US2068745A

US2068745A - Power tool

Info

Publication number: US2068745A
Application number: US28528A
Authority: US
Inventors: Hall Walter
Original assignee: MICHAEL O MEARA J
Current assignee: J MICHAEL O'MEARA; MICHAEL O MEARA J
Priority date: 1935-06-26
Filing date: 1935-06-26
Publication date: 1937-01-26
Anticipated expiration: 1954-01-26

Description

W. HALL POWER TOOL Jan. 26, 1937.

Filed June 26, 1935 2 Sheets-Sheet l www mw n mw Y v l i l IJ W. HALL POWER TOOL .'.Im 26, 1937'.A

Filed June 26; v1935 2 Sheets-Sheet 2 Patented ".an. n 26, 937

UNI-TED STATES PATE-NT. OFFICE half to Calif.

J. Michael OMeara, Los Angeles,

Application Junev 26, 1935, Serial No. 28,528

20 Claims. -(Cl. 192-150) This invention relates to power driven devices and relates more particularly to portable power driven tools such as power wrenches, power drills,

power screw driversfetc. A 'general object of this invention is to provide a power tool such as a power wrench having a simple, .practical and effe tive automatic control clutch.

P wer wrenches, etc. are widely used in assembling plants for tightening down bolts, screws,

l0 nuts, etc. in fastening together and assembling machine parts. Power wrenches commonly embody an electric motor governed by a switch under the control of the operator and a releasable clutch between the motor shaft and the driven tool carrying spindle that releases when the screw, bolt, nut or the like is tightened down.

In assembling plants and the likethere is usually a great amount of noise and the operator of a power wrench does not always hear the sound produced by the clutch teeth or clutch parts slipping one past'the other following the release of thepclutch of his tool, with the result that the clutch parts are allowedl to ratchet or slip past one another for a considerable period following the reljease of the clutch. This subjects the clutch parts to excessive Wear and consumes or wastes considerable time. Further, care and skill are required in the operation oiga typical power wrench as the clutch must release against the weight of the wrench and the inward pressure exerted on the tool by the operator andin the event that the operator maintains an inward carrying spindle that automatically de-energizes" the motor when it releases upon tightening down of the nut r securing member, thus preventing excessive v ear of the clutch partsand conserv-I ing time.

Anotherobject of this invention isto provide an automatic circuit controlling or motor con--A trolling clutch embodied in a simple compact attachment lfor application to or vuse on 'a power wrench of the class now inpgeneral use.

Another object of .this inventionis to` provide an attachment for a power tool that embodies an automatic clutch for controlling the motor ofthe tool which-,attachment maybe easily ap- .'55 plied to a typical power wrench with but: little modification or alteration of the wrench structure. y

Another object of this invention is to 4provide a power tool that is operable to tighten down a securing member to a definite degree of tightness 5 and therefore does not require that theI operator employ great skill or care in its operation.

Another object of the invention is to provide a power tool such as a power wrench that embodies a clutch between the driving shaft and 10 tool-carrying spindle that automatically releases when the nut or other securing member offers a definite resistance to'rotation, said release of the clutch being entirely irrespective of and independent of the inward pressure which the op- 15 erator may maintain on the tool.

Another object of this invention is to provide a power tool of the character mentioned in which the torque controlled clutch controls the driving motor operating to automatically de-energize 20 the motor when it releases, under the torque resulting from the resistance o'iiered by a securing member which has been tightened down out which description reference. is made to the accompanying drawings, in which:

Fig. 1 is a side elevation of one form of the present invention showing the clutch and the adjacent parts in longitudinal cross section. Fig. 40 2 is a transverse detailed sectional view taken substantially as indicated by line 2--2 on Fig. 1. Fig. 3 is an enlarged fragmentary transverse detailed sectional view taken as indicated by line 3-3 on Fig. 1. Fig. 4 is a fragmentary side ele- 45 vation of a portion oi.' the wrench showing the clutch and the adjacent parts in longitudinal cross section withl the clutch in engagement and illustrating in a diagrammatic manner the electric circuit embodied in the tool. Fig. 5 is a side 50 elevation of a power tool with the attachment provided by this invention provided thereon illustrating the attachment and the adjacent parts of the tool in longitudinal cross section showing the clutch in the released condition. Fig. 6 is a 55 transverse detailed sectional view taken as indicated by line 6-6 on Fig. 5. Fig. Tis an enlarged fragmentary detailed sectional view taken as indicated by line 1 1 on Fig. 5 and Fig. 8 is a fragmentary side elevation showing the clutch in the engaged condition illustrating the attachment in longitudinal cross section and diagrammatlcally illustrating the motor circuit.

The form of the present invention illustrated in Figs. 1 to 4, inclusive, of the drawings, in-

cludes, generally, a housing or body III containing a motor M for operating a shaft II, a spindle I2 carrying a socket I3 or other suitable means for engaging a securing member, anl automatic releasable clutch Il between the shaft I| and`the spindle I2, and a control I5 for the motor M operatively associated with the clutch I4.

The body III is provided to encase the operating motor M and the reduction drive (not` shown) usually employed in power tools of this class. v'Ihe body I0 has a main part I6 for enclosing the motor M and a reduced forward part I1 which may be considered as enclosing the reduction gearing (not shown). The present invention is not primarily concerned with the character or details of the motor M or the reduction gearing and these elements have been omitted from the present disclosure as they are well known to those skilled in the art. A suitable handle I8 is provided at the rear or outer end of the body I0 and conductors I9 and 20 carrying the current for energizing the motor M may enter the tool through the lower end portion of the handle I8. 'I'he shaft II, which is driven by the motor M through the reduction gearing (not shown) projects from the forward end of the reduced body portion I1. In the preferred arrangement illustrated the shaft II is co-axial with the body I0. The spindle I2 is provided to carry the socket I3, al screw driver bit, or other device for nonrotatably engaging a. securing member to be tightened by the tool or wrench. In the particular application of the invention illustrated in the drawings the socket I3 is fixed to the outer or forward end portion of the spindle I2 to engage or receive a nut, the head of a bolt, stud, screw, or the like. The spindle I2 is co-axial with the shaft II and body I0 projecting forwardly from a point spaced from the forward end of the shaft II. The tool-carrying spindle I2 may'be cylindrical and may be of any suitable or desired length.

The clutch Il is provided to transmit rotation from the shaft II to the spindle I2 when the socket I3 is engaging a nut or securing member and the operator is maintaining a suitable inward pressure on the wrench. The clutch I4 is an important feature of the invention as it is adapted to automatically'release when the securing 4member has been tightened to a selected degree of tightness, its release causing actuation or opening of the control I5 and its release being entirely irrespective of the inward pressure maintained on the tool bythe operator.

In accordance with the invention the automatic clutch I4 includestwo members 2| and 22 axially shiftable into and out of rotation transmitting cooperation, one member being on the shaft |I and the other member being shiftable on the spindle I2. In the particular form of the invention illustrated in the drawings the clutch member 2| is fixed to the shaft I I and the clutch member 22 is shiftably carried by the spindle I2. As sliown in the-drawings, the member 2| is integral with the shaft II, it being understood that the member 2| may be a separable part suitably xed or attached to the shaft. The clutch member 22 has a sleeve portion 23 surrounding and shiftable on the spindle I2. member 22 is splined or keyed to the spindle I2 to turn therewith and to be shiftable longitudinally thereon. In the simple form of the invention illustrated in the drawings a key 24 cooperates with grooves or key-ways in the spindle I2 and member 22 to connect the member with the spindle for rotation and relative longitudinal movement. A flange or head 25 is provided on thc-inner end of the spindle I2 and is adapted to cooperate with or t a socket 26 in the member 22 to limit the inward or rearward movement of the clutch member on the spindle. The clutch members 2| and 22 have axially projecting parts 21 on their opposing ends or sides. 'I'he parts 21 are adapted to mesh or interlock to connect the spindle I2 with the shaft II for rotation by the shaft. The engaging sides or faces 25 of the clutch parts 21 are bevelled or pitched so that they tend to slip one on the other when subjected to torque. 'I'he outer edges of the cooperating clutch parts 21 are preferably chamfered or bevelled.

'Ihe clutch Il includes yieldable means for urging the member 22 rearwardly or toward the clutch member 2|. A longitudinally adjustable collar 30 surrounds the spindle I2 and is adapted to be releasably locked or set in a selected position by a set screw 3| or equivalent means. A spring 32 surrounds the spindle I2 and is under compression between the collar 30 and a washer 33 bearing on the outer end of the sleeve portion 23 of the clutch member 22. The spring 32 operates to normally hold the clutch member 22 in a position where the bottom Wall of its socket 26 engages the head 25. In accordance with the invention the shaft II and the spindle l2 are related for limited relative longitudinal movement whereby the engagement of the clutch parts 21 of the clutch members 2| and 22 is accomplished by the operator moving the body III inwardly when the socket I3 is in engagement with a nut or securing member.

The clutch I4 includes a slack connection between the shaft II and the spindle I2 whereby the shaft II may be moved forwardly relative to the spindle I2 to engage the clutch parts 21. The clutch member 22 carries a tube or sleeve Il which projects from the active end of the clutch member to surround the clutch member 2 I. The sleeve 3l may be threaded or otherwise attached to the periphery of the member 22. vAn inwardly projecting annular flange 35 is provided on the inner end of the sleeve 34 and is adapted to engage the inner or rear surface of the clutch member 2| to limit the relative axial movement between the shaft Il and the spindle I2 in one direction. The forward faces of the clutch parts 21 on the member 2| are adapted to engage the face of the head 25 to limit the relative longitudinal movement betweenthe shaft I'I and the spindle .I2 in the other direction.` The sleeve 3l and its ange 35 may have sliding bearing cooperation .with the clutch member 2| to assist in carrying and steadying the spindle |2.

A reduced stem 36 projects rearwardly from the head 25 and is slidable in a central socket 31 inthe shaft II. A spring 3B is arranged under compression between opposing parts or faces on the shaft I I and the spindle I2 to normally yieldingly hold the spindle in an yout position where the clutch parts 21 are disengaged and the flange The tudinal axis of the tool.

35 engages the rear surface of the member 2|.

In the particular form of the invention shown inv the drawings the spring 38 is arranged in the socket 31 under compression between the end of the stem 36 and the bottom wall of the socket. The spring 38 is preferably weaker than the spring 32 for the reason to be hereinafter described. The spring 32 normally holds the clutch member 22 in a position wherev the bottom wall of its socket 26 engages the head 25 and the spring 38 normally holds the spindle 32 in a position Where the clutch parts 21 are disengaged and the flange 35 engages the rear surfaceof the clutch part 2I.- When the socket I3 is engaged with a nut or securing member the operator pushes inwardly on the handle I8 to compress the spring 38 and move the body I0 and the shaft II inwardlyy bringing the clutch parts 21 against one another or in meshing engagement. In the event that the clutch parts 21 on the members 2| and 22 do not come into mesh the operator -partially turns or rocks thebody I0 to bring the clutch parts 21 into proper meshing engagement. When the clutch parts 21 are in meshing or interlocking engagement the parts 21 of the clutch member 2| cooperate with the parts 21 of the clutch member 22 to transmit rotation from the shaft II to the spindle I2.

The control for the motor M is associated with and operated by the clutch I4 to automatically cie-energize the motor M when the clutch IIIreleasesunder torque caused by resistance to rodowny securing member with ywhich the socket I3 l is engaged. The motor M is adapted to be energized or operated by electric current carried by the conductors I9 and 28. One lead of the energizing circuit, say the conductor 28, may be connected to one side or post of the motor M. A conductor 40 extends from the other post of the motor M to a binding post or screw 4I on the forward end of the reduced body part I1. The second conductor or lead I 8 of the energizing circuit extends through the body I to a post or screw 42 on the forward end of the body part I1. The control I includes contacts 43 connected with or carried by the screws 4| and 42. The contacts 43 comprise flexible strapsv or members having base flanges 44. The flanges 44 are provided with longitudinal slots 45 receiving the screws 4I and 42. The screws 4| and 42 secure the contezts in position while the slots 45 allow the contacts to be adjusted toward and away from the longitudinal center of the tool when the screws are loosened. The contacts 43 and the screws 4| and 42 are suitably insulated from the body part I1 by blocks 9 of insulation. The contacts 43 projectvaxially or 'forwardly from their bases 44 and are provided at their outer ends with spherical parts or heads 46. l I

An annular or tubular extension 41 is threaded on thev'inner end of the sleeve 34 and has anl inwardly projecting annular` flange 48. The inner 'surface of the flange 48 is bevelled or inclined rearwardly and outwardly relative to the longi- 'Ihe particular control I5 illustrated includes a ring contact 5I|which may be rotatably carried between the flange 35` and the ange 48. In the construction shown l ,contact against rotation. The periphery and sides of the vring contact 58 are provided with Vinsulation or thesesurfaces of the contact bear on a lining 49 of suitable insulation. A groove 5I is provided in the internal wall or side of the ring 58? The groove 5I has spherically concaved walls and is adapted to receive the substantial- Gly spherical heads 46 of the contacts 43.

contact 50 is, of course, formed of conducting material and constitutes a bridge between the conductors or lines I9 and 40 when it is in the position where its groove 5I receives the contact heads 46. g The insulating lining 48 preferably covers the inclined face of the flange 48. The contacts 43 are positioned and formed so that their heads 46 vare engaged by the lining 49 on the inclined face 'of the flange 48 upon inward movementof the body I0 relative to the spindle I2 and this engagement results in inward flexing of the contact 43 so that the heads 46 snap into the groove 5I and remain in Yproper bearing contact with the wall of the groove through the outward pressure exerted by the resilient contacts.

The control I5 includes a manual switch 52 connected in one of the energizing lines or conductors I9 or 2D. Inthe particular case illustrated in the drawings the switch 52 is provided in the line I9. The switch 52 includes a spring 53 which normally acts to hold the switch in its open position. The switch 52 includes a handle or trigger 54 whereby it may be readily closed by the operator of the wrench. The trigger 54 rprojects from the inner side of the portion of the handle I8 gripped by the users fingers so that the vuser engaging the handle I8 has full control over the switch 52. It will be apparent how the user may easily depress the trigger| 54 to close the switch 52. The control I5 may include a second manual switch 55 provided in a line 56 to shunt past the switch 52. The switch 55 which may or may not be employedis located for convenient engagement by the operator and is such that it may be operated to a closed position to remain closed until deliberately opened so/that the operation of the wrench may be automatic or completely under the'control of the clutch I4. A protective shell 58 may be secured 4to the re-n duced body portion I1 and may extendjirwardly to telescope over the extension 41 and' thus enclose the space between the body portion I1 and the extension and protect the contacts 43 and the adjacent parts.

In operation assuming the switch 55 to be open and the socket I3 to be in engagement with a nut or the head of a securing member, the operator gripping the handle lI8 depresses the trigthe clutch member 2| toward the clutch member 22 bringing the clutch parts 21 of the two,

members into cooperation.v .In the event that the clutch parts 21 do not mesh or' interlock the operator may partially turn'or rock the'body I0 eration. During the inward movement of the body I0 into engagement of the clutch parts 21 the heads 46 of the contacts 43 aremoved in- The' . 65 bringing the clutch niembers to positions where Y their clutch parts 21 come into meshing coopeures the proper engagement of the heads 46 in the groove 6I. snapping of the contact heads 46 into the groove 5I of the bridge contact or ring contact 50 completes the energizing circuit to the motor M so that the motor is automatically energized.

Operation or energization of the motor M of course results in rotation of the shaft II and the parts 21 of the clutch member 2| cooperate with the parts 21 of the clutch member 22 to transmit rotation from the shaft II to the spindie I2. The operator may maintain a suitable or desirable inward pressure on the handle I8 as the motor operates to turn the spindle I2 and thus tighten down the nut or securing member engaged by the socket I3. The inward pressure exerted by the spindle on the handle I8 ol' course must be sufficient to overcome the spring 38 and maintain the clutch member 2| in proper engagement with the clutch member 22. In practice the spring 38 may be comparatively light and easily compressed. As the nut or securing member is tightened down it offers increased resistance to rotation of the spindle I2. Upon the nut or securing member being tightened down toga definite or predetermined degree of tightness itoflers such resistance to rotation of the spindle I2 that the torque imposed on the contacting clutch parts 21 overcomes the frictional cooperation between their sloping faces 28 and overcomes the pressure exerted by the spring 32 and results in outward movement of the clutch member 22 on the spindle I2. This outward movement of the clutch member 22 of course disengages the clutch parts 21. Outward movement of the clutch member 22 on the spindle I2 caused by the release of the clutch parts 21 moves the ring contact 58 outwardly disengaging it from the contact heads 48 breaking or opening the energizing circuit to the motor M. Thus the release of the clutch C causes opening of the motor circuit and de-energization of the motor. Accordingly, the rotation of the shaft I I stops substantially simultaneously with the disengagement of the clutch C .so that the clutch parts are not subjected to excessive wear. As soon as the motor M is automatically de-energized by the disengagement of the clutch I4 the operator may relieve the pressure on the trigger'64 to allow the switch 62 to open and may relieve the inward pressure on the wrench and disengage the` socket I3 from the nut or securing member.

From theabove it will be noted that the disengagement or release of theclutch member 22 -from the clutch' member 2| is entirely automatic and independent of the inward pressure exerted on the wrench by the operator.` The inward pressure put o n the wrench by the operator is 4transmitted from the shaft II to the spindle I2 by the engagement of the outer faces of the clutch parts 21 on the clutch member 2I with the face of the head 25. This engagement of the parts 21 with the head 26 in no way affects the disengagement of the clutch I4. As the control I5 is operated or governed by the clutch I4 to open the motor circuit simultaneously with the disengagement of the clutch I4 the motor is automatically cie-energized simultaneously with the opening of the switch so that no time is lost following the disengagement of the clutch. The wrench may be adjusted or regulated to tighten down the securing members te any selected or desired degree of tightness by loosening the set screw 3| and adjusting the collar 30 longitudinally on the spindle I2. Longitudinal adjustment of the collar 30 of course adjusts or regulates the pressure exerted on the clutch part 22 by the spring 32 determines the torque under which the clutch I4 releases and thus determines the degree to which the wrench tightens down the securing members before the motor M becomes deenergized. If the operator closes the switch 56 and leaves it closed during the operation of the wrench, the motor M is governed solely by the control I5. In other words, the inward movement of the body I0 relative to the spindle I2 when the socket I3 is in engagement witha securing member moves the contacts 46 into engagement with the ring 56 to automatically energize the motor M and the release of the clutch I4 as described above results in de-energization of the motor M. As the operation of the wrench may be entirely automatic or under the control of the clutch I4 and the control I5 the operator may leave the switch closed, if desired.

The form of the invention illustrated in Figs. 5 to 8, inclusive, of the drawings, is in the nature of an attachment for a power tool or wrench T. The tool T which is typical of wrenches and tools of this class includes a body 60 enclosing an elec tric motor 6I and a suitable speed reduction gearing (not shown). The reduction gearing is provided in a reduced forward portion 62 of the body 60 and the shaft 63 driven by the motor 6I through the gearing projects from the forward end of the forward portion 62. The wrench or tool T further includes a spindle 64 carrying a screw driver bit, a socket 65 or other means for engaging screws, nuts, bolts or the like. A releasable clutch is provided between the shaft 63 and the spindle 64. The clutch comprises two clutch members '66 and 61. The member 66 is integral with .the shaft 63 and the member 61 is integral with the spindle 64. Clutch parts 68 are provided on the opposing faces of the members 66 and 61 to mesh or interengage for the transmission of rotation from the shaft 63 t0 the spindle 64. The engaging faces or sides 68l of the parts 68 are pitched and tend to disengage` when the sides are under torque. A reduced stem 69 on the rear end of the spindle 64 or its clutch member 61 is slidable in a central socket 10 in the shaft 63. A spring 1I is provided in the socket 16 and is under compression between the bottom of the socket and the end of the stem 69 to normally yieldingly urge the spindle 64 to an out position where the clutch parts 68 are disengaged. A handle 12 is provided on the rear or outer end of the body 60 to facilitate the manipulation of the tool. The motor 6I is adapted to be manually controlled by a switch 13 connected in one lead 14 of the motor circuit 14-15. The switch 13 includes a spring 16 which normally holds it in the open position and includes a trigger- 11 projecting from the forward side of the portion of the handle 12 gripped by the operators fingers. The structure of the tool T described above may be considered as typical of the general class of power tools to which the attachment' of the invention is applicable.

The attachment provided by the present in? vention illustrated in Figs. 5 to 8, inclusive, of the drawings, includes, generally, spaced contacts 18 connected in the motor energizing circuit 14--15, a sleeve 19 carried by the spindle 64 and a ring contact 80 carried by the sleeve 15 and engageable by the contacts 18 to complete the circuit to the motor 6I. Y

The contacts 18 are preferably mounted on or attached to the forward end of the body portion rearwardly from the sleeve.

62 at spaced points. They are shown at diametrically opposite sides of the shaft 63. 'I'he contacts 18 may be carried by blocks 8| of insulation secured to the body portion 62 in any suitable manner. The contacts 18 are flexible straplike members each having a base flange 82 seated on an insulation block 8|. Screws 83 threaded into openings in the blocks 8| pass through slots 84 in the flanges 82 to adjustably attach the contacts 18 to the blocks. When the screws 83 are loosened the contacts 18 may be adjusted toward and away from the longitudinal axis of the tool T. The contacts 18 project outwardly from their base flanges 82 and are provided at their outer ends with spherical heads 85. The leads or

conductors

14 and 15 of the motor energizing circuit may be electrically connected with the contacts 18 in any suitable manner. In the particular case illustrated in the drawings the conductors 14 and 15.are wrapped on or soldered to the screws 83 to be electrically connected with the contacts 18. `The

conductors

14 and 15 are preferably trained over the exterior of the tool body 68 and its reduced forward portion 62 to the conductors 18 so that it is unnecessary to disturb the interior of the tool to provide for the arrangement of the conductorsf'on the tool. y

The sleeve 19 is provided to carry or support ,the ring contact 88. The sleeve 19 replaces the means originally provided on the tool T for connecting the spindle 64 with the shaft 63 for longitudinal movement relative to the shaft. In accordance with the invention the sleeve 19 is secured to the clutch member 61 of the spindle 64. The sleeve 19 surrounds the member 61 and projects rearwardly therefrom to surround and slidably engage the periphery of the clutch member 66. The sleeve '|'9 may be fixed to the clutch member 61 in any suitable manner, for example, it may be welded to the member 61 as at 86. An inwardly projecting annular ange 81 isv provided on the rear end of the sleeve 19 and is adapted to engage the rear face of the clutch member 66 to limit relative longitudinal movement between the shaft 61 and the spindle 64 in one direction. An extension 88 is threaded on the rear end portion of the sleeve 19 to project y The extension 88 has an inwardly projecting annular flange 89 spaced from theiiange 81 to leave or provide an annular groove 98. The internal surface 9| of the flange 89 is inclined outwardly and rearwardly as clearly illustrated in Figs. 5 and 8 of the drawings.V A'protective sheath or shell 99 may be providedv on the reduced portion 62 ofthe tool body 68 to extend-forwardly and telescope over the extension 88 of the sleeve 19 and thus enclose orsurround the space between the extension andl theforwardend of the-body.

The ring contact 88 is engageableby the contacts 18 when there is inward movement of the orffreeto float in the groove 90. 'Ihe groove 98 a lining 92 of insulation to prevent engageme'niof the Contact so with the mange a1 or the vextexrsiox'i 88. 'Ihe lining 92'of insulation contlnp'es rearwardly to extend over and cover the inclinedsurface .9| of the flange 89 so that the heads .85 of the contacts 18 cannot engage the surface 9| simultaneously with their engagement with theiring contact 88. An annular groove 93 is provided in the interior or internal surface of the ring contact 88. The groove 93 has a spherically concaved wall and is proportioned to effectively receive the spherical heads 85 of the contacts 18.

If desired or found practical a manual switch 94 may be connected in a line 15 to shunt out the switch 13. The switch 94 is such that it may remain in either the open or closed condition until deliberately shifted or operated by the user of the tool. The switch 84 may be an original element ofthe tool T or may be applied to the tool when the attachment is embodied in the tool.

It is believed that it will be apparent how the contacts 18 may be easily and quickly attached to the forward end of the body portion 62 and properly connected in the motor circuit. The sleeve 91 carrying the extension 88 the contact ring 88 and the shell 9|.may be easily and quickly attached to the clutch member 69. The attachment of the invention is such that it may be readily applied to or embodied in the power tool with very little alteration or modification of the original tool structure. Y

-In the operation of the tool T provided with the attachment the operator may prefer to have the switch 94 in its open condition in which case he iirst engages the socket 65 with the nut, bolt or'other securing member and then moves or pushes the tool body 68 inwardly. This inward movement may be accomplished by engaging or grasping the handle 12 Vand pushing inwardly thereon. As the operator moves the tool body 68 inwardly he may depress the trigger 11 to close the switch 13. The engagement of the socket 65 withthe securing member or the work holds-the spindle 64 against inward or longitudinal movement and as the tool' body 68 is moved inwardly the heads 85 ofthe contacts 18 engage the lining of insulationon the inclined surface 9| and the contacts are flexed inwardly so that their heads 85 may snap into the groove 93 of the contact ring 88. The resiliency of the contacts 98 holds their heads 85 in proper engagement with the wall of the groove 93. The engagement of the contact tially simultaneously with the energizaton of-the Rotation of the spindle 64 by the motorl 6| driving through the shaft 63 and the clutch causes the nut, bolt or other. securing member to be turned down or tightened. When the securing member has been tightened to a suitable degree of tightness the yinclined cooperating faces 68il of the contact parts 68 slip and disengage under the increased torque causing the shaft 63 and the tool body 58 to move or kick rearwardly. This movement of the shaft 63 and the tool body 68 of course releases the clutch and is accompanied b y disengagement of the contact heads 85 from the contact ring 88 so that the motor y6| is deenergized substantially simultaneously with the disengagement or release ofthe clutch. Thus the motor of the power Atool T is automatically deenergized when the nut or securing member has been tightened to the desired degree of tightness so that the clutch parts 68 are not subjected to excessive unnecessary wear and no time is lost in the operation of the tool. erator may have the switch 95 in a closed condition during the operation of the tool. When the switch 94 is closed the tool may be operated automatically or without the depression oi the trigger 11. With the switch 9! in the closed condition the engagement of the contact heads 85 with the contact ring 80 results in closing of the motor circuit regardless of the condition oi the switch 13 so that the tool is automatically energized or actuated by the inward movement of the tool body 80. The contacts 1l may be adjusted radially to insure the proper engagement of their heads 85 with the ring contact 80.

Having described only typical preferred forms and applications of my invention I do not wish to be limited or restricted to the specific details set forth, but wish to reserve to'myselt any variations or modiilcations that may appear to those skilled in the art or fall within the scope of the following claims.

Having described my invention, I claim:

1. In a portable power tool having a driving motor and an energizing circuit for the motor, the combination of a driving element driven by the motor, a driven element, a clutch comprising clutch members on the elements, the clutch members being related for relative movement be tween an engaged rotation transmitting position and a released position and being formed to move one relative to the other to said released position when subjected to a heavy torque, and means normally yieldingly holding the clutch members in the released position, and a control for the motor governed by movement between the clutch members including cooperable contacts movable axially with the clutch members.

2. In a portable power tool having an energiz# ing circuit,- the combination of a driving element, a driven element, a clutch comprising clutch members on the elements, the clutch members being related for relative movement between an engaged rotation transmitting position and a released position and being formed to move one relative to the other to said released position when subjected to a heavy torque, and a control for the energizing circuit including contacts in said circuit, one of the contacts being movable axially with one clutch member, the other contact being movable axially with the other clutch member, the contacts being engaged when the clutch members are in the engaged position and disengaged when the clutch members are in the released position.

3. In a portable power tool having an energizing circuit. the combination o! a driving element, a driven element. a clutch comprising clutch members on the elements, the clutch members being related for relative movement between an engaged rotation transmitting position and a released position and being Lormed to move one 'relative to the other to said releasedposition whim subjected to a heavy torque. a spring normally yieldingly holding the clutch members in the released podtion,r and a control for the energizing circuit including a contact in the circuit associated with one element to be movable axially therewith, and a contact in the circuit movable axially with the clutch member on the other element, the contacts being disengaged to open said circuit upon movement o! the clutch members to the released pomtion.

-4. In a power tool a motor, an energizing circuit for the motor, a driving element operated by the motor a driven element, clutch members on If desired, the opthe elements, the clutch members being related for relative movement between engaged rotation transmitting positions and released positions, parts on the clutch members cooperable when the members are in the engaged positions and shaped to cause relative movement of the members to the released .positions when substantial resistance is offered to rotation of the driven element, and contact means operable to open said circuit when the clutch members are-moved one relative to the other to the released positions, said means including a contact in said circuit movable axially with one clutch member, and a contact in said circuit movable axially with and rotatably carried by the other clutch member for cooperation with the first mentioned contact.

5. In a portable power tool having a motor and an energizing circuit for the motor, `the combination of, a driving element driven by the motor, a driven element, the elements being related for relative axial movement, clutch members on the elements, the clutch members being related for relative movement between engaged rotation transmitting positions and released positions, parts on the clutch members cooperable when the members are in the engaged positions and shaped to cause relative movement of the members to the released positions when substantial resistance is oiered to rotation of the driven element, means normally yieldingly holding the clutch members in the released position, and a control for said circuit including contacts connected in the circuit and associated with the elements and the clutch members to come into engagement to energize the motor when the elements are shifted axially one relative to the other v to engage the clutch members and to disengage to deenergi'ze the motor when the clutch members are released.

6. In a power tool having a motor and an energizing circuit for the motor, the combination of a driving element driven by the motor, a driven element, clutch members on the elements, the clutch members being related for relative movement between engaged rotation transmitting positions and released positions, parts on the clutch members cooperable when the members are in the engaged positions and shaped to cause relative movement of the members to the released positions when substantial resistance is offered to rotation of the driven element, and a control for said circuit including spaced contacts each connected with a lead of said circuit and mounted to move longitudinally with one oi the clutch members. and a contact mounted to move longitudinally with the other clutch member and cooperable with the spaced contacts when the clutch members are engaged and disengaged irom the spaced contacts when the clutch members are released.

7. In a powertool having a motor and an energizing circuit for the motor, the combination of a driving element driven by the motor, a driven element, clutch members on the elements, the clutch members being related for relative movement between engaged rotation transmitting positions and released positions, parts on the clutch members cooperable when the members are in the engaged positions and shaped to cause relative movement oi the members to the released positions when the part engaged by the socket offers substantial resistance to rotation, and a control for said circuit including spaced contacts each connected with a lead of said circuit and mounted to move longitudinally with one of the clutch members, 'and a rotatable ring contact mounted to move longitudinally with the other clutch member and cooperable with the spaced contacts when the clutch members are engaged and disengaged from the spaced contacts when the clutch members are released.

8. In a portable power tool having a driving motor, an energizing circuit'for the motor, a driving element driven by the motor, a driven element shiftable relative to the driving element, and cooperable clutch members on the elements releasable under torque to cause relative longitudinal movement between the elements, the combination of spaced contacts connected in the circuit and mounted to move 1ongitudina11y with mel release.

9. In a portable power tool having a driving motor, an energizing circuit for the motor, a driving element driven by the motor, a driven element shiftable relative to the driving element,.

and cooperable clutch members on the elements releasable under torque tocause relative longitudinal movement between the elements, the combination of spaced contacts connected in the circuit and mounted on the driving element to move longitudinally with the driving element, a sleeve carried by the driven element, and a contact rotatably carried by the sleeve and cooperable with the spaced contacts to complete the motor circuit when the clutch members are engaged and, disengageable from the spaced contacts to open the motor circuit when the clutch members release.

v10. An attachment for a power tool having a driving motor, a circuit for energizing the motor, a shaft driven by the motor, a tool spindle, the shaft and spindle being related for relative longitudinal movement and cooperable clutch -members xed on the shaft and spindle releasable 'under torque to cause relative longitudinal movement between the shaft and spindle,the attachment including a contact adapted to be mounted on the tool to be movable longitudinally with the shaft, means for mounting said contact on the tool free of the shaft the contact being connected in said circuit, and a contact .adapted to be mounted on the spindle to move longitudinally.= therewith and cooperable with the iirst mentioned contact when the clutch members are engaged and disengageable from the first mentioned contact to open the motor circuit when the clutch members release.

11. An attachment for a power tool having a ldriving motor, a circuit for energizing the motor, a shaft driven by the motor, a toolspindle,

Athe shaft and spindle being related for relative members are engaged and disengageable fromthe rst mentioned contact to open the circuit when the members release.

12. An attachment for a power tool having a driving motor, a circuit for energizing the motor, a shaft driven by the motor, a tool spindle,

the shaft and spindle being related or relative longitudinal movement and cooperable clutch members fixed on the shaft and spindle releasable under torque to cause relative longitudinal movement between the shaft and spindle, the attachment includingl a contact adapted to be mounted on the tool to be movable longitudinally with the shaft, the contact being connected in said circuit, asleeve adapted to be attached to the clutch member on the spindle, and a ring contact rotatable in the sleeve and having a groove for receiving the first mentioned contact to'close the circuit when the members are engaged, the ring contact being disengageable from the iirst mentioned contact to open the circuit when the members release.

13. A portable'power tool includingy a body, a motor carried by the body, a circuit for actuating the motor, two rotatable elements related for relative longitudinal movement, one element being a driving element driven vby the motor, the other element being a driven element, clutch members on the elements engageable upon relative longitudinal movement between the elements to connect the elements for rotation, means normally yieldingly holding theyclutch member out of engagement, a control for the circuit includingtwo contacts one being movable longitudinally with each clutch member, the contacts being cooperable when the clutch members`are engaged t0 4complete the circuit, one clutch. member being longitudinally shiftable on its element, and en- -gaging parts on the clutch members operable to cause longitudinal shifting of the shiftable member to disengage the contacts when there is heavy Y resistance to rotation'of the driven element.

14. In a portable power tool having a body, a motor carried by the body and a circuit for actuating the motor, the combination of two rotatable elements related for relative longitudinal movement, one element being a shaft driving element driven by the motor, the other element being a driven element, clutch membersv on the elements engageable uponl relative longitudinal movement between-theA elements to connect the elements forrotation, means normally yieldingly holding the clutch members out of engagement, a control for the circuit including two contacts one being movable longitudinally with each clutch member, thev contacts being cooperable when the clutch members are engaged to complete the circuit, one

clutch member being longitudinally shiftable on its f element, means normally yieldingly resisting longitudinal shifting of the shiftable member, and engaging parts on the. clutch members operable to cause longitudinal shifting of the shiftable member to disengage the contacts when there is heavy resistance to rotation of the driven element.

15. In a portable power tool of the character described having a motor and a circuit fortactuating the motor, the combination of two rotatable elernents related for relative longitudinal movement, one being a driving element driven by the motor, the other being a driven element, clutch members on the elements engageable upon relative longitudinal movement between the elements to connect the elements for rotation, means normally yieldingly holding the clutch members dismeans, a contact movable longitudinally with each element, the contacts being cooperable when the clutch members are engaged to complete the circuit, and parts on the clutch members operable to cause longitudinal shifting of said member when under torque to disengage the contacts.

' 16. A portable power tool including a body, a motor carried by the body, a circuit for actuating the motor, two rotatable elements related for relative longitudinal movement, one being a driving element driven by the motor and movable longitudinally with the body, the other being a driven element movable axially relative to the body, clutch members on the elements engageable upon relative longitudinal movement between the elements to connect the elements for rotation. means normally yieldingly holding the clutch members out of engagement, one of the clutch members being axially shiftable on its element, a contact mounted to move longitudinally with one element, a contact carried by the axially shiftable member. the contacts cooperating when the clutch members are engaged to complete said circuit, and cooperating parts on the clutch members operable to cause axial shifting of said members to disengage the members and the contacts when a heavy torque is imposed on the members.

17. A portable power tool including a body, a motor carried by the body, a circuit for actuating the motor, two rotatable elements related for relative longitudinal movement, one being a driving element driven by the motor, the other being a driven element shii'table axially relative to the body, clutch members on the elements engageable upon relative longitudinal movement between the elements to connect the elements for rotation, means normally yieldingly holding the clutch members out of engagement, one of the clutch members being axially shiftable on its element, a contact mounted to move longitudinally with one element, a spring bearing on the axially shiftable member to resist its axial movement, a contact carried by the axially shiftable member, the contacts cooperating when the clutch members are engaged to complete said circuit, and cooperating parts on the clutch members operable to cause axial shifting of said members to disengage the members and the contacts when a heavy torque is impod on the members.

18. A portable power tool including a body, a motor carried by the body, a circuit for actuating the motor, two rotatable elements related for relative longitudinal movement, one being a driving element driven by the motor, the other being a tool driven element shiftable axially relative to the body, clutch members on the elements engageable upon relative longitudinal movement between the elements to connect the elements for rotation, means normally yieldingly holding the clutch members out of engagement, one of the clutch members being axially shiftable on its element, a contact mounted to move longitudinally with one element, a spring bearing on the axially shiftable member to resist its axial movement, means for regulating the pressure exerted by the spring, a contact carried by the axially shiftable member, the contacts cooperating when the clutch members are engaged to complete said circuit, and cooperating parts on the clutch members operable to cause axial shifting of said members to disengage the members and the contacts when a heavy torque is imposed on the members.

19. In a portable power tool having a driving motor and an energizingV circuit for the motor, the combination of, a driving element driven by the motor, a driven element, a clutch comprising, clutch members on the elements related for relative movement between an engaged position and a released position and being formed to move relative to one another to the released position when subjected to heavy torque, a control i'or the motor circuit governed by movement between the clutch members, and an optional manual switch in said circuit. a

20. In a portable power tool having a driving motor and an energizing circuit for the motor, the combination ol', a driving element driven by the motor, a driven element, a clutch comprising, clutch members on the elements related for relative movement between an engaged position and a released position and being formed to move relative to one another -to the released position when subjected to heavy torque, contact means in said circuit associated with the clutch members to automatically control said circuit, and a manual switch for controlling said circuit at ther option of the operator.

WALTER HALL.