Abstract:
A tool holder for a power tool comprising: a body defining a passageway in which a shank of a cutting tool can be located; at least one axial locking element moveably mounted within the body and which is capable of being moved between and held in at least a first release position and a second locking position where it projects into the passageway where it is capable of engagingly a shank of a cutting tool when located within the passageway in order to axially restrict the movement of the shank in the passageway; and at least one axial guide moveably mounted within the body and which can be moved between and held in at least two positions, including one position where it projects into the passageway where it is capable of engagingly supporting a side of a shank of a cutting tool when located within the passageway.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to UK Application No. GB 1411392.2, filed on Jun. 26, 2014, entitled “A Tool Holder.” The content of this application is incorporated herein by reference in its entirety. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to a tool holder for a drill, such as a hammer drill. 
       BACKGROUND OF THE INVENTION 
       [0003]    Hammer drills are power tools that can often operate in three modes of operation. A hammer drill will comprise a tool holder in which a cutting tool, such as a drill bit, can be supported and driven by the hammer drill. The hammer drill can actively drive the cutting tool in three different ways, each being referred to as a mode of operation. The cutting tool can be driven in a hammering mode, a rotary mode and a combined hammer and rotary mode. A hammer drill will typically comprises an electric motor and a transmission mechanism by which the rotary output of the electric motor can either rotationally drive the cutting tool to perform the rotary mode or repetitively strike the cutting tool to perform the hammer mode or rotationally drive and repetitively strike the cutting tool to perform the combined hammer and rotary mode. 
         [0004]    EP1157788 discloses a typical hammer drill. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    Cutting tools for hammer drills typically comprise two sections: a first section which connects to a tool holder of a hammer drill and a second section which performs the cutting task of the cutting tool when driven by the hammer drill. The design of first section can vary. 
         [0006]      FIG. 1  shows one design of a first section  20  of a cutting tool which is referred to as a hex shank cutting tool. The first section  20  of the shank of the hex shank cutting tool comprises two sub sections  2 ,  4  which have a hexagon cross section and which are separated by a circumferential groove  6  of circular cross section. The dimensions of the first section  20  of the hex shank cutting tool are fixed in accordance with a set standard. 
         [0007]      FIG. 2  shows another design of a first section  22  of a cutting tool which is referred to as a SDS plus shank cutting tool. The first section  22  of the shank of the SDS plus shank cutting tool is circular in cross section and has two grooves  10  located on opposite sides of the shank which extend axially to the rear of the shank and two elongate axial recesses  12  located between the grooves on opposite sides of the shank. The dimensions of the first section  22  of the SDS plus shank cutting tool are fixed in accordance with a set standard. 
         [0008]    Different types of tool holders are presently required for use with cutting tools having different designs of first sections. This results in the requirement to provide a number of tool holders for each hammer drill in order for the hammer drill to be able to utilize different types of cutting tool. This increases cost as well as requiring the user to swop tool holders when different designs of cutting tool are to be utilized. Furthermore, tool holders of hammer drills are typically incorporated into the design of the hammer drill in an integral manner and therefore cannot be simply be detached and interchanged with another tool holder. This results in a user having to have several hammer drills, each having a different tool holder to hold different designs of cutting tools. Alternatively, if the user only wanted to use a single hammer drill, the user would need to utilize an adaptor to alter the function of the existing tool holder to accommodate the different designs of cutting tool, incurring extra cost and complexity. 
         [0009]    The object of the present invention is to provide a tool holder which is capable of supporting and driving cutting tools which have at least two different designs of first section for connecting the cutting tool to the tool holder. 
         [0010]    Accordingly, there is provided a tool holder in accordance with claim  1 . 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    Three embodiments of the present invention will now be described with reference to accompanying drawings of which: 
           [0012]      FIG. 1  shows a hex shank cutting tool; 
           [0013]      FIG. 2  shows a SDS plus cutting tool; 
           [0014]      FIG. 3  shows a side view of the first embodiment of the tool holder; 
           [0015]      FIG. 4  shows the front end of the spindle of a hammer drill with the positioning ball bearings and locking ball bearing in their respective apertures; 
           [0016]      FIG. 5  shows the first inner sleeve mounted on the front end of the spindle together with the biasing spring; 
           [0017]      FIG. 6  shows the inside view of the second outer sleeve with the radial groove; 
           [0018]      FIG. 7A  shows a side view of the tool holder with the first section of a hex shank cutting tool being inserted into the tool holder with the second outer sleeve in the released position; 
           [0019]      FIG. 7B  shows a cross section of tool holder of  FIG. 7A  in the direction of Arrows A; 
           [0020]      FIG. 7C  shows a cross section of tool holder of  FIG. 7A  in the direction of Arrows B through the front positioning ball bearings; 
           [0021]      FIG. 7D  shows a cross section of tool holder of  FIG. 7A  in the direction of Arrows C through the locking ball bearing; 
           [0022]      FIG. 8A  shows a side view of the tool holder with the first section of a hex shank cutting tool located within the tool holder with the second outer sleeve in the locked position; 
           [0023]      FIG. 8B  shows a cross section of tool holder of  FIG. 8A  in the direction of Arrows D; 
           [0024]      FIG. 8C  shows a cross section of tool holder of  FIG. 8A  in the direction of Arrows E through the front positioning ball bearings; 
           [0025]      FIG. 8D  shows a cross section of tool holder of  FIG. 8A  in the direction of Arrows F through the locking ball bearing; 
           [0026]      FIG. 9A  shows a front view of the tool holder with the first section of a SDS plus shank cutting tool being inserted within the tool holder with the second outer sleeve in the released position; 
           [0027]      FIG. 9B  shows a cross section of tool holder of  FIG. 9A  in the direction of Arrows G; 
           [0028]      FIG. 9C  shows a cross section of tool holder of  FIG. 9B  in the direction of Arrows H through the locking ball bearing; 
           [0029]      FIG. 9D  shows a cross section of tool holder of  FIG. 9B  in the direction of Arrows I through the front positioning ball bearings; 
           [0030]      FIG. 10A  shows a front view of the tool holder with the first section of a SDS plus shank cutting tool located within the tool holder with the second outer sleeve in the locked position; 
           [0031]      FIG. 10B  shows a cross section of tool holder of  FIG. 10A  in the direction of Arrows J; 
           [0032]      FIG. 10C  shows a cross section of tool holder of  FIG. 10B  in the direction of Arrows K through the locking ball bearing; 
           [0033]      FIG. 10D  shows a cross section of tool holder of  FIG. 10B  in the direction of Arrows L through the front positioning ball bearings; 
           [0034]      FIG. 11  shows a side view of the second embodiment of the tool holder; 
           [0035]      FIG. 12  shows the front end of the spindle of a hammer drill with the positioning ball bearings and locking ball bearing in their respective apertures; 
           [0036]      FIG. 13  shows the two positioning sleeves, the locking sleeve, and the end plate mounted on the front end of the spindle together with a biasing spring; 
           [0037]      FIG. 14  shows the inside view of the twisting sleeve; 
           [0038]      FIG. 15  shows a perspective view of the end plate; 
           [0039]      FIG. 16  shows a perspective view of the positioning sleeve; 
           [0040]      FIG. 17  shows a perspective view of the locking sleeve; 
           [0041]      FIG. 18A  shows a front view of the tool holder with the first section of a hex shank cutting tool being inserted into the tool holder with the twisting sleeve in the released position; 
           [0042]      FIG. 18B  shows a cross section of tool holder of  FIG. 18A  in the direction of Arrows A; 
           [0043]      FIG. 18C  shows a cross section of tool holder of  FIG. 18B  in the direction of Arrows B through the locking ball bearing; 
           [0044]      FIG. 18D  shows a cross section of tool holder of  FIG. 18B  the direction of Arrows C through the front positioning ball bearings; 
           [0045]      FIG. 19A  shows a front view of the tool holder with the first section of a hex shank cutting tool located within the tool holder with the twisting sleeve in the locked position; 
           [0046]      FIG. 19B  shows a cross section of tool holder of  FIG. 19A  in the direction of Arrows D; 
           [0047]      FIG. 19C  shows a cross section of tool holder of  FIG. 19B  in the direction of Arrows E through the front positioning ball bearings; 
           [0048]      FIG. 19D  shows a cross section of tool holder of  FIG. 19B  in the direction of Arrows F through the locking ball bearing; 
           [0049]      FIG. 20A  shows a front view of the tool holder with the first section of a SDS plus shank cutting tool being inserted within the tool holder with the twisting sleeve in the released position; 
           [0050]      FIG. 20B  shows a cross section of tool holder of  FIG. 20A  in the direction of Arrows G; 
           [0051]      FIG. 20C  shows a cross section of tool holder of  FIG. 20B  in the direction of Arrows H through the front positioning ball bearings; 
           [0052]      FIG. 20D  shows a cross section of tool holder of  FIG. 20B  in the direction of Arrows I through the locking ball bearing; 
           [0053]      FIG. 21A  shows a front view of the tool holder with the first section of a SDS plus shank cutting tool located within the tool holder with the twisting sleeve in the locked position; 
           [0054]      FIG. 21B  shows a cross section of tool holder of  FIG. 21A  in the direction of Arrows J; 
           [0055]      FIG. 21C  shows a cross section of tool holder of  FIG. 21B  in the direction of Arrows K through the front positioning ball bearings; 
           [0056]      FIG. 21D  shows a cross section of tool holder of  FIG. 21B  in the direction of Arrows L through the locking ball bearing; 
           [0057]      FIG. 22  shows a side view of the third embodiment of the tool holder; 
           [0058]      FIG. 23  shows the front end of the spindle of a hammer drill with the positioning ball bearings and locking ball bearing in their respective apertures; 
           [0059]      FIG. 24  shows the first inner sleeve mounted on the front end of the spindle together with the biasing spring and support washer; 
           [0060]      FIG. 25  shows the inside view of the second outer sleeve with the radial groove; 
           [0061]      FIG. 26A  shows a side view of the tool holder with the first section of a hex shank cutting tool being inserted into the tool holder with the second outer sleeve in the released position; 
           [0062]      FIG. 26B  shows a cross section of tool holder of  FIG. 26A  in the direction of Arrows A; 
           [0063]      FIG. 26C  shows a cross section of tool holder of  FIG. 26B  in the direction of Arrows B through the front positioning ball bearings; 
           [0064]      FIG. 26D  shows a cross section of tool holder of  FIG. 26B  in the direction of Arrows C through the locking ball bearing; 
           [0065]      FIG. 27A  shows a side view of the tool holder with the first section of a hex shank cutting tool located within the tool holder with the second outer sleeve in the locked position; 
           [0066]      FIG. 27B  shows a cross section of tool holder of  FIG. 27A  in the direction of Arrows D; 
           [0067]      FIG. 27C  shows a cross section of tool holder of  FIG. 27B  in the direction of Arrows E through the front positioning ball bearings; 
           [0068]      FIG. 27D  shows a cross section of tool holder of  FIG. 27B  in the direction of Arrows F through the locking ball bearing; 
           [0069]      FIG. 28A  shows a side view of the tool holder with the first section of a SDS plus shank cutting tool being inserted within the tool holder with the second outer sleeve in the released position; 
           [0070]      FIG. 28B  shows a cross section of tool holder of  FIG. 28A  in the direction of Arrows G; 
           [0071]      FIG. 28C  shows a cross section of tool holder of  FIG. 28B  in the direction of Arrows H through the front positioning ball bearings; 
           [0072]      FIG. 28D  shows a cross section of tool holder of  FIG. 28B  in the direction of Arrows I through the locking ball bearing; 
           [0073]      FIG. 29A  shows a side view of the tool holder with the first section of a SDS plus shank cutting tool located within the tool holder with the second outer sleeve in the locked position; 
           [0074]      FIG. 29B  shows a cross section of tool holder of  FIG. 29A  in the direction of Arrows J; 
           [0075]      FIG. 29C  shows a cross section of tool holder of  FIG. 29B  in the direction of Arrows K through the front positioning ball bearings; and 
           [0076]      FIG. 29D  shows a cross section of tool holder of  FIG. 29B  in the direction of Arrows L through the locking ball bearing. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0077]    The hammer drill disclosed comprises a tubular spindle  100  which is capable of being rotatably driven by an electric motor (not shown) to perform the rotary mode of operation. The front end  102  of the spindle  100  comprises a tubular passage  114  which is adapted to receive a first section of a cutting tool and forms part of a tool holder of the hammer drill. Rotation of the spindle  100  results in rotation of a cutting tool when held within the front end  102 . A ram (not shown) and a beat piece (not shown) are slideably supported within the spindle  100 . The ram can be reciprocatingly driven within the spindle  100  by a reciprocating piston (not shown) via an air spring and which repetitively strikes the beat piece which beat piece in turn repetitively strikes the end of a cutting tool when held in the tool holder. 
         [0078]    The first embodiment of the tool holder will now be described with reference to  FIGS. 3 to 10 . 
         [0079]    The tool holder comprises the front end of the spindle  102 , a first inner sleeve  104  and a second outer sleeve  106 . 
         [0080]      FIG. 4  shows the tubular front end  102  of the spindle  100  with the inner and outer sleeves  104 ,  106  removed which is formed by a wall of uniform thickness. The front end  102  comprises seven circular apertures  108 , 110 ,  112  formed through the sides walls of the front end  102 . The apertures  108 ,  110 ,  112  are arranged in two sets of three  108 ,  112  with the seventh  110  located between the two sets  108 ,  112 . Each set  108 ,  112  of three comprises three apertures located at the same axial position as each other along the spindle and arranged angularly about the longitudinal axis of the front end  102  at 120 degrees relative to each other in a symmetrical fashion. The apertures  108 ,  112  in each set are angularly aligned with the apertures in the other set  108 ,  110 . The diameter of each aperture  108 ,  112  in both sets are all the same as each other. The seventh aperture  110  is located axially between the two sets  108 ,  112  and angularly between two adjacent apertures in each set. The diameter of the seventh aperture is slightly larger than that of the six apertures in the two sets  108 ,  112 . 
         [0081]    Six positioning ball bearings  116  are located within the two sets  108 ,  112  of three apertures, each having the same diameter. The diameter of the cross section of each of the six apertures  108 ,  112  is slightly reduced at the entrance to the six apertures  108 ,  112  formed in the inner wall of the front end  102  where the apertures  108 ,  112  meet the tubular passage  114  to prevent the positioning ball bearings  116  from exiting the apertures  108 ,  112  and entering the tubular passage  114  whilst allowing part of the sides of positioning ball bearings  116  to project into the tubular passage  114  from the apertures. The diameter of the support ball bearings  116  is greater than the thickness of the wall of the front end  102  and therefore a part of the sides of the positioning ball bearings  116  either project into the tubular passage  114  or project radially outwardly from the front end  102 . 
         [0082]    A seventh locking ball bearing  118  is located within the seventh aperture  110 . The diameter of the seventh ball bearing  118  is larger than that of the six positioning ball bearings  116 . The diameter of the cross section of each of the seventh aperture  110  is slightly reduced at the entrance to the seventh aperture  110  formed in the inner wall of the front end  102  where the aperture  110  meets the tubular passage  114  to prevent the ball bearing  118  from exiting the aperture  110  and entering the tubular passage  114  whilst allowing part of the side of the locking ball bearing  118  to project into the tubular passage  114  from the aperture  110 . The diameter of the ball bearing  118  is greater than the thickness of the front end  102  and therefore a part of the side of the ball bearing  118  either projects into the tubular passage  114  or projects radially outwardly from the front end  102 . 
         [0083]      FIG. 5  shows the first inner sleeve  104  mounted on the front end  102 . The first inner sleeve  104  can axially slide along the front end  102  and rotate around the front end  102 . 
         [0084]    The first inner sleeve  104  comprises seven holes  120 ,  122 ,  124  formed through the side walls of the first inner sleeve. The holes  120 ,  122 ,  124  are arranged in two sets of three  120 ,  124  with the seventh  122  located between the two sets  120 ,  124 . 
         [0085]    Each set  120 ,  124  of three comprises three holes located at the same axial position as each other along the sleeve  104  and arranged angularly about the axis of the first inner sleeve  104  at 120 degrees relative to each other in a symmetrical fashion. The holes  120 ,  124  in each set are angularly aligned with the holes in the other set  120 ,  124 . The shape of the cross section of the six holes  120 ,  124  is that of an oval with the longer side extending axially along the inner sleeve  104 . The width of the holes  120 ,  124  in the lengthwise direction remains substantially constant and is the same as that of the diameter of the apertures  108 ,  112  for the positioning ball bearings  116  in the front end  102 . The dimensions of each hole  120 ,  124  in both sets are all the same as each other. The location of the holes  120 ,  124  on the first inner sleeve  104  correspond to those of the apertures  108 ,  112  for the positioning ball bearings  116  in the front end  102  of the spindle  102  so that, when the first inner sleeve  104  is in a particular angular position on the front end  102 , the holes,  120 ,  122 ,  124  and apertures become aligned. 
         [0086]    The seventh hole  122  is located axially between the two sets  120 ,  124  and angularly between two adjacent holes in each set. The shape of the cross section of the seventh hole  122  is that of an oval with the longer side extending circumferentially around the inner sleeve  104 . The width of the hole  122  in the lengthwise direction remains substantially constant and is slightly larger than that of the diameter of the seventh aperture  110  in the front end  102 . 
         [0087]    The second outer sleeve  106  is rigidly mounted onto the first inner sleeve  104 . Formed in the inner wall  130  of the outer sleeve is a radial groove  132  as best seen in  FIG. 6 . The depth of the groove  132  across the width of the groove in an in axial direction of the outer sleeve  106  increases in the forward direction (as shown in  FIG. 8B ), the shape of the cross section of the width of the grove  132  remaining constant along the length of the groove  132  around the inner wall of the second outer sleeve  106 . When the second outer sleeve  106  is mounted on the first inner sleeve  104 , the groove  132  aligns with and faces towards the seventh hole  122  in the inner sleeve. The width of the groove is larger than the width of the seventh hole  122 . 
         [0088]    A spring  134  is sandwiched between a shoulder  136  on the spindle  100  and the second inner sleeve  104 , biasing the inner and outer sleeves  104 ,  106  in a forward direction. 
         [0089]    When the six apertures  108 ,  112  for the positioning ball bearings  116  and corresponding holes,  120 ,  122 ,  124  are in angular alignment due to the angular position of the inner and outer sleeves  104 ,  106  on the front end  102 , the length of the six oval holes  120 ,  124  for the positioning balls  116  is such that a part of each of the oval holes  120 ,  124  remains in alignment with the corresponding aperture  108 ,  112  over the full range of axial sliding movement of the inner and outer sleeves on the front end  102 . 
         [0090]    The size of the seventh hole  122  aligns with the seventh aperture  110  when the inner and outer sleeves  104 ,  106  at a rearward axial position on the front end  102 . When the seventh aperture  110  and seventh hole  122  are in axial alignment due to the rear axial position of the inner and outer sleeves  104 ,  106  on the front end  102 , the length of the seventh hole  122  is such that a part of the seventh hole  122  remains in alignment with the seventh aperture  110  over the full range of angular movement of the inner and outer sleeves  104 ,  106  on the front end  102 . 
         [0091]    The inner and outer sleeves  102  may be rotated to one of two angular positions on the front end  102 , a first where the angular position of the inner sleeve  104  and outer sleeve  106  relative to the front end  102  are such that the six holes  120 ,  124  in the inner sleeve  104  are aligned with the six apertures  108 ,  112  for the positioning ball bearings  116  and a second where the six holes  120 ,  124  in the inner sleeve  104  are offset relative to the apertures  108 ,  112  for the positioning ball bearings  116 . When the six holes  120 ,  124  are aligned with the six apertures  108 ,  112 , when the sleeves  104 ,  106  are in their first position, a part of the sides of the positioning ball bearings  116 ,  118  can either project from the apertures  108 ,  112  into the tubular passage  114  or project radially outwardly from the apertures  108 ,  112  in the front end  102  and into the corresponding holes  120 ,  124 . When the six oval holes  120 ,  124  are offset relative the apertures  108 ,  112  for the positioning ball bearings  116 , when the sleeves  104 ,  106  are in their second position, a part of the sides of the positioning ball bearings  116 ,  118  project from the apertures  108 ,  112  into the tubular passage  114  as they are prevented from projecting radially outwardly from the apertures  108 ,  112  in the front end  102  by the inner wall of the inner sleeve  104 , the inner wall of the inner sleeve  104  holding the positioning ball bearings  116  in this inner position. 
         [0092]    When the tool holder is unused prior to the insertion of a cutting tool, the inner and outer sleeves  104 ,  106  are biased forwards by the spring  134  to a maximum forward position on the front end  102 . When the sleeves  104 ,  106  are in their first position with the holes  120 ,  122 ,  124  aligned with the apertures  108 ,  110 ,  112 , it is the rear parts of the oval holes  120 ,  124  that are in alignment with the apertures  108 ,  112  for the positioning ball bearings  116  as the sleeves  104 ,  106  are biased forwards by the spring  134  when the tool holder is unused. 
         [0093]    The inner and outer sleeves  102  may also be axially slid between one of two axial positions on the front end  102 , a first rearward axial position of the inner sleeve  104  and outer sleeve  106  relative to the front end  102  where the seventh hole  122  in the inner sleeve  104  is aligned with the seventh aperture  110  of the front end  102  and a second forward position where the seventh hole  122  in the inner sleeve  104  is offset relative to the seventh aperture  110  of the front end  102 . When all the seventh hole  122  is aligned with the seventh aperture  110 , when the sleeves  104 ,  106  are in their first rearward axial position, a part of the side of the locking ball bearing  118  can either project from the aperture  110  into the tubular passage  114  or project radially outwardly from the aperture  110  in the front end  102  and into the seventh hole  122  and groove  132 . When the seventh hole  122  is offset relative the seventh aperture  112 , when the sleeves  104 ,  106  are in their second forward position, a part of the side of the locking ball bearing  118  projects from the seventh aperture  110  into the tubular passage  114  as it is prevented from projecting radially outwardly from the aperture  110  in the front end  102  by the inner wall of the inner sleeve  104 , the inner wall of the inner sleeve  104  holding the locking ball bearing  118  in this inner position. 
         [0094]    The present embodiment of tool holder can be used to hold cutting tools with two different design of first section, namely a cutting tool with a hex shank and a cutting tool with a SDS plus shank. 
         [0095]    The use of the first embodiment of the tool holder with a hex shank cutting tool will now be described with reference to  FIGS. 7 and 8 . 
         [0096]    In order for the tool holder to be used with a hex shank, the positioning ball bearings  116  must be in their inner position. When the positioning ball bearings  116  are in their inner position, they provide support to the sides of the shank of the hex shank. If the positioning ball bearings  116  are in an out outer position, they would not provide any support to the sides of the hex shank, allowing too much movement of the cutting tool in a direction perpendicular to its longitudinal axis. 
         [0097]    Firstly, the inner and out sleeves  104 ,  106  are rotated on the front end  102  so that they in their second angular position with the six holes  120 ,  124  of the inner sleeve  104  are offset to the corresponding apertures  108 ,  112  of the front end  102 . This results in the positioning ball bearings  116  being moved to their inward position inside of the inner sleeve  104  as best seen in  FIGS. 7B and 7C . The side walls of the apertures  108 ,  112  may be angled slightly to encourage the movement of the positioning ball bearings  116  to their inner position. In this position, a part of the sides of each of the positioning ball bearings  116  projects from the apertures  108 ,  112  into the tubular passage  114  and are held in this inner position. The dimensions of the tool holder are such that when the positioning ball bearings  116  are in this position, they correspond to the outer dimensions of the centre of the flat sides  140  of the hex shank. 
         [0098]    Secondly the inner and outer sleeves  104 ,  106  are slid rearwardly on the front end  102  against the biasing force of the spring  134  so that the seventh hole  122  and groove  132  align with the seventh aperture  110 . This allows the locking ball bearing  118  to move outwardly, with part of the locking ball bearing  118  entering the seventh hole  122  and groove  132 . 
         [0099]    The first section  20  of the hex shank is then inserted into the tool holder (as shown in  FIGS. 7A to 7D ). The positioning ball bearings  116  engage with the centre of the flat sides  140  of the hex shank and guide the movement of the first section  20  inside the tubular passage  114 , preventing movement of the hex shank in a direction perpendicular to the longitudinal axis of the hex shank. The hex shank is inserted to a depth where the groove  6  of the first section is aligned with the locking ball bearing  118 . The inner and outer sleeves are then released, allowing the spring  134  to move the sleeves  104 ,  106  in a forward direction. As the sleeves  104 ,  106 , move in a forward direction, the groove  132  and seventh hole  122  move forward of the seventh aperture  110 , causing the locking ball bearing  118  to move to its inner position where it is held by the inner wall of the inner sleeve  104 . The shape of the groove  132  in the outer sleeve encourages the movement of the locking ball bearing into its inner position. The side walls of the seventh aperture  110  may be angled slightly to encourage the movement of the locking ball bearing  116  to its inner position. In its inner position (as shown in  FIGS. 8A to 8D ), part of the locking ball bearing  118  extends into the tubular passageway  114  and into the groove  6  of the first section  20  of the hex shank. The hex shank is axially locked into the tool holder by locking ball  118  being held in the groove  6  of the first section  20  of the hex shank. 
         [0100]    The positioning ball bearings  116  located against the centre of the flat sides  140  of the two sub sections  2 ,  4 . As the positioning ball bearings  116  are held in this position by the inner sleeve, they are prevented from moving outwardly and therefore cannot pass over the axial ridges formed between adjacent flat faces  140  of the hex shank. Therefore, each positioning ball bearing is locked against the flat side  140  it is engaged with in a circumferential direction. As such, when the tool holder is rotated, the rotary movement of the tool holder is transferred to the hex shank via the positioning ball bearings  116  which are locked against the face of the flat sides  140 . 
         [0101]    The first section of the hex shank is released from the tool holder by the inner and outer sleeves  104 ,  106  being slid rearwardly against the biasing force of the spring  134  to align the groove  132 , the seventh hole  122  and the aperture  110 . This allows part of the locking ball bearing  118  to move outwardly from the seventh aperture into the seventh hole  122  and groove  132 . As such, the part of locking ball bearing  118  in the tubular passage  114  moves out of the tubular passage  114 , disengaging from the groove  6  of the first section  20  of the hex shank, allowing it to be withdrawn from the tool holder. 
         [0102]    The use of the first embodiment of the tool holder with a SDS plus shank cutting tool will now be described with reference to  FIGS. 9 and 10 . 
         [0103]    In order for the tool holder to be used with a SDS plus shank, the positioning ball bearings  116  must be in their outer position. When the positioning ball bearings  116  are in their outer position, they provide support to the sides of the shank of the SDS plus shank. If the positioning ball bearings  116  are in their inner position, the first section of the SDS plus shank would be prevented from entering the tubular passage  114  of the tool holder. 
         [0104]    Firstly, the inner and out sleeves are rotated on the front end  102  so that they in their first angular position with the six holes  120 ,  124  of the inner sleeve  104  are aligned with the corresponding apertures of the front end  102 . This results in the positioning ball bearings  116  being able to move to their outer position inside of the apertures  108 ,  112  in the inner sleeve  104  as best seen in  FIG. 9D . In this position, a part of the sides of each of the positioning ball bearings  116  are able to project outwardly from the apertures  108 ,  112  into the holes  120 ,  124  of the inner sleeve  104 . The dimensions of the tool holder are such that when the positioning ball bearings  116  located in their outer position, they correspond to the outer dimensions of the first section of the SDS plus shank 
         [0105]    Secondly the inner and outer sleeves  104 ,  106  are slid rearwardly on the front end  102  against the biasing force of the spring  134  so that the seventh hole  122  and groove  132  align with the seventh aperture  110 . This allows the locking ball bearing to move outwardly, with part of the locking ball bearing  118  entering the seventh hole  122  and groove  132 . 
         [0106]    The first section  22  of the SDS plus shank is then inserted into the tool holder (as shown in  FIGS. 9A to 9D ). The positioning ball bearings  116  engage with the end of the first section  22  of the SDS plus shank and move them to their outer most position. Subsequently, the positioning ball bearings  116  engage with the sides of the first section  22  of the SDS plus shank and guide the movement of the first section  22  inside the tubular passage  114 , preventing movement of the SDS plus shank in a direction perpendicular to the longitudinal axis of the SDS plus shank. The SDS plus shank is inserted to a depth where one of the elongate axial recesses  12  of the first section  22  is aligned with the locking ball bearing  118 . The inner and outer sleeves  104 ,  106  are then released, allowing the spring  134  to move the sleeves  104 ,  106  in a forward direction. As the sleeves  104 ,  106 , move in a forward direction, the groove  132  and seventh hole  122  move forward of the seventh aperture  110 , causing the ball bearing to move to its inner position where it is held by the tapered rear wall  131  inner wall of the inner sleeve  104  (as shown in  FIGS. 10A to 10D ). The shape of the groove  132  in the outer sleeve  106  and the tapered rear side wall  131  encourages the movement of the locking ball bearing  118  into its inner position. In its inner position, part of the locking ball bearing  118  extends into the tubular passageway  114  and into the elongate axial recess  12  of the first section  22  of the SDS plus shank. The SDS plus shank is axially locked into the tool holder by locking ball  118  being held in the axial recess  12  of the first section  22  of the SDS plus shank. The SDS plus shank can axially slide over a limited range of movement due to the locking ball bearing  118  sliding along the axial recess  12 . 
         [0107]    Formed insides of the tubular passage  114 , along the length of the passage  114 , are two ribs  150  which are located opposite each other within the tubular passage  114 . The ribs  150  engage with the grooves  10  in the first section  22 . Rotary movement of the tool holder is transferred to the first section  22  of the SDS plus shank via the ribs  150  engagement with the grooves  10 . The height of the ribs  150  is such that they do not interfere with the insertion of a hex shank into the tubular passageway  114  of the tool holder. 
         [0108]    The first section of the SDS plus shank is released from the tool holder by the inner and outer sleeves  104 ,  106  being slid rearwardly against the biasing force of the spring  134  to align the groove  132 , the seventh hole  122  and the aperture  110 . This allows part of the locking ball bearing  118  to move outwardly from the seventh aperture into the seventh hole  122  and groove  132 . As such, the part of locking ball bearing  118  in the tubular passage  114  can move out of the tubular passage  114 , disengaging from the axial recess  12  of the first section  22  of the SDS plus shank, allowing it to be withdrawn from the tool holder. 
         [0109]    The second embodiment of the tool holder will now be described with reference to  FIGS. 11 to 21 . 
         [0110]    The second embodiment of the tool holder comprises the front end  102  of the spindle, two positioning sleeves  200 , a locking sleeve  202 , an end plate  204 , and an outer twisting sleeve  206 . Where the same features in the second embodiment were present in the first, the same reference numbers have been used. 
         [0111]      FIG. 12  shows the tubular front end  102  of the spindle  100  without the sleeves  200 ,  202 ,  206  and end plate  204  which is formed by a wall of uniform thickness except along one side at the front where a flat surface  208  has been formed. The front end  102  comprises seven circular apertures  108 ,  110 ,  112  formed through the sides walls of the front end  102  away from the flat surface  208 . The apertures  108 ,  110 ,  112  are arranged in two sets of three  108 ,  112  with the seventh  110  located between the two sets  108 ,  112 . Each set  108 ,  112  of three comprises three apertures located at the same axial position as each other along the front end  102  and arranged angularly about the longitudinal axis of the front end  102  at 120 degrees relative to each other in a symmetrical fashion. The apertures  108 ,  112  in each set are angularly aligned with the apertures in the other set  108 ,  110 . The diameter of each aperture  108 ,  112  in both sets are all the same as each other. The seventh aperture  110  is located axially between the two sets  108 ,  112  and angularly between two adjacent apertures in each set. The diameter of the seventh aperture is slightly larger than that of the six apertures in the two sets  108 ,  112 . 
         [0112]    Six positioning ball bearings  116  are located within the two sets  108 ,  112  of three apertures, each having the same diameter. The diameter of the cross section of each of the six apertures  108 ,  112  is slightly reduced at the entrance to the six apertures  108 ,  112  formed in the inner wall of the front end  102  where the apertures  108 ,  112  meet the tubular passage  114  to prevent the positioning ball bearings  116  from exiting the apertures  108 ,  112  and entering the tubular passage  114  whilst allowing part of the sides of positioning ball bearings  116  to project into the tubular passage  114  from the apertures. The diameter of the support ball bearings  116  is greater than the thickness of the wall of the front end  102  and therefore a part of the sides of the positioning ball bearings  116  either project into the tubular passage  114  or project radially outwardly from the front end  102 . 
         [0113]    A seventh locking ball bearing  118  is located within the seventh aperture  110 . The diameter of the seventh ball bearing  118  is larger than that of the six positioning ball bearings  116 . The diameter of the cross section of each of the seventh aperture  110  is slightly reduced at the entrance to the seventh aperture  110  formed in the inner wall of the front end  102  where the aperture  110  meets the tubular passage  114  to prevent the ball bearing  118  from exiting the aperture  110  and entering the tubular passage  114  whilst allowing part of the side of the locking ball bearing  118  to project into the tubular passage  114  from the aperture  110 . The diameter of the ball bearing  118  is greater than the thickness of the front end  102  and therefore a part of the side of the ball bearing  118  either projects into the tubular passage  114  or projects radially outwardly from the front end  102 . 
         [0114]    As best seen in  FIG. 13 , two positioning sleeves  200  are rotationally mounted on the front end  102 , each of which surrounds one set of the positioning ball bearings  116 . One locking sleeve  204  is mounted between the two positioning sleeves  200  and surrounds the locking ball bearing  118 . The end plate  204  is mounted on the end of the front end  102 . The end plate  204  (as shown in  FIG. 15 ) comprises an aperture  210  which has a corresponding cross section in shape to that of the end of the front end  102 , the end being inserted into the aperture  210 . The aperture  210  comprises a corresponding flat surface  212  which engages with the flat surface  208  of the front end  102 . This prevents the end plate  204  from rotating around the front end  102  making it rotationally fixed to the front end  102 . 
         [0115]    The outer twisting sleeve  206  (as shown in  FIG. 14 ) is mounted on and rigidly attached to the two positioning sleeves  200  and the locking sleeve  202  by axial ribs  214  formed on the inside of the twisting sleeved  206  locating in and engaging with axial slots  215  formed on the outer periphery to the two positioning sleeves  200  (as shown in  FIG. 16 ) and the locking sleeve  202  (as shown in  FIG. 17 ). Rotation of the twisting sleeve  206  results in rotation of the two positioning sleeves  200  and the locking sleeve  202  by the same amount. The twisting sleeve  206  is prevented from sliding rearwardly by abutting against a shoulder  216  formed on the front end  102  of the spindle  100 . The twisting sleeve  206  is prevented from sliding forward by the end plate  204 . As such the twisting sleeve  206  is prevented from moving axially on the front end  102 , which in turn prevents any axial movement of the two positioning sleeves  200  and the locking sleeve  202  on the front end  102 . 
         [0116]    A recess  218  is formed in the front end of the twisting sleeve  206  in which the end plate  204  is located. The end plate comprises two arms  220 ,  222  which project radially outwards in opposite directions. The edge of the recess  218  comprises two pockets  224 ,  226  into each of which projects an arm  220 ,  222 . When the twisting sleeve  206  is rotated about front end  102  and the end plate  204 , the arms  220 ,  222  slide along the pockets  224 ,  226  until they engage with the ends of the pockets  224 ,  226  where they are prevented from any further rotational movement. The arms  220 ,  222  and pockets  224 ,  226  limit the amount of angular movement of the twisting sleeve  206  on the front end  102 . A spring  228  is attached between the end plate  204  and the twisting sleeve  206  and angularly biases it towards a first angular end position where the arms  220 ,  222  are located at one end of the pockets  224 ,  226 . 
         [0117]      FIG. 16  shows the positioning sleeve  200 . Formed symmetrically around the internal wall  230  are three identical cam surfaces  232 , each of which has three locating positions  234 ,  236 ,  238 . When the positioning sleeve  200  is mounted on the front end  12 , one positioning ball bearing  116  locates against each cam surface  232 , the positioning ball bearing  116  engaging with the cam surface at different positions along the cam surface depending on the angular position of the positioning sleeve  200  on the front end  102 . When each ball bearings  116  is located at the three locating positions  234 ,  236 ,  238 , the positioning ball bearings  116  are located in a different radial positions. The spring  228  urges the twisting sleeve towards its first end position which is where the cam surfaces urges the positioning ball bearings  116  to their inner most position. 
         [0118]      FIG. 17  shows the locking sleeve  202 . Formed on the internal wall  240  is a cam surface  242  which has three locating positions  244 ,  246 ,  248 . When the locking sleeve  200  is mounted on the front end  12 , the locking ball bearing  118  locates against the cam surface  242 , the locking ball bearing  118  engaging with the cam surface at different positions along the cam surface depending on the angular position of the locking sleeve  202  on the front end. When the locking ball bearing  118  is located at the three locating positions, the locking ball bearing  118  is located in a different radial position. The spring  228  urges the twisting sleeve towards its first end position which is where the cam surface  242  urges the locking ball bearing  118  to its inner most position. 
         [0119]    In order to insert a cutting tool into the tool holder, the twisting sleeve  206  is rotated against biasing force of the spring  228  so that each of the arms  220 ,  222  of the end plate  204  move from one end of the pocket  224 ,  226  to a second end position at the other end of the pocket  224 ,  226 . When it is in this position, the cams  232  which are in engagement with the positioning ball bearings  116  moving over the position ball bearings  116  (which are rotationally fixed relative the front end  102  due to being located within the apertures  108 ,  112 ) until the ball bearings  116  are capable of locating in a first locating position  234  on the cam  232 . The first locating position  234  is the position where the ball bearings  116  can locate in their most radially outward position. Similarly, when the twisting sleeve  106  is in the second end position, the cam  242  which is in engagement with the locking ball bearing  118  moves over the locking ball bearing  116  (which is rotationally fixed relative the front end  102  due to be located within the seventh aperture  110 ) until the ball bearing  118  is capable of locating in a first locating position  244  on the cam  242 . The first locating position  244  is the position where the locking ball bearing  118  can locate in the most radially outward position. When the positioning ball bearings  116  and locking ball bearing  118  are in these positions, first section of either a hex shank cutting tool or a SDS plus cutting tool can be inserted into the tubular passageway  114 . 
         [0120]    The insertion of a first section of the hex shank cutting tool will now be described with reference to  FIGS. 18 and 19 . 
         [0121]    When the twisting sleeve  206  is twisted to its second end position, the first section  20  of the hex shank is inserted into the tubular passage  114  (as shown in  FIGS. 18A to 18D ). As the cams  232 ,  242  for the positioning ball bearings  116  and the locking ball bearing  118  are located with their first locating position  234 ,  244  facing the ball bearings  116 ,  118 , the ball bearings  116 ,  118  can move to their outer most position allowing the first section  20  to pass by. The twisting force applied to twisting sleeve  206  is then removed, allowing the twisting sleeve  206  to rotate due to the biasing force of the spring  228 . The rotation of the twisting sleeve  206  causes the positioning sleeves  200  and locking sleeve  202  to rotate such that the third locating positions  238 ,  248  face and engage with the ball bearings  116 ,  118 . When the third locating positions  238 ,  248  are engagement with the ball bearings  116 ,  1118 , the ball bearings  116 ,  118  are urged to the inner most position. In this position, the positioning ball bearings  116  engage with the flat surfaces  140  of sides of the first section  20  and the locking ball bearing  118  engages with the groove  6  (as shown in  FIGS. 19A to 19D ). The positioning ball bearings  116  prevent movement of the first section  20  in a direction perpendicular to the longitudinal axis of the cutting tool. The locking ball bearing  118  axially locks the first section  20  within the tubular passage  114 . Rotational movement of the tool holder is transferred to the first section  20  via the positioning ball bearings  116  and their engagement with the flat surfaces  140  of the first section  20 . 
         [0122]    In order to release the first section  20  of the hex shank from the tool holder, the twisting sleeve  206  is rotated against the biasing force of the spring  228  until it is located in its first end position. When the twisting sleeve  206  is in this position, the cams  232 ,  242  for the positioning ball bearings  116  and the locking ball bearing  118  are located with their first locating position,  234 ,  244  facing the ball bearings  116 ,  118 . This allows the ball bearings  116 ,  118  to move to their outer most position allowing the first section  20  to pass by and be removed from the tool holder. 
         [0123]    The insertion of a first section of the SDS plus shank cutting tool will now be described. 
         [0124]    When the twisting sleeve  206  is twisted to its second end position, the first section  22  of the SDS shank is inserted into the tubular passage  114 . As the cams  232 ,  242  for the positioning ball bearings  116  and the locking ball bearing  118  are located with their first locating position  234 ,  244  facing the ball bearings  116 ,  118  the ball bearings  116 ,  118  can move to their outer most position allowing the first section  22  to pass by. The twisting force applied to twisting sleeve  206  is then removed, allowing the twisting sleeve  206  to rotate due to the biasing force of the spring  228 . The rotation of the twisting sleeve  206  causes the positioning sleeves  200  and locking sleeve  202  to rotate such that a second intermediate locating position  236 ,  246  of the cams  232 ,  242  face and engage with the ball bearings  116 ,  118 . When the second locating positions  236 ,  246  are in engagement with the ball bearings  116 ,  118 , the positioning ball bearings  116  are urged into engagement with the sides of the first section  22  and the locking ball bearing  118  engages with an axial recess  12 . The positioning ball bearings  116  prevent movement of the first section  22  in a direction perpendicular to the longitudinal axis of the cutting tool. The locking ball bearing  118  axially locks the first section  22  within the tubular passage  114 . Rotational movement of the tool holder is transferred to the first section  22  via ribs  150  formed inside of the tubular passage  114  which engage with the grooves  10  in the first section  22 . 
         [0125]    In order to release the first section  22  of the SDS plus shank from the tool holder, the twisting sleeve  206  is rotated against the biasing force of the spring until it is located in its first end position. When the twisting sleeve  206  is in this position, the cams  232 ,  242  for the positioning ball bearings  116  and the locking ball bearing  118  are located with their first locating position  234 ,  244  facing the ball bearings  116 ,  118 . This allows the ball  116 ,  118  bearings to move to their outer most position allowing the first section  22  to pass them by and be removed from the tool holder. 
         [0126]    The third embodiment of the tool holder will now be described with reference to  FIGS. 22 to 29 . Where the same features are present in third embodiment, which were present in the first, the same reference numbers have been used. 
         [0127]    The tool holder comprises the front end  102  of the spindle, a first inner sleeve  104  and a second outer sleeve  106 . 
         [0128]      FIG. 23  shows the tubular front end  102  of the spindle  100  which is formed by a wall of uniform thickness except for a fat surface  300  formed on one side along the length at the front end  102 . The front end  102  comprises seven circular apertures  108 , 110 ,  112  formed through the side walls of the front end  102 . The apertures  108 ,  110 ,  112  are arranged in two sets of three  108 ,  112  with the seventh  110  located between the two sets  108 ,  112 . Each set  108 ,  112  of three comprises three apertures located at the same axial position as each other along the spindle and arranged angularly about the longitudinal axis of the front end  102  at 120 degrees relative to each other in a symmetrical fashion. The apertures  108 ,  112  in each set are angularly aligned with the apertures in the other set  108 ,  110 . The diameter of each aperture  108 ,  112  in both sets are all the same as each other. The seventh aperture  110  is located axially between the two sets  108 ,  112  and angularly between two adjacent apertures in each set. The diameter of the seventh aperture is slightly larger than that of the six apertures in the two sets  108 ,  112 . 
         [0129]    Six positioning ball bearings  116  are located within the two sets  108 ,  112  of three apertures, each having the same diameter. The diameter of the cross section of each of the six apertures  108 ,  112  is slightly reduced at the entrance to the six apertures  108 ,  112  formed in the inner wall of the front end  102  where the apertures  108 ,  112  meet the tubular passage  114  to prevent the positioning ball bearings  116  from exiting the apertures  108 ,  112  and entering the tubular passage  114  whilst allowing part of the sides of positioning ball bearings  116  to project into the tubular passage  114  from the apertures. The diameter of each of the support ball bearings  116  is greater than the thickness of the wall of the front end  102  and therefore a part of the sides of the positioning ball bearings  116  either project into the tubular passage  114  or project radially outwardly from the front end  102 . 
         [0130]    A seventh locking ball bearing  118  is located within the seventh aperture  110 . The diameter of the seventh ball bearing  118  is larger than that of the six positioning ball bearings  116 . The diameter of the cross section of each of the seventh aperture  110  is slightly reduced at the entrance to the seventh aperture  110  formed in the inner wall of the front end  102  where the aperture  110  meets the tubular passage  114  to prevent the ball bearing  118  from exiting the aperture  110  and entering the tubular passage  114  whilst allowing part of the side of the locking ball bearing  118  to project into the tubular passage  114  from the aperture  110 . The diameter of the ball bearing  118  is greater than the thickness of the front end  102  and therefore a part of the side of the ball bearing  118  either projects into the tubular passage  114  or projects radially outwardly from the front end  102 . 
         [0131]      FIG. 24  shows the first inner sleeve  104  mounted on the front end  102 . The first inner sleeve  104  can axially slide along the front end  102 . However, the first inner sleeve has a flat inner surface  302  which engages that of the front end  102  of the spindle. The engagement of the flat surfaces  300 ,  302  prevents the first inner sleeve  104  from rotating around the front end  102 . 
         [0132]    The first inner sleeve  104  comprises seven holes  120 ,  122 ,  124  formed through the side walls of the first inner sleeve. The holes  120 ,  122   124  are arranged in two sets of three  120 ,  124  with the seventh  122  located between the two sets  120 ,  124 . 
         [0133]    Each set  120 ,  124  of three comprises three holes located at the same axial position as each other along the sleeve  104  and arranged angularly about the axis of the first inner sleeve  104  at 120 degrees relative to each other in a symmetrical fashion. The holes  120 ,  124  in each set are angularly aligned with the holes in the other set  120 ,  124 . The shape of the cross section of the six holes  120 ,  124  is that of an oval with the longer side extending axially along the inner sleeve  104 . The width of the holes  120 ,  124  in the lengthwise direction remains substantially constant and is that same as that of the diameter of the apertures  108 ,  112  for the positioning ball bearings  116  in the front end  102 . The dimensions of each hole  120 ,  124  in both sets are all the same as each other. The location of the holes  120 ,  124  on the first inner sleeve  104  correspond to those of the apertures  108 ,  112  for the positioning ball bearings  116  in the front end  102  of the spindle  102  so that, when the first inner sleeve  104  is in a particular axial position on the front end  102 , the holes,  120 ,  122 ,  124  and apertures  108 ,  110 ,  112  become aligned. 
         [0134]    The seventh hole  122  is located axially between the two sets  120 ,  124  and angularly between two adjacent holes in each set. The shape of the cross section of the seventh hole  122  is that of a rectangle with the longer side extending circumferentially around the inner sleeve  104 . The width of the holes  120 ,  124  in the lengthwise direction remains substantially constant and is slightly larger than that of the diameter of the seventh aperture  110  in the front end  102 . 
         [0135]    The second outer sleeve  106  is rigidly mounted onto the first inner sleeve  104 . Formed in the inner wall  130  of the outer sleeve is a radial groove  132  as best seen in  FIG. 25 . The depth of the groove  132  across the width of the groove  132  in an in axial direction of the outer sleeve  106  increases in the forward direction (as shown in  FIG. 26B ), the shape of the cross section of the width of the grove  132  remaining constant along the length of the groove  132  around the inner wall of the second outer sleeve  106 . When the second outer sleeve  106  is mounted on the first inner sleeve  104 , the groove  132  aligns with and faces towards the seventh hole  122  in the inner sleeve. The width of the groove  132  is greater than the width of the seventh hole  122 . 
         [0136]    A spring  134  is sandwiched between a washer  304  which abuts against a shoulder  136  on the spindle  100  and the base of a circular groove  306  formed inside of the outer sleeve  106 , biasing the inner and outer sleeves  104 ,  106  in a forward direction. 
         [0137]    The seventh hole  122  aligns with the seventh aperture  110  when the inner and outer sleeves  104 ,  106  are at a rearward axial position on the front end  102 . 
         [0138]    The inner and outer sleeves  102  can be axially slid between one of two axial end positions on the front end  102 , a first rearward axial position where the seventh hole  122  in the inner sleeve  104  is aligned with the seventh aperture  110  of the front end  102  and a second forward position where the seventh hole  122  in the inner sleeve  104  is offset relative to the seventh aperture  110  of the front end  102 . When the inner and outer sleeves  104 ,  106  are axially slid to the rearward axial end position on the front end  102 , the six apertures  108 ,  112  of the front end  102  and the six holes  120 ,  124  of the inner sleeve  104  are also aligned. When the inner and outer sleeves  102  are axially slid to the forward axial end position on the front end  102 , the six apertures  108 ,  112  of the front end  102  and the six holes of the inner sleeve are off set. Similarly, when the inner and outer sleeves  102  are axially slid to the forward axial end position on the front end  102 , the seventh aperture  110  of the front end  102  and the seventh hole  122  of the inner sleeve are off set. 
         [0139]    When all the holes  120 ,  122 ,  124  are aligned with the apertures  108 ,  110 ,  112  when the sleeves are in their rearward axial position, a part of the side of the ball bearings  116 ,  118  can either project from the apertures  108 ,  110 ,  112  into the tubular passage  114  or project radially outwardly from the apertures  108 ,  110 ,  112  in the front end  102  and into the holes  120   122 ,  124  and groove  132 . When the holes  120 ,  122 ,  124  are offset relative the apertures  108 ,  110 ,  112  when the sleeves are in their forward axial position, a part of a side of the ball bearings  116 ,  118  projects from the apertures  108 ,  110 ,  112  into the tubular passage  114  as are prevented from projecting radially outwardly from the apertures  108 ,  110 ,  112  in the front end  102  by the inner wall of the inner sleeve  104 , the inner wall of the inner sleeve  104  holding the ball bearings  116 ,  118  in their inner position. 
         [0140]    The insertion of a first section of the hex shank cutting tool will now be described with reference to  FIGS. 26 and 27 . 
         [0141]    When the inner and outer sleeves  104 ,  106  are slid to their rearward position against the biasing force of the spring  134 , the first section  20  of the hex shank is inserted into the tubular passage  114 . In the rearward position, all of the apertures  108 ,  110 ,  112  and the holes  120 ,  122   124  are aligned and therefore, the ball bearings  116 ,  118  can move to their outer most positions, allowing the first section to pass by. The force applied to inner and outer sleeves  104 ,  106  is then removed, allowing the inner and outer sleeves  104 ,  106  to slide forward to their forward position due to the biasing force of the spring  134 . When the sleeves  104 ,  106  are in their forward position, the holes  108 ,  110 ,  112  and apertures  120 ,  122 ,  124  are offset. When they are off set, the ball bearings  116 ,  118  are urged inwardly and held in this position, the positioning ball bearings  116  engaging with the flat surfaces  140  of sides of the first section  20  and the locking ball bearing  118  engaging with the groove  6 . The spring  234  holds the sleeves in their forward position, ensuring the holes  108 ,  110 ,  112  and apertures  120 ,  122   124  are offset and therefore locking the ball bearings  116 ,  118  in their inner position. The positioning ball bearings  116  prevent movement of the first section in a direction perpendicular to the longitudinal axis of the cutting tool. The locking ball bearing  118  axially locks the first section  20  within the tubular passage  114 . Rotational movement of the tool holder is transferred to the first section via the positioning ball bearings  116  and their engagement with the flat surfaces  140  of the first section  20 . 
         [0142]    In order to release the first section of the hex shank from the tool holder, the inner and outer sleeves are slid rearwardly against the biasing force of the spring until it is located in its rearward end position. When the sleeves are in this position, the apertures and holes are aligned, allowing the ball bearings to move to their outer most position allowing the first section to pass by and be removed from the tool holder. 
         [0143]    The insertion of a first section of the SDS plus shank cutting tool will now be described with reference to  FIGS. 28 and 29 . 
         [0144]    When the inner and outer sleeves  104 ,  106  are slid to their rearward position, the first section  22  of the SDS shank is inserted into the tubular passage  114 . As the apertures  108 ,  110 ,  112  and the holes  120 ,  122 ,  124  are aligned, the ball bearings  116 ,  118  can move to their outer most position allowing the first section  222  to pass by (as shown in  FIGS. 28A to 28D ). The force applied to the inner and outer sleeves  104 ,  106  is then removed, allowing the inner and outer sleeves  104 ,  106  to slide forward due to the biasing force of the spring  134 . The inner and outer sleeves  104 ,  106  slide to an intermediate position between the rearward position and the forward position (as shown  FIGS. 29A  top  29 D). In this position, the six apertures  108 ,  112  for the positioning ball bearings  116  and the six corresponding holes  120 ,  124  remain aligned. As such, they positioning ball bearings  116  can be located in their radially outer position in engagement in the sides of the first section  22  of the shank. However, the seventh aperture  110  and seventh hole  122  become partially offset, urging the locking ball bearing  118  into the axial recess  12  of the first section. However, as the seventh aperture  110  and seventh hole  122  are only partially offset, the locking ball bearing  118  is urged to a lesser depth than when they are totally offset. The locking ball bearing  118  is held in its inner position by the force of the spring  134 . The positioning ball bearings  116  prevent movement of the first section in a direction perpendicular to the longitudinal axis of the cutting tool. The locking ball bearing  118  axially locks the first section within the tubular passage  118  (whilst allowing limited axial movement as the locking ball bearing  118  can slide within the axial recess  12 ). Rotational movement of the tool holder is transferred to the first section  22  via ribs  150  formed inside of the tubular passage  114  which engage with the grooves  10  in the first section  22 . 
         [0145]    In order to release the first section  22  of the SDS plus shank from the tool holder, the sleeves  104 ,  106  are slid back against the biasing force of the spring  134  until it is located in its rearward position. When the sleeves  104 ,  106  are in this position, the holes  108 ,  110 ,  112  and apertures are all aligned, allowing the ball bearings  116 ,  118  to move to their outer most positions allowing the first section  22  to pass them by and be removed from the tool holder. 
         [0146]    Whilst the three embodiments describe tool holders which are integrally formed with the spindle of the hammer drill, it will be appreciated that embodiments of the invention can comprise tool holders which are constructed as separate discreet devices capable of being attached to a hammer drill. 
         [0147]    Whilst the three embodiments of tool holder have been described in relation to holding hex shanked and a SDS plus shanked cutting tools, it will be appreciated that such a design can be utilized on other designs of shank.