EP1446266B1

EP1446266B1 - Tool holder for hammer

Info

Publication number: EP1446266B1
Application number: EP02781180A
Authority: EP
Inventors: Norbert Hahn; Andreas Hanke
Original assignee: Black and Decker Inc
Current assignee: Black and Decker Inc
Priority date: 2001-09-12
Filing date: 2002-09-09
Publication date: 2009-04-01
Anticipated expiration: 2022-09-09
Also published as: GB0121955D0; ATE427192T1; WO2003022531A1; EP1446266A1; DE60231824D1

Abstract

A tool holder (2) for a powered hammer comprising a tube-like tool holder body (66) which has a forward end for non-rotatably receiving a hexagonally cross-sectioned shank (3) of a hex-shanked tool. The forward ha an axially extending slot (10). A locking body (54) extends through the slot and is moveable between a radially inward locked position in which it engages an axial closed groove (88) in the tool and a radially outward release position. A locking member (52) and associated sleeve (50) are manually axially slidable to move locking body (54) between the locked and release positions. Should the tool be inserted in an incorrect orientation, the locking body (54) is trapped by the shank (3) of the tool in its release to its locked position. This provides a clear visual indication that the tool has been inserted incorrectly.

Description

This invention relates to a tool holder for a hand held electrically powered hammer and to a hand held electrically powered hammer incorporating such a tool holder. In particular this invention relates to tool holders for demolition hammers.
Such hammers generally comprise a housing within which is located an electric motor and a gear arrangement for converting the rotary drive of the motor to a reciprocating drive to drive a piston within a hollow spindle or cylinder, which spindle is located within the hammer housing. A ram is located in front of the piston within the spindle so as, in normal operating conditions, to form a closed air cushion within the spindle between the piston and the ram. The reciprocation of the piston reciprocatingly drives the ram via the air cushion. A hollow piston arrangement may be used. A beatpiece is generally located within the spindle and transmits repeated impacts that it receives from the ram to a tool or bit releaseably mounted for limited reciprocation in front of the beatpiece in a tool holder portion. The impacts on the tool or bit are transmitted to a workpiece against which the tool or bit is pressed in order to break up or make a bore in the workpiece.
Some hammers may also be employed in combination impact and drilling mode in which the tool holder, and hence the tool inserted therein, will be caused to rotate at the same time as the tool is struck by the beatpiece. The present invention is also applicable to such hammers.
A common form of chiselling tool or bit, for performing heavy duty work is a so called hex-shanked tool or bit. An example of the shank end, ie. the end inserted into the tool holder portion of a hammer is shown in Figures 6a to 6d. The portion of the tool which is locked within the tool holder of the hammer has a hexagonal transverse cross-section. The bore in the tool holder which receives the hexagonal shank portion generally has a corresponding hexagonal transverse cross-section. Accordingly, the tool can be fitted within the tool holder in one of six orientations. The hexagonal portion is formed on one of its flats with an axially extending groove which is closed at both its ends. The hex-shanked tool can be locked within the tool holder by a locking body of the tool holder engaging in the groove to enable limited reciprocation of the tool within the tool holder. Traditionally, a cross bolt arrangement is used to lock the tool within the tool holder. The bolt extends tangentially of the toolholder to engage the groove in the tool. The bolt can be retracted or pivoted outwardly to allow insertion or removal of the tool. Such tool holders do not provide any damping of the forward impact from the tool when the hammer enters idle mode.
It is advantageous to provide a type of tool holder comprising a radially shiftable locking body which can be releaseably locked within the groove of a tool inserted into the tool holder. Such a tool holder is ergonomic and can be designed to provide damping of the forward impact from the tool when the hammer enters idle mode. This reduces the maximum impact force which has to be withstood by the tool holder main body.
However, so far such tool holders have generally only been used in relation to smaller hammers which use SDS-type bits or tools. The SDS-type bits have a tool shank which is insertable into the bit holder in one orientation only because the bits are provided with suitably positioned axially extending grooves, open at their rearward end in the tool shank which co-operate with radially inwardly extending splines in the bore of the tool holder. As stated above, for larger hammers, the standard tool shank is the hex-shanked tool described above and the problem arises that it is possible to insert a hex-shanked bit completely into a tool holder in a wrong orientation so that the axial groove in the tool does not face the locking body of the tool holder.
It is known from DE-A-7429418U to have a tool holder for a hex-shanked tool in which a single locking body can be locked in a radially inward position by a rotatable cam ring to engage the axial groove in the tool. The cam ring can be rotated to an unlocked position in which a pocket in the cam ring lies radially outwardly of the locking body to allow the locking body to move radially outwardly for a hex-shanked tool to be inserted into or removed from the tool holder. If the hex-shanked hit is inadvertently inserted into the tool holder in the wrong orientation, then the cam ring is prevented from being rotated back into its locked position. However, there is no visual indication on the external surface of the tool holder that can be observed by the user to indicate that the tool is not firmly locked within the tool holder. In addition the design of tool holder in DE-A-7429418U does not damp the forward impact from the tool on entry into idle mode.
The present invention aims to overcome at least some of the problems discussed above by providing an ergonomic design of tool holder with a radially moveable locking body suitable for use with a hex-shanked tool or bit and which prevents inadvertent insertion of the tool into the tool holder in the incorrect orientation for the locking body to engage the groove of the hex-shanked tool holder. The invention also aims to provide such a tool holder design which can absorb the forward impact from the tool on entry into idle mode.
According to an emodiment of the present invention there is provided a tool holder for an electrically powered hammer comprising the combined features of claim 1.
In the arrangement according to the present invention the tool holder release sleeve has to be manually axially shifted in order to enable a hex-shanked bit to be inserted into the forward end of the tool holder body. Then if the hex-shanked bit is inadvertently inserted into the forward end of the tool holder in the incorrect orientation, so that the locking body cannot engage in the groove in the tool to lock the tool in the tool holder, the user of the tool is warned by the continued positioning of the manually actuable tool holder release sleeve in its released position. This is clearly visible to the user of the hammer because in its release position the release sleeve is axially shifted from its locked position and so is located in a different axial position with respect to the tool holder of the hammer The user can then remove the tool and re-insert it in the correct orientation in which the locking body engages the groove to securely lock the tool within the tool holder. When the tool is correctly inserted and locked within the tool holder the release sleeve can shift axially into its locked position.
In a preferred version of the tool holder the rearward end of the slot in the forward end of the tool holder body prevents the locking body from moving to a radially outward position rearward of the locking member which means that the tool release sleeve has to be axially shifted manually to enable the locking body to move into a radially outward position to allow insertion of a tool.
An impact damping arrangement which is mounted on the tool holder body against axially forward movement is located forwardly of the locking bodv to prevent the locking body from moving into a radially outward position forward of the locking member when the locking member is in its locked position. This means that the tool release sleeve has to be axially shifted manually to enable the locking body to move into a radially outward position to allow insertion of a tool. In addition when the hammer enters its idle mode when the tool is removed from a workpiece, the forward impact from the tool is transferred to the locking body and the forward impact from the locking body is damped by the impact damping arrangement before it is transmitted to the tool holder body. This means that the maximum impact that has to be absorbed by the tool holder body is significantly reduced.
Preferably, the tool release sleeve is biased by at least one spring member into the locked position, thus after the sleeve has been axially shifted into its release position and a hex-shanked bit correctly inserted into the tool holder body, when released by a user the sleeve is urged back into its locked position by the spring member(s). The tool holder according to the preferred embodiments of the present invention may additionally include a biasing member for biasing the locking body forwardly within the slot. The biasing force provided by the biasing member helps to guide the locking body between its radially outward and inward positions. The biasing member can also be used to bias the locking member forwardly and thereby to biases the tool release sleeve forwardly.
In a preferred embodiment the tool release sleeve is axially rearwardly slideable to axially shift the locking member from its locked to its release position. In this case the tool release sleeve can be biased forwardly into its locked position.
The locking member may be a locking ring which fits non-rotatably around the forward end of the tool holder body and the tool release sleeve may be non-rotatably mounted on the locking ring to thereby non-rotatably fix the tool release sleeve onto the tool holder body. The use of a locking ring provides a robust locking member for absorbing impacts transmitted from the locking body during use of the hammer when the locking ring locks the locking body in the groove in the hex-shanked tool.
To improve guidance of the locking body between its radially inward and radially outward positions it is preferred that the radially outermost surface of the locking body engages the radially innermost surface of the locking member in the locked position and a sloping surface on the locking body which extends radially inwardly of the radially outermost surface of the locking body engages a sloping surface of the locking member which extends radially outwardly of the radially innermost surface of the locking member in the release position. The use of the sloping surfaces prevents the locking body becoming jammed in its movement between its radially inward and radially outward position. The sloping surfaces may be forward and/or rearward facing.
A preferred feature of the tool holder is that the forward movement of the locking body within the slot is limited by a damping arrangement which arrangement is axially fixed against forward movement on the forward portion of the tool holder body. When the hammer moves from operating mode to idle mode there is a high forward impact on the locking body from the last forward impact from the tool and the damping arrangement damps this impact as it transmits this impact from the locking body to the tool holder body. This means that the maximum impact force received by the tool holder body can be reduced. The damping arrangement may comprise a metal ring located directly in front of the locking body, a resilient ring for damping the impact, located forwardly of the metal ring and a fixing ring located forwardly of the resilient ring by which axially forward movement of the damping arrangement on the tool holder body is limited. The forward end of the tool holder may be of reduced diameter and may have a radially inward facing surface which has a hexagonal transverse cross-section.
According to a second embodiment of the present invention there is provided an electrically powered hammer, preferably having a pneumatic striking mechanism comprising a piston and ram located so as to reciprocate within a hollow spindle, and additionally including a tool holder according to any one of the preceding claims. The tool holder may be located forward of and co-axially with the hollow spindle.
One form of rotary hammer incorporating a tool holder according to the present invention will now be described by way of example with reference to the accompanying drawings in which:

Figure 1 shows a longitudinal cross section through a tool holder of a demolition hammer according to the present invention with a tool locked within it;
Figure 2 shows a perspective partially cut away view of the tool holder shown in Figure 1;
Figure 3 shows a longitudinal cross section through the tool holder of Figures 1 and 2 with a hex-shanked tool inserted in an incorrect orientation;
Figure 4 shows a perspective partially cut away view of the tool holder shown in Figure 3;
Figure 5 shows a partially cut-away longitudinal cross-section of a demolition hammer having a tool holder as shown in Figures 1 to 4;
Figure 6A shows a first perspective view of the shank of a hex-shanked tool or bit with the axially extending groove uppermost;
Figure 6B shows a second perspective view of the shank of a hex-shanked tool or bit with the axially extending groove facing sideways;
Figure 6C shows a third perspective view of the shank of a hex-shanked tool or bit with the axially extending groove uppermost with the remote faces of the shank indicated by dotted lines; and
Figure 6D shows a view of the end of the shank of a hex-shanked tool or bit which end is inserted into the tool holder portion of a hammer;

A demolition hammer incorporating a tool holder (2) according to the present invention is shown in Figure 5. The hammer comprises an electric motor (13), a gear arrangement and a piston drive arrangement which are housed within a metal gear housing (not shown) surrounded by a plastic housing (4). A rear handle housing incorporating a rear handle (6) and a trigger switch arrangement (8) is fitted to the rear of the housing (4). A cable (not shown) extends through a cable guide (10) and connects the motor to an external electricity supply. Thus, when the cable is connected to the electricity supply and the trigger switch arrangement (8) is depressed the motor (2) is actuated to rotationally drive the armature of the motor.
The motor pinion rotatingly drives a first gear wheel of an intermediate gear arrangement which is rotatably mounted on a spindle, which spindle is mounted in an insert to the gear housing. The intermediate gear has a second gear wheel which rotatingly drives a drive gear. The drive gear is non-rotatably mounted on a drive spindle (5) which spindle is rotatably mounted within the gear housing. A crank plate (30) is non-rotatably mounted at the end of the drive spindle (5) remote from the drive gear, which crank-plate is formed with an eccentric bore for housing an eccentric crank pin (32). The crank pin (32) extends from the crank plate into a bore at the rearward end of a crank arm (34) so that the crank arm (34) can pivot about the crank pin (32). The opposite forward end of the crank arm (34) is formed with a bore through which extends a trunnion pin (36) so that the crank arm (34) can pivot about the trunnion pin (36). The trunnion pin (36) is fitted to the rear of a piston (38) by fitting the ends of the trunnion pin (36) into receiving bores formed in a pair of opposing arms which extend to the rear of the piston (38). The piston is mounted in a cylindrical hollow spindle (40) so that it can reciprocate within the hollow spindle. An O-ring seal is fitted in an annular recess formed in the periphery of the piston (38) so as to form an air tight seal between the piston (38) and the internal surface of the hollow spindle (40).
Thus, when the motor (13) is actuated, the armature pinion rotatingly drives the intermediate gear arrangement via the first gear wheel and the second gear wheel of the intermediate gear arrangement rotatingly drives the drive spindle via the drive gear. The drive spindle rotatingly drives the crank plate (30) and the crank arm arrangement comprising the crank pin (32), the crank arm (34) and the trunnion pin (36) convert the rotational drive from the crank plate (30) to a reciprocating drive to the piston (38). In this way the piston (38) is reciprocatingly driven back and forth along the hollow spindle (40) when the motor is actuated by a user depressing the trigger switch (8).
A ram (58) is located within the hollow spindle (40) forwardly of the piston (38) so that it can also reciprocate within the hollow spindle (40). An O-ring seal is located in a recess formed around the periphery of the ram (58) so as to form an air tight seal between the ram (58) and the spindle (40). In the operating position of the ram (58) a closed air cushion is formed between the forward face of the piston (38) and the rearward face of the ram (58). Thus, reciprocation of the piston (38) reciprocatingly drives the ram (58) via the closed air cushion.
After a period of hammering, when the tool (3) fitted in the tool holder is removed from the workpiece, the hammer enters idle mode. With no workpiece to urge the tool rearwardly, the next forward impact from the ram (58) meets with no rearward resistance and the ram (58), beatpiece (64) and tool (3) move forwardly until the forward movement of the tool is halted by the engagment of the locking body (52) with the rearward end of the groove (88) in the tool. As the ram (58) moves forwardly in the hollow spindle (40) it passes over venting holes on the hollow spindle and the air cushion between the piston (38) and the ram (58) is vented. Thereafter, the ram (58) is no longer reciprocatingly driven by the piston (38). Some mechanism is generally employed for holding the ram (58) and/or beatpiece (64) in their forward positions until the tool (3) is again urged against a workpiece to urge the ram (58) and beatpiece (64) into their rearward working positions again in which the air cushion is closed. As indicated above on entry into idle mode the last forward impact from ram (58) to the beatpiece (64) is transmitted to the tool (3) which tool transfers the forward impact to the locking body (54) when the rearward end of the groove (88) impacts the rearward end of the locking body (54).
A beatpiece (64) is guided so that it can reciprocate within a tool holder body (66) which tool holder body is mounted at the forward end of the hammer housing co-axially with the spindle. The tool holder body is mounted within a flange (68) which is fitted to the main housing of the hammer by a plurality of bolts (not shown) which extend axially through receiving bores (70) in a collar located at the rearward end of the flange (68). The bolts extend into co-operating receiving screw threaded bores formed in the forward part of the main housing of the hammer. A hex-shanked hit or tool (3) can be releasably mounted within the tool holder body (66) so that the tool can reciprocate to a limited extent within the tool holder body (66). When the ram (58) is in its operating mode and is reciprocatingly driven by the piston (38) the ram repeatedly impacts the rearward end of the beatpiece (64) and the beatpiece (64) transmits these impacts to the rearward end of the tool (3) as is known in the art. These impacts are then transmitted by the tool (3) to the material being worked.
The tool holder (2) of the hammer of Figure 5 is shown in more detail in Figures 1 to 4. The tool holder (2) comprises a tube-like tool holder body (66). The tool holder body had a relatively large internal diameter cylindrical portion at its rearward end for housing the beatpiece (64) and a relatively small diameter hexagonally cross-sectioned portion at its forward end for receiving the shank of a hex-shanked tool (3) of the type shown in Figures 6A to 6D.
A single axially extending slot (10) is formed in the hexagonally cross-sectioned portion of the tool holder body (66) through which a single locking body (54) extends. The locking body (54) is prevented from radially outward movement by a locking ring (52) which extends around the hexagonally cross-sectioned portion of the tool holder body (66). The locking ring (52) has a radially inward facing face which has a generally hexagonal transverse cross-section, except for a recess in said face for accommodating the locking body (54). Due to the hexagonal transverse cross-section of the radially outwardly facing face of the hexagonally cross-sectioned portion of the tool holder body (66), the locking ring is non-rotatable on said portion of the tool holder body. The locking ring (52) has an irregularly shaped radially outwardly facing surface which is non-rotatably received within a co-operating recess of a tool release sleeve (50). The recess in the tool release sleeve (50) is formed by a rearwardly facing internal shoulder formed in the tool release sleeve. In this manner the tool release sleeve (50) is non-rotatably mounted on the tool holder body via the locking ring (52).
The locking body (54) and locking ring (52) are urged axially forwardly by a biasing sleeve (27) which has a recessed forward facing face (27a) with a raised rim (27b). The recessed forward face (27a) bears on the rearward end of the locking body (54) and the raised rim (27b) bears on the locking ring (52). The biasing sleeve (27) is urged forwardly by a first small diameter compression spring (26). A second larger diameter compression spring (24) bears against the tool release sleeve (50) to urge it axially forwardly. The tool holder release sleeve (50) is also forwardly biased by the biasing sleeve (27) via the locking ring (52). The forward end (24a) of the compression spring (24) is mounted within an axially extending recess formed in the tool release sleeve (50). The springs (24, 26) are mounted at their rearward ends on parts of an arrangement for adjusting the orientation of the tool holder body (66) within the flange (68), which arrangement comprises an actuation sleeve (12) and a lock ring (4) and is not described further here.
The forward movement of the locking body (54) is limited by a damping mechanism for damping the forward impact to the locking body (54) when the hammer enters idle mode. The damping arrangement comprises an axially tapered metal ring (72) located in front of the locking body (54) and the locking ring (52) which is non-rotatably mounted over the hexagonal portion of the tool holder body (66). In front of the metal ring (72) is located a resilient ring (74) which is also mounted over the hexagonal portion of the tool holder body (66). The rings (72, 74) are held in place against axially forward movement by a washer (78) which is non-rotatably fitted over the hexagonal portion of the tool holder body (66) and held in place by a snap ring (79) which is fitted into an annular recess (80) formed in the radially outwardly facing surface of hexagonal portion of the tool holder body (66). A resilient rubber nose ring (82) is snap fitted over the forward portion of the hexagonal portion of the tool holder body (66) so that part of the nose ring (82) is retained in an annular recess (84) formed in the radially outwardly facing surface of hexagonal portion of the tool holder body (66). The locking ring (52) is held against axially forward movement by the damping mechanism (72, 74, 78) and by the tool release sleeve (50) which is itself prevented against axially forward movement by the resilient ring (74) of the damping mechanism and by the nose ring (82).
As described above, when the hammer enters idle mode, the last impact is transmitted to the locking body (54). This impact is transmitted via the metal ring (72), the resilient ring (74) and the washer (78) to the tool holder body (66). The resilient ring damps this impact, so that the impact transmitted to the tool holder body is less that the impact transmitted to the locking body (54). This means that the maximum force that has to be withstood by the tool holder body is reduced, which eases the design constraints regarding for example, materials and dimensions, for the tool holder body.
The axially extending slot (10) formed in the hexagonal portion of the tool holder body (66) extends only a small distance rearwardly of the rearward end of the locking body (54). This means that the locking body cannot be pushed rearwardly of the locking ring (52) when a tool (3) is inserted into the tool holder body (66) and so cannot be moved radially outwardly automatically by the insertion of a tool. Instead to insert a hex-shanked tool the locking sleeve (50) must be moved axially rearwardly against the force of the springs (24,26) into the position shown in Figures 3 and 4. When the sleeve (50) is moved rearwardly, a pocket (42) formed within the sleeve (50) is moved radially outwardly of the locking body (54), thus enabling the locking body (54) to move radially outwardly to allow a hex shanked tool to be fitted into the tool holder body (66). If the hex-shanked tool is inserted into the tool holder in the correct orientation, then once the locking groove (88) in the hex-shanked tool (3) is aligned with the locking body (54), the sleeve (50) can be released and moves forwardly into its locked position by the action of the springs (24,26). As the sleeve moves forwardly (to the left in the Figures) into its locked position the locking body (54) is pushed radially inwardly into its locked position by the locking ring (52) due to the engagement of the sloped edges of the locking ring (52) and locking body (54). In the locked position the locking body (54) and the tool release sleeve (50) are in the position shown in Figures 1 and 2. The locking body (54) is maintained in the locking groove (88) of the hex shanked tool by the locking ring (52).
If the hex-shanked tool is inserted in the incorrect orientation, as shown in Figures 3 and 4, when the sleeve (50) is moved rearwardly a pocket (42) formed within the sleeve (50) is moved radially outwardly of the locking body (54), thus enabling the locking body (54) to move radially outwardly to allow a hex shanked tool to be fitted into the tool holder body (66), as before. However, a flat surface (89) of the shank of the hex-shanked tool will be facing the locking body (54). Thus, the locking body (54) is unable to move radially inwardly from its location in the pocket (42) formed within the sleeve (50). The location of the locking body (54) in the pocket (42) prevents forward motion of the tool release sleeve (50) and so when the tool release sleeve (50) is released by a user, it remains in its rearward position, as shown in Figures 3 and 4. The tool release sleeve (50) will not move forwardly into its unlocked position unless the orientation of the tool is correct. This is because if the hex-shanked tool is not correctly oriented there is no locking groove (88) radially inwardly of the locking body (54) for the locking body (54) to move into. In an incorrect orientation a flat side (89) of the hex shanked tool prevents the locking body (54) from moving radially inwardly from its locked position and so the locking body is locked in the pocket (42) in the sleeve (50) by a flat side of the tool. This means that the locking body (54) blocks the forward movement of the tool release sleeve (50). The user will notice that the tool release sleeve (50) has not moved forwardly into its locked position, firstly because the user will notice that the sleeve (50) has not moved forwardly on release and secondly because it will remain positioned axially shifted from its locked position. A user is alerted that the tool release sleeve (50) remains in its unlocked position by the different appearance of the tool holder, in that the washer (78) and resilient ring (74) will be exposed at the front of the tool release sleeve (50) and the rear of the tool release sleeve will cover the forwardly extending portion of the spindle orientation sleeve (12). An indication of the difference between the appearance of the tool holder when a tool is correctly inserted and locked within it and when a tool is incorrectly inserted and not locked within it can be appreciated by comparing Figures 2 and 4.

Claims

A tool holder (2) for an electrically powered hammer comprising:
a tube-like tool holder body (66) which can be adapted to fit or be formed at the front of the hammer and having a forward end for non-rotatably receiving a hexagonally cross-sectioned shank (3) of a hex-shanked tool or bit wherein said forward end is formed with a single axially extending slot (10);

a single locking body (54) extending through said slot for releasably engaging an axially extending closed groove (88) formed in a hex-shanked tool fitted in said forward end of the tool holder body (66);

a locking member (52) which in a locked position locks the locking body in a radially inward position in which the locking body is engageable with the groove in the tool and in a release position allows the locking body to move into a radially outward position to allow a tool to be inserted into or removed from the forward end of the tool holder body;

a manually actuable tool release sleeve (50) which is moveable to move the locking member from its locked to its release position to enable insertion of a tool and to enable removal of a tool from the forward end of the tool holder body;

the manually actuable tool release sleeve (50) is axially slideable to axially shift the locking member (52) from its locked to its release position so that when a hex-shanked tool is inserted into the forward end of the tool holder body in an incorrect orientation, the locking body (54) is trapped by the shank of the tool in its radially outward position and so prevents axial movement of tool release sleeve (50) from its release to its locked position, characterised in that an impact damping ring (72) which is mounted on the tool holder body (66) against axially forward movement is located forwardly of the locking body (54) and prevents the locking body (54) from moving into a radially outward position forward of the locking member (52) when the locking member (52) is in its locked position.
A tool holder according to claim 1 wherein the rearward end of the slot (10) in the forward end of the tool holder body (66) prevents the locking body (54) from moving to a radially outward position rearward of the locking member (52).
A tool holder according to any one of the preceding claims wherein the tool release sleeve (50) is biased by at least one spring member (24, 26) into the locked position.
A tool holder according to any one of the preceding claims additionally including a biasing member (27, 27') for biasing the locking body (54) forwardly within the slot (10).
A tool holder according to claim 4 wherein the biasing member (27, 27') biases the locking member (52) forwardly and thereby biases the tool release sleeve (50) forwardly.
A tool holder according to any one of the preceding claims wherein the tool release sleeve (50) is axially rearwardly slideable to axially shift the locking member (52) from its locked to its release position.
A tool holder according to claim 6 when dependent on claim 4 wherein the tool release sleeve (50) is biased in the forward direction.
A tool holder according to any one of the preceding claims wherein the locking member is a locking ring (52) which is non-rotatably mounted around the forward end of the tool holder body (66).
A tool holder according to any one of the preceding claims wherein the radially outermost surface of the locking body (54) engages the radially innermost surface of the locking member (52) in the locked position and a sloping surface on the locking body which extends radially inwardly of the radially outermost surface of the locking body engages a sloping surface of the locking member which extends radially outwardly of the radially innermost surface of the locking member in the release position or positions.
A tool holder according to claim 9 wherein the sloping surfaces are forward and/or rearward facing.
A tool holder according to any one of the preceding claims wherein the forward movement of the locking body (54) within the slot (10) is limited by a damping arrangement (72, 74, 78) which arrangement is axially fixed against forward movement on the forward portion of the tool holder body (66).
A tool holder according to claim 11 wherein the damping arrangement comprises a metal ring (72), a resilient ring (74) located forwardly of the metal ring and a fixing ring (78) located forwardly of the resilient ring (74).
A tool holder according to any one of the preceding claims wherein the forward end of the tool holder body is of reduced diameter.
A tool holder according to any one of the preceding claims wherein the forward end of the tool holder has a radially inward facing surface which has a transverse hexagonal cross-section.
An electrically powered hammer including a tool holder according to any one of the preceding claims.
A hammer according to claim 15 having a pneumatic striking mechanism comprising a piston and ram located so as to reciprocate within a hollow spindle.
A hammer according to claim 16 wherein the tool holder is located forward of and co-axially with the hollow spindle.