US3161242A

US3161242A - Rotary-hammer devices and tool element accessories therefor

Info

Publication number: US3161242A
Application number: US32759A
Authority: US
Inventors: Elmer F Etzkorn; Oliver O Amundsen
Original assignee: Skil Corp
Current assignee: Skil Corp
Priority date: 1960-05-31
Filing date: 1960-05-31
Publication date: 1964-12-15
Anticipated expiration: 1981-12-15
Also published as: CH397512A; GB969009A; DE1427753A1

Description

1964 E. F. ETZKORN ETAL 3,161,242

ROTARY-HAMMER DEVICES AND TOOL ELEMENT ACCESSORIES THEREFOR Filed May 51, 1960 2 Sheets-Sheet l 3-? Q Q 506/352 M 26/Zj75/Z BY 0Zwef0 dirzarzaifierz, WM W 1964 E. F. ETZKORN ETAL 3,

ROTARY-HAMMER DEVICES AND TOOL ELEMENT ACCESSORIES THEREFOR Filed May 31, 1960 2 Sheets-Sheet 2 mmvrons.

United States Patent Ofitice 3,161,242 Patented Dec. 15, 1964 3,161,242 RUTARY-HAMMER DEVICES AND TGOL ELEMENT AOCESSKBREES THEREFGR hner F. Etzitorn, Parh Ridge, and Oliver 0. Amundsen, Chicago, 111., assignors to Skil Corporation, Chicago,

11L, a corporation of Delaware Filed May 31, 1960, Ser. No. 32,759 Claims. (6]. 173-1t)9) The present invention relates to improvements in a hand operable rotary-hammer device, and more particularly to tool element accessories adapted for use in such a device.

It is an important object of the invention to provide an improved rotary-hammer device and new and novel one-piece tool elements for use in such a device.

Another object of the invention is to provide a series of one-piece tool elements for a rotary-hammer device wherein the shank portions of the tool elements are provided with suitable driving configurations whereby the tool elements may be rotated and reciprocated with a hammer-like action either separately or simultaneously.

A further object of the invention is to provide a series of new and novel one-piece tool elements of the character described wherein means are provided on the shank por tions of the tool elements for engagement by a tool element retainer member carried on the rotary-hammer device whereby to retain the tool elements in the device during reciprocal actuation thereof and when the tool elements are being withdrawn from the material being worked.

Certain other objects of the invention will, in part, be obvious, and will in part appear hereinafter.

For a more complete understanding of the nature and scope of the invention reference may now be had to the accompanying drawings wherein:

FIG. 1 is a generally longitudinal vertical section taken through the improved rotary-hammer device of the invention;

FIG. 2 is a fragmentary vertical section of the nose portion of the rotary-hammer device of FIG. 1 and show ing a percussion-type drill bit mounted in the device for combined rotary and hammering actions;

FIG. 3 is a horizontal section taken generally on line 3-3 of FIG. 2 and showing the operable and inoperable positions of the tool element retaining member in full and broken lines, respectively;

FIG. 4 is a vertical section similar to FIG. 2 showing a chisel-like tool element mounted in the nose of the device for hammering action only;

FIG. 5 is a horizontal section similar to FIG. 3 showing a star-drill mounted in the device for hammering action thereby, the retaining member being disposed in its inoperable position;

FIG. 6 is a vertical section similar to FIGS. 2 and 4 showing a drill chuck mounted in the device for rotary actuation only; and

FIG. 7 is a vertical section similar to FIGS. 2, 4 and 6 showing a tool element adapter mounted in the device for actuation thereby.

As illustrated in FIG. 1, a rotary-hammer device 19 embodying the invention is provided with a mulit-part housing including a tool-supporting housing portion 12, a gear housing portion 13, and a power unit supporting portion 14. A suitable handle 15 is secured between the housing portions 13 and 14.

The tubular housing portion 12 has a bearing 19 mounted in its 'outer end and a bearing 22 mounted in its inner end. A bevel gear 24 having a gear formation 25 is mounted in the bearing 22 for rotation about a horizontal axis. An open ended cylinder 26 which is disposed in the housing portion 12 has its outer end rotatably mounted in the bearing 19 and its inner end projecting through a bore formed in the bevel gear 24 in rotary driving engagement therewith. The cylinder 26, therefore, is rotatable in the housing portion 12 during rotation of the bevel gear 24. A drive member 32 having an axial through bore 30 provided with an internal hexagonal formation 33 is secured in the outer end of the cylinder 26. A non-rotatable collar-like nose member 38 having an internal hexagonal formation 39 formed therein is secured to the outer end of the housing portion 12. The outer surface of the nose member 38 is provided with a pair of diametrically opposite radial bores 41).

A tool element retainer member 42 of a heat treated steel wire construction is mounted on the nose member 38 for movement between an operable position as shown in full line in the drawings and an inoperable position as shown in broken line in FIG. 3 of the drawings. The retainer member 42 is characterized by a pair of spaced arms 43 having inwardly bent end portions 44 which are pivotally mounted in the radial bores 49 of the nose member 38. The opposite ends of the arms 43 are interconnected by a loop portion 45' adapted for retaining engagement with various new and novel tool elements in a manner to be described.

A free piston or striker member 48 is mounted in the rotatable cylinder 26 for reciprocation therein whereby to impart a hammer-like action to long shank tool elements mounted in the device 141 and having their shank portions projecting into the outer end of the cylinder 26. in the rotary-hammer device 10 illustrated in FIG. 1, the striker member 48 is pneumatically reciprocated through the reciprocal action of a power driven piston 50 in the inner end of the cylinder 26. In accordance with the pneumatic operation of the device 10, novel porting is provided. A series of relatively large exhaust ports 51 are formed in the cylinder 26 adjacent the outer end thereof. Theports 51 communicate with an expansion chamber 53 defined between the outer surface of the cylinder 26 and the inner surface of the tubular housing portion 12. A bleeder port 54 in the housing portion 12 connects the expansion chamber 53 to atmosphere. A relatively small diameter venting port 55 is formed in the cylinder 2s adjacent to and forwardly of the forwardmost position of the power driven piston 50. The portion is completed by a series of vacuum-counteracting ports 57 formed in the cylinder 26 and spaced a slightly greater distance from the inner end of the drive member 32 than the longitudinal length of the striker member 4-8. The pneumatic operation of the rotary-hammer device 16 will be described hereinafter. Preferably, the small bleeder port 54 is formed adjacent the inner or rear end of the housing portion 12 away from the material-engaging end of the device 10 whereby to substantially eliminate the problem of dust and other particles, kicked up during operation of the device, entering the sleeve-like expansion chamber 53.

The power piston 50, which includes an internal lubricating wick 59, is reciprocated by a driven crank arm 60 which is pivotally connected to the piston 50 by a dowel pin 61 mounted in the piston 50 and extending through a bore formed in the end of the crank arm 60. The re ciprocal power piston 50 and the rotatable cylinder 26 are both driven by an electric motor 63 which is mounted by suitable fastening means in the housing portion 14 and which has a vertically disposed drive shaft 64. The drive shaft 64 is rotatably supporting in bearings 65 and 66 with the upper end of the shaft 64 projecting somewhat into the housing portion 13. Preferably, a fan blade 67 is mounted on the drive shaft 64. The power circuit for the electric motor 63 is a standard type circuit Well known in the art and is, therefore, not shown and described in detail herein. A power cord 68 and an tooth formation 70 which is meshed in driving engagement with a pinion gear 71 which is keyedto a shaft 72, which shaft is rotatably supported in bearings 73 and 74. An enlarged flat disc member 75 is provided on the upper end of the shaft '72. An upstanding post 76 is (115- posed eccentrically'on the disc member 75 relative to the axis of rotation of the shaft 72. The opposite end of the crank arm 60 is bored whereby to permit rotatable mounting thereof on the upstanding post '76; by means of asuitable bearing 77. Thus, during operation of the motor 63, the piston 50 is reciprocated in the inner end of the cylinder 26 in a manner'well known in the art.

A' pinion gear 78 is keyed to the lower portion of a shaft 79 which is rotatably supported in parallel relationship to the shaft '72 in bearings 80 and 81. The pinion gear 78 is meshed in driving engagement with a gear formation 82 formed on the shaft 72 and a bevel gear formation 83 on the upper end of the shaft 79 is meshed in driving engagement with the gear formation,

'25 of the bevel gear 24. Thus, the cylinder 26, which is driven by the motor 63 through the described gear train, is simultaneously rotated as the piston 50 is re 'ciprocated therein.

In order to use standard tool elements in the rotaryhammer device illustrated in the drawings, it is necessary to provide tool adapters having specially designed shank portions for driving engagement with the .drive member 32 and for impact engagement by" the strike member 48. It has been determined that appreciable power loss results between such tool adapters and the rotary. driving engagement with the cylinder 26 and projecting into the cylnider 26 for impact engagement by the striker member 48, the drill .bit 85 will be simultaneously rotated and reciprocated with a hammer-like action during operation of the motor 63.

Each tool'element, such as the drill bit 85, is inserted into the nose end of the device 10 when the retainer member 42 is in its inoperable position, as indicated in broken line in FIG. 3, after which the retainer member '42 is pivoted into its operable position with the loop portion 45 thereof embracingly engaged in the annular groove 90.

In FIG. 4, a one-piece cold chisel 95 is shown mounted in the rotary-hammer device 10 for hammering action only. The chisel 95 is provided with a body portion 96 having a chisel formation 97 on its outer end and a specially designed integral shank portion 98 which projects through the drive member 32 andinto the cylinder 26 for impact engagement by the striker'member 48. The portion of the shank 98 extending through the drive member 32 is rounded whereby the chisel 95is not mounted in rotary driving engagement with the cylinder 26 through the drive member 32. In order to insure non-rotation of the cold chisel 95 during the hammer-like action imparted thereto bythe striker member 48, the portion of the shank 98 extendingthrough the nose member 38 maybe provided with'an external hexagonal formation 99 which is slidably interengageable with'the internal hexagonal formation 39 of the non-rotatable nose member 33.

The shank portion 99 of the cold chisel 95 is provided' with a reduced-in-diameter portion defining an tool elements, especially the larger tool elements adapted for demolition work. The invention, therefore, is primarily considered with the development of a series of: new and novel one-piece tool elements adapted for use with the rotary-hammer device 10. i

As illustrated in FIGS. 2 and 3, a one-piece percussiontype drill bit 85 is mounted in the nose end of the rotaryhamrner device 10 for combined rotary and hammering actions. The drill bit 85 includes a fluted body portion 86 having a carbide drilltip 87 on the leading end thereof and an integral elongated shank portion 88 of special design adapted to project through the drive member 32 and into the cylinder 26 for impact engagement by the striker member 48. A reduced-in-diameter end portion of the shank 88, which extends through the drive member 32, is provided with an external hexagonal formation 89 for slidable'interengagement with the internal.hex a-- gonal formation 33 of the drive member 32 whereby to provide a rotary driving connection between the rotary cylinder 26 and the drill bit 85. The portion of the shank 88 extending through the nose member 38 is rounded to prevent engagementof the internal hexagonal formation 39 of the non-rotatable nose member 38 with the drill bit 85.

The shank portion 38 of the drill bit is also pro-- vided with a reduced-in-diameter portion defining an annular groove 90 having radial shoulders 91 at opposite ends thereof, As illustrated in FIGS. 2 and 3, the loop portion 45' of the retainer member 42 is embracingly engageable in the annular groove 90 whereby to retainthe drill bit 85 in the device 10 when the bit 85 is being withdrawn from the material being drilled through engagement of the loop portion 45 of the retainer member 42 with the rear shoulder 91. Should the rotaryehammer device 10 be actuated when the bit 85 is not disposed against the material to be drilled, the retainer member 42 prevents ejection of the bit 85 from the device 10, as a annular groove having radial shoulders 101 at its opposite ends. The annular groove 100is adapted to receive the loop portion 45 of the retainer member 42 in the same manner described .for the drill'bit 85. Thus,

' during operation of the motor 63, the cold chisel 95 will be reciprocated with a hammer-likeactionby the striker member 48 and may be held against rotation by the nose member 38. The chisel 95 is retained in the rotaryhamrner device 10 by the retainer member 42 in the same manner asdescribed for the drill bit 85. It is to be understood-that the chisel 95 could be provided with any of the many other chisel formations on'the working end thereof.

In FIG. 5, a one-piece star drill 105 is shown mounted inrthe rotary-hammer device 10 for reciprocal hammerlike action imparted thereto by the striker member 48. The star drill 105 is provided with a body portion 106 having a typical straightdiuted star drill formation 107 formed on one end and having a specially designed integral shank portion 108 projecting through the drive member 32 and into the cylinder 26 for impact engagement by the striker member 48. The portion of the shank 108 extending through the drivemem-ber 32 is rounded whereby'the star drill 105is not. coupled to the rotary cylinder 26 through the drive member 32 for rotation therewith. Likewise, the portion of the shank 108 extending through the nose member 38 is rounded whereby desired manual turning or cranking of the star drill 105 is not hindered by the hexagonal formation 39 ofthe nose member 38.

The shank portion 108 of the star-drill 105 is provided with an enlarged portion having a square outer configuration 110 adapted for engagement by a. suitable handle or wrench whereby to permit manual turning or cranking of the star-drill'105 as desired during the reciprocal hammerlike action thereof. During reciprocal actuation of the star drill 105, the retainer member 42 is swung into its inoperable or ,outof-the-way position, as illustrated in FIG. 5, so asnot to interfere with the hand-cranking of In FIG. 6, a drill chuck 115 adapted to support conventional non-percussion type drill bits is shown mounted in the device for rotary actuation only. The drill chuck 115 includes a specially designed integral short shank 117 having a reduced-in-diameter portion 119 which projects into the drive member 32 with the end of the shank portion 119 terminating within the drive member 32. Inasmuch as no portion of the shank 117 projects into the cylinder 26 there is no impact engagement therewith by the striker member 48. The shank portion 119 is provided with an external hexagonal formation 118 adapted for interfitting engagement with the internal hexagonal formation 33 of the drive member 32 whereby the drill chuck 115 is coupled to the rotary cylinder 26 through the drive member 32 for rotation therewith. The portion of the shank 117 extending through the nose member 38 is rounded whereby the internal hexagonal formation 39 on the nose member 38 does not interfere with the rotation of the drill chuck 115.

The shank portion 117 of the drill chuck 115 is provided with a reduced-in-diameter portion defining an annular groove 120 in which the loop portion 45 of the retainer member 42 is received when the retainer member 42 is pivoted into its operable position whereby to retain the drill chuck 115 in the rotary-hammer device 10 during rotation thereof and during withdrawal of the non-percussion type drill bits from the material being drilled.

Inasmuch as it has not proved feasible to provide the relatively small tool elements adapted for fine or light work with the specially designed integral shank portions described herein, tool adapter members having specially designed shank portions have been developed for mounting these small tool elements in the rotary-hammer device It) for actuation thereby. In the light work which these small tool elements are used for, the slight power loss due to the use of separate adapter members has not proved objectionable. Such adapter members are provided on one end with the usual recess for tightly receiving the tapered shanks of these standard small tool elements. The specially designed shank portions of such tool adapter members may be similar to any of the shank portions of the one-piece tool elements shown and described thus far herein whereby to provide either combined rotaryhammering action or separate rotary and hammering actions of the small tool elements supported thereby.

In FIG. 7, a tool adapter member 125 adapted for combined rotary and hammering actions is mounted in the nose end of the rotary hammer-device 10. The adapter member 125 includes a recessed end portion 126 adapted to receive the tapered shank of conventional small tool elements and has a specially designed integral shank portion 127 which projects through the drive member 32 into the cylinder 26 for impact engagement by the striker member 48. The shank 127 of the adapter member 125 is provided with an external hexagonal formation 128 for slidable interengagement with the internal hexagonal formation 33 of the drive member 32 whereby the adapter member 125 is coupled to the rotary cylinder 26 for rotation therewith. The shank 127 is provided with a rounded portion extending through the nose member 33 and includes a reduced-in-diameter portion defining an annular groove 129 for receiving the loop portion 45 of the retainer member 42. A conventional tool element knockout opening 131 is provided in the recessed end portion 126 of the adapter 125 to facilitate removal of the particular tool element supported therein. The illustrated tool adapter 125 would be well adapted for supporting a small size percussion-type drill bit adapted for combined rotary and hammering actions. The illustrated adapter 125 may be readily modified as a chuck wrench for use with the smaller star drills by providing it with a rounded shank portion extending through the drive member 32 and a handle or crank 133, illustrated in broken line in FIG. 7, to facilitate manual cranking of the star drill.

In operation, tool elements having hexagonal formations on their shank portions are rotatable with the cylinder 26 through their rotary driving connection with the drive member 32. The gear train drive for the cylinder 26 has been previously described herein. Tool elements having rounded shank portions will, of course, not be rotated during rotation of the cylinder 26. Tool elements having short shank portions which do not project into the cylinder 26 will not have a reciprocal hammer-like action imparted thereto by the striker member 48. On the other hand, tool elements having long shank portions which normally project into the cylinder 26 will have a reciprocal, hammer-like action imparted thereto by the striker member 48.

The pneumatic operation of the striker member 48 will now be briefly described. Upon rearward movement of the power piston 50, a vacuum is created between the piston 50 and the striker member 48 which initiates the rearward stroke of the striker member 48. This movement of the striker member 48 continues due to its momentum after the piston 50 has begun its forward stroke whereby the air disposed therebetween is compressed and a tremendous pressure is created between the piston 50 and the striker member 48. This pressure serves both as an air cushion preventing contact of the piston 51) and the striker member 48 and as the driving force that reverses the direction of the striker member 48 and propels it forwardly at a very high velocity to deliver an impact blow to the end of the shank of a tool element projecting into the cylinder 26. During the forward stroke of the striker member 48, the air disopsed forwardly thereof fiows through the exhaust ports 51 into the expansion chamber 53. Sufficient air may be drawn into the space between the piston 50 and the striker member 48 during the rearward stroke of the piston 50 through the venting port 55 to compensate for any air lost past the striker member 48 during the forward stroke of the piston 50.

When a short shank tool element is mounted in the device 10, the first forward stroke of the striker member 48 will propel the striker member 48 into abutting engagement with the inner end of the drive member 32, whereby to expose the vacuum-counteracting ports 57 to the space between the piston 50 and the striker member 48. The ports 57 serve to prevent the creation of a vacuum between the piston 50 and the striker member 48 during the rearward stroke of the piston 50 whereby to render the striker member 48 inoperable when a short shank tool element is mounted in the device 10 whereby to prevent unnecessary wear of the parts.

It will be understood that certain changes may be made in the construction or arrangement of the rotaryhammer device and the tool element accessories therefor disclosed herein without departing from the spirit and scope of the invention as defined in the appended claims.

We claim:

1. In combination, a rotary-hammer device of the type characterized by a tubular housing having an axially extending cylinder rotatably mounted therein, which cylinder has a striker member reciprocal therein and a tool drive member in one end thereof, said drive member being disposed adjacent the corresponding end of the housing and including a central bore extending axially of the cylinder, power means in said device for simultaneously actuating said striker member and rotating said cylinder, a nose member fixedly attached to said end of the housing, which nose member includes a centrally disposed multi-sided opening extending axially of the housing, an elongated tool element axially disposed in said opening, which tool element has a shank extending into said bore with the portion of the tool element just forward of the opening having a forwardly facing annular shoulder, a retainer member pivotally mounted on said nose memher for swinging movement between operable and inoperable positions, which retainer includes a tool engaging portion adapted for axial alignment with said opening when the retainer is in said operable position, said tool engaging, portion being adapted in the operative position of the retainer to receive rotatably and 'slidably said tool element forward of said shoulder, whereby said tool element is retained in said device during operation thereof.

2. In combination, a rotary-hammer device of the type member fixedly attached to said end of the housing, which nose member includes a centrally disposed, multi-sided, opening extending axially of the housing, an elongated tool element axially disposed in said opening, which tool element has a shank extending into said bore with the portionof the tool element just forward of the opening having a forwardly facing annular shoulder, a retainer member pivotally mounted on said nose member for swinging movement between operable and inoperable, positions, which retainer includes, a pair of oppositely. disposed arm portions each having one end'thereof pivotally attached to said nose member and a generally U-shaped loop portion supported between the other ends of said arms, said loop portion being adapted to receive rotatably and slidably said tool element forward of said shoulder when said retainer is in said operable position, whereby said tool, element is retained in said device during operation thereof. Y I i 3. In combination, a rotary-hammer device of the type characterized by a .tubularhousing having an axially extending cylinder rotatablymounted therein, which cylinder has a striker member reciprocal therein and a tool drive member in one end thereof, said tool drive member being disposed adjacent the corresponding end of the housing, the tool drive member being provided with a central bore extending axially of the cylinder, power means in said device for simultaneously actuating said striker and rotating said cylinder, a nose member fixedly attached tosaid housing at said end thereof, which nose member includes a centrally disposed, multi-sided opening co-axial with said bore, an elongated tool element axially disposed in said opening, which tool element includes a shank portion freely extending through said bore and into said cylinder for engagement by said striker member, said tool element being provided with a multisided portion in non-rotatable engagement with said opening, said tool element having-a forwardly facing annular shoulder forward of said nose membena retainer member pivotallymounted on said nose member for swinging movement between operable and inoperable positions, which retaine r includes a tool engaging portion adapted for axial alignment with said opening when the retainer is in' said operable position, said tool engaging portion housing, the tool drive member being provided with a multi-sided, centr-al bore extending axially of the cylinder, power means in said device for simultaneously actuating said striker and rotating said cylinder, a nose member fixedly attached to said housing at said end thereof, which nose member includes a centrally disposed, multi-sided opening co-axial with said bore, an elongated tool element axially and rotatably disposed in said opening, which tool element includes a -multi sided shank portion extending through said bore and into said cylinder for engagement by said striker member and for rotation by said drive member, said tool element having a forwardly facing annular shoulder forward of said'nose member, a retainer member pivotally mounted on said nose member for swinging movement between operable and inoperable positions, which retainer includes a tool engaging portion adapted for axial alignment with said. opening when the retainer is in said operable position, said tool engaging portion being adapted in the operative position of the retainer to receive rotatably and slidably said tool element forward of said shoulder, whereby said tool element is retained in said device and adapted for rotation and limited axial movement.

4. In combination, a rotary-hammer device of the type 7 characterized by a tubular housing having an axially ex-' tending cylinder rotatably mounted therein, which cylinder has a striker member reciprocal therein and a tool drive member in one end thereof, said drive member being disposed adjacent the corresponding end of the being adapted in the operative postion of the retaner slidably to receive said tool element forward of said shoulder, whereby saidv tool element is retained in said device and adapted for limited axial movement therein.

5. lnarotary-h ammer device of the type characterized by a tubular housing having an axially extending cylinder rotatably mounted therein, Whichcylinder has a striker member reciprocal therein and a tool drive member in one end thereof, said drive member being disposed adjacent the corresponding end of the housing, the tool drive member being provided with a multi-side'd, central bore extending axiallyof the cylinder, power. means in said device for simultaneously actuating said striker and rotating said cylinder, a nose'member fixedly attached to said housing at said end thereof, which nose .member includes a centrally disposed, multi-sided opening co-axial with said bore, an elongated tool element axially and rotatably disposed in said opening, which tool element includes a multisided shank portion extending into and terminating in said bore for rotation by said drive memher, said tool element havinga forwardly facing annular shoulder forward of said nose member, a retainer member pivotally mounted'on said nose member for swinging movement between operable and inoperable positions, which retainer includes a tool engaging portion adapted for axial alignment with said opening when the retainer is in said'ope'rabl'eposition, said tool engaging portion being adapted inithe'operativeposition of the retainer rotatably to receive said tool element forward of said shoulder, whereby said'tool element is retained in said device and adapted for rotation therein.

References Cited in the file of this patent UNITED STATES PATENTS Na'shlund Dec. 17, 1963

Claims

1. IN COMBINATION, A ROTARY-HAMMER DEVICE OF THE TYPE CHARACTERIZED BY A TUBULAR HOUSING HAVING AN AXIALLY EXTENDING CYLINDER ROTATABLY MOUNTED THEREIN, WHICH CYLINDER HAS A STRIKER MEMBER RECIPROCAL THEREIN AND A TOOL DRIVE MEMBER IN ONE END THEREOF, SAID DRIVE MEMBER BEING DISPOSED ADJACENT THE CORRESPONDING END OF THE HOUSING AND INCLUDING A CENTRAL BORE EXTENDING AXIALLY OF THE CYLINDER, POWER MEANS IN SAID DEVICE FOR SIMULTANEOUSLY ACTUATING SAID STRIKER MEMBER AND ROTATING SAID CYLINDER, A NOSE MEMBER FIXEDLY ATTACHED TO SAID END OF THE HOUSING, WHICH NOSE MEMBER INCLUDES A CENTRALLY DISPOSED MULTI-SIDED OPENING EXTENDING AXIALLY OF THE HOUSING, AN ELONGATED TOOL ELEMENT AXIALLY DISPOSED IN SAID OPENING, WHICH TOOL ELEMENT HAS A SHANK EXTENDING INTO SAID BORE WITH THE PORTION OF THE TOOL ELEMENT JUST FORWARD OF THE OPENING HAVING A FORWARDLY FACING ANNULAR SHOULDER, A RETAINER MEMBER PIVOTALLY MOUNTED ON SAID NOSE MEMBER FOR SWINGING MOVEMENT BETWEEN OPERABLE AND INOPERABLE POSITIONS, WHICH RETAINER INCLUDES A TOOL ENGAGING PORTION ADAPTED FOR AXIAL ALIGNMENT WITH SAID OPENING WHEN THE RETAINER IS IN SAID OPERABLE POSITION, SAID TOOL ENGAGING PORTION BEING ADAPTED IN THE OPERATIVE POSITION OF THE RETAINER TO RECEIVE ROTATABLY AND SLIDABLY SAID TOOL ELEMENT FORWARD OF SAID SHOULDER, WHEREBY SAID TOOL ELEMENT IS RETAINED IN SAID DEVICE DURING OPERATION THEREOF.