at least on some portion thereof. According to an embodiment the synchronization means comprise shape surfaces formed to the first and the second clamping arm on a portion between the pivot joints. The 25 shape surfaces are interconnected by a connecting piece separate from the clamping arms and arranged against the shape surfaces. However, the connecting piece is not attached to the clamping arms and the shape surfaces provided in them. During synchronization, movement may 30 take place between the form surfaces and the connecting piece. 2686388_1 (GHMatters) P86408.AU 3/06/11 -6 According to an embodiment the first clamping arm comprises at least two first connecting cams arranged at an axial distance from one another, when the retainer is observed in the direction of the centre. Correspondingly, 5 the second clamping arm comprises at least two second connecting cams on a portion between pivot joints, the cams being arranged at an axial distance from one another. The first connecting cams and the second connecting cams are interleaved on the portion between the pivot joints. 10 Further, the first and the second connecting cams are provided with connecting slots that open towards each other and are arranged to coincide when observed in the direction of the centre, the connecting slots being arranged to form a connecting channel when observed in the 15 direction of the centre. This connecting channel is provided with a connecting pin that serves as a transmission member between the interleaved connecting cams. The connecting pin moves in a vertical direction when the clamping arms are moved. The vertical movement of 20 the connecting pin is allowed through a longitudinal hole or the like provided in the body of the retainer. The connecting pin is a separate piece not attached to the clamping arms. According to an embodiment the first clamping arm is 25 provided with an immobile connecting pin, whose outer surface serves as a first shape surface. The second clamping arm comprises a longitudinal connecting opening that serves as a second shape surface. The connecting pin is arranged through the connecting opening, their shape 30 surfaces transmitting synchronization movements between the clamping arms. 2686388_1 (GHMatters) P86408.AU 3/06/11 According to an embodiment the retainer comprises only a single actuator arranged between the clamping arms and connected to act simultaneously on both clamping arms. According to an embodiment the retainer comprises only 5 a single actuator arranged to act on the first clamping arm only. In that case movement to the second clamping arm is transmitted by the synchronization means. According to an embodiment the retainer comprises at least two actuators, at least a first actuator being 10 connected to act on the first clamping arm only and at least one second actuator being arranged to act on the second clamping arm only. According to an embodiment the actuator is a hydraulic cylinder connected to a clamping arm by a pivot. 15 According to an embodiment the actuator is arranged to direct the forces needed for moving the clamping arms directly to the clamping arms. This is advantageous for the durability of the construction. According to an embodiment the actuator is connected 20 to the clamping arm by a pivot. The pivoting makes the construction durable and, moreover, it may be used to reduce friction. According to an embodiment the actuator is a pressure medium cylinder arranged transversally in relation to the 25 longitudinal axis of the clamping arms. The linear travel direction of the actuator is thus arranged to substantially correspond to the travel directions of the clamping jaws. 2686388_1 (GHMatters) P86408.AU 3/06/11 -8 According to an embodiment the actuator is placed outside the portion between the pivot points of the clamping arms. Hence a fixing point, where the actuator is connected to the clamping arm, may be located at a greater 5 distance from a pivot point of the clamping arm, thus allowing a greater torque arm to be achieved and thereby the clamping force produced by the actuator to be increased. According to an embodiment the clamping jaws comprise 10 a slot of a substantially V-shaped cross-section on their surfaces facing each other, thus allowing the clamping jaws to centre a drill rod or the like pressed between them. Due to the shape of the jaws also drill rods and the like with differing diameters may be centred. 15 According to an embodiment the clamping jaws are arranged to move at the same travel speed, for the same distance and symmetrically in relation to each other. BRIEF DISCLOSURE OF THE FIGURES Some embodiments of the invention will be described in 20 greater detail with reference to the accompanying drawings, in which Figure 1 is a schematic side view of a rock drilling rig provided with booms and drilling units arranged thereto and a second excavation apparatus; 25 Figure 2 is a schematic perspective view of a drilling unit; Figure 3 is a schematic view of a retainer of the invention, seen from the direction of the front end of the feed beam; 2686388_1 (GHMatters) P86408.AU 3/06/11 - 9 Figure 4 is a schematic perspective view of the retainer of Figure 3 without a body plate; Figure 5 is a schematic cross-sectional view along line E - E of the retainer of Figure 2; 5 Figure 6 is a schematic cross-sectional view along line D - D of the retainer of Figure 2; Figure 7 is a schematic cross-sectional view along line F - F of the retainer of Figure 2; Figure 8 is a schematic view of a retainer of the 10 invention seen from the direction of the front end of the feed beam, each clamping arm of the retainer being acted on by a separate actuator; Figure 9 is a schematic view of a retainer of the invention seen from the direction of the front end of the 15 feed beam, only one clamping arm of the retainer being acted on by an actuator; Figure 10 is a schematic view of a second alternative solution for synchronizing the turning movement between the clamping arms by toothed peripheries; 20 Figure 11 is a schematic view of a third alternative solution for synchronizing the turning movement between the clamping arms by transverse longitudinal openings provided in the clamping arms and a connecting pin arranged through the openings; 25 Figure 12 is a further schematic view of a fourth alternative solution for synchronizing the turning movement between the clamping arms by a fixed connecting pin and a longitudinal opening. 2686388_1 (GHMatters) P86408.AU 3/06/11 - 10 For the sake of clarity, some embodiments shown in the figures have been simplified. Like parts are referred to with like reference numbering throughout the figures. DETAILED DESCRIPTION OF SOME EMBODIMENTS OF THE INVENTION 5 Figure 1 shows an excavation apparatus 1 comprising a movable carrier 2 provided with one or more booms 3. A first boom 3a is a drilling boom provided with a rock drilling unit 4. The drilling unit 4 comprises a rock drilling machine 5 that is movable on a feed beam 6 by a 10 feed device 7. The rock drilling machine 5 may be provided with a tool 8 coupled thereto and comprising a plurality of successive drill rods 9, which are attached to each other by connecting means, such as a threaded joint. Further, at the distal end of the drill rod there is a 15 drill bit 10 having drill buttons for making a drilling hole 12 into rock 11. The rock drilling machine 5 may comprise an impact device used for delivering impact pulses to the tool 8 that transmits them to the drill bit 10 and further to the rock 11 to be broken. The rock 20 drilling machine 5 may also comprise a rotating device allowing the tool 8 to be rotated about its longitudinal axis during drilling. The drilling unit 4 may also be provided with a rod magazine 13 supported on the feed beam 6. The rod magazine 13 may be used for storing extension 25 rods 9 and other drilling tools needed in long hole drilling. The rod magazine 13 is provided with transfer means for transferring drilling tools between the rod magazine 13 and the drilling axis, i.e. the centre K. The distal end portion of the feed beam 6 is provided with 30 retainer 14 that has jaws for clamping the tool 9 and centring it in the drilling centre K. The jaws may take hold of the shaft or the connecting sleeve of the drill 2686388_1 (GHMatters) PB6408.AU 3/06/11 - 11 rod 9, thus allowing the rod to be held in place when the joints are screwed or unscrewed. Further, it is possible to grab the drill bit 10 with the retainer and to hold it in place when the drill bit 10 is to be changed. In 5 addition to the rod magazine 13 the feed beam 6 may be provided with a drill bit magazine. A second boom 3b of the excavation apparatus 1 of Figure 1 is provided with another excavation device 15 for handling excavation tools 16, such as rock bolts, 10 injection tubes and the like. Also these may need to be held by the jaws or the tool may need to be centred to the centre K of the apparatus. In such cases also these excavation devices 15 may be provided with the retainer 14 of the invention. 15 Figure 2 shows a rock drilling unit 4 in which the feed beam 6 is provided with a rod magazine 13 in which drill rods 9 needed in drilling are. The distal end of the feed beam 6 is provided with a retainer 14, the possible structural alternatives of which are shown in greater 20 detail in Figures 3 to 12. The retainer 14 of Figure 3 comprises a body 17 allowing it to be attached to the feed beam. The retainer 14 also comprises a first clamping arm 18a connected by a first pivot joint 19a to the body 17 and a second clamping 25 arm 18b connected by a second pivot joint 19b to the body 17. The clamping arms 18 may be moved in relation to the pivot joints 19 by an actuator 20 located between them, whereby clamping jaws 21a, 21b at the distal ends of the clamping arms 18 move either towards or away from each 30 other, depending naturally on the direction of movement of the actuator 20. The actuator 20 may be a pressure medium 2686388_1 (GHMatters) P86408.AU 3/06/11 - 12 cylinder, such as a hydraulic cylinder, that may be connected to the clamping arm 18 by joints 22. The actuator 20 then transmits the forces directly to the clamping arms. The actuator 20 is placed outside the 5 portion between the pivot joints 19a and 19b. The point of connection of the actuator 20, i.e. the joint 22, is located at a distance from the pivot joint 19a, 19b, whereby a torque arm is generated between the joints 19 and 22. The clamping jaws 21 may comprise centring 10 surfaces on their surfaces facing each other and thus, when they move towards each other, they may centre the drill rod 9 or other tool between them precisely into the centre K. The centring surfaces 23 may have a substantially V-shaped cross-section and they naturally 15 open towards the centre K. Of course other inclined or conical centring surfaces 23 may also be used in the clamping jaws 21. The clamping arms 18 are made to move interdependently by synchronization means 24 provided on the portion between the pivot joints 19. In other words, 20 the synchronization means 24 are separate from the actuator 20. Figure 3 shows a connecting pin 25 which is parallel with the centre K and may belong to the synchronization means 24. As is seen, the body 17 is provided with a longitudinal opening 26 in the vertical 25 direction, the opening allowing the connecting pin 25 to move in vertical direction V, when the clamping arms 18 are moved. In Figure 4 part of the body 17 has been removed for better visibility of the synchronization means 24. On the 30 portion between the pivot joints 19 the first clamping arm 18a may comprise two or more first connecting cams 27, which are at an axial distance from one another when the 2686388_1 (GHMatters) P86408.AU 3/06/11 - 13 retainer 14 is observed in the direction of the centre K. Correspondingly, the second clamping arm 18b may comprise two or more second connecting cams 28. The connecting cams 27, 28 are interleaved on the portion between the pivot 5 joints 19, as shown in Figure 4. Further, the connecting cams 27, 28 are provided with connecting slots 29 that may open towards each other and are arranged to coincide in the axial direction so that together they form a kind of a connecting channel 30. This axial connecting channel 30 is 10 provided with a connecting pin 25 that may serve as a transmission member between the connecting cams 27, 28. When the clamping arms 18 are moved, movement takes place in the contact surfaces of the connecting slots 29 and the connecting pin 25, and in addition, the connecting pin 25 15 moves linearly in a vertical direction, i.e. it moves either towards the centre K or away from it. In this application the shape surfaces belonging to the synchronization means 24 are implemented by surfaces of the connecting channel 30, which are in contact with the 20 connecting pin 25. The cross-section of Figure 5 further clearly shows the formation of a connecting channel 30 between the connecting cams 27, 28. For vertical movement of the connecting pin 25 the body 17 is provided with 25 longitudinal openings 26a, 26b. The cross-sectional Figures 6 and 7 further clarify the construction of this embodiment. Unlike in Figures 4 to 7, it may be possible to provide connecting slots 29 with a closed shape. The cross-section of the connecting pin 25 is preferably 30 circular. In the embodiment of Figure 8 a first actuator 20a transmits force to a first clamping arm 18a only and a 2686388 1 (GHMatters) P86408.AU 3/06/11 - 14 second actuator 20b transmits force to a second clamping arm 18b only. The synchronization means 24 ensure the simultaneity of the movement of the clamping arms 18. In the embodiment of Figure 9 the force from the 5 actuator 20 is transmitted only to the first clamping arm 18a and the synchronization means 24 transmit the movement to the second clamping arm 18b. Figure 10 shows a strongly simplified embodiment of synchronization means 24 including teeth 31a, 31b formed 10 to the clamping arms 18. The teeth are formed to the curved transmission surfaces of the pivot joints 19. In this application the synchronization movements are transmitted directly through contact with the teeth, therefore no connecting pins or a similar connecting 15 members are needed. The teeth 31 serve as the necessary shape members between the clamping arms 18. Figure 11 shows a strongly simplified embodiment of synchronization means 24 provided with a first longitudinal connecting opening 32a in the first clamping 20 arm 18a and a second longitudinal connecting opening 32b in the second clamping arm 18b. At least on the portions of the connecting openings 32 the clamping arms 18 are interleaved in relation to each other. The clamping arms 18 may be provided with connecting cams 27, 28 or 25 corresponding projecting portions on these interleaved portions. The connecting openings 32 are arranged transversally with respect to each other, whereby they together define a connecting channel 30 with a connecting pin 25 arranged therein. The connecting pin 25 is not 30 attached to the connecting openings 32 but it is allowed to move in the longitudinal direction of the connecting 26863881 (GHMatters) P86408.AU 3/06/11 - 15 openings 32 and, at the same time, also in a vertical direction with respect to the centre K, when the clamping arms 18 are moved by applying a turning force to the force transmission points 22. 5 Figure 12 shows yet another strongly simplified embodiment of the synchronization means 24 having a longitudinal connecting opening 32 formed to the first clamping arm 18a and an immovably fixed connecting pin 25 provided on the second clamping arm 18b.The clamping arms 10 18 are interleaved with respect to each other on the portion of the connecting opening 32 and the connecting pin 25. The clamping arms 18 may be provided with connecting cams 27, 28 or similar protruding portions on these interleaved portions. When the actuator 20 turns the 15 clamping arms 18 with respect to their pivots 19, the connecting pin 25 follows a curved path and, at the same time, its position in the connecting opening 32 changes. Further, it is possible that the connecting cam 27 comprises a slot-like connecting opening 32 that opens 20 towards the second clamping arm 18b. In this application the outer surface of the connecting pin 25 and the edges of the connecting opening 32 serve as shape surfaces transmitting the synchronization movements. In the embodiments of Figures 3 to 7, 11 and 12 the 25 connecting pin 25 is arranged between the interleaved portions and is to be subjected substantially to shearing forces only. In that case the connecting pin 25 may be relatively thin, yet it is able to transmit even strong forces between the clamping arms 18. In the embodiments of 30 Figures 3 to 7 and 11 there is a separate connecting pin 25 that is easy to detach and replace. 2686388_1 (GHMatters) P86408.AU 3/06/11 - 16 It should be noted that the opening movement of the clamping jaws 21 of the retainer 14 may be arranged to be sufficiently large to allow it to be used for clamping both the shaft of the drill rod 9 and the connecting 5 sleeve between successive drill rods 9. Also the drill bit 10 or any other tool used in excavation may be gripped with it. When in this application reference is made to a vertical direction or a vertical movement, this means a 10 vertical movement in relation to the basic position of the feed beam and the retainer, the feed beam being horizontal in that position. When the boom and the feed beam are turned during operation, this naturally changes also the position of the retainer. Although in absolute terms the 15 direction changes, the retainer nevertheless maintains its relative position with respect to the feed beam. In some cases the characteristics presented in this application may be used as such, independently of other features. However, the characteristics presented in this 20 application may also be combined, when necessary, to provide different combinations. The drawings and the related specification are only meant to illustrate the inventive idea. The details of the invention may vary within the scope of the claims. 25 In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, 30 i.e. to specify the presence of the stated features but 2686388_1 (GHMatters) P86408.AU 3/06/11 - 17 not to preclude the presence or addition of further features in various embodiments of the invention. It is to be understood that, if any prior art publication is referred to herein, such reference does not 5 constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country. 2686388_1 (GHMatters) P86408.AU 3/06/11

Claims

1. A method for using a retainer belonging to an excavation apparatus, the retainer comprising: a body, a first clamping arm and a second clamping arm, which are 5 pivoted to the body, clamping jaws at the distal ends of the clamping arms, and at least one actuator; and the method comprising the steps of turning with the actuator the clamping arms with respect to their pivot points, whereby the clamping jaws 10 move towards each other and, correspondingly, away from each other depending on the direction of movement of the actuator; clamping a tool in the centre of the excavation apparatus with the clamping jaws to centre and gripping it 15 while positioned in the centre; connecting the clamping arms with each other by separate mechanical synchronization means, the movements of the clamping arms being thus interdependent and the clamping jaws moving simultaneously and symmetrically, 20 and arranging shape members on the portion between the pivot points of the clamping arms and synchronizing the movement between the first clamping arm and the second clamping arm with the shape members in both travel directions of the clamping arms; 25 arranging at least one portion of both the first clamping arm and the second clamping arm in an interleaved manner and arranging shape surfaces provided in the form of openings in the interleaved portions to coincide; and transmitting movement between the clamping arms by 30 means of a connecting pin parallel with the centre, the pin being in contact with the shape surfaces of the clamping arms. 26863881 (GHMatters) P86408.AU 3/06/11 - 19

2. A method according to claim 1, including allowing a transverse movement of the connecting pin in a vertical direction when the clamping arms are moving.

3. A retainer comprising 5 a body allowing the retainer to be attached to a feed beam of an excavation apparatus; a first clamping arm connected by a first pivot joint to the body and a second clamping arm connected by a second pivot joint to the body; 10 clamping jaws arranged on the portions of the distal ends of the clamping arms and facing each other; at least one actuator for moving the clamping arms in relation to the pivot joints, the clamping jaws being movable towards and away from each other; 15 mechanical synchronization means separate from the actuator for connecting the movement of the first clamping arm and that of the second clamping arm to be interdependent; and wherein the synchronization means of the 20 retainer are arranged on the portion between the first and the second pivot joint; and the synchronization means comprise shape members formed to the first and the second clamping arm and arranged to transmit synchronization movements between the 25 clamping arms in both travel directions of the clamping arms; wherein the first clamping arm and the second clamping arm are interleaved at least on the portion of the shape 30 surfaces; the shape surfaces defining a connecting channel; 2686388_1 (CHMatters) P86408.AU 3/06/11 - 20 and a connecting pin arranged in the connecting channel, whereby the connecting pin transmits movement between the shape surfaces of the clamping arms.

4. A retainer according to claim 3, wherein 5 the first clamping arm comprises at least two first connecting cams on the portion between the pivot joints, the cams being arranged at an axial distance from one another; the second clamping arm comprises at least two 10 second connecting cams on the portion between the pivot joints, the cams being arranged at an axial distance from one another; the first connecting cams and the second connecting cams are interleaved; 15 the first connecting cams and the second connecting cams are provided with connecting slots opening towards each other and arranged to coincide in such a way that connecting slots on opposite sides are arranged to form a connecting channel in an axial direction; 20 a connecting pin is arranged to the connecting channel and arranged to serve as a transmission member between the first and the second connecting cam; and the connecting pin is tree to move in a vertical direction when the clamping arms are moved. 25 5. A retainer according to claim 3, wherein the first clamping arm comprises a connecting pin parallel to the centre on a portion between the pivot joints, the pin being immovably fixed to the first clamping arm; 30 the second clamping arm comprises a longitudinal connecting opening on the portion between the pivot joints; and 2686388_1 (GHMatters) P86408.AU 3/06/11 - 21 the connecting pin is arranged through the connecting opening, whereby they act as shape members and transmit synchronization movements between the clamping arms.

5

6. A retainer according to any one of the preceding claims 3 to 5, wherein the retainer comprises only one actuator, which is arranged between the clamping arms and connected to act directly on both clamping arms. 10

7. A retainer according to any one of the preceding claims 3 to 5, wherein the retainer comprises only one actuator, which is arranged to act only on the first clamping arm, the second clamping arm being arranged to move under the influence of 15 the synchronization means.

8. A retainer according to any one of the preceding claims 3 to 5, wherein the retainer comprises at least two actuators, at least one first actuator being connected to act directly 20 on the first clamping arm only and at least one second actuator being arranged to act directly on the second clamping arm only.

9. A method for using a retainer belonging to an excavation apparatus or a retainer, substantially as 25 herein described with reference to the accompanying drawings. 2686388_1 (GHMatters) P86408.AU 3/06/11