BACKGROUND 
     The invention relates to a clutch/brake assembly for use on a lawnmower or other powered equipment. 
     Clutch/brake assemblies of the type described herein are commonly used on devices such as riding lawnmowers and small tractors. The clutch/brake assembly allows the user to selectively engage the clutch to drive auxiliary equipment such as a lawnmower blade, snowblower screw, etc. In addition, the clutch/brake assembly provides a brake mechanism that stops the rotation of the auxiliary equipment when the user disengages the clutch. Thus, the clutch gives the user full control of the rotation of the auxiliary equipment. 
     Due to the limited size of lawn tractors and riding lawnmowers, the mechanical components such as the clutch/brake assembly and the engine are made as small as possible. However, the clutch mechanism must be large enough to efficiently transfer the engine power to the blade or other driven accessory without wearing excessively or failing. 
     SUMMARY 
     The present invention provides a clutch/brake assembly including a plurality of disks that engage each other to transfer the rotation of a drive shaft to a driven shaft and associated an output pulley. 
     More particularly, the present invention provides a clutch/brake assembly including a pair of input disks movable between a braking position and a driving position and a pair of output disks movable between a braking position and a driving position. The assembly further includes a housing including a braking surface and a biasing member biasing at least one of the output disks against the braking surface of the housing to resist rotation when the disks are in their respective braking positions. An actuator assembly is operable to substantially simultaneously disengage the output disks from the braking surface of the housing and sandwich the input and output disks together in the driving position such that the input and output disks are coupled together for rotation by the frictional forces therebetween. 
     In preferred constructions, the input and output disks are movable axially relative to one another. A plurality of biasing members bias the disks toward the braking position. 
     In another embodiment, the invention provides a brake/clutch assembly comprising a housing, an input shaft supported for rotation relative to the housing, and a plurality of input disks connected to the input shaft. The assembly also includes a plurality of output disks rotatable relative to the input shaft. The plurality of output disks are selectively engagable with the plurality of input disks. At least one of the plurality of output disks is selectively engagable with the housing. A biasing member biases the at least one of the plurality of output disks into engagement with the housing. The assembly further includes an actuating member operable to move the input disks into engagement with the output disks and to simultaneously move the output disk out of engagement with the housing. 
     In preferred constructions, the input disks and the output disks are positioned to intermesh with one another when engaged. 
     In yet another construction, the invention provides a clutch/brake assembly comprising a housing, an input shaft supported for rotation relative to the housing, and an output device supported by the input shaft and selectively rotatable relative to the input shaft. The apparatus also includes a plurality of input disks coupled to the input shaft and axially movable relative to the input shaft and to one another between a braking position and a driving position. The input disks including a plurality of drive surfaces. A plurality of output disks are coupled to the output device and are movable axially relative to the output device and to one another between a braking position and a driving position. The output disks including a plurality of drive surfaces and a brake surface. An actuator member is operable between a braking position and a drive position. When in the braking position the brake surface contacts the housing and when in the drive position the drive surfaces of the input disks contact the drive surfaces of the output disks such that the output device rotates in conjunction with the input shaft. A biasing member biases the output disk brake surface into contact with the housing. 
    
    
     Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view of a clutch/brake assembly embodying the invention. 
     FIG. 2 is a partial cross-sectional view of the inner hub and transaxle pulley portion of the assembly. 
     FIG. 3 is a partial view of a bearing of the assembly. 
     FIG. 4 is a cross-sectional view of the cup-shaped washer of the assembly taken along line  4 — 4  of FIG.  5 . 
     FIG. 5 is a top view of the cup-shaped washer. 
     FIG. 6 is a top view of the housing of the assembly. 
     FIG. 7 is a cross-sectional view taken along line  7 — 7  in FIG.  8 . 
     FIG. 8 is a bottom view of the housing of the assembly. 
     FIG. 9 is a top view of half of the output pulley. 
     FIG. 10 is a cross-sectional view taken along line  10 — 10  in FIG.  9 . 
     FIG. 11 is a top view of the output pulley assembly. 
     FIG. 12 is a cross-sectional view of the output pulley assembly taken along line  12 — 12  in FIG.  11 . 
     FIG. 13 is a top view of the support plate of the assembly. 
     FIG. 14 is a side view of the support plate. 
     FIG. 15 is an enlarged cross-sectional view of the portion of the support plate taken along line  15 — 15  in FIG.  13 . 
     FIG. 16 is a bottom view of an upper output disk of the assembly. 
     FIG. 17 is a cross-sectional view of the upper output disk taken along line  17 — 17  in FIG.  16 . 
     FIG. 18 is a top view of a lower output disk of the assembly. 
     FIG. 19 is a cross-sectional view of the lower output disk taken along line  19 — 19  in FIG.  18 . 
     FIG. 20 is a top view of an input disk of the assembly. 
     FIG. 21 is a cross-sectional view of the input disk taken along line  21 — 21  in FIG.  20 . 
     FIG. 22 is a cross-sectional view taken along line  22 — 22  in FIG.  20 . 
     FIG. 23 is a top view of a thrust bearing of the assembly. 
     FIG. 24 is a cross-sectional view of the thrust bearing taken along line  24 — 24  in FIG.  23 . 
     FIG. 25 is a perspective view of a drive stud of the assembly. 
     FIG. 26 is a top view of a separator spring of the assembly. 
     FIG. 27 is a top view of a support spring of the assembly. 
     FIG. 28 is a top view of a top plate of the actuator assembly. 
     FIG. 29 is a cross-sectional view taken along line  29 — 29  in FIG.  28 . 
     FIG. 30 is a cross-sectional view taken along line  30 — 30  in FIG.  28 . 
     FIG. 31 is a bottom view of a bottom plate of the actuator assembly. 
     FIG. 32 is a cross-sectional view taken along line  32 — 32  in FIG.  31 . 
     FIG. 33 is an enlarged view of the portion encircled in FIG.  32 . 
     FIG. 34 is a cross-sectional view taken along line  34 — 34  in FIG.  31 . 
     FIG. 35 is a cross-sectional view taken along line  35 — 35  in FIG.  31 . 
     FIG. 36 is a side view of an actuator ball of the actuator assembly. 
     FIG. 37 is a cross-sectional view of the clutch/brake assembly of FIG. 1 in the driving position. 
     Before one embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The use of “consisting of” and variations thereof herein is meant to encompass only the items listed thereafter. The use of letters to identify elements of a method or process is simply for identification and is not meant to indicate that the elements should be performed in a particular order. 
    
    
     DETAILED DESCRIPTION 
     Reference is made to a prior art clutch/brake assembly disclosed in U.S. Pat. No. 5,570,765, and invented by the present inventor. The entire contents of U.S. Pat. No. 5,570,765 are incorporated herein by reference. 
     FIG. 1 illustrates a portion of a drive system for a powered implement or vehicle (not shown), such as a riding lawnmower. Although the invention is discussed below with respect to the illustrated embodiment, the invention may be embodied in other implements, and should not be regarded as limited to a riding lawnmower application. 
     The vehicle includes an internal combustion engine which is mounted to a riding lawnmower chassis. The engine could alternatively be an electric engine in some applications. The engine includes (FIG. 1) an output shaft  20  that extends down from the chassis and extends into an inner hub  24 . The outer surface of the inner hub  24  is stamped to provide an indent or key  28  that extends inwardly of the inner hub  24 . The output shaft  20  includes a keyway  32  (shown in phantom in FIG. 1) that engages the key  28  to afford common rotation of the output shaft  20  with the inner hub  24 . The distal end of the output shaft  20  includes a threaded bore  36 . The output shaft  20  is tightened against an inner shoulder  40  in the inner hub  24  by a bolt  44  that is threaded into the threaded bore  36 . The head of the bolt  44  bears against the bottom surface of the inner hub  24 . 
     As shown in FIGS. 1 and 2, a transaxle pulley  48  is welded to the outer surface of the inner hub  24 , and rotates in common with the inner hub  24  and the output shaft  20 . The transaxle pulley  48  engages a drive belt  52  that is operably driven by the transmission (not shown) of the riding lawnmower or other power equipment to which the engine is mounted. 
     The inner hub  24  also includes an outer downwardly-facing shoulder  56  and a threaded lower end  60 . Between the outer shoulder  56  and the threaded lower end  60  are upper and lower bearings  64 ,  68  (FIG.  3 ), a splined collar  72 , and a cup-shaped washer  76  (FIGS.  4  and  5 ). The upper and lower bearings  64 ,  68  each include an inner race  80  and an outer race  84  separated by balls  88 , and the splined collar  72  includes a lower portion that has splines  92 . A nut  96  is threaded onto the threaded lower end  60  of the inner hub  24  to capture the splined collar  72  and the cup-shaped washer  76  between the inner races  80  of the upper and lower bearings  64 ,  68 . Tightening the nut  96  causes a frictional engagement between the inner races  80  of the upper and lower bearings  64 ,  68 , the splined collar  72 , the cup-shaped washer  76 , and the inner hub  24 , such that those parts rotate in common. Alternatively, a shaft including an integral splined section could be used. 
     A housing  100  (FIGS. 6-8) is affixed to the outer race  84  of the upper bearing  64 . The housing  100  extends radially from the upper bearing  64 , and includes a lower flange portion  104  that provides a downwardly-facing braking surface  108 . Below the housing  100  is an output pulley  112  (FIGS.  9 - 12 ), a support plate  116  (FIGS.  13 - 15 ), upper and lower output disks  120 ,  124  (FIGS.  16 - 19 ), upper and lower input disks  128 ,  132  (FIGS.  2022 ), a thrust bearing  136  (FIGS.  23  and  24 ), and an actuator assembly  140 . 
     The output pulley  112  is affixed to the outer race  84  of the lower bearing  68 , and receives a drive belt  144 . The drive belt  144  is interconnected with pulleys (not shown) that are interconnected to working shafts, such as blade shafts (also not shown) having cutting blades attached thereto. The blade shafts are generally vertically-oriented, and are generally parallel to the output shaft  20  of the engine. When rotated, the blade shafts cause the blades to rotate and cut the grass over which the riding lawnmower is traveling. In an alternative construction, the output pulley  112  may be replaced with a shaft coupling that couples a blade shaft to the lower output disk  124  to drive the blade shaft directly without the drive belt  144 . 
     The output pulley  112  has extending therein three holes  148  that receive drive studs  152  (FIG.  25 ). Each drive stud  152  includes a threaded shank  156 , an increased diameter smooth portion  160 , and a flared top  164 . Nuts  168  are threaded onto the threaded shanks  156  to sandwich the output pulley  112  between the nuts  168  and the increased diameter portions  160  of the studs  152 . The support plate  116  and lower output disk  124  include holes  172  (FIGS. 13,  18 , and  19 ) in alignment with the holes  148  in the output pulley  112 . The increased diameter portions  160  of the drive studs  152  extend through the holes  172  in the support plate  116  and lower output disk  124 . The output pulley  112 , support plate  116 , and lower output disk  124  are coupled for rotation together by the drive studs  152 . Braking springs  176  surround the increased diameter portions  160  of the drive studs  152  and bias the support plate  116  and lower output disk  124  upwardly. The flared ends  164  of the drive studs  152  prevent the support plate  116  and lower output disk  124  from sliding off the top of the drive studs  152 . 
     The upper output disk  120  (FIGS. 16 and 17) includes a substantially horizontal portion  180  and six depending tabs  184  extending substantially vertically down from the horizontal portion  180 . The tabs  184  extend through corresponding slots  188  in the lower output disk  124  (FIGS.  18  and  19 ), and are received in corresponding pockets  192  (FIGS. 13-15) in the support plate  116 . The upper output disk  120  is thereby coupled for rotation with the lower output disk  124  by virtue of the engagement between the tab  184  and slot  188 , and is supported by the support plate pockets  192 . The support plate  116  is preferably constructed of relatively thin material and acts as a resilient diaphragm or spring plate. More specifically, the support plate  116  is deflectable under the influence of a force acting on the upper output disk  120  (as shown in FIG.  37 ), and will return to an undeflected position illustrated in FIG. 1 once the force is removed. 
     The upper and lower input disks  128 ,  132  are interconnected to the splined collar  72  by virtue of the splines  92 . The splined interconnection causes the input disks  128 ,  132  to be rotationally fixed relative to the splined collar  72 , but affords axial movement of the input disks  128 ,  132  along the splines  92 . A separator spring  196  (FIG. 26) is interposed between the input disks  128 ,  132  to maintain separation therebetween, and a support spring  200  (FIG. 27) is interposed between the cup-shaped washer  76  and the lower input disk  132  to support the input disks  128 ,  132 . The separator spring  196  and support spring  200  are preferably coil springs, but may alternatively take the form of any suitable biasing member. In their undeflected conditions (i.e., when the assembly is in the braking condition illustrated in FIG.  1 ), the springs maintain a space of 0.007-0.010 inches between the input disks  128 ,  132  and the respective output disks  120 ,  124 . 
     With reference to FIGS. 28-36, the actuator assembly  140  includes upper and lower plates  204 ,  208  having central holes  210  through which the inner hub  24  extends. The upper plate  204  also includes three tabs  212  that each extend through three corresponding slots  216  (FIGS. 6 and 8) in the housing  100  to thereby fix the upper plate  204  to the housing  100 . The lower plate  208  also includes an actuator handle or arm  220  that extends out of a side slot  224  (FIG. 8) in the housing  100 . The lower plate  208  may be pivoted about the inner hub  24  with respect to the upper plate  204  by actuating the handle  220 . The upper and lower plates  204 ,  208  each include three tear-drop shaped recesses  228  that face down and up respectively. The recesses  228  of the plates  204 ,  208  are generally mutually aligned and in opposed facing relation to define therebetween a cavity. An actuator ball  232  (FIG. 36) is captured within each cavity. 
     The lower plate  208  also includes a central hub  236  that extends up through the upper plate  204 , and that receives a top race of the thrust bearing  136 . A lower race of the thrust bearing  136  contacts the top of the upper input disk  128 . The thrust bearing  136  is slidable along the outer surface of the inner hub  24 . 
     As shown in FIG. 1, the clutch/brake assembly can be moved into a braking position. When in the braking condition, the outer portion of the lower output disk  124  is biased by the braking springs  176  against the braking surface  108  of the lower flange portion  104  of the housing  100 . The frictional engagement between the lower output disk  124  and the braking surface  108  of the spring housing  100  resists rotation of the output pulley  112 , which in turn stops the rotation of the cutting blades that are otherwise driven by the output pulley  112 . 
     Also, while the clutch/brake assembly is in the braking position, the input disks  128 ,  132  are separated from the output disks  120 ,  124  by the springs  196 ,  200 . The input disks  128 ,  132 , splined collar  72 , and output shaft  20  are therefore free to rotate without being coupled to the output disks  120 ,  124  and the output pulley  112 . 
     To drivingly engage the output shaft  20  with the output pulley  112 , as shown in FIG. 37, the actuator handle  220  is pivoted to move the tear drop recesses  228  in the lower plate  208  out of alignment with the tear drop recesses  228  of the upper plate  204 . The actuator balls  232  contacting the recesses  228  act as wedges between the plates  204 ,  208 , and drive the lower actuator plate  208  away from the upper actuator plate  204 . The separation of the lower actuator plate  208  from the upper activator plate  204  causes the thrust bearing  136  to act on the upper input disk  128  down as well. The separator and support springs  196 ,  200  deflect under the downward force of the actuator assembly. 
     The upper input disk  128  engages the upper output disk  120  and pushes it against the support plate  116 . The support plate  116  is deflected by the force transmitted through the upper output disk  120 , and permits the upper output disk  120  to move down. The upper output disk  120  is pushed against the lower input disk  132 , which in turn is pressed against the lower output disk  124 . The braking springs  176  are also deflected, and the lower output disk  124  is moved down out of engagement with the braking surface  108  of the housing  100 . 
     The input and output disks  120 ,  124 ,  128 ,  132  are therefore sandwiched together and are coupled by friction forces for common rotation. The frictional engagement of the input and output disks  120 ,  124 ,  128 ,  132  drivingly connects the output shaft  20  to the output pulley  112  so that rotation of the output shaft  20  causes rotation of the output pulley  112 . In this manner, the blade shafts are rotated under the power of the engine. Because there are multiple disks  120 ,  124 ,  128 ,  132  in the assembly, more power may be transferred from the output shaft  20  to the output pulley  112  than in conventional clutch/brake assemblies. 
     While only a single embodiment of the invention has been illustrated and described, it is not intended to be limited thereby, but only by the scope of the appended claims.
A clutch/brake assembly for use on a riding lawnmower or other powered equipment includes a pair of input disks, a pair of output disks, and a housing. An output pulley is coupled for rotation with the output disks and is coupled to at least one working shaft, such as a blade shaft supporting a cutting blade of the lawnmower. The input and output disks are disengaged from each other when the clutch/brake assembly is in a braking condition. Also, when in the braking condition, at least one of the output disks is biased against a braking surface of the housing to resist rotation of the output pulley and the working shafts. An actuator assembly is also included in the clutch/brake assembly, and is actuable to substantially simultaneously disengage the output disks from the braking surface of the housing and sandwich the input and output disks together. When sandwiched together, the input and output disks are coupled for rotation together by the frictional forces therebetween.