Abstract:
A wedge clutch assembly for power tools, drilling rigs and like machinery utilizing rotating drills. The wedge clutch assembly has a pinion shaft adapted in shape to support a pinion gear, a bronze clutch cup, an optional thrust bearing, and a steel wedge clutch spring washer retained by a fastener.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This is a continuation-in-part of my prior application Ser. No. 11/316,963, filed on Dec. 27, 2005, which is a continuation-in-part of application Ser. No. 11/050,786, filed on Jan. 27, 2005, now abandoned, which is a continuation-in-part of application Ser. No. 10/317,140, filed Dec. 12, 2002, now issued as U.S. Pat. No. 6,848,998. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to gear systems. More specifically, the invention is a wedge clutch assembly for insertion in power hand tools and drilling apparatus to prevent damage to a gear drive system upon excessive stress. 
         [0004]    2. Description of the Related Art 
         [0005]    The related art of interest describes various clutch assemblies, but none of the cited references discloses the present invention. There is a need to provide a mechanism to avoid gear failure in power hand tools and even in well drilling apparatus. The relevant art will be discussed in the order of perceived relevance to the present invention. 
         [0006]    U.S. Patent Application Publication No. 2002/0062967, published on May 30, 2002, describes an electrical handheld power tool with an electromagnetic safety clutch provided between a pinion shaft and a rotor shaft. The pinion shaft is formed as a hollow shaft provided in its interior with an inner bearing which rotatably supports the pinion shaft. The rotor shaft has its end received in the interior of the pinion shaft and supported against the inner bearing. The safety clutch is distinguishable for requiring an electromagnetic means. 
         [0007]    U.S. Pat. No. 3,625,292, issued on Dec. 7, 1971 to Michael T. Lay, describes an insulated slip clutch for a power cutting tool such as a lawn edger and grass trimmer. A slip clutch made of Bellville washer springs is held in place by a retaining nut which allows the D-shaped end of the drive shaft to continue to rotate, but to immobilize the drive pinion and any cutting motion. The slip clutch is housed between the cutting blade and a plastic casing in two insulating cups and a liner with a D-shaped hole. The clutch assembly is deemed distinguishable for requiring the driving shaft end to have a flattened D-shaped cross-section, Bellville washer springs and a two-cup insulating casing. 
         [0008]    U.S. Pat. No. 4,606,443, issued on Aug. 19, 1986 to Misao Kimura, describes a planetary drive with an overload clutch release means for a telescopic antenna comprises an intermediate gear which meshes with a gear portion provided on an inner surface of a driven rotary member and a clutch gear which meshes with the intermediate gear to comprise the planetary gears. The clutch assembly is distinguishable for requiring a planetary drive with an intermediate gear for raising and lowering a telescopic antenna. 
         [0009]    U.S. Pat. No. 3,752,278, issued on Aug. 14, 1973 to Ronald F. States, describes an improved power operated wrench or screwdriver having two dog clutches in series for the transmission of the drive in which one is a torque sensitive dog clutch having ramped interengaging driving surfaces adapted to be induced to become displaced against the action of a spring when the torque applied by the tool exceeds a predetermined value. The other dog clutch is a non-torque sensitive clutch that is adapted to become disengaged by displacement of the torque sensitive clutch. The dog clutches are distinguishable for requiring two having different torque sensitivities. 
         [0010]    U.S. Pat. No. 4,053,980, issued on Oct. 18, 1977 to Arthur G. Poehlman, describes a chain saw featuring an over-torque releasing clutch mechanism comprising a drive member driven by the drive shaft and a driven member for rotating the chain sprocket. One of the members is axially movable relative to the other between an engaged or driving position and a released position wherein they are disengaged from each other. The drive and driven members have intermeshing clutch teeth, which co-act to produce an axial force in a direction tending to separate the members, which are releasably held by a resilient member. The clutch mechanism is distinguishable for requiring intermeshing clutch teeth. 
         [0011]    U.S. Pat. No. 4,066,136, issued on Jan. 3, 1978 to Karl Wanner et al., describes a torque and impulse transmitting portable hammer drill having a safety overload clutch mechanism inserted in series between the rotary shaft of the motor and the tool to terminate the transmission of torque from the rotary shaft to the tool when resistance to rotation exceeds a predetermined value. An intermediate gear with smaller teeth is positioned between the crank gear and the coupling gear. The clutch is distinguishable for requiring a third gear. 
         [0012]    U.S. Pat. No. 4,809,572, issued on Mar. 7, 1989 to Katsuhiko Sasaki, describes a power driven screwdriver having a claw clutch comprising a fixed clutch member with teeth on the end of a main gear on a support shaft. The spindle has a movable clutch member with teeth and an engaging ball in an inclined groove. A spring is located between the movable clutch member and the fixed clutch member. The claw clutch is distinguishable for requiring engaging teeth and an engaging ball. 
         [0013]    U.S. Pat. No. 4,883,130, issued on Nov. 28, 1989 to Paul H. Dixon, describes a rotating dual speed transmission for a screw fastener driving tool of an automatic assembly machine which acts in conjunction with two torque-responsive clutches to tighten a threaded fastener such as a screw or a nut during rotation of the spindle. A first torque-responsive clutch automatically switches the drive from a fast speed to a slow speed when torque of a predetermined magnitude is imposed on the fastener, and a second torque-responsive clutch automatically interrupts the drive to the fastener when torque of a higher predetermined magnitude is imposed on the fastener. The first lower clutch has lugs that lock with the lower cam segments supported with a coil spring around the spindle. The upper clutch has lugs that lock with the jaw members of the lower clutch. The clutches are distinguishable for requiring locking elements such as lugs and cam segments. 
         [0014]    U.S. Pat. No. 4,967,888, issued on Nov. 6, 1990 to Wolfgang Lippacher et al., describes a safety clutch for a motor-driven hammer drill that breaks the rotational drive train when a working tool becomes seized in a receiving material. A pair of coupling balls upon seizure leave their recesses in the power take-off spindle housing to permit the drive to continue to rotate. However, the motor must be stopped and restarted. The safety clutch assembly is distinguishable for requiring coupling balls. 
         [0015]    U.S. Pat. No. 5,060,772, issued on Oct. 29, 1991 to Heinz-Gerhard Anders et al., describes a pneumatic power-operated screw driving tool that includes a switching clutch to transfer the torque from the drive shaft to an output shaft when the tool seizes. The driver has a first clutch having clutch coupling jaws at its end that engages the coupling jaws of the second clutch. The clutch system is distinguishable for requiring two engaging clutches with jaws. 
         [0016]    U.S. Pat. No. 5,094,133, issued on Mar. 10, 1992 to Wolfgang Schreiber, describes a power-operated screwdriver with a switch-off means for screw-in depth and screw-in torque having three clutch elements. A first clutch element arranged between the drive and the tool drive shaft, and transferable by axial displacement of the tool drive shaft from a rest position to a working position. A second clutch element connected to the tool drive shaft. A third clutch element arranged between the first and second clutch elements forms an entrainment clutch with the first clutch element and forms a release clutch with the second clutch element. The clutch system is distinguishable for requiring three connecting clutches. 
         [0017]    U.S. Pat. No. 5,134,909, issued on Aug. 4, 1992 to Katsuhiko Sasaki, describes a power driven screwdriver including a driving or frictional clutch mechanism interposed between the drive motor and the spindle. A claw clutch mechanism is interposed between the spindle and a second driving member that is separated from a first driving member. The clutch system is distinguishable for requiring a frictional clutch and a claw clutch. 
         [0018]    U.S. Pat. No. 5,138,916, issued on Aug. 18, 1992 to Yuichi Sato et al., describes a power operated screwdriver having two clutches, a compression spring between a support shaft and an intermediate clutch disc and urges the clutch disc toward the main spindle to disengage the first clutch. The clutch system is distinguishable for requiring two clutches. 
         [0019]    U.S. Pat. No. 5,350,026, issued on Sep. 27, 1994 to Heule Markus et al., describes an electric power-driven screw-driver having a single friction coupling consisting of first and second coupling elements that undoes the drive connection between a driving electric motor and the tool output shaft. 
         [0020]    U.S. Pat. No. 5,372,206, issued on Dec. 13, 1994 to Katsuhiko Sasaki et al., describes a tightening tool including a drive member rotatably driven by a motor. An intermediate member is interposed between the drive member and a spindle, and rotatable with the drive member. A claw clutch is formed between the spindle and the drive member. The clutch system is distinguishable for requiring a claw clutch. 
         [0021]    U.S. Pat. No. 5,538,089, issued on Jul. 23, 1996 to Christopher P. Sanford, describes a power tool clutch assembly having a first spindle configured to rotate in a gear case. A drive clutch element is fixed to the first spindle. A second spindle rotates independently of the first spindle. An output clutch element is fixed to the second spindle. A compression spring is provided between the intermediate and output clutch elements. The clutch housing and clutch components can be removed from a power tool gear casing for easy service. The clutch assembly is distinguishable for requiring two clutches. 
         [0022]    U.S. Pat. No. 5,566,458, issued on Oct. 22, 1996 to Thomas R. Bednar, describes two embodiments of a clutch mechanism for reciprocating saws having a wobble plate drive member including a spindle reciprocally supported by the housing, and a clutch drivingly connecting the motor to the shaft and providing slippage between the motor and the shaft if there is binding of the spindle. The clutch mechanisms are distinguish-able for requiring structurally different elements. 
         [0023]    U.S. Pat. No. 5,573,091, issued on Nov. 12, 1996 to Michael Hung, describes an electrically powered or manually driven clutch and brake assembly for an electric winch cooperating with a transmission assembly. The clutch mechanism is provided with a thrust bearing on a clutch shaft, and a large clutch gear is inserted thereon. A lining plate is attached to a clutch plate of the large gear, and a pinion gear is attached tightly to the lining plate. Another thrust bearing is placed behind the pinion gear and a compression spring is inserted on the clutch shaft. The large gear and the pinion gear are pushed tightly together or loosened as a function of the resiliency of the spring. A clutch hand wheel can be provided for manual operation. The clutch mechanism is distinguishable for requiring a large clutch gear, a lining plate and two thrust bearings. 
         [0024]    U.S. Pat. No. 5,622,230, issued on Apr. 22, 1997 to David A. Giardino et al., describes a rotary impact wrench clutch comprising a two-part, readily assembled and disassembled pin cage-coupler. One part is a cylindrical, longitudinally grooved cage contains a clutch mechanism and capped at one end by a lobed end plate coupler. The clutch device is distinguishable for requiring a pin-cage coupler. 
         [0025]    U.S. Pat. No. 5,778,989, issued on Jul. 14, 1998 to Anton Neumaier, describes a manually operable screw driving tool having a drive pinion axially fixed with a housing. A spindle in the housing is axially displaceable relative to the drive pinion against the force of a first spring. A clutch element is located in a passageway in a collar on the drive pinion, and is radially displaceable by an actuating member for engaging the spindle to the drive pinion. In the engaged position the clutch element sits against a stop surface in the spindle. The actuation member is axially displaceable by stops located on the spindle, and can be axially fixed to the drive pinion by a retaining element and a snap-element. The clutch element is distinguishable for requiring an actuation member axially displaceable by stops on the spindle. 
         [0026]    U.S. Pat. No. 6,283,226 B1, issued on Sep. 4, 2001 to Kenneth Chen, describes a clutch-buffer assembly for a power wrench comprising a driven wheel having an outwardly positioning tube disposed at a power-input end. A retaining spring, a retaining disc, a driven gear, an anchor ring, and a reversible motor are collared onto the positioning tube sequentially. The retaining disc is limited to move back and forth along the positioning tube without rotation. A pair of protruding teeth and reception cavities in respective contact faces of the retaining disc and the driven gear, and the reversible motor is used to drive the driven gear. When the driven wheel rotates at a higher speed, the retaining disc can be detached from the driven gear for control of the power consumption to lessen the imposed load in order not to blow a fuse. The clutch-buffer assembly is distinguishable for requiring a pair of protruding teeth and reception cavities in the respective contact faces of the retaining disc and the driven gear. 
         [0027]    U.S. Pat. No. 6,439,091 B1, issued on Aug. 27, 2002 to John E. Dibbern et al., describes a clutch mechanism for a power tool having a hole and first and second clamps connected to the arbor to clamp the blade. One of the cutting tool and at least one of the first and second clamps and arbor have a first drive surface for contacting a second drive surface on the other of the cutting tool, and at least one of the first and second clamps and arbor. The second drive surface is movable between a first position and a second position bypassing the first drive surface. The second drive surface is resiliently connected to the other of the cutting tool and at least one of the first and second clamps and arbor. At least one metal strip connects the second drive surface to the other of the blade and at least one of the first and second clamps and arbor. The clutch mechanism is distinguishable for requiring two clamps for the blade and first and second drive surfaces. 
         [0028]    German Patent Publication No. 3,807,308, published on Sep. 14, 1989, describes a radially acting safety friction clutch positioned inside a component of a power tool with an axial mode of action to obtain a shorter and more compact tool. The clutch has compression or cup springs. The clutch is distinguishable for requiring a radially acting safety friction clutch assembly. 
         [0029]    German Patent Publication No. 4,101,705, published on Mar. 26, 1992, describes a positive, frictionless clutch for a hedge trimmer that has a locking ring to disengage the main gear from a driven bushing by moving two drive rollers into a clear space. The clutch assembly comprises a main drive gear, the driven bushing and a locking ring mounted co-axially on a fixed central shaft. One end of the drive bushing has eccentrics that drive the trimmer blades. Roller located in apertures of the driven bushing transmit the drive through ledges on the inside diameter of the main drive gear. When the trimmer handle grips are released a stop pin enters a hole in the flange of the locking ring and prevents rotation. The main drive gear and the driven bushing continue rotating, causing the rollers to enter a clear space between the two members and immediately disengaging the drive. A preloading coil spring connects the locking ring to the driven bushing, and together with friction brings the trimmer blades to rest. The clutch assembly is distinguishable for requiring an eccentric drive bushing containing two rollers. 
         [0030]    French Patent Publication No. 2,799,113, published on Apr. 6, 2001, describes a jointed dental hand drill as a continuously rotating instrument having a torque limiter in the form of a spring-loaded sliding gear clutch on the primary drive shaft and a fixed gear on the secondary drive shaft. In the event of a set torque being exceeded, the sliding gear moves along the primary shaft against the pressure of the spring and disengages the transmission. The two gears have asymmetrical teeth to give different torque levels according to the direction of motion. The dental drill clutch system is distinguishable for requiring asymmetrical gear teeth on two gears. 
         [0031]    None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus, a wedge clutch assembly solving the aforementioned problems is desired. 
       SUMMARY OF THE INVENTION 
       [0032]    The present invention is directed to multiple embodiments of a wedge clutch assembly requiring a minimum of space for inclusion in any electric or pneumatic power tool and drilling rig to prevent damage to an electrically powered rotary or reciprocal hand drill, screwdriver, well drill, and the like tool or apparatus. The first embodiment utilizes the wedge clutch assembly on a pinion or drive shaft having a configuration sequentially as a first small diameter and a proximate threaded region, a second conical region increasing in diameter, a third increased diameter region, a fourth gear region, and a fifth decreased diameter region. A steel clutch wedge spring washer is positioned adjacent the pinion gear, and a retaining nut is threaded on the proximate threaded region for retaining the steel clutch wedge spring washer. A clutch cup is inserted on the conical enlarged region of the pinion shaft and inside the pinion gear. 
         [0033]    A thrust bearing may be disposed on the pinion or drive shaft. The thrust bearing may be disposed either between the spring washer and the pinion gear, or between the retaining nut and the spring washer. The thrust bearing helps to take pressure off of the retaining nut. 
         [0034]    The second embodiment utilizes a pinion gear having a throughbore with inclined sides; a cylindrical pinion shaft having a conical enlarged region proximate to a first end thereof for supporting the pinion gear and a second end having a threaded region; and a bearing spacer element, a bearing, a clutch wedge spring steel washer, and a retaining nut sequentially secured on the threaded region of the pinion shaft. 
         [0035]    A third embodiment utilizes a driven cylindrical motor shaft; a clutch cup having a first enlarged region adapted with a keyway for passing said motor shaft therethrough; the clutch cup having a second conical reduced region and a third externally threaded neck region; a sprocket wheel frictionally fitted on the second conical reduced region of the clutch cup; a steel clutch wedge spring washer positioned adjacent the sprocket wheel; and a nut retaining the steel spring washer on the motor shaft. Further embodiments, including the addition of a housing in order to protect the wedge clutch assembly from environmental contamination, are further described. 
         [0036]    Accordingly, it is a principal object of the invention to provide a wedge clutch assembly for hand tools and drilling rigs. 
         [0037]    It is another object of the invention to provide a wedge clutch assembly incorporating a clutch wedge spring washer. 
         [0038]    It is a further object of the invention to provide a wedge clutch assembly incorporating a clutch cup. 
         [0039]    Still another object of the invention is to provide a wedge clutch assembly adaptable to several different pinion and drive shafts. 
         [0040]    It is an object of the invention to provide improved elements and arrangements thereof for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes. 
         [0041]    These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0042]      FIG. 1  is a schematic elevational view of a first embodiment of a wedge clutch assembly for installation in a hand tool or a drilling rig according to the present invention. 
           [0043]      FIG. 2  is an exploded elevational view of the  FIG. 1  wedge clutch assembly according to the present invention. 
           [0044]      FIG. 3  is a schematic elevational view of a second embodiment of a wedge clutch assembly for installation in a hand tool or a drilling rig according to the present invention. 
           [0045]      FIG. 4  is an exploded elevational view of the  FIG. 3  wedge clutch assembly according to the present invention. 
           [0046]      FIG. 5  is a schematic elevational view of a third embodiment of a wedge clutch assembly for installation in a hand tool or a drilling rig according to the present invention. 
           [0047]      FIG. 6  is a perspective view of the  FIG. 5  wedge clutch cup according to the present invention. 
           [0048]      FIG. 7  is a schematic elevational view of a wedge clutch assembly according to the present invention similar to  FIG. 1 , but including a thrust bearing. 
           [0049]      FIG. 8  is an exploded view of the clutch assembly of  FIG. 7 . 
           [0050]      FIG. 9  is an exploded view of a wedge clutch assembly similar to  FIG. 8 , but with the thrust bearing disposed between the spring washer and the jam nut. 
           [0051]      FIG. 10  is a side view of a frustoconical section of an alternative embodiment of the wedge clutch assembly according to the present invention. 
           [0052]      FIG. 11  is a top view of the frustoconical section of the wedge clutch assembly of  FIG. 10 . 
           [0053]      FIG. 12  is a partial side cut-away view of another alternative embodiment of the wedge clutch assembly according to the present invention. 
           [0054]      FIG. 13  is a top view of a frustoconical section of the wedge clutch assembly of  FIG. 12 . 
           [0055]      FIG. 14  is a partial side cut-away view of yet another alternative embodiment of the wedge clutch assembly according to the present invention, illustrating the frustoconical section housed within a protective housing. 
           [0056]      FIG. 15  is a side attachment view of a frustoconical section and a corresponding sealing bolt according to yet another embodiment of the wedge clutch assembly according to the present invention. 
           [0057]      FIG. 16  is an exploded partial side cut-away view of yet another alternative embodiment of the wedge clutch assembly according to the present invention. 
           [0058]      FIG. 17  is an exploded partial side cut-away view of yet another alternative embodiment of the wedge clutch assembly according to the present invention. 
           [0059]      FIG. 18  is a partially-assembled side view of the wedge clutch assembly of  FIG. 17 . 
           [0060]      FIG. 19  is a top view of an outer wedge of the wedge clutch assembly of  FIG. 17 . 
           [0061]      FIG. 20  is a side, cut-away view of wedge clutch assembly of  FIG. 17 . 
       
    
    
       [0062]    Similar reference characters denote corresponding features consistently throughout the attached drawings. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0063]    The present invention is directed to three embodiments of a wedge clutch assembly that can be utilized in rotatable electrically or pneumatically driven machinery, such as hand tools and drilling rigs, which would prevent expensive broken gear damage. 
         [0064]    A first embodiment  10  of a wedge clutch assembly is illustrated in  FIGS. 1 and 2 . A pinion gear  12  has a through-bore  14  with inclined sides  16  to define a frustoconical configuration and a countersink  18  on its upper surface to frictionally accommodate a spring washer  46 . A cylindrical pinion drive shaft  22  has in sequence from the top, a first small diameter neck  24  and a proximate threaded region  26 , a second frustoconical region  28  increasing in diameter, a third increased diameter region  30 , a fourth gear region  32 , and a fifth decreased diameter region  34 . The pinion gear  12  revolves with the pinion driven shaft  22  in order to drive a drill bit or other load. A fillet  36  is provided to support the frustoconical region  28  on one side and fillets  36  are also provided on both sides of the gear region  32 . 
         [0065]    The frustoconical bronze clutch cup  20  is 1/16 inch thick (shown also in  FIG. 6 ) and has a wide aperture  40  and a smaller aperture  42 . The bronze clutch cup  20  is inserted inside the throughbore  14  of the pinion gear  12  and fits over the frustoconical region  28  of the pinion drive shaft  22  to prevent the pinion gear  12  and the pinion drive shaft  22  from gouging or otherwise damaging the clutch wedge spring washer  46  by shear forces. The spring washer  46  is shaped as a shallow cup with open ends. The clutch wedge spring washer  46  is made of spring steel and is placed inside the countersink  18  and over the smaller aperture  42  of the clutch cup  20 . A fastener, such as a retaining nut or jam nut  48 , is placed on the externally threaded region  26 . The jam nut  48  secures the spring washer  46  to the assembly and adjusts the sensitivity of the clutch wedge spring washer  46 , or frictional force applied by the spring washer  46  to the pinion gear  12 , in the countersink  18  to a specific applied torque on the drive shaft  22  of the tool, which will energize the clutching action to eliminate any damage to the mechanical drive system of the tool. 
         [0066]    Under normal load the spring washer  46  applies sufficient frictional force against the pinion gear  12  to cause the pinion gear  12  to rotate with shaft  22  to drive the load. However, the clutch wedge spring washer  46  collapses and assumes a more flattened shape when excessive torque is applied to the main drive system by the load in order to permit the pinion gear  12  to stop and the pinion drive shaft  22  to spin freely under an excessive load. This prevents the gears from being stripped or damage to the motor when the load requires more torque than the motor can supply. This principle applies to all of the embodiments described herein. 
         [0067]    As shown in  FIGS. 7-9 , a thrust bearing may be disposed between the pinion gear  12  and the jam nut  48  to relieve pressure on the jam nut  48  and to prevent premature wear of the spring washer  46 . In  FIGS. 7 and 8 , the thrust bearing  45  is disposed between the pinion gear  12  and the spring washer  46 . In this configuration, under normal load the spring washer  46  exerts sufficient tension against the thrust bearing  45  to cause the bearing  45  to frictionally engage pinion gear  12 , causing pinion gear  12  to rotate with shaft  22 , thereby driving the load. When the load exerts excessive torque on pinion gear  12 , spring washer  46  collapses and flattens, relieving the frictional force exerted by the spring washer  46  on bearing  45 , thereby permitting pinion gear  12  to stop while shaft  22  rotates freely. 
         [0068]    Alternatively, the thrust bearing  45  may be disposed between the jam nut  48  and the spring washer  46 , as shown in  FIG. 9 . In this configuration the spring washer  46  again directly exerts frictional force against the pinion gear  12  by contact with the wall of the pinion gear  12  in countersink  18  under normal load, but collapses and flattens under excessive torque applied by the load to disengage pinion gear  12  from shaft  22  to allow free rotation of the shaft  22 . Thrust bearing  45  relieves pressure against jam nut  48  and prevents excessive wear of spring washer  46 . 
         [0069]      FIGS. 3 and 4  depict a second embodiment of a wedge clutch assembly  50  comprising a pinion gear  52  having a frustoconical throughbore  54  with inclined sides  56  for accepting a bronze clutch cup  58 . The pinion gear  52  has a reinforcement ring  59  on the smaller opening of the throughbore  54 . A cylindrical pinion shaft  60  has a frustoconical enlarged region  62  proximate to a first end  64  thereof for supporting the pinion gear  52  and a second end  66  having an externally threaded region  68 . A bearing spacer element  70  with a shoulder  72  supports a bearing  74  with evenly spaced blind bores  76 , a steel clutch wedge spring washer  78  which is inverted, and a retaining jam nut  80  sequentially secured on the threaded region  68  of the pinion shaft  60 , whereby the pinion gear  52  revolves with a pinion gear of a driven shaft (not shown). Again, the sensitivity of the clutch wedge spring washer  78  is adjusted by the amount of pressure exerted by the jam nut  80 . Upon excessive torque on the driven shaft due to sticking in a bore, the clutch wedge spring washer  78  will compress to disengage the pinion gear  52  from the driven gear to avoid damage to the driving system of the tool. 
         [0070]      FIG. 5  shows a third embodiment  82  of a wedge clutch assembly for a sprocket drive wheel  84  having cogs  102  on a driven cylindrical motor shaft  86 . A bronze clutch cup  88  is provided with a first enlarged region  90  adapted with a keyway  92  for passage of the motor shaft  86  therethrough. The clutch cup  88  has a second frustoconical reduced region  94  and a third externally threaded neck region  96 . The driven sprocket wheel  84  is frictionally fitted on said second frustoconical reduced region  94  of the clutch cup  88 . A steel clutch wedge spring washer  98  is positioned abutting the driven sprocket wheel  84 , and its sensitivity is adjustably maintained by a jam nut  101  on the threaded neck region  96 . Thus, the driven sprocket wheel  84  is protected from damage by the efficient operation of the steel clutch wedge spring washer  98  on the motor shaft  86 . 
         [0071]      FIG. 6  illustrates a bronze clutch cup  20  used in the first two embodiments having a wide lower aperture  40  and a narrow upper aperture  42  to define a frustoconical configuration. The clutch cup preferably has a peripheral thickness between 1/16 of an inch and 3 inches. As noted above, clutch cup  20  is the only element in the wedge clutch assemblies made of bronze, the remaining elements being made of hardened steel. 
         [0072]    It should be noted that it may be desirable, in the alternative, to remove clutch cup  20  from the wedge clutch assembly. By forming frustoconical region  16  and frustoconical section  28  from relatively soft materials, clutch cup  20  may be removed from system  10  without affecting operation of the clutch assembly. Such a configuration may be desirable in that friction between the moving parts will be decreased, and the chances for misalignment between the frustoconical pieces are minimized. 
         [0073]    In the alternative embodiments illustrated in  FIGS. 10 ,  11  and  12 , the frustoconical section  28  and upper externally threaded neck  24  are formed as a unitary structure having a channel  100  formed axially therethrough. Channel  100  receives a central shaft  120 , which drives rotation of the wedge clutch assembly. As best shown in the top view of  FIG. 11 , channel  100  is patterned to include a plurality of axially extending projections, forming an engaging inner wall surface  110 . In  FIG. 12 , central shaft  120  has a substantially cylindrical contour, however, depending on the needs of the user, shaft  120  could be contoured to include corresponding axially extending projections, forming an engaging outer wall surface for inner wall surface  110  of  FIG. 1 . Engagement of the extending projections of inner wall surface  110  with those of the outer wall surface of the shaft  120  releasably locks shaft  120  to frustoconical section  28  and neck portion  24 . This releasable locking of shaft  120  aids in driving rotation of the frustoconical section  28  and wedge clutch assembly  10  when shaft  120  is driven by an external motive force. 
         [0074]    Further, in the embodiment illustrated in  FIG. 12 , a housing  130  is provided for covering the upper externally threaded neck portion  24  and the frustoconical section  28 . Clutch assemblies are typically used in combination with some sort of motor, engine or other rotary machine. Thus, clutch assemblies are often exposed to dirt and other contaminants and pollutants, which can clog the moving parts of the clutch assembly. The embodiment illustrated in  FIG. 12  is well adapted for usage with lawn mower blades and the like. Cover  130  is provided to prevent clogging and contamination of the rotary section of the clutch assembly  10 , when used in combination with a rotary drive system. A removable lid  140  is provided to allow the user selective access to the interior of housing  130  for repair or replacement of parts. Removable lid  140  is secured to housing  130  through a plurality of releasable fasteners, such as screws or bolts  150 , as shown. 
         [0075]    Additionally, a threaded bore hole  160  may be formed through frustoconical section  28 , extending radially therethrough from the outer surface of frustoconical section  28  to channel  100 , as best shown in the top cut-away view of  FIG. 13 . The user may insert a threaded engaging member, such as a screw or a bolt, for selective locking engagement with central shaft  120 , thus securing shaft  120  to the frustoconical section  28  and upper neck portion  24 . This additional locking engagement may be used with a smooth or keyed shaft, such as that shown in  FIG. 12 , a patterned shaft as would be necessary for the embodiment of  FIG. 11 , or may be used with a shaft contoured dependent upon the needs and the desires of the user. Additionally, as further shown in  FIG. 12 , housing  130  may be contoured to include threads or the like for securely receiving and holding the threads  26  of threaded neck portion  24 . 
         [0076]    In the alternative embodiment shown in  FIG. 14 , the upper portion (in the configuration as shown) of frustoconical section  28  is housed within a first housing  170 . First housing  170  includes an open upper end and an open lower end. A gasket or o-ring  210  is received within the open upper end of first housing  170 , preventing contamination from dirt and other contaminants where the remainder of cylindrical pinion shaft  22  projects outwardly therefrom. The embodiment of  FIG. 14  is well adapted for usage with the drive lines of heavy duty vehicles and the like. 
         [0077]    The open lower end of first housing  170  is in communication with a second housing  180 , which receives the remainder of frustoconical section  28  and the threaded neck portion  24 . The lower end of second housing  180  is open and is covered with a releasable lid  190 . Similar to that shown in  FIG. 12 , lid  190  is releasably held to housing  180  by a plurality of fasteners  200 , which may be bolts, screws or the like. Lid  190  seals the internal parts from external contaminants, and further allows the system to be bolted to one side of the driveline. Further, as shown, a washer  75  is sandwiched between a jam nut  71  and an adjustment nut  73 . These are received about the threaded portion  24 , as shown. Further, a pair of Belleville springs or disc springs  79  are sandwiched between adjustment nut  73 , and a thrust washer  83 . Thrust bearing  74  is sandwiched between the lower thrust washer  83  and an upper thrust washer  81 , as shown. 
         [0078]    In the similar embodiment shown in  FIG. 16 , a single housing  240  is provided for receiving and covering frustoconical section  28  and threaded neck portion  24 . The remainder of pinion shaft  22  projects downwardly and outwardly from the lower end of housing  240 , and a gasket or O-ring  210  is provided for sealing the open lower end of housing  240  about the shaft. The embodiment of  FIG. 16  is well adapted for use with marine-type vehicles and the like. 
         [0079]    The open upper end  250  is adapted, dimensioned and configured to receive thrust bearing  74 , a pair of fasteners, such as nuts  280 , a washer  290  sandwiched between the fasteners  280 , and a locking fastener  300 . Washer  290  may be a locking-type washer for preventing further movement of jam nuts  280 . Particularly, washer  290  may be a keyed locking-type washer. Additionally, at least one resilient element, such as a disc spring,  270 , is provided, as shown. Although shown as a stack of three disc springs, it should be understood that the number of resilient elements and the type of resilient elements may vary. 
         [0080]    Each of the fasteners  280  and  300  has a threaded passage formed centrally therethrough for engaging threads  26  of neck portion  24 . Additionally, a second gasket or O-ring  310  may be provided within the passage formed through fastener  300  for forming a seal against contamination with neck portion  24 . Additionally, a third gasket or O-ring  320  may be provided around the external surface of fastener  300  in order to form a seal with the inner wall of housing  240 , which defines opening  250 . 
         [0081]    Further, a vertical channel  260  may be formed in the external surface of threaded neck portion  24 , as shown in  FIG. 16 . The user may engage vertical channel  260  with an engaging element, such as a bolt or a screw, in order to selectively and releasably lock threaded neck portion  24  to housing  240 . 
         [0082]    Additionally, under certain conditions, such as in environments where a great quantity of pollutants might enter the clutch assembly  10 , it may be necessary to seal off the interior of frustoconical section  28 . As shown in  FIG. 15 , frustoconical section  28  may have an internal bore passage  230  formed through the upper end thereof. A threaded sealing element, such as bolt  220 , is provided for selective and releasable engagement with passage  230  to seal the upper open portion of the frustoconical section  28  from contamination. 
         [0083]    The alternative embodiment illustrated in  FIG. 17  is similar to that of  FIG. 16 , in that the clutch cup of previous embodiments is replaced by an inner wedge or pinion shaft  400 , which includes an upper, threaded neck portion  402 , a frustoconical section  404  adjacent the threaded neck portion  402 , and an increased diameter section  406 , which is formed on a lower end of frustoconical section  404  and extends downwardly therefrom. As in the previous embodiments, the upper threaded neck portion  402  includes a central threaded portion, and smooth, or non-threaded, upper and lower portions, sandwiching the threaded portion. The increased diameter section  406 , as shown, has a diameter greater than that of the threaded neck portion  402 . 
         [0084]    A lower section  408  is formed adjacent a lower end of the increased diameter section  406 , as shown, with the lower section  408  preferably having a diameter less than the diameter of the increased diameter section  406 , but greater than the diameter of threaded neck portion  402 . A gasket or O-ring  410  is mounted annularly about the lower section  408 , as shown. The pinion shaft or inner wedge  400  is preferably formed from a relatively soft material, such as bronze, allowing for the elimination of the bronze clutch cup of previous embodiments. As shown in  FIG. 18 , a central passage  412  (shown in phantom) is formed through the inner wedge  400 , allowing the inner wedge  400  to be mounted on one side of the driveline or drive shaft  448 . 
         [0085]    An outer wedge or housing  414  is further provided, with the housing  414  having an upper portion  416 , a lower portion  418 , and a central passage  420  formed therethrough for receiving the inner wedge  400  (as best shown in  FIG. 18 ). The upper portion  416  is mounted about the lower end of threaded portion  402 , and the lower portion  418  covers the frustoconical section  404 . As shown, the increased diameter portion  406  and the lower portion  408  project outwardly from the lower end of housing  414 . As shown in  FIG. 19 , the housing  414  preferably is substantially hexagonal. As in the previous embodiments, the inner wedge  400  preferably is substantially circular when viewed from above, including the threaded section  402 , the frustoconical portion  404 , the increased diameter portion  406 , and the lower section  408 . Similarly, the ancillary elements, such as the washers and thrust bearing, all have circular cross-sectional contours, and only outer wedge or housing  414  has a hexagonal contour. Outer wedge  414  is preferably formed from relatively hard stainless steel or the like, and the hexagonal shape allows the outer wedge  414  to fit within a cavity of the other side of the driveline. When the clutch slips, the outer wedge  414  will begin to spin only when sufficient torque is applied thereto.  FIG. 20  illustrates the assembled housing and pinion shaft (and associated components, described in detail below) seated within cavity  444  of the driveline  446  of the clutch. 
         [0086]    A thrust bearing  424  (similar to thrust bearing  74  of  FIG. 16 ) is sandwiched between a pair of thrust washers  422 , as shown, and bearing  424  and washers  422  are mounted about the threaded portion  402 . Thrust bearing  424  aids in preventing locknut  426  from loosening and provides enhanced release on the clutch. A pair of spring washers or disc springs  428 , such as Belleville spring washers, are mounted on top of the upper thrust washer  422  (similar to disc springs  270  of  FIG. 16 ), and are also received about the threaded portion  402 . The spring washers  428  provide spring-biasing between the inner wedge  400  and the outer wedge  414 . The locknut  426  is mounted on top of spring washers  428 , and is secured to threaded portion  402  by a threaded opening  432  formed centrally therethrough. The locknut  426  allows for adjustment in pressure between the spring washers  428 , the thrust bearing  424 , the inner wedge  400  and the outer wedge  414 . A set screw  430  is mounted in the locknut  426 , allowing the locknut  426  to be further fastened to the threaded portion  402 . 
         [0087]    A seal flange  434  is mounted above locknut  426 , and includes an outer gasket  436 , and an inner gasket  438  mounted about an inner passage  440  (similar to outer gasket  320  and inner gasket  310  of  FIG. 16 ). As shown in  FIG. 20 , the lower gasket  410  acts to seal the lower portion, and the upper gaskets  436 ,  438  act to seal the upper portion, thus preventing contaminants from entering cavity  444  and interfering with operation of the internal components. The seal flange  434  is preferably formed from plastic. 
         [0088]    It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.