Abstract:
A one-way clutch includes a first race having mutually spaced pockets formed with an opening at a periphery of the first race, each pocket being at least partially bounded by a wall that extends along at least a portion of a margin of the pocket and contains a drive surface. A second race includes a series of alternating notches and cam surfaces formed on a periphery of the second race facing the openings. A plurality of rockers is located in the pockets. Each rocker includes an engagement surface for driveably engaging and disengaging a notch, a reaction surface for contacting the drive surface when the engagement surface driveably engages a notch, and guide surfaces for contacting the pocket wall to guide movement of the rocker from a disengaged position toward an engaged position. Springs, located on the first race, urge the rockers toward engagement with the cam surfaces.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application is a continuation-in-part of pending U.S. application Ser. No. 10/899,918, filed Jul. 27, 2004. 
     
    
     BACKGROUND OF THE NVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The invention relates in general to a clutch that produces a drive connection between components when their relative rotation is in one direction, and overruns when relative rotation is in the opposite direction. In particular, the invention pertains to such clutches having rockers that engage or disengage at least partially due to the effect of centrifugal force acting on the rocker.  
         [0004]     2. Description of the Prior Art  
         [0005]     Conventional one-way clutches for producing a one-way drive connection between inner and outer races of the clutch include sprags or rollers for releasably driveably connecting the races and the components of a mechanical assembly connected to the races. Such clutches are commonly used in the powertrain or driveline of an automotive vehicle. One-way clutches perform satisfactorily in many cases, but certain applications, such as those in which large magnitudes of torque are transmitted by the clutch, or those that provide only a small space for the clutch, require one-way clutches other than conventional sprag-type or roller-type clutch to meet desire requirements.  
         [0006]     Conventional one-way clutch assemblies have at least one sprag or roller, which driveably locks two notched or pocketed races together mutually in one rotary direction and allows the races to rotate freely in the other direction. Rocker and sprag type one-way clutch assemblies can increase the torque capacity for a given package size compared to those of a roller-type clutch, but they are generally limited in torque transmitting capacity by the magnitude of the contact or bearing stresses caused by contact of the rockers or sprags with the races.  
         [0007]     To overcome these and other difficulties, a one-way overrunning clutch described in U.S. Pat. No. 5,070,978 includes a drive member and a driven member, which are mounted for clockwise and counterclockwise rotation about a common axis. The drive member includes a planar drive face, normal to the common axis, which connects with a source of power for rotating the planar drive face either clockwise or counterclockwise. The driven member includes a planar driven face, positioned in close proximity to and in confronting relationship with the drive face. The drive and driven members are coupled to one another through a series of pockets in one of the drive faces, and a plurality of cooperating struts carried by the other face, such that when the drive member is driven counterclockwise, it drives the driven member with it. When the drive member is driven clockwise, it does not drive the driven member, but rotates freely relative to the driven member. Column stability of the strut, which transmits the torsion load between the races, is an importance factor in the design.  
         [0008]     U.S. Pat. No. 5,954,174 discloses a ratchet one-way clutch assembly having an inner race with notches, an outer race with pockets, and rockers located in the pockets to engage the notches. The rockers have a pivot ridge which mates with a peak or recess in the pockets in the outer race to position the rocker in the pocket. The center of mass of each rocker is located such that the rocker tends to engage or disengage a notch in the inner race. A spring is used to provide a tilting force on each rocker directed to produce engagement of the rocker with a notch.  
         [0009]     Conventional one-way clutches develop relatively large magnitudes of hoop stress in the races when torque is transmitted through the clutch; therefore, the races of conventional one-way clutches are formed of bearing grade steel in order to withstand the operating hoop stress. Because the clutches disclosed in the &#39;978 and &#39;245 patents develop relative low operating hoop stresses in service, those clutch can be formed of powered metal. Clutches formed for powered metal potentially can be produced at relative low cost compared to the cost to form and produce a conventional clutch of high grade steel, provided extensive machining is avoided.  
         [0010]     The clutches described in the &#39;978 or &#39;245 patents, however, require a significant amount of machining of the components that are formed of powered metal. Excessive internal backlash, which can produce noise at unacceptable levels, is a potentially problem under certain operating conditions with these clutches.  
         [0011]     A need exits, therefore, for a low cost, reliable one-way clutch that produces low operating bearing stresses and is able to be formed readily from powered metal. The clutch should occupy little space, minimize in-service noise, and require little or no machining. Preferably, the desired clutch should include features that facilitate its assembly in a drive system.  
       SUMMARY OF THE INVENTION  
       [0012]     The present invention provides a one-way clutch having an inner race, outer race, and pivoting rockers that driveably connect the races in one rotary direction and overrun in the opposite direction. The clutch is preferably formed of powered metal. The rockers are located in one of the races, such that the clutch can employ centrifugal force to assist in disengaging the rockers from a notch plate during an overrun condition by biasing the rockers to pivot away from the notch plate. Alternately, the clutch can employ centrifugal force to assist in engaging the rockers with a notch plate by urging the rockers to pivot toward notch plate.  
         [0013]     The shape of a pocket plate, which contains the rockers, uniquely requires no secondary machining operations for any purpose, such as to eliminate densifiers and de-densifiers in the powered metal components. The components of the clutch that are formed from powered metal require no machining after they are formed.  
         [0014]     The number of notches for a given diameter is greater than other one-way clutches, thereby significantly reducing backlash. The design lends itself to easy assembly due to its configuration. A pocket plate subassembly contains the rockers and a return spring for each rocker. Before its assembly in the clutch, the pocket plate subassembly restricts the ability of each rocker to pivot in the pocket, and the force of the respective return spring prevents the rocker from exiting the pocket laterally by forcing the rocker into contact with its pocket. This arrangement permits the subassembly to be handled and transported prior to its installation in the clutch with the rockers and springs already installed in the pocket plate subassembly.  
         [0015]     A one-way clutch according to this invention includes a first race having mutually spaced pockets formed with an opening at a periphery of the first race, each pocket being at least partially bounded by a wall that extends along at least a portion of a margin of the pocket and contains a drive surface. A second race includes a series of alternating notches and cam surfaces formed on a periphery of the second race facing the openings. A plurality of rockers is located in the pockets. Each rocker includes an engagement surface for driveably engaging and disengaging a notch, a reaction surface for contacting the drive surface when the engagement surface driveably engages a notch, and guide surfaces for contacting the pocket wall to guide movement of the rocker from a disengaged position toward an engaged position. Springs, located on the first race, urge the rockers toward engagement with the cam surfaces.  
         [0016]     Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]      FIG. 1  is a side view of a clutch according to the present invention showing rockers located in an inner race and engaged with notches in an outer race;  
         [0018]      FIG. 2  is an isometric view of the clutch assembly showing the components mutually spaced axially;  
         [0019]      FIG. 3  is a isometric view of the clutch assembly of  FIG. 2  partially in cross section taken at a diametric plane showing the components in spaced relationship;  
         [0020]      FIG. 4  is an isometric view of the clutch assembly of  FIG. 2  partially in cross section through a diametrical plane showing the components assembled;  
         [0021]      FIG. 5  is a side view, partial cross section through a diametrical plane showing the components assembled;  
         [0022]      FIG. 6  is side view of a portion of an inner race showing a rocker, pocket, and return spring;  
         [0023]      FIG. 7  is side view of a portion of an inner race showing a rocker, pocket, return spring, and a CF vector;  
         [0024]      FIG. 8  is a side view of a clutch showing rockers located in an outer race and engaged with notches in an inner race; and  
         [0025]      FIG. 9  is side view of a portion of an outer race showing a rocker, pocket, return spring, and a CF vector;  
         [0026]      FIG. 10  is side view of an accordion return spring;  
         [0027]      FIG. 11  is side view of a helical return spring;  
         [0028]      FIG. 12  illustrates a rocker  160  having a preferred outer surface.  
         [0029]      FIGS. 13-18  is a series of figures showing movement of the rocker from an overrunning position to an engaged position; and 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0030]     Referring now to the drawings, there is illustrated in  FIG. 1 a  one-way clutch assembly  20  in accordance with the present invention. The clutch assembly  20  includes an inner race or rocker plate  22 , an outer race or cam plate  24 , and a plurality of rockers  26 , each rocker being located in a pocket  28  formed in the inner race  22  and angularly spaced mutually about a central axis  30 . The inner periphery of the outer race  24  is formed with a plurality of notches  32  angularly spaced mutually about axis  30 . There are twelve rockers  26  and pockets  28  and thirty-six notches  32  in the clutch illustrated in  FIG. 1 .  
         [0031]     When the inner race  22  rotates clockwise faster than the outer race  24 , each rocker  26  pivots counterclockwise in its pocket  28  away from engagement with the notches  32  due to contact of the rockers with the inner radial surface of the outer race. This allows the inner race  22  to rotate freely clockwise about axis  30  relative to the outer race  24 . When the inner race  22  attempts to rotate counterclockwise relative to the outer race  24 , the inner race and outer race are engaged or driveably connected mutually by engagement of the rockers  26  with the notches  32 .  
         [0032]     When the clutch  20  is engaged, each engaged rocker  26  transmits a force F between the inner and outer races  22 ,  24  due to its contact with the inner surface  34  of the pocket and with the radially directed surface  36  of the engaged notch  32 .  
         [0033]     A recesses  40 , located at each pocket  28 , contains a spring, such as a helical coiled compression spring  42  or an accordion compression spring  44 , for urging each rocker to pivot in its pocket toward engagement with the notches.  
         [0034]      FIG. 2-5  show a clutch having a rocker plate  22  formed with angularly spaced pockets  28  and spring recesses  40 , each pocket containing a rocker  26  that pivots in a respective pocket alternately to engage and to disengage the notches  32  formed on the radially inner surface of the cam plate  24 . A bushing  46  of powered metal fits within the cam plate  24 .  
         [0035]     As seen best in  FIG. 5 , when clutch  20  is assembled, an axial surface of bushing  46  contacts an inner axial surface  48  of a flange  50 . Surface  48  is formed with radially directed grooves  52 , which carry fluid lubricant, preferably transmission oil, radially outward a radial inner surface of the bushing  46 . Oil enters the radial grooves  52  through holes  49  formed through a drive system component  72 , which is connected to the clutch  20 . The oil travels axially leftward across the inner radial surface  51  on the bushing  46 , to a radial space  53 , which directs the oil radially outward to surface  55 , across the width of the rocker plate  22  and across the surface of the rockers  26 . Bushing  46  pilots the inner and outer races  22 ,  24  and eliminates need to machine along the notches or cams  32  of the outer race or the radial outer surface area  66  of the rocker plate  22 . Lubricating oil is precisely directed radially along grooves  52  to the bushing  46 , then axially between surfaces  68  on the rocker plate  22  and the inside diameter  51  of the bushing to the rockers  26 . The lubricant flows along this path due to a centrifugal pressure head developed as the clutch rotates about axis  30 .  
         [0036]     The radial outer surface of the cam plate  24  is formed with splines  54 , by which the cam plate is driveably connected to a drive system. Similarly, the radially inner surface of the rocker plate  24  is formed with splines  56 , by which the rocker plate is driveably connect to a component of the drive system.  
         [0037]     An axial surface  58  of rocker plate  22  contacts a retainer ring  60 , which closes the axial end of each pocket  28  and is retained in position by a snap ring  62 , which engages a recess  64  formed on the cam plate  24 .  
         [0038]      FIGS. 3 and 4  show the components of the clutch  20  located immediately adjacent their assembled positions and in the assembled positions, respectively. The clutch  20  is assembled with the cam plate  24  driveably connected by splines  70  to a drum  72  of a vehicle drive system.  
         [0039]     Referring now to  FIG. 6 , a preferred embodiment of a rocker  26  may include several surfaces  80 ,  82 ,  84 ,  86 ,  88 , and a defined pivot center  90 . Surfaces  80  and  82  are both circular cylindrical surfaces whose arcs are concentric with the pivot center  90 . Surfaces  80 ,  82  guide rotation or pivoting of the rocker  26  and limit that pivoting to one degree of freedom.  
         [0040]     Surface  80  is a guiding surface. When force F is applied while the clutch is driving and the rockers  26  are engaged with the notches  32 , preferably no reaction force is developed on surface  80 . Surface  82  is a surface on which the reaction to force F is developed when clutch  20  is transmitting torque between the outer race and inner race  22  through the rocker  26 . Because the center of surface  82  is located at the pivot center  90 , the reaction to force F is distributed along surface  82  is centered at pivot center  90 , and produces no torque tending to pivot the rocker  26  about the pivot center.  
         [0041]     Surface  84  limits clockwise pivoting of the rocker  26  and assists assembly of the race  22  or  24  that contains the pockets  28 , rockers  26  and springs  42 ,  44 . That race is prepared for installation by inserting a rocker  26  in each pocket and placing a spring  42 ,  44  in each recess  40 . The force applied by the spring on its respective rocker rotates the rocker to the position shown in  FIG. 6  where surface  84  contacts the base  96  of the pocket  28 . The spring force and its reaction force on the base  96  retains the rocker in the pocket without the presence of the other race or another assembly aid. The race containing the rockers can be transported readily with the rockers in this retained condition preparatory to installing the race subassembly in the clutch assembly  20 .  
         [0042]     By limiting pivotal rotation of the rocker  26  about pivot center  90 , a counter-rotation reaction force on the strut is generated at surface  84  when the clutch is driving or engaged. When clutch  20  is driving, force F, applied to rocker surface  86 , produces a clockwise torque on the rocker about the pivot center  90 . Torque about center  90  produced by force F is reacted by a force P 1  where rocker surface  84  contacts pocket surface  96 . Without surface  84 , the full reaction torque would be reacted elsewhere. For example, if the full torsion reaction to force F were applied to rocker surface  88 , a large hoop stress would be generated on the race contacted by surface  88  tending to shear the wall of that race due to a high angle of incidence of the reaction force. If the torsion reaction to force F were applied to surface  82 , it would be applied at the extremity of the inner race at its weakest point. Preferably, the torsion reaction to force F is located normal to the pocket base  96  at rocker surface  84 , and on surface  82  where friction is developed due to contact with the pocket.  
         [0043]     Surface  86  is the surface on which force F is applied when the clutch  20  is driving and the rockers  26  are engaged with the radial surfaces  36  of the notches  32 . Surface  86  performs this function by creating a mechanical interference when the rocker is pivoted to the engaged position.  
         [0044]     Surface  88 , located at the contour of the strut portion  92  of the rocker  26 , contacts the crest  98  of the radial surfaces  36  of the notches  32  to ensure no interference when the clutch  20  is overrunning and the rockers  26  are disengaged from the notches  32 . Surface  88  is curved to facilitate formation of a film of lubricant while the clutch is overrunning. Surface  88  is curved also to minimize impact with the crests  98  while the clutch overruns by providing transitional positions that minimize the rate of rotation of the rocker into the pocket relative to the rate of rotation of the outer race. This minimizes angular acceleration on the rocker as the clutch overruns.  
         [0045]     The center of mass  100  of the rocker  26  can be located in relation to the pivot center  90  such that centrifugal force tends either to engage or to disengage the rocker, whether the rocker is located on the outer race or the inner race.  
         [0046]     When viewed as in  FIG. 7 , the center of mass  100  is located rightward from a line connecting the axis  30  and the pivot center  90 , and the rocker is carried in a pocket located on an inner race  22 . As the clutch assembly  20  rotates about axis  30 , centrifugal force on the rocker is directed radially outward along a line  102  that passes through axis  30  and the center of mass  100 , causing the rocker  26  to pivot counterclockwise about the pivot center  90 . This counterclockwise pivoting of the rocker opposes the force of the spring  42 ,  44  and tends to pivot rocker surface  86  away from contact with pocket surface  36  on the inner race  24 . This counterclockwise pivoting of the rocker tends to move the rocker to a disengaged position, and allows the inner race  22  to overrun and the clutch  20  to disengage. The magnitude of the moment about pivot center  100  tending to compress spring  42  and to pivot the rocker  26  to the disengaged position varies with the speed of rotation of the inner race and the distance of the center of mass  100  from the pivot center  90 .  
         [0047]     Alternatively the center of mass may be located leftward from a line connecting the axis  30  and the pivot center  90 , when the rocker is carried in a pocket located on an inner race  22 . In that case, as the clutch assembly  20  rotates about axis  30 , centrifugal force on the rocker causes the rocker  26  to pivot clockwise about the pivot center  90 . This clockwise pivoting of the rocker adds to the effect of the force of spring  42 , tends to move surface  86  of the rocker toward contact with radial surface  36  on the outer race  24 , i.e., to pivot the rocker  26  to an engaged position, and causes the clutch to engage.  
         [0048]      FIG. 8  illustrates an embodiment of a clutch assembly  120 , in accordance with the present invention. The clutch assembly  120  includes an inner race or rocker plate  122 , an outer race or cam plate  124 , and a plurality of rockers  126 , each rocker being located in a pocket  128  formed in the outer race  124  and angularly spaced mutually about a central axis  130 . The outer periphery of the inner race  122  is formed with a plurality of cams or notches  132 , angularly spaced mutually about axis  30 . There are nine rockers  126  and pockets  128  and thirty-six notches  132  in the clutch illustrated in  FIG. 1 .  
         [0049]     When the outer race  124  rotates clockwise faster than the inner race  122 , each rocker  126  pivots clockwise in its pocket  128  away from engagement with the notches  132  due to contact of the rockers with the outer radial surface of the inner race. This allows the outer race  124  freely to rotate clockwise about axis  130  relative to the inner race  122 . When the outer race  124  attempts to rotate counterclockwise relative to the inner race  122 , the inner race and outer race are engaged or driveably connected mutually by engagement of the rockers  126  with the notches  132 .  
         [0050]     When the clutch  120  is engaged, one or more engaged rockers  126  transmit a force between the inner race  122  and outer race  124  due to the rocker&#39;s contact with the inner surface  134  of the pocket  126  and with the radially directed surface  136  of the engaged notch  132 .  
         [0051]     A recesses  140 , located at each pocket  28 , contains a spring, such as a helical coiled compression spring  142  or an accordion compression spring  144 , for urging each rocker to pivot in its pocket toward engagement with the notches.  
         [0052]     When the clutch assembly  120  is viewed as in  FIG. 9 , the center of mass  150  of each rocker  126  is located rightward from a line connecting the axis  130  and the pivot center  152 . As the outer race  124  rotates about axis  130 , centrifugal force on the rocker is directed radially outward along a line  154  that passes through axis  130  and the center of mass  150 , causing the rocker  126  to pivot counterclockwise about the pivot center  152 . This counterclockwise pivoting of the rocker cooperates with the force of the spring  42 ,  44 , tends to pivot the rocker to an engaged position with surface  136 , and engages the clutch.  
         [0053]     Alternatively, in the clutch assembly  120 , the center of mass  150  of each rocker  126  may be located leftward from a line connecting the axis  130  and the pivot center  152 . In that case, as the outer race  124  rotates about axis  30 , centrifugal force on the rocker causes the rocker  126  to pivot clockwise about the pivot center  152 . This clockwise pivoting of the rockers opposes the effect of the spring force and tends to pivot rotate surface  86  of the rocker away from contact with radial surface  136  on the inner race  122 . This action tends to move the rocker to a disengaged position, and allows the clutch to overrun and to disengage.  
         [0054]      FIG. 12  illustrates a rocker  160  having a preferred configuration. Surfaces  162  and  164 , both convex circular cylindrical surfaces extending across the thickness of the rocker and centered at  166  and  168 , respectively, are mutually connected by a surface  170 , which is slightly concave. A planar lateral surface  172 , tangent to surface  164 , extends to an internal fillet  174 , from which another planar surface  176 , tangent to fillet  174 , extends to an external fillet  178 , which is located adjacent an engagement surface  180 . A convex circular cylindrical lateral surface  182  blends into surface  162 . A ratchet surface  184 , another convex circular cylindrical surface, which extends from engagement surface  180  toward surface  182 , is the rocker surface that contacts the cam surfaces  194  when the clutch overruns.  
         [0055]      FIGS. 13-18  show progressive movement of the rocker  160  as the outer race  24  rotates clockwise relative to the inner race  22 . When the clutch is disengaged or overrunning, the ratchet surface  184  of the rocker slides across the cam surfaces  194  on the outer race  24 . When the clutch is engaged, the engagement surface  180  engages one of the notches  32  on the outer race  24 .  
         [0056]      FIG. 13  shows the rocker  160  nearly fully retracted within a pocket  28  on the inner race  22 , as ratchet surface  184  contacts the outer race  24  at the crest  186  of a cam surface  194 . With the clutch so positioned, the force of spring  44 , applied to surface  176 , forces rocker ratchet surface  184  into contact with the cam  194 , first lateral surface  182  contacts the side wall of pocket  28  at A, and the second lateral surface  172  contacts the side wall of pocket  28  at B. The centrifugal force CF of the rocker, directed radially from axis  30  through the center of mass of the rocker, in this example, urges the rocker clockwise causing clutch engagement. A line  188 , normal to the tangent at point A on the rocker, intersects at  190  a line  192 , normal to the tangent at point B on the rocker. This intersection  190  is the instantaneous center about which the rocker pivots clockwise in the pocket.  
         [0057]      FIG. 14  shows the rocker  160  having pivoted from the position shown in  FIG. 11  due to the outer race  24  having rotated about its axis  30  two degrees clockwise from the position of  FIG. 13 . Ratchet surface  184  maintains contact with cam surface  194 , whose crest  186  has moved away from surface  194 . The first and second lateral surfaces  182 ,  172  of the rocker  160  also contact the side walls of pocket  28  at points A and B, which have moved from their positions in  FIG. 13 . The instantaneous pivot center is also relocated to  190 .  
         [0058]      FIG. 15  shows the outer race  24  having rotated five degrees clockwise about its axis  30  from the position shown in  FIG. 13 . Rocker ratchet surface  184  maintains contact with cam surface  194 , and the first and second lateral surfaces  182 ,  172  of the rocker  160  also contact the side walls of pocket  28  at point A on surface  182  and point B on surface  172 , which have moved from the positions of  FIGS. 13 and 14 . The instantaneous pivot center is relocated to  190 .  
         [0059]      FIG. 16  shows the outer race  24  having rotated eight degrees clockwise about axis  30  from the position shown in  FIG. 13 . Ratchet surface  184  maintains contact with the cam  194 , and first and second lateral surfaces  182 ,  172  of rocker  160  contact the side walls of the pocket  28  at point A on surface  182 , and at point B, which has moved to cylindrical surface  164 . The instantaneous pivot center is relocated at  190 .  
         [0060]      FIG. 17  shows the outer race  24  having rotated eleven degrees clockwise about axis  30  from the position shown in  FIG. 13 . Ratchet surface  184  maintains contact with the cam  194 , and the first and second lateral surfaces  182 ,  172  of rocker  160  contact the side walls of the pocket  28  at point A, which is now located on or near cylindrical surface reaction  162 , and at point B, which is on convex cylindrical surface  164 . The instantaneous pivot center is relocated to  190 .  
         [0061]      FIG. 18  shows the clutch engaged due the outer race  24  having rotated fourteen degrees clockwise about axis  30  from the position shown in  FIG. 13 . Due to this rotation, cam surface  194  has moved across ratchet surface  184  bringing engagement surface  180  of rocker  160  into engagement with the notch  32 . Thereafter, the inner and outer races rotate clockwise as a unit. Ratchet surface  184  maintains contact with the cam  194 , and the reaction surface  162  of the rocker  160  contacts the drive surface of the pocket  28  at point A, which is now located near the mid-point of reaction surface  162  and drive surface  200 . But the rocker  160  no longer contacts the side wall of the pocket  28  at point B. A force C is developed at point A in reaction to the engagement force K applied by the outer race  24  to the rocker contact surface  180 .  
         [0062]     Preferably, the radius of reaction surface  162  is equal, or substantially equal to the radius of the drive surface  200 , so that those surfaces are engaged when the clutch is engaged, the position shown in  FIG. 18 . When the clutch is the engaged, the first lateral surface  182  is spaced from the adjacent pocket surface  196 , rocker surface  170  is spaced from the adjacent pocket surface  198  due to the slightly concavity of surface  170 , convex rocker surface  164  is spaced from the adjacent concave corner surface of the pocket, and the second lateral rocker surface  172  is spaced from the adjacent side wall of the pocket. The only contact between the rocker  160  and the pocket when the clutch is engaged is at point A, where the concave drive surface  200  engages the convex drive surface  162 . When the clutch is engaged, engagement surface  180  contacts a notch  32 , and ratchet surface  184  contacts cam surface  194 , thereby ensuring that rocker  160  engages the pocket drive surface  200  at point A, where the principal reaction to force K is applied to the rocker.  
         [0063]     While the clutch is engaged, the inner race  22  and outer race  24  rotate clockwise as a unit until the clutch again overruns due to the inner race rotating clockwise faster than the outer race, or the outer race rotating counterclockwise relative to the inner race. When the clutch overruns, surfaces  32  and  180  separate, and the rocker ratchet surface  184  moves counterclockwise relative to cam surface  194 , which causes the rocker to pivot counterclockwise in its pocket  28  toward the position of  FIG. 13 .  
         [0064]     In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.