A tool including selectively operable torque-limiting mechanism is provided. The tool includes a housing, a torque-limiting mechanism disposed within the housing and including a first gear engaged with the housing and including a number of first recesses, a second gear rotatably disposed within the housing adjacent the first gear and including a number of second recesses, a number of bearings disposed between the first gear and the second gear partially within the first recesses and partially within the second recesses, and a variable force-applying assembly engaged with the first gear opposite the second gear, a drive body engaged with the second gear and extending outwardly from the housing, and a cover disposed around the housing and selectively engaged with the drive body to control the operation of the torque-limiting mechanism.

FIELD OF THE INVENTION

The present invention relates to tools used to rotate and/or drive fasteners, and more specifically to a torque-limiting mechanism for use with these types of tools.

BACKGROUND OF THE INVENTION

With regard to hand-held and powered tools used to drive features into or out of an item, especially those used in medical applications, there are several common problems associated with tools incorporating existing torque-limiting devices. These problems include loss of consistent torque value after repeated autoclave sterilization cycles, internal components breaking due to high forces and loads on internal cams and gears, inconsistent torque values due to wear on internal components, a strong recoil or snap when set at higher torque values, and difficulty in servicing the mechanism.

More particularly, as shown inFIGS. 20 and 21, in prior art torque-limiting devices, the devices include gears100,101including a number of generally angular teeth102disposed along one side of the gears100,101. Each tooth102includes an angled sliding surface104and a flat, vertical locking surface106located between the sliding surfaces104of adjacent teeth102. These gears100,101are positioned in the mechanism with the teeth102facing one another in a manner where one of the gears100can rotate with respect to the other gear101. This is due to the construction of the mechanism in which one gear100is fixed to mechanism and the other gear101can move with a drive body (not shown) for the tool to provide the torque-limiting function. When the tool incorporating the gears100,101is subjected to a torquing force greater than a preset maximum, the moveable gear101rotates with respect to the fixed gear100, such that the sliding surfaces104of the opposed teeth102slide against one another and urge the fixed gear100against a spring member (not shown) that biases the gears100,101towards one another. The movable gear101can continue to rotate in response to the excessive torque until the flat locking surface106on the opposed teeth102are moved past the edges105of the sliding surfaces104. In this position the gears100,101move or snap back towards one another due to the bias of the spring member, and the respective flat surfaces106come into contact with one another to secure the gears100,101in a camming position.

In order to enable the prior art mechanism to provide a closely controllable amount of torque resistance, the mechanism requires that the forces biasing the gears100,101towards one another from: 1) the spring member; 2) the surface friction provided by the contact of the angled surfaces104on the opposed teeth102sliding with respect to one another; and 3) the drag of the gears100,101on a housing (not shown) for the mechanism all be known and properly maintained. To enable the surface friction and drag to be controlled, a proper amount of lubrication is required to be present both on the teeth102and on the back of the rotatable gear101in contact with the housing in order to maintain the constant drag forces on the angled surfaces104and the movable gear101. However, due to the cleaning and/or sterilization of tools including devices of this type, each sterilization cycle causes an inherent loss of the lubrication in the mechanism. As a result, the amount of surface friction and drag between the gears100,101changes over time. This in turn drives the torque values up such that a consistent amount of torque resistance is not provided by the device.

Further, as a result of the particular shape of the teeth102on each gear100,101the rotation of the gear101results in the locking surfaces106on each gears100,101“snapping” into engagement with one another in both the axial and circumferential directions after passing one another. This movement of the locking surfaces106into engagement with one another necessarily creates vibrations in the mechanism which are transmitted through the mechanism and the tool incorporating the mechanism to the fastener and/or the person on which the device is being utilized. In many situations, these vibrations are highly undesirable. Also, the stress exerted on the surfaces106as they strike one another also leads to fracturing or chipping of the teeth102, lessening the useful life of the mechanism. When the teeth102are chipped, this additional material can also collect on the sliding surfaces104of the teeth102, thereby causing even more inconsistent torque values for the mechanism.

In addition, prior art torque limiting devices include one piece calibration nuts (not shown) that engage the spring members of the mechanism to calibrate or set the amount of torque necessary to rotate the gears100,101with respect to one another. The calibration nut is normally secured to the mechanism by adhesives, by pairs of jam or locking nuts to reduce space and/or a mechanical interruption of threads to which the calibration nut is mounted. The design of each of these prior art calibration nut assemblies increases the complexity of the overall mechanism, and provides an additional manner in which the mechanism can break down.

Due to the multitude of problems associated with prior art torque limiting devices, it is desirable to develop or design a torque-limiting device which greatly reduces each of the problems associated with prior art devices at this time.

SUMMARY OF THE INVENTION

According to a one aspect of the present invention, a torque-limiting device for use in hand-held and power tools is provided in which the torque-limiting device includes a number of rolling ball bearings disposed partially within opposed pairs of recesses located in a pair of opposed gears that, in conjunction with springs acting on the gears and ball bearings, are utilized to control the movement and resistance to movement of the mechanism. The recesses in one of the gears are connected by a raceway along which the bearings can move between recesses when the mechanism is in operation. The use of the ball bearings and a raceway on one of the gears that the ball bearings can move along between the recesses enables the mechanism to be operated in a manner that greatly reduces the amount of variation over time of the preset torque values for the mechanism by reducing the wear experienced by the internal components controlling the actuating of the mechanism, and by avoiding the significant recoil or snap experienced by prior art mechanisms. This construction also greatly reduces the effects of varying levels of friction present in prior art mechanism by using ball bearings as the main friction generating members in the mechanism. The shape of the bearings creates much less overall friction, as well as a relatively constant amount of friction over extended periods of use of the mechanism, without the need for significant amounts of lubricants within the mechanism.

According to another aspect of the present invention, the ability of the mechanism to provide consistent torque values is also enhanced by the use of a split locking calibration nut that is securable to the mechanism in a simple manner, thereby avoiding the previous issues concerning the shifting of the nut and the consequent variation of the torque value applied by the mechanism. The calibration nut is threadedly engaged with a housing for the tool and with single locking nut that selectively positions the calibration nut within the housing to provide the desired amount of force against the springs that are used to determine the maximum torque level at which the mechanism will operate. By varying the position of the calibration nut, the amount of torque at which the mechanism slips can be set as desired, while the locking nut can maintain position of the calibration nut at this desired value. In addition to using a locking nut to hold the calibration nut in position, the calibration nut itself may include protrusions that are urged outwardly into engagement with the housing for the mechanism when the locking nut is engaged within the calibration nut. Thus, the calibration nut can be easily adjusted or removed in order to service the mechanism, without the need for disengaging any additional securing means, such as adhesive, or additional lock nuts as used in prior art mechanism.

According to still a further object of the present invention, a mechanism is enclosed within housing having a cover secured to the housing in an easily removable manner. The cover also includes an access cap that can be removed from the cover to enable the mechanism to be serviced without having to completely disassemble the mechanism. Further, the access cap engages the cover in a manner that prevents the cover from being inadvertently disengaged from the housing while the tool including the mechanism is in use.

According to still another aspect of the present invention, cover can be attached to the housing in a manner that allows the cover to move relative to the housing to enable the cover to function as a locking member for the mechanism. Thus, the cover can be moved from one position where the mechanism functions normally to another position where the cover operably locks the gears to one another, thereby disabling the operation of the mechanism.

Numerous other advantages, features, and objects of the present invention will remain apparent from the following detailed description taken together with the drawing figures.

DETAILED DESCRIPTION OF THE INVENTION

With reference now to the drawing figures in which like reference numerals designate like parts throughout the disclosure, a tool including a torque-limiting mechanism constructed according to the present invention is indicated generally at200inFIGS. 1-4. The tool200can be virtually any type of hand-held or power-driven tool that is used to apply torque to a driven member, e.g., a fastener, but in a preferred embodiment, is a hand-held torque wrench that includes a handle202with a gripping part201operatively connected to a drive body204extending outwardly from the handle202by the torque-limiting mechanism206. The handle202is preferably formed of a suitably rigid, but relatively lightweight material, such as a light metal or plastic, to reduce the weight of the tool200. Also, the handle202can be formed to have any desired configuration, and may include on the gripping part201an inner portion203aformed of a more rigid material, and an outer portion203bof a more flexible material to increase the ease of use of the tool200.

The drive body204is preferably an elongate member that is used to transfer the torque applied to the tool200via the handle202, or motor (not shown) in power-driven tool embodiments, to the fastener to be rotated, such as a screw, engaged by the drive body204opposite the handle202. The drive body204is formed of a generally rigid material, such as a metal or hard plastic, and is preferably circular in cross-section, but can be formed to have other cross-sectional configurations as desired. Opposite the mechanism206, the drive body204supports a connector208. The connector208can have any desired configuration for releasably retaining thereon a suitable fastener-engaging implement (not shown), but in one embodiment best shown inFIGS. 3 and 4, includes a locking collar210slidably secured to the exterior of the connector208by a spring212and retaining ring214. When the collar208is urged against the bias of the spring212towards the drive body204, a retaining ball216on the connector208is moved out of the interior of the connector208. This enables the implement to be inserted into the interior of the connector208without interference from the retaining ball216. When the collar210is released, allowing the collar210on the connector208to return to its original position due to the bias of the spring212, the retaining ball216is urged by the collar210back into the interior of the connector208into engagement with an aligned recess (not shown) in the implement, thereby securing the implement within connector208.

Referring now toFIGS. 3-19, the torque-limiting mechanism206includes a pair of gears218,220formed of a rigid material, such as a metal, or hard plastic that are positioned generally opposite one another within the mechanism206. The gear218, best shown inFIGS. 5-8is a fixed gear secured within a generally cylindrical housing234attached to or integrally formed with one end of the handle202opposite the gripping part201. The fixed gear218is preferably secured within the housing234by a pair of locking pins222that extend through the housing234into connection with the gear218. The pins222extend through bores223in the housing234into slots224formed on opposite sides of the gear218to prevent rotation of the gear218within the housing234. In an alternative embodiment, best shown inFIGS. 9-13, the fixed gear218can be formed with a pair of flats252on opposite sides of the gear218that are engaged with similarly shaped flat surfaces (not shown) located on the interior surface of the housing234. The flats252take the place of the pins222and slots224to hold the fixed gear218in position within the housing234to enable the transfer of torque from the handle202to the fixed gear218.

The fixed gear218also includes a number of dimples225spaced around a central opening227in the gear218on one surface of the fixed gear218. The opening227can be cylindrical or can define an annular shoulder327therein to assist in the formation of the dimples225. A number of generally spherical ball bearings226are disposed partially within the dimples225and are able to rotate therein. The depth of the dimples225in the gear218is preferably sufficient to receive approximately one half of the volume of each bearing226, such that while the bearings226can rotate within the dimples225, the bearings226are each maintained within the dimples225. In a particularly preferred embodiment, the bearings226, which are formed of a rigid and smooth material, such as a metal, are formed to have a diameter slightly less than the diameter of the dimples225. This allows the bearings226to rotate more freely within the dimples225when the tool200and mechanism206are in use and also enables the mechanism206to be assembled more easily.

The gear220, i.e., the rotatable or slip gear, is also positioned within the housing234immediately adjacent the fixed gear218between the fixed gear218and the gripping part201of the handle202. The slip gear220, best shown inFIGS. 5-8 and 14-19, is formed similarly in shape and material to the fixed gear218, with a central opening227and a number of dimples228spaced around the opening227on one side of the gear220that is positioned to face the dimples225in the fixed gear218. The dimples228receive the end of each of the bearings226extending outwardly from dimples225in fixed gear218, but are less deep than dimples225in the fixed gear218. The slip gear220also includes an arcuate raceway230extending around the surface of the gear220along a circular centerline between the dimples228. During operation of the mechanism206, the bearings226, while retained in dimples225on the fixed gear218, can move along the raceway230in order to displace the bearings226between the respective dimples228as the slip gear220rotates with respect to the fixed gear218when a torque level above a pre-selected maximum is applied to the tool200.

Additionally, the slip gear220includes a cross pin opening221that extends across and through the slip gear220generally perpendicular to the central opening227. The opening221is positionable in alignment with a bore229formed in the drive body204in order to enable a cross pin329to be inserted through the opening221and bore229to secure the slip gear220to the drive body204. Further, while the diameter of the bore229and opening221within which the pin329is received can be formed to closely conform to the outer diameter of the pin329, in a preferred embodiment, the diameter of the opening221and bore229are formed to be greater than required for insertion of the pin329. This gap created between the pin329and the opening221and bore229enables a certain amount of play between the drive body204and the slip gear220, thereby providing a smoother feel to the mechanism206. Additionally, in an attempt to further enhance the feel of the mechanism206and reduce the potential for unwanted drag or friction acting on the mechanism206, in a preferred embodiment, the outer diameter of the slip gear220is selected to allow for a space between the outer periphery of the slip gear220and the interior surface of the housing234, allowing the slip gear220to “float” within the housing234, and not rub against the sides of the housing234.

Referring now toFIGS. 3-8, to provide the torque level control for the mechanism206, the fixed gear218and slip gear220are biased into engagement with the bearings226and one another by a number of biasing members or springs232. The springs232can each be formed from any suitable biasing member or material, but are preferably formed as Belleville washers and are disposed within the housing234. Each spring232is generally circular in shape with a central opening235through which the drive body204can extend and are disposed within the housing234against the fixed gear218opposite the slip gear220. The springs232can be selectively compressed into engagement with one another and with the fixed gear218in order to provide the desired amount of force resisting the rotation of the gears218,220and the bearings226with respect to one another during use of the tool200.

In order to enable the force applied to the gears218,220by the springs232to be varied as desired, an open end235of the housing234opposite the gripping portion201of the handle202is covered by a generally circular calibration nut236disposed around the drive body204in engagement with the springs232opposite the fixed gear218. The calibration nut236preferably includes an expansion slot237that extends across the nut236and separates opposed portions239of the nut236. The opposed portions239can be deflected away from one another and into engagement with the interior of the housing234to secure the nut236within the housing234and provide the desired force on the gears218,220from the springs232by a tapered lock nut238also positioned around the drive body204and engaged between the body204and nut236. To enable calibration nut236to be deflected, the nut236, as well as the locking nut238, is formed of a somewhat rigid material, such as a metal or hard plastic.

To utilize the calibration nut236, the nut236is advanced into engagement with the springs232within the housing234until the desired spring force is exerted by the springs232against the gears218,220. In a preferred embodiment, the calibration nut236is advanced into the housing234by the engagement of exterior threads (not shown) on the nut236with interior threads (not shown) disposed on the interior of the housing234. When the calibration nut236is positioned against the springs232at a location which provides the desired spring force to the gears218,220, the tapered lock nut238is engaged within the calibration nut236to urge the portions239of the nut236on opposite sides of the expansion slot237outwardly against the interior of the housing234and hold the calibration nut236in position. To further enhance the engagement of the calibration nut236with the housing234, the nut236can include a number of a outwardly extending drive tangs (not shown) disposed on the exterior of the calibration nut236that engage the threads on the interior of the housing234in a manner to further prevent movement of the nut236with respect to the housing234.

Looking now atFIGS. 5-8, to reduce any drag exerted by the inner housing234on the rotation of the slip gear220, and to ensure that the force acting on the gears218,220is limited as much as possible to only the force of the springs232, the slip gear220is isolated from the inner end of the housing234by a hardened washer241and thrust bearing240. The thrust bearing240includes roller bearings242therein that rotate within the thrust bearing240and contact the slip gear220to enable the slip gear220to rotate easily within the housing234. A hardened washer243is also positioned between the springs232and the fixed gear218to enhance the frictional contact between the fixed gear218and the springs232.

Look now atFIGS. 3-5 and 7, the interior components of the mechanism206described previously are enclosed within the housing234of the tool200by a generally cylindrical cover244that is releasably engaged with the exterior of the housing234, such as by mating threads344on the exterior of the housing234and the interior of the cap244. The cap244can be quickly and easily removed from the handle202in order to expose the mechanism206and enable the easy adjustment, service and/or replacement of any parts of the mechanism206. The cover244defines a central opening245at an outer end thereof that receives an access cap246releasably secured to the cover244within the opening245around the drive body204. The access cap246is fixed to the cover244by any suitable means in order to prevent the rotation of the cover244with respect to the housing234, thereby preventing the inadvertent detachment of the cover244from the handle202, such as during use of the tool200. Preferably a number of fasteners (not shown) are engaged within bores247in the cap246to deflect the cap246into engagement with the cover244around the opening245. The access cap246includes an O-ring248disposed around an inner opening249of the cap246that sealingly engages, but does not impede the rotation of the drive body204within the cap246, in order to seal off the interior of the cover244and prevent the mechanism206from encountering any water, dust or other debris which can negatively affect the operation of the mechanism206. A similar O-ring250can be disposed on the inner end of the drive body204located within the handle202to effectively seal the interior of the tool200to protect the components of the mechanism206.

Other alternatives to the preferred embodiment described previously can be formed by changing the orientation of the fixed gear218, slip gear220and springs232from the order of these components shown in the drawing Figs. Also, the location of the calibration nut236can also be altered depending upon the location of the springs232, or can be positioned to engage the gears218,220instead of the springs232. Further, the bearing members226can be other than ball bearings, such as pin bearings, with corresponding changes to the shape of the dimples225,228in the respective gears218,220. Additionally, the housing234can be formed separately from the handle202while the cover244can be formed as part of the handle202.

In addition, in order to further provide a tool200with the ability to control the torque applied using the tool200, another embodiment of the torque-limiting mechanism206, each of the fixed gear218and the slip gear220can include teeth (not shown) positioned on the outer periphery of the gears218and220. The teeth are spaced equidistant from one another around the periphery of each gear218and220in a form so as to be positioned in a one-way locking engagement when the gears218and220are assembled in the mechanism206. In this configuration, the teeth, which each include a sloped friction surface (not shown) and a locking surface (not shown) similar to the teeth102, oppose the rotation of the slip gear220with regard to the fixed gear218by the frictional engagement of the sloped surfaces and vertical surfaces of each of the teeth. However, as opposed to prior art gears100,101, the locking surfaces of the teeth are formed to be inclined from the vertical at an angle of between ten degrees (10°) to twenty-five degrees (25°), and preferably around fifteen degrees (15°), similar to the angle for the friction surfaces from the horizontal. The angle of the locking surfaces allow the teeth to slip more easily with regard to one another and prevent the snapping and vibrations caused by the shape of the teeth102in prior art gears100,101.

In an additional variation to the construction of the gears218and220, it is possible to vary depth of dimples225and/or228to vary the amount of torque provided by the friction generated between the gears218and220and the bearings226without changing biasing or spring pressure provided by the particular springs232being utilized in the tool200.

Further, as an alternative to the lock nut238, it is possible to drill a hole (not shown) into the side of the housing234and insert therein a pin (not shown) through the side of the housing234to engage the calibration nut236.

Looking now atFIGS. 22-29, a fifth embodiment of the tool200′ is illustrated that is formed similarly to the tool200and in which the housing234′ is formed to extend from the handle202′ to create a sleeve260′ that projects outwardly from the housing234′. The gears218′ and220′, the springs232′ and apportion of the drive body204′ are disposed within the sleeve260′. The sleeve260′ defines an inner portion262′ disposed adjacent the handle202′ and within which the main components of the torque limiting mechanism206′ are disposed, namely, the gears218′ and220′ and the bearings226′, and an outer portion264′ adjacent the inner portion262′ opposite the handle202′ within which the springs232′ are located. The diameter of the inner portion262′ is dimensioned to be slightly larger than the diameter of the gears218′ and220′ to enable one of the gears218′ or220′ to be fixed to the housing234′ and the other gear218′ or220′ to be fixed to the drive body204′. Thus, the gear218′ or220′ fixed to the drive body204′ is able rotate within the inner portion262′ in conjunction with a suitable bearing266′ to operate the mechanism206′.

The positioning of the gears218′ and220′ within the inner portion262′ positions the gear218′ or220′ opposite the handle202′ partially out of the inner portion262′ within the outer recess264′. This enables this gear218′ or220′ to be engaged by the springs232′ located within the outer portion264′. This allows the springs232′ to exert the desired force on the gears218′ and220′ to control the operation of the mechanism206′. The desired force provided by the springs232′ is controlled by a locking nut268′ engaged with the housing234′ within an open end270′ of the sleeve260′, such as by threads or another suitable engagement mechanism, such that the nut268′ extends into the outer portion264′ of the sleeve260′ in engagement with the springs232′. The position of the nut268′ on the drive body204′ further in the sleeve260′ increases the force exerted by the springs232′ by increasing the compression the springs232′, while positioning the nut268′ further out of the outer portion264′ lessens the compression of the springs232′. The nut268′ also includes a radial recess269′ within which is disposed a sealing member271′, such as an O-ring, that is engaged with the drive body204′ to seal off the interior of the housing234′ and maintain the integrity of the operation of the mechanism206′.

To enable the drive body204′ to extend into the housing234′ and be engaged and acted upon by the mechanism206′, the outermost of the gears218′ or220′, the springs232′ and the nut268′ each have a central aperture formed therein. The apertures272′ in the gear218′ or220′ has a diameter less than that of the apertures274′ in the springs232′ which have a diameter less than that of the aperture276′ in the nut268′. The outermost of each of the apertures272′ and274′ contacts a corresponding shoulder280′ and282′ disposed on and defining separate diameter sections286′,288′ and290′ on the drive body204′. The engagement of the shoulders280′ and282′ with the apertures272′ and274′ maintains the alignment of the drive body204′ within the sleeve260′ during operation of the tool200′. In addition, the outermost gear218′ or220′ can include a recess292′ formed around the aperture272′ therein′ that is disposed immediately adjacent the outer portion264′. This recess292′ is dimensioned to receive a corresponding portion of the drive body204′ therein. The drive body204′ can rotate relative to the recess292′, but is maintained in alignment with the gear220′ and the remainder of the tool200′ by the recess292′, as well as other features of the tool200′, as described previously.

Referring now toFIGS. 22 and 30-33, the exterior surface of the housing234′ is formed with a wide inner section294′ and a narrow outer section296′. The wide section294′ and the narrow section296′ are separated by a ring298′ having a number of ridges300′ thereon. In the illustrated embodiment, the ridges300′ are formed such that the tip302′ of each ridge300′ is positioned generally co-planar with the wide section294′, and with a number of spaces304′ located therebetween.

The section290′ of the drive body204′ is also formed to include ribs306′ shaped similarly to the ridges300′ located on the housing234′. The ribs306′ in the illustrated embodiment are formed to be generally in radial alignment with the ridges300′.

The ridges300′ and the ribs306′ are engaged by a cover308′ disposed over the housing234′. The cover308′ is formed to conform to the shape of the housing234′ and in the illustrated embodiment is formed to be generally cylindrical in shape. The cover308′ defines an open end310′ positioned over and around the housing234′ and a closed end312′. The closed end312′ includes a central opening314′ through which the drive body204′ can extend. The inner or interior surface316′ of the cover308′ is formed with a ring316′ spaced inwardly from the open end312′ and formed to be complementary to the ring298′ on the exterior of the housing234′ with a number of first notches318′ spaced around the interior of the ring316′ that can mate with the ridges300′ on the housing234′ to engage the cover308′ with the housing234′. The cover308′ also includes a number of second notches320′ that are disposed in the periphery of the central opening314′. The notches320′ in the illustrated embodiment extend partially through the opening314′ and are shaped complementary to the ribs306′ on the drive body204′ to engage the cover308′ with the drive body204′. However, the notches318′ are formed with a length along the ring316′ that is greater than the length of the notches320′ around the central opening314′ for a purpose to be described.

Looking now atFIGS. 23-25, 27-29 and 34-39, the cover308′ is also positioned around the housing to be slidable with respect to the housing234′. The cover308′ is maintained on the housing234′ at one end by a stop322′ formed on the drive body204′ and engageable with the closed end ‘312of the cover308’ around the opening314′ and by a number of detents324′ engaged with the cover308′ generally opposite the closed end312′.

The stop322′ is positioned on the outside of the main shaft326′ of the drive body204′ and has a diameter slightly larger than that of the opening314′. Thus, when the cover308′ is moved away from the handle202′ the closed end312′ will strike the stop322′, thereby causing the motion of the cover308′ to stop at that point. In the illustrated embodiment, the stop322′ can be formed as a part of the shaft securing member328′ that is attached to the drive body204′ to enable drive implements (not shown) of various types to be engaged with the tool200′.

The detents324′, which can be formed as a single detent324′ or multiple detents324′, with three detents324′ spaced equally around the housing234′, are formed in the wide section294′ of the housing234′ by a blind bore330′ formed in the wide section294′, a spring member332′ disposed in the bore330′ and a ball bearing334′ or other suitable structure disposed in the bore330′ to compress the spring332′ into the bore330′. The spring332′ is selected to have a sufficient spring force to urge the bearing334′ out of the bore330′ and into engagement with one of a number of channels336′ formed on the interior of the cover308′ between the open end310′ and the ring316′. The channels336′ are shaped to be generally complementary to the shape of the bearing334′, such that the bearing334′ can seat reliably within the channels336′. Also, the channels336′ are positioned on the cover308′ to correspond to the positions of the cover308′ where the ridges300′ and ribs306′ are either fully engaged or fully disengaged by the notches318′ and320′.

As best shown inFIGS. 23, 25, 27, 29, and 34-39, when the cover308′ is in the disengaged or unlocked position, the closed end312′ of the cover308′ is disposed against the stop322′ and the detent324′ is disposed in the channel336′ located closest to the open end310′. In this position, the notches320′ are spaced from the ribs306′ but, due to longer length of the notches318′, the notches318′ are still engaged with the ridges300′ to maintain the alignment of the cover308′ with respect to the housing234′. In this configuration, best shown inFIGS. 35 and 36, the cover308′ remains engaged with the housing234′ via the ridges300′ and notches318′, but is disengaged from the drive body204′ as a result of the separation of the notches320′ from the ribs306′. This configuration for the mechanism206′ is able to function to allow for rotation of the drive body204′ separate from the handle202′ when a torque limit for the mechanism206′ is exceeded, thereby providing the torque-limiting function for the tool200′.

Alternatively, when the cover308′ is slid into the locked position, an individual presses the cover308′ rearwardly towards the handle202′. When the force exerted by the individual exceeds the spring force exerted by the spring member332′ on the bearing334′, the bearing334′ is moved into the bore330′ allowing the cover308′ to move towards the handle202′. The cover308′ is then moved into the locked position where the ridges300′ are engaged with the notches318′, and also pressed against the wide section294′ of the housing234′ which functions as a stop for the cover308′ when moved to the locked position, and the ribs306′ are engaged by the notches320′. In this position, best shown inFIGS. 38 and 39, the cover308′, via the engagement of the ribs306′ with the notches320′ on the drive body204′, locks the drive body204′ to the handle202′, such that the torque limiting mechanism206′ is rendered inoperative and the entire amount of torque applied to the handle202′ is transmitted through the drive body204′, even in excess of the maximum allowed by the mechanism206′.

In alternative embodiments, the mechanism206′ and the cover308′ can be configured for use with tools200′ having different configurations, such as a T-handle tool400′ having a torque-limiting mechanism therein, as shown inFIGS. 40-43, including those disclosed in U.S. Pat. Nos. 7,272,998; 7,430,945; 7,5650,821 and 7,913,594, which are each hereby incorporated by reference herein in their entirety.

Various additional alternatives are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter regarded as the invention.