BI-DIRECTIONAL OVERRUNNING CLUTCH

RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application Serial No.

60/716,870 filed on September 14, 2005, the entire contents of which is incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to clutches, and more particularly to bi-directional overrunning clutches.

BACKGROUND OF THE INVENTION

[0003] Overrunning clutches are commonly used to selectively transfer torque from an input shaft to an output ring. Such clutches commonly include a housing fixed for rotation with the input shaft, and a slipper positioned between the housing and the output ring. The slipper and housing commonly include respective bearing surfaces, upon which a plurality of rollers ride to space the slipper from the housing. The respective bearing surfaces of the slipper and housing define a plurality of longitudinal ridges against which the rollers wedge during relative movement between the slipper and the housing. When the rollers wedge against the ridges on the bearing surfaces, the rollers move the slipper radially outwardly from the housing, causing the slipper to engage the output ring. The output ring then receives torque from the input shaft.

[0004] When such overrunning clutches are not engaged, the slipper can form an efficient hydrodynamic bearing by introducing a fluid film (e.g., oil) between the slipper and the output ring.

SUMMARY OF THE INVENTION

[0005] When it is desired to lock an overrunning clutch, however, the hydrodynamic oil film between the slipper and the output ring can sometimes prevent the slipper from expanding outwardly to engage the output ring. The present invention facilitates engagement at high speeds and/or during high viscosity lubricant conditions, such as during cold temperatures.

[0006] Slippers are typically manufactured by a drawing process, which must be completed before heat treating. As a result of heat treating, the slippers typically distort. Such distortion typically causes a high contact force between the slipper and the mating ring or member because a small clearance must exist to avoid excessive backlash in the clutch. This high contact force typically causes excessive wear to the slipper and increases parasitic drag at the interface between the slipper and the mating ring or member. The present invention reduces these contact forces between the slipper and the mating ring or member.

[0007] The present invention provides, in one aspect, a clutching device operable to selectively engage or disengage first and second members. The clutching device includes a first race coupled to the first member, a second race having a slipper surface selectively engageable with a mating surface of the second member, and a bearing member positioned between the second race and the second member for reducing a contact force between the slipper surface of the second race and the mating surface of the second member.

[0008] The present invention also provides, in one aspect, a bi-directional overrunning clutch adapted to selectively couple an input member and an output member. The bi-directional overrunning clutch includes an outer race fixed for rotation with the output member and an inner race selectively coupled for rotation with the input member about a central axis. The inner race includes an inner surface in facing relationship with the input member. The inner race also includes a first bearing surface, and the outer race includes a second bearing surface in facing relationship with the first bearing surface. The bi-directional overrunning clutch further includes a plurality of rollers positioned between the first and second bearing surfaces. The rollers and bearing surfaces cause the inner surface to move radially inwardly to engage the input member upon relative rotation between the inner race and the outer race.

[0009] The present invention provides, in another aspect, a control member coupled for rotation with the inner race about the central axis. The control member includes a projection and the outer race includes a receiving portion. The control member is movable along the central axis with respect to the outer race between a first position, in which the projection is positioned in the first receiving portion to operate the clutch in a first mode, and a second position, in which the projection is positioned outside the receiving portion to operate the clutch in a second mode different from the first mode.

[0010] The present invention provides, in yet another aspect, a bearing member positioned between the inner race and the input member. When the control member is in a first position, the bearing member reduces a contact force between an inner surface of the inner race and the input member. Also, when the control member is in the first position, the bearing member facilitates relative rotation between the inner race and the input member. When the control member is in a second position, the effect of the bearing member can be reduced, creating a higher contact force between the inner surface of the inner race and the input member.

[0011] The present invention provides, in another aspect, an electromagnetic actuator configured to provide relative rotation between the inner race and the outer race.

[0012] Other features and aspects of the invention will become apparent by consideration of the following detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 is a cross-sectional view of a portion of a bi-directional overrunning clutch of the present invention, illustrating the clutch in an overrunning configuration.

[0014] FIG. 2 is a cross-sectional view of a portion of the bi-directional overrunning clutch of FIG. 1, illustrating the clutch in a locked configuration.

[0015] FIG. 3 is a perspective view of a portion of the bi-directional overrunning clutch of FIG. 1, illustrating a control member being movable between a first position and a second position.

[0016] FIG. 4 is a cross-sectional view of a portion of a second construction of a bidirectional overrunning clutch of the present invention, illustrating the clutch in an overrunning configuration.

[0017] FIG. 5 is a cross-sectional view of a portion of a third construction of a bidirectional overrunning clutch of the present invention, illustrating the clutch in an overrunning configuration.

[0018] FIG. 6 is cross-sectional view of the portion of the bi-directional overrunning clutch of FIG. 5 along line 6 — 6.

[0019] FIG. 7 is a cross-sectional view of a portion of a fourth construction of a bidirectional overrunning clutch of the present invention, illustrating the clutch in an overrunning configuration.

[0020] FIG. 8 is a cross-sectional view of a portion of a fifth construction of a bidirectional overrunning clutch of the present invention, illustrating the clutch in an overrunning configuration.

[0021] FIG. 9 is a cross-sectional view of a portion of a sixth construction of a bidirectional overrunning clutch of the present invention, illustrating the clutch in a locked position.

[0022] FIG. 10 is a perspective view of a portion of the bi-directional overrunning clutch of FIG. 9, illustrating a control member in a first position allowing one-way locking of the clutch.

[0023] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be 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," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms "mounted," "connected," "supported," and "coupled" and variations

thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, "connected" and "coupled" are not restricted to physical or mechanical connections or couplings.

DETAILED DESCRIPTION

[0024] With reference to FIGS. 1 and 2, a bi-directional "slipper" or overrunning clutch

10 is mounted between an input member 14 (e.g., an inner ring) rotatable about a central axis 18 and a fixed output member 22 (e.g., an outer ring) to selectively couple the input member 14 and the output member 22. The clutch 10 includes an outer race 26 fixed for rotation with the output member 22. In the illustrated construction, the outer race 26 is press fit into the output member 22. Alternatively, other methods may be utilized to fix the outer race 26 to the output member 22. The clutch 10 also includes a "slipper" or an inner race 30 positioned over the input member 14 such that an inner "slipper" surface 34 of the inner race 30 selectively engages an outer surface 38 of the input member 14. In the illustrated construction, the inner race 30 is interference fit over the input member 14. However, the inner race 30 includes a longitudinal slit (not shown) causing the inner race 30 to have a non-continuous circumference. As such, the inner race 30 may exert only a light pressure on the input member 14 (e.g., less than 2 lbs per square inch) when the inner race 30 is not pressed against the input member 14.

[0025] The outer and inner races 26, 30 include respective bearing surfaces 42, 46 upon which a plurality of rollers 50 contact. Although not shown in FIGS. 1 and 2, the respective bearing surfaces 42, 46 define a plurality of undulations or longitudinal ridges that form pockets into which individual rollers 50 are positioned (see FIG. 6 for a similar configuration). Such bearing surfaces 42, 46 including the plurality of longitudinal ridges are shown and described in U.S. Patent No. 6,409,001 issued to Kerr (hereinafter "Kerr"), the entire contents of which is hereby incorporated by reference. Alternatively, the pockets may be configured to receive more than one roller 50, and the ridges that form the pockets may be configured to be more or less inclined than the ridges shown in Kerr.

[0026] As shown in FIGS. 1 and 2, the outer and inner races 26, 30 include respective shoulders 54, 58 which restrain the movement of the rollers 50 along the central axis 18. Also, in the illustrated construction, the output member 22 includes a shoulder 62 which restrains the

movement of the rollers 50 along the central axis 18. Alternatively, other structure may be utilized to restrain axial movement of the rollers 50. The clutch 10 also includes a bearing 66 having a row of balls 70 spaced around the input member 14 by a cage 74. The bearing 66 maintains the axial relationship between the input member 14 and the output member 22, while allowing relative rotation between the input member 14 and the output member 22.

[0027] With reference to FIGS. 1-3, the clutch 10 also includes a control member 78

(e.g., a generally cylindrical actuator ring) coupled for rotation with the inner race 30. The control member 78 includes an axially-extending projection 82 that may be positioned in respective slots 86, 90 in the inner race 30 and the outer race 26, depending upon the position of the control member 78 along the central axis 18. In the illustrated construction, the slot 86 in the inner race 30 is sized to snugly receive the projection 82, while the slot 90 in the outer race 26 is wider than the slot 86 in the inner race 30. The control member 78 also includes a tab 94 which selectively contacts a retaining ring 98 fixed to the output member 22 (see FIGS. 1 and 2). The retaining ring 98 therefore limits the movement of the control member 78 along the central axis 18. Alternatively, other structure may be utilized to limit the axial movement of the control member 78.

[0028] With reference to FIGS. 1 and 2, the clutch 10 includes another bearing 102 coupled for movement with the control member 78. The bearing 102 includes a row of balls 106 spaced around the input member 14 by a cage 110. As shown in FIG. 1, when the control member 78 is in a first position with respect to the outer race 26, a spring 114 may be positioned between the control member 78 and the bearing cage 110 to axially bias the bearing 102 against the inner race 30. As will be explained further below, the spring 114 thereby creates a separation force between the inner race 30 and the input member 14. Particularly, the spring 114 may bias the balls 106 against a portion 118 of the inner race 30 having a shallow contact angle θ (e.g., between about 5 degrees and about 15 degrees) to substantially disengage or at least significantly reduce the contact force between the inner surface 34 of the inner race 30 and the input member 14. While FIG. 1 illustrates the inner race 30 spaced from the input member 14 for clarity, it is also understood that the inner race 30 and the input member 14 may be in contact or in partial contact when the control member 78 is in the first position illustrated in FIG. 1, with the balls 106 operating to reduce the contact force between the inner race 30 and the input member 14.

Alternatively, other structure may be utilized to bias the bearing 102 against the inner race 30 when the control member 78 is in the first position.

[0029] When the control member 78 is in a second position with respect to the outer race

26, as shown in FIG. 2, the bearing 102 may be spaced and disengaged from the inner race 30. Particularly, the balls 106 may be axially displaced with the control member 78 away from the inner race 30 to allow the inner surface 34 of the inner race 30 to engage the input member 14 with increased contact force between the inner race 30 and the input member 14. In the illustrated construction, the retaining ring 98 contacts the balls 106 in the bearing 102 when the control member 78 is in the second position, therefore limiting the movement of the bearing 102 along the central axis 18. Alternatively, other structure may be utilized to limit the movement of the bearing 102 along the central axis 18.

[0030] With reference to FIGS. 1 and 2, the clutch 10 is adjustable between different modes of operation by moving the control member 78 along the central axis 18 relative to the outer race 26. Particularly, when the control member 78 is moved to the first position as shown in FIG. 1 (indicated by the phantom projection 82 in FIG. 3), the clutch 10 is operable in a first mode in which the projection 82 is positioned in the respective slots 86, 90 of the inner race 30 and the outer race 26 to allow the inner race 30 to rotate about the central axis 18 in a single direction relative to the outer race 26. Again, the illustrated gap between the inner race 30 and the input member 14 in FIG. 1 is exaggerated for clarity, where in reality there may be contact or partial contact between the inner race 30 and the input member 14. However, the contact force between the inner race 30 and the input member 14 is reduced by the positioning of the balls 106. When the clutch 10 operates in the first, or one-way mode illustrated in FIG. 1, engagement occurs upon motion reversal with only minimal contact force needed between the inner race 30 and the input member 14 to cause engagement.

[0031] When the control member 78 is moved to the second position as shown in FIG. 2

(indicated by the solid projection 82 in FIG. 3), the clutch 10 is operable in another mode in which the projection 82 is positioned outside the axial extent of the slot 90 in the outer race 26, such that the inner race 30 is rotatable about the central axis 18 in any direction relative to the outer race 26. In this full lock mode, higher contact forces between the inner race 30 and the input member 14 may be necessary to engage the clutch 10 due to the higher relative velocities

observed and the associated tendency for developed hydrodynamic film to prevent engagement. Thus, the balls 106 are positioned as shown in FIG. 2.

[0032] Together, the control member 78 and the mechanism or device utilized to move the control member 78 (e.g., an electromagnetic coil or a pressurized chamber) define an actuator operable to selectively allow the inner race 30 to move between a first position, in which the slipper or inner surface 34 engages the outer surface 38 of the input member 14, and a second position, in which the slipper or inner surface 34 is spaced from the outer surface 38.

[0033] With reference to FIG. 3, the inner race 30 is shown relative to the outer race 26 in a neutral configuration. In other words, in the neutral configuration, the rollers 50 nest between the ridges on the bearing surfaces 42, 46. With reference to FIG. 1, the clutch 10 is shown in the mode of operation corresponding with the first position of the control member 78, in which the projection 82 is positioned in the respective slots 86, 90 in the inner race 30 and the outer race 26. The projection 82 is prevented from moving in the slot 90 in the direction indicated by arrow "X" when the inner race 30 is rotated in the direction indicated by arrow X (see the phantom projection 82 in FIG. 3). Therefore, little to no rotational movement occurs between the inner race 30 and outer race 26, and the rollers 50 maintain the non-jammed, neutral configuration in the pockets between the inner race 30 and the outer race 26. Therefore, the inner race 30 is prevented from moving radially inwardly and engaging the input member 14 to transfer torque from the input member 14 to the output member 22.

[0034] However, as shown in FIG. 3, the projection 82 is free to move in the slot 90 in the outer race 26 in a direction indicated by arrow "Y" when the inner race 30 and the projection 82 are rotated in the direction indicated by arrow Y. Therefore, the inner race 30 is allowed to rotate relative to the outer race 26, causing the rollers 50 to jam against the ridges on the respective bearing surfaces 42, 46. This displaces the rollers 50 radially inwardly from the outer race 26, such that each of the rollers 50 applies a force to the bearing surface 46 of the inner race 30. These forces on the bearing surface 46 cause the inner race 30 to move radially inwardly, as provided by the axial cut or slit in the inner race 30, to engage the inner surface 34 of the inner race 30 and the outer surface 38 of the input member 14 to transfer torque from the input member 14 to the output member 22.

[0035] This mode of operation of the clutch 10 may be referred to as the "one-way lock" mode because the clutch 10 will "lock" together the input member 14 and the output member 22 if the inner race 30 and the input member 14 are rotated in one direction about the central axis 18 (e.g., the direction indicated by arrow Y), but will overrun or not "lock" together the input member 14 and the output member 22 if the inner race 30 and the input member 14 are rotated in the opposite direction about the central axis 18 (e.g., the direction indicated by arrow X).

[0036] Also, when the control member 78 is in the first position, and when the inner race

30 and the projection 82 are rotated in the direction indicated by arrow X, the spring 114 biases the balls 106 against the portion 118 of the inner race 30 having the shallow contact angle θ, such that the balls 106 expand the inner race 30 and cause the inner surface 34 of the inner race 30 to substantially disengage the outer surface 38 of the input member 14 to reduce sliding contact. The force exerted by the spring 114 decreases as the balls 106 move toward the inner race 30, and does not cause a large drag on the balls 106 because the force exerted by the spring 114 is directed along the respective spin axes of the balls 106. The bearing 102, rather than a hydrodynamic oil film between the inner surface 34 of the inner race 30 and the outer surface 38 of the input member 14, may then provide relative rotation between the inner race 30 and the input member 14.

[0037] Although not shown in the drawings, the inner race 30 includes a cross-section slightly tilted to a conical form in its inner periphery, with a reduced diameter on the side adjacent the portion 118 of the inner race 30 having the shallow contact angle θ. As the balls 106 move toward the inner race 30 and expand the inner race 30 as described above, the off- center loading of the balls 106 against the portion 118 of the inner race 30 having the shallow contact angle θ twists the inner race 30 to provide uniform contact along the lengths of the rollers 50 and bearing surfaces 42, 46.

[0038] However, when the control member 78 is in the first position, and when the inner race 30 and the projection 82 are rotated in the direction indicated by arrow Y, the off-center loading of the balls 106 by the portion 118 of the inner race 30 having the shallow contact angle θ causes the balls 106 to move axially away from the inner race 30 against the bias of the spring 114, therefore allowing the inner race 30 to move radially inwardly as described above.

[0039] With reference to FIG. 2, the clutch 10 is shown in the mode of operation corresponding with the second position of the control member 78, in which the projection 82 is positioned outside the axial extent of the slot 90 in the outer race 26. As a result, the inner race 30 is allowed to rotate relative to the outer race 26 when the inner race 30 is rotated in either of the directions indicated by arrows X or Y, as shown in FIG. 3. As described above, when the inner race 30 rotates relative to the outer race 26, the rollers 50 jam against the ridges on the respective bearing surfaces 42, 46 and move the inner race 30 radially inwardly to cause the inner surface 34 of the inner race 30 to engage the input member 14 to transfer torque from the input member 14 to the output member 22. This mode of operation of the clutch 10 may be referred to as the "two-way lock" or "full lock" mode because the clutch 10 will "lock" together the input member 14 and the output member 22 if the inner race 30 and the input member 14 are rotated in any direction about the central axis 18 (e.g., the directions indicated by arrows X and

Y)-

[0040] Also, when the control member 78 is in the second position, and when the inner race 30 and the projection 82 are rotated in either of the directions indicated by arrows X or Y, the bearing 102 is spaced from the inner race 30 such that the balls 106 may not engage the portion 118 of the inner race 30 having the shallow contact angle θ. Therefore, the inner race 30 is allowed to move radially inwardly as described above without interference from the balls 106.

[0041] If the clutch 10 is configured in "full lock" mode, and it is desired to adjust the clutch 10 to the "one-way lock" mode, the control member 78 may be moved toward the outer race 26 to the first position of the control member 78 (as shown in FIG. 1). However, since the inner race 30 is already tightly engaged with the input member 14, the balls 106 may not follow the movement of the control member 78 toward the outer race 26, due to an insufficient radial gap between the portion 118 of the inner race 30 having the shallow contact angle θ and the outer periphery of the input member 14. However, when the direction of rotation of the input member 14 reverses (e.g., from a direction corresponding with arrow Y to a direction corresponding with arrow X), the direction of rotation of the inner race 30 also reverses and the rollers 50 resume their non-jammed, neutral configuration in the pockets between the inner race 30 and the outer race 26. The slot 90 in the outer race 26 is sized to block rotation of the projection 82 in the direction indicated by arrow X past the neutral configuration of the rollers 50. Subsequently, the

inner race 30 substantially disengages the input member 14, and the balls 106 move axially along the portion 118 of the inner race 30 having the shallow contact angle θ to displace the inner race 30 radially outwardly from the input member 14.

[0042] As shown in an exaggerated manner in FIG. 1, the bearing 102 may provide a gap between the inner surface 34 of the inner race 30 and the outer surface 38 of the input member 14 sufficiently large to reduce or substantially prevent the formation of a hydrodynamic oil film between the inner race 30 and the input member 14. Again, the gap can also represent contact or partial contact between the inner race 30 and the input member 14, but with only relatively low contact forces therebetween. Although not shown in FIGS. 1 and 2, the inner surface 34 of the inner race 30 and the outer surface 38 of the input member 14 may include circumferential and/or lateral grooves to allow any built-up hydrodynamic oil film to be rapidly removed from the area between the inner surface 34 of the inner race 30 and the outer surface 38 of the input member 14 when the inner race 30 is moved radially inwardly, providing quick and reliable locking of the clutch 10.

[0043] With reference to FIG. 4, a second construction of a bi-directional overrunning clutch 10 may include a ring 122 having a cylindrical inner periphery contacting the balls 106 and an outer periphery that contacts the portion 118 of the inner race 30 having the shallow contact angle θ. The ring 122 may provide a continuous surface over which the balls 106 may traverse, rather than the non-continuous inner race 30 described above. As a result, the balls 106 will not encounter the slit in the inner race 30 when the input member 14 rotates relative to the inner race 30 (i.e., when the clutch 10 is overrunning or not "locked"). The ring 122 may be made from brass to reduce wear against the harder inner race 30.

[0044] FIGS. 5 and 6 illustrate a third construction of a bi-directional overrunning clutch

200 mounted between an input member 204 (e.g., an inner ring) rotatable about a central axis 208 and a fixed output member 212 (e.g., an outer ring) to selectively couple the input member 204 and the output member 212. The clutch 200 includes an outer race 216 fixed for rotation with the output member 212. In the illustrated construction, the outer race 216 is press fit into the output member 212. Alternatively, other methods may be utilized to fix the outer race 216 to the output member 212. The clutch 200 also includes an inner race 220 positioned over the input member 204 such that an inner "slipper" surface 224 of the inner race 220 selectively engages an

outer surface 228 of the input member 204. In the illustrated construction, the inner race 220 is interference fit over the input member 204. However, the inner race 220 includes a longitudinal slit 232 (see FIG. 6) causing the inner race 220 to have a non-continuous circumference. As such, the inner race 220 may exert only a light pressure on the input member 204 when the inner race 220 is not pressed against the input member 204.

[0045] The outer and inner races 216, 220 include respective bearing surfaces 236, 240 upon which a plurality of rollers 244 contact. With reference to FIG. 6, the respective bearing surfaces 236, 240 define a plurality of longitudinal ridges 248 that form pockets 252 into which individual rollers 244 are positioned. With reference to FIG. 5, the outer and inner races 216, 220 include shoulders 256 which restrain the movement of the rollers 244 along the central axis 208. Also, in the illustrated construction, the output member 212 includes a shoulder 260 which restrains the movement of the rollers 244 along the central axis 208. Alternatively, other structure may be utilized to restrain axial movement of the rollers 244.

[0046] With continued reference to FIG. 5, the clutch 200 also includes a control member

264 coupled for rotation with the outer race 216. The control member 264 includes a radially inward-extending projection 268 that may be positioned in respective slots 272, 276 in the outer race 216 and the inner race 220, depending upon the position of the control member 264 along the central axis 208. In the illustrated construction, the slot 272 in the outer race 216 is sized to snugly receive the projection 268, while the slot 276 in the inner race 220 is wider than the slot 272 in the outer race 216. In other words, the slot 272 in the outer race 216 may be substantially similar to the slot 86 in the inner race 30, and the slot 276 in the inner race 220 may be substantially similar to the slot 90 in the outer race 26 of the clutch 10 of FIGS. 1-4.

[0047] As shown in FIGS. 5 and 6, a circumferential groove 280 may be formed in the outer periphery of the input member 204. A spring ring 284, which is flexible in the radial direction, may be positioned in the groove 280. The spring ring 284 may include a cut or a slit 288 to make the spring ring 284 a non-continuous circular member to allow for installation in the groove 280. A ball race 292 may be positioned over the spring ring 284 in the groove 280. Like the spring ring 284, the ball race 292 may also include a cut or a slit 296 to make the ball race 292 a non-continuous circular member to allow for installation in the groove 280. A plurality of balls 298 may be positioned on the ball race 292 between the inner race 220 and the ball race

292. The groove 280 may have a depth suitable to allow the spring ring 284 to fully compress and to fully extend. Because the spring ring 284 has a natural tendency to expand radially outwardly, the assembly of the spring ring 284, the ball race 292, and the plurality of balls 298 should also tend to self-center relative to the central axis 208.

[0048] With reference to FIG. 5, the clutch 200 is adjustable between different modes of operation by moving the control member 264 along the central axis 208 relative to the outer and inner races 216, 220. Particularly, when the control member 264 is moved to position "A," the clutch 200 is operable in a first mode (i.e., the "one-way lock" mode) in which the projection 268 is positioned in the respective slots 272, 276 of the outer race 216 and the inner race 220 to allow the inner race 220 to rotate about the central axis 208 in a single direction relative to the outer race 216 in a substantially similar manner as the clutch 10 of FIGS. 1-4. When the control member 264 is moved to position "B," the clutch 200 is operable in another mode (i.e., the "full- lock" mode) in which the projection 268 is positioned outside the axial extent of the slot 276 in the inner race 220, such that the inner race 220 is rotatable about the central axis 208 in any direction relative to the outer race 216 in a substantially similar manner as the clutch 10 of FIGS. 1-4. Together, the control member 264 and the mechanism or device utilized to move the control member 264 (e.g., an electromagnetic coil or a pressurized chamber) define an actuator operable to selectively allow the inner race 220 to move between a first position, in which the slipper or inner surface 224 engages the outer surface 228 of the input member 204, and a second position, in which the slipper or inner surface 224 is spaced from the outer surface 228.

[0049] FIGS. 5 and 6 illustrate the inner race 220 in its neutral configuration relative to the outer race 216, in which the rollers 244 nest between the ridges 248 on the bearing surfaces 236, 240. In this configuration, the spring ring 284 preloads the balls 298 against the inner surface 224 of the inner race 220 to create a separation force that spaces the inner surface 224 from the input member 204. As a result, the inner race 220 rides substantially on the balls 298 when the inner race 220 is in its neutral configuration, such that the contact forces between the inner race 220 and the input member 204 due to the non-circular distortions caused by the heat treating process may be reduced. Due to these reduced contact forces, the mating surfaces of the inner race 220 and input member 204 can be rougher without causing unacceptable wear to the

inner race 220. The rougher surfaces reduce the formation of a hydrodynamic oil film, allowing engagement of the clutch 200 at higher speeds.

[0050] ^' However, the radial forces applied to the balls 298 by the spring ring 284 are not large enough to prevent some drag between the inner surface 224 of the inner race 220 and the input member 204, which enables the clutch 200 to lock. In other words, when the clutch 200 is adjusted to the full-lock mode, for example, the reduced drag between the inner race 220 and the input member 204 is sufficient to cause the inner race 220 to rotate relative to the outer race 216 and cause the rollers 244 to jam against the ridges 248 on the respective bearing surfaces 236, 240, as described above with reference to the clutch 10 of FIGS. 1-4. The inner race 220, the ball race 292, the spring ring 284, and the balls 298 may then be displaced radially inwardly to allow the inner surface 224 to engage the input member 204 to lock together the input member 204 and the output member 212.

[0051] FIG. 7 illustrates a fourth construction of a bi-directional overrunning clutch 300 mounted between an input member 304 (e.g., an inner ring) rotatable about a central axis 308 and a fixed output member 312 (e.g., an outer ring) to selectively couple the input member 304 and the output member 312. The clutch 300 includes an outer race 316 fixed for rotation with the output member 312. In the illustrated construction, the outer race 316 is press fit into the output member 312. Alternatively, other methods may be utilized to fix the outer race 316 to the output member 312. The clutch 300 also includes an inner race 320 positioned over the input member 304 such that an inner "slipper" surface 324 of the inner race 320 selectively engages an outer surface 328 of the input member 304. The inner race 320 includes a longitudinal slit like the inner races 30, 220 of FIGS. 1-6, causing the inner race 320 to have a non-continuous circumference.

[0052] The outer and inner races 316, 320 include respective bearing surfaces 336, 340 upon which a plurality of rollers 344 contact. Like the bearing surfaces 42, 46 of FIGS. 1-4 and the bearing surfaces 236, 240 of FIGS. 5 and 6, the respective bearing surfaces 336, 340 define a plurality of longitudinal ridges that form pockets into which individual rollers 244 are positioned. With reference to FIG. 7, the outer and inner races 316, 320 include shoulders 356 which restrain the movement of the rollers 344 along the central axis 308. Also, in the illustrated construction, the output member 312 includes a shoulder 360 which restrains the movement of the rollers 344

along the central axis 308. Alternatively, other structure may be utilized to restrain axial movement of the rollers 344.

[0053] With continued reference to FIG. 7, the clutch 300 also includes a control member

364 coupled for rotation with the inner race 320. The control member 364 includes a radially inward-extending projection 368 that may be positioned in a slot 376 in the inner race 320. In the illustrated construction, the slot 376 in the inner race 320 is sized to snugly receive the projection 368. The clutch 300 further includes an electromagnetic coil 378 coupled for rotation with the control member 364 and positioned adjacent the control member 364. The coil 378 may be selectively electrically connected to a source of power (not shown).

[0054] A disk-shaped outer plate 386 is coupled for rotation with the input member 304 and positioned adjacent the coil 378. In the illustrated construction, the outer plate 386 includes a key 388 positioned in a keyway 390 formed in the input member 304. Alternatively, other structure may be utilized to couple the outer plate 386 for rotation with the input member 304. The outer plate 386 also includes a first braking surface 394 located radially outward from the coil 378 and a second braiding surface 396 located radially inward of the coil 378. The first and second braking surfaces 394, 396 may engage respective surfaces 402, 404 on the control member 364 to transfer torque to the control member 364. Together, the outer plate 386, the control member 364, and the coil 378 comprise an actuator in the form of a controllable friction device operable to selectively allow the inner race 320 to move between a first position, in which the slipper surface 324 engages the outer surface 328 of the input member 304, and a second position, in which the slipper surface 324 is spaced from the outer surface 328, and to allow the inner race 320 to overcome the separation force and engage the outer surface 328.

[0055] As shown in FIG. 7, a circumferential groove 380 may be formed in the outer periphery of the input member 304. A spring ring 384, which is flexible in the radial direction, may be positioned in the groove 380. The spring ring 384 may include a cut or a slit to make the spring ring 384 a non-continuous circular member to allow for installation in the groove 380. The spring ring 380 may include a higher spring rate than the spring ring 280 of FIGS. 5 and 6. A ball race 392 may be positioned over the spring ring 384 in the groove 380. Like the spring ring 384, the ball race 392 may also include a cut or a slit to make the ball race 392 a non- continuous circular member to allow for installation in the groove 380. A plurality of balls 398

may be positioned on the ball race 392 between the inner race 320 and the ball race 392. The outer periphery of the input member 304 may also include one or more circumferential grooves 400 to reduce the build-up of a hydrodynaniic film between the inner race 320 and the input member 304.

[0056] The clutch 300 is adjustable between different modes of operation depending on whether the coil 378 is energized or de-energized. Particularly, when the coil 378 is de- energized, the clutch 300 is operable in a first mode (i.e., the "no-lock" mode) in which there is little or no frictional drag force between the outer plate 386 and the control member 364 allowing the inner race 320 to remain stationary relative to the outer race 316. When the coil 378 is energized, a frictional drag force is created between the control member 364 and the outer plate 386, and the clutch 300 is operable in another mode (i.e., the "full-lock" mode) in which the inner race 320 rotates about the central axis 308 relative to the outer race 316. The operation of the clutch 300 is discussed in more detail below.

[0057] FIG. 7 illustrates the inner race 320 in its neutral configuration relative to the outer race 316, in which the rollers 344 nest between the ridges on the bearing surfaces 336, 340. In this configuration, the spring ring 384 preloads the balls 398 against the inner surface 324 of the inner race 320 to create a separation force that spaces the inner surface 324 from the input member 304. As a result, the inner race 320 rides on the balls 398 when the inner race 320 is in its neutral configuration, such that the contact forces between the inner race 320 and the input member 304 due to the non-circular distortions caused by the heat treating process may be substantially eliminated. The neutral position is held because the radial force generated by the balls 398 causes the rollers 344 to contact both the clockwise and counter-clockwise facing bearing surfaces 336, 340. The tangential component of these contact forces opposes any relative motion between the inner and outer races 320, 316 unless an overcoming torque is applied between them due to the coil 378 being energized.

[0058] Unlike the clutch 200 of FIGS. 5 and 6, slight contact forces that may develop between the inner surface 324 and the input member 304 of the clutch 300 are insufficient to cause the inner race 320 to rotate relative to the outer race 316 because the spring ring 384 has a higher spring rate than the spring ring 284 of FIGS. 5 and 6. As such, the spring ring 384 may have sufficient stiffness to maintain the spacing of the inner race 320 from the input member

304. Due to the substantial elimination of the contact forces between the inner surface 324 and the input member 304 when the inner race 320 is in its neutral configuration, the mating surfaces of the inner race 320 and input member 304 can be rougher without causing unacceptable wear to the inner race 320. The rougher surfaces prevent the formation of a hydrodynamic oil film, allowing engagement of the clutch 300 at higher speeds.

[0059] The clutch 300 may be locked on demand by energizing the coil 378, which creates a frictional drag torque between the outer plate 386 and the control member 364. Since the projection 368 on the control member 364 is positioned in the slot 376 in the inner race 320, the torque from the outer plate 386 is also transferred to the inner race 320 to cause the inner race 320 to rotate about the central axis 308 relative to the outer race 316 and cause the rollers 344 to jam against the ridges on the respective bearing surfaces 336, 340, as described above with reference to the clutch 10 of FIGS. 1-4. The inner race 320, the ball race 392, the spring ring 384, and the balls 398 may then be displaced radially inwardly to allow the inner surface 324 to engage the input member 304 to lock together the input member 304 and the output member 312. It is to be understood that other methods and other controllable friction devices for creating drag force between the outer plate 386 and the control member 364 (e.g., hydraulic actuators) can also be substituted for the coil 378.

[0060] The clutch 300 will remain locked after the coil 378 is de-energized, and the clutch 300 will not unlock until the torque carried through the clutch 300 reverses. This action can take the place of a one-way clutch in an automatic transmission. In a lower gear the coil 378 may be energized to transmit torque through the clutch 300. When an upshift is desired, the coil 378 may be de-energized as the higher gear is activated. When the higher gear starts to drive, the tendency is to overrun the clutch 300, which had been supplying torque in the lower gear. This causes a torque reversal on the clutch 300, which causes the clutch 300 to disengage or unlock. To downshift, the coil 378 may be energized again.

[0061] FIG. 8 illustrates a fifth construction of a bi-directional overrunning clutch 500 mounted between an input member 504 (e.g., an inner ring) rotatable about a central axis 508 and a rotatable output member 512 (e.g., an outer ring) to selectively couple the input member 504 and the output member 512. The clutch 500 includes an outer race 516 fixed for rotation with the output member 512. In the illustrated construction, the outer race 516 is press fit into

the output member 512. Alternatively, other methods may be utilized to fix the outer race 516 to the output member 512. The clutch 500 also includes an inner race 520 positioned over the input member 504 such that an inner "slipper" surface 524 of the inner race 520 selectively engages an outer surface 528 of the input member 504. The inner race 520 includes a longitudinal slit like the inner races 30, 220, 320 of FIGS. 1-7, causing the inner race 520 to have a non-continuous circumference.

[0062] The outer and inner races 516, 520 include respective bearing surfaces 536, 540 upon which a plurality of rollers 544 contact. Like the bearing surfaces 42, 46 of FIGS. 1-4, the bearing surfaces 236, 240 of FIGS. 5 and 6, and the bearing surfaces 336, 340 of FIG. 7, the respective bearing surfaces 536, 540 define a plurality of longitudinal ridges that form pockets into which individual rollers 544 are positioned. With reference to FIG. 8, the outer and inner races 516, 520 include shoulders 556 which restrain the movement of the rollers 544 along the central axis 508. Also, in the illustrated construction, the output member 512 includes a shoulder 560 which restrains the movement of the rollers 544 along the central axis 508. Alternatively, other structure may be utilized to restrain axial movement of the rollers 544, such as a retaining ring 562 positioned between the rollers 544 and the shoulders 556.

[0063] With continued reference to FIG. 8, the clutch 500 also includes a control member

564 coupled for rotation with the inner race 520. The control member 564 includes a radially inward-extending projection 568 that may be positioned in a slot 576 in the inner race 520. In the illustrated construction, the slot 576 in the inner race 520 is sized to snugly receive the projection 568. The clutch 500 further includes an annular electromagnetic coil 578 coupled to a stationary housing 572. The coil 578 may be selectively electrically connected to a source of power (not shown).

[0064] A disk 586 including an inner portion 608, an outer portion 612, and a central portion 616 connecting the inner portion 608 and the outer portion 612 is coupled for rotation with the input member 504 and positioned between the control member 564 and the coil 578. In the illustrated construction, the central portion 616 is made from a non-metallic material (e.g., a polymeric material). Also, in the illustrated construction, the inner portion 608 of the disk 586 includes a key 588 positioned in a keyway 590 formed in the input member 504. Alternatively, other structure may be utilized to couple the disk 586 for rotation with the input member 504.

The outer portion 612 of the disk 586 includes a first braking surface 594, and the inner portion of the disk 586 includes a second braking surface 596. The first and second braking surfaces 594, 596 may engage respective surfaces 602, 604 on the control member 564 to transfer torque to the control member 564. Together, the disk 586, the control member 564, and the coil 578 comprise an actuator in the form of a controllable friction device operable to selectively allow the inner race 520 to move between a first position, in which the slipper surface 524 engages the outer surface 528 of the input member 504, and a second position, in which the slipper surface 524 is spaced from the outer surface 528, and to allow the inner race 520 to overcome the separation force and engage the outer surface 528.

[0065] As shown in FIG. 8, a circumferential groove 580 may be formed in the outer periphery of the input member 504. A spring ring 584, which is flexible in the radial direction, may be positioned in the groove 580. The spring ring 584 may include a cut or a slit to make the spring ring 584 a non-continuous circular member to allow for installation in the groove 580. The spring ring 580 may include a high spring rate, like the spring ring 380 of FIG. 7. A ball race 592 may be positioned over the spring ring 584 in the groove 580. Like the spring ring 584, the ball race 592 may also include a cut or a slit to make the ball race 592 a non-continuous circular member to allow for installation in the groove 580. A plurality of balls 598 may be positioned on the ball race 592 between the inner race 520 and the ball race 592. The outer periphery of the input member 504 may also include one or more circumferential grooves (not shown) to reduce the build-up of a hydrodynamic oil film between the inner race 520 and the input member 504.

[0066] The clutch 500 is adjustable between different modes of operation depending on whether the coil 578 is energized or de-energized. Particularly, when the coil 578 is de- energized, the clutch 500 is operable in a first mode (i.e., the "no-lock" mode) in which there is little or no drag force between the control member 564 and the disk 586, allowing the inner race 520 to remain stationary relative to the outer race 516. When the coil 578 is energized, a frictional drag force is created between the control member 564 and the disk 586, and the clutch 500 is operable in another mode (i.e., the- "full-lock" mode) in which the inner race 520 rotates about the central axis 508 relative to the outer race 516. The operation of the clutch 500 is discussed in more detail below.

[0067] FIG. 8 illustrates the inner race 520 in its neutral configuration relative to the outer race 516, in which the rollers 544 nest between the ridges on the bearing surfaces 536, 540. In this configuration, the spring ring 584 preloads the balls 598 against the inner surface 524 of the inner race 520 to create a separation force that spaces the inner surface 524 from the input member 504. As a result, the inner race 520 rides on the balls 598 when the inner race 520 is in its neutral configuration, such that the contact forces between the inner race 520 and the input member 504 due to the non-circular distortions caused by the heat treating process may be substantially eliminated. The neutral position is held because the radial force generated by the balls 598 causes the rollers 544 to contact both the clockwise and counter-clockwise facing bearing surfaces 536, 540. The tangential component of these contact forces opposes any relative motion between the inner and outer races 520, 516 unless an overcoming torque is applied between them due to the coil 578 being energized.

[0068] Like the clutch 300 of FIG. 7, slight contact forces that may develop between the inner surface 524 and the input member 504 of the clutch 500 are insufficient to cause the inner race 520 to rotate relative to the outer race 516. The spring ring 584 may have sufficient stiffness to maintain the spacing of the inner race 520 from the input member 504. Due to the substantial elimination of the contact forces between the inner surface 524 and the input member 504 when the inner race 520 is in its neutral configuration, the mating surfaces of the inner race 520 and input member 504 can be rougher without causing unacceptable wear to the inner race 520. The rougher surfaces prevent the formation of a hydrodynamic oil film, allowing engagement of the clutch 500 at higher speeds.

[0069] The clutch 500 may be locked on demand by energizing the coil 578. The coil

578 generates a magnetic flux in a circuit which includes both the control member 564 and the disk 586. The resulting attractive force between the control member 564 and the disk 586 creates a frictional drag torque between the disk 586 and the control member 564. Since the projection 568 on the control member 564 is positioned in the slot 576 in the inner race 520, the torque from the disk 586 is also transferred to the inner race 520 to cause the inner race 520 to rotate about the central axis 508 relative to the outer race 516 and cause the rollers 544 to jam against the ridges on the respective bearing surfaces 536, 540, as described above with reference to the clutch 10 of FIGS. 1-4. The inner race 520, the ball race 592, the spring ring 584, and the

balls 598 may then be displaced radially inwardly to allow the inner surface 524 to engage the input member 504 to lock together the input member 504 and the output member 512. It is to be understood that other methods and other controllable friction devices for creating drag force between the disk 586 and the control member 564 (e.g., hydraulic actuators) can also be substituted for the coil 578.

[0070] Like the clutch 300 of FIG. 7, the clutch 500 will remain locked after the coil 578 is de-energized, and the clutch 500 will not unlock until the torque carried through the clutch 500 reverses.

[0071] Alternative embodiments of the clutch 300, 500 may utilize additional control features to block locking of the clutch 300, 500 in a particular direction. Such blocking may be controlled by a solenoid, a hydraulic cylinder, or a mechanical linkage. Additionally, such control features can also be incorporated into the clutches 10 and 200 to actuate the control members 78 and 264.

[0072] FIG. 9 illustrates a sixth construction of a bi-directional overrunning clutch 600 mounted between a first member (e.g., a stationary inner ring 603) and a second member rotatable about a central axis 609 (e.g., a rotatable outer ring 611) to selectively couple the inner ring 603 and the outer ring 611. A non-rotating support or housing 610 may be coupled to the inner ring 603 by a plurality of inter-engaging splines 614. Also, a machine component 618 may be coupled to the outer ring 611 by a plurality of inter-engaging splines 622. Alternatively, the non-rotating housing 610 and the machine component 618 may be coupled to the inner ring 603 and the outer ring 611, respectively, by any of a number of different ways (e.g., press-fits, key and keyway connections, etc.)

[0073] The clutch 600 includes an outer race 615 fixed for rotation with the outer ring

611. In the illustrated construction, the outer race 615 is press fit into the outer ring 611. Alternatively, other methods may be utilized to fix the outer race 615 to the outer ring 611. The clutch 600 also includes an inner race 620 positioned over the inner ring 603 such that an inner "slipper" surface 624 of the inner race 620 selectively engages an outer surface 628 of the inner ring 603. The inner race 620 includes a longitudinal slit like the inner races 30, 220, 320 of FIGS. 1-7, causing the inner race 620 to have a non-continuous circumference.

[0074] The outer and inner races 615, 620 include respective bearing surfaces 636, 640 upon which a plurality of rollers 644 contact. Like the bearing surfaces 42, 46 of FIGS. 1-4, the bearing surfaces 236, 240 of FIGS. 5 and 6, the bearing surfaces 336, 340 of FIG. 7, and the bearing surfaces 536, 540 of FIG. 8, the respective bearing surfaces 636, 640 define a plurality of longitudinal ridges that form pockets into which individual rollers 644 are positioned. With reference to FIG. 9, the outer and inner races 615, 620 include shoulders 656 that restrain the movement of the rollers 644 along the central axis 609. Also, in the illustrated construction, the outer ring 611 includes a shoulder 660 that restrains the movement of the rollers 644 along the central axis 609. Alternatively, other structure may be utilized to restrain axial movement of the rollers 644, such as a retaining ring 662 positioned between the rollers 644 and the shoulders 656.

[0075] With continued reference to FIG. 9, the clutch 600 also includes an actuator including a control member 664 coupled for rotation with the inner race 620. A thrust washer 666 is positioned between the control member 664 and the outer ring 611. The control member 664 includes a radially inward-extending projection 668 that may be positioned in a slot 676 in the inner race 620. In the illustrated construction, the slot 676 in the inner race 620 is sized to snugly receive the projection 668 (see FIG. 10). Particularly, the slot 676 is configured as a generally rectangular slot 676 for receiving the generally rectangular projection 668 of the control member 664. The projection 668 may also be positioned in different slots 702, 706 in the outer race 615. Likewise, the slots 702, 706 are configured as generally rectangular slots 702, 706 for receiving the generally rectangular projection 668 of the control member 664. As shown in FIG. 10, the slot 676 has a width substantially equal to the width of the projection 668, while the slot 702 is wider than the slot 676, and the slot 706 is even wider than the slot 702.

[0076] With reference to FIG. 9, the projection 668 is movable along the central axis

609, and a spring 677 is positioned between the projection 668 and an axially adjacent portion of the control member 664 to bias the projection 668 away from the axially adjacent portion of the control member 664. The actuator also includes a resilient disk 679 and an annular pressurized chamber 681 coupled to the resilient disk 679. The pressurized chamber 681 may be fluidly connected to a source of pressurized fluid (e.g., pressurized air or liquid). The chamber 681 is selectively pressurized to move the resilient disk 679 toward the projection 668, and thereby

move the projection 668 along the central axis 609. When the chamber 681 is pressurized, the resilient disk 679 bends and moves the projection 668, along the central axis 609, into the slot 706 (see FIG. 10). When the chamber 681 is de-pressurized, the resilient disk 679 springs back to the position shown in FIG. 9, and the spring 677 biases the projection 668 back into the slot 702.

[0077] With reference to FIG. 9, the actuator further includes a resilient brake arm 670 having a brake ring 672 thereon, and an annular pressurized chamber 678 coupled to the stationary housing 610. Like the pressurized chamber 681 , the pressurized chamber 678 may be fluidly connected to a source of pressurized fluid (e.g., pressurized air or liquid). The brake ring 672 may engage a braking surface 682 on the control member 664 to transfer torque to the control member 664. When the brake ring 672 engages the braking surface 682 of the control member 664, little torque is transferred directly from the control member 664 to the outer ring 611 because the thrust washer 666 allows the control member 664 to slip relative to the outer ring 611. Together, the resilient arm 670, the brake ring 672, the control member 664, and the pressurized chamber 678 comprise an actuator in the form of a controllable friction device operable to selectively allow the inner race 620 to move between a first position, in which the slipper surface 624 engages the outer surface 628 of the inner ring 603, and a second position, in which the slipper surface 624 is spaced from the outer surface 628, and to allow the inner race 620 to overcome the separation force imparted by the spring ring 684 and engage the outer surface 628.

[0078] As shown in FIG. 9, a circumferential groove 680 may be formed in the outer periphery of the inner ring 603. A spring ring 684, which is flexible in the radial direction, may be positioned in the groove 680. The spring ring 684 may include a cut or a slit to make the spring ring 684 a non-continuous circular member to allow for installation in the groove 680. The spring ring 680 may include a high spring rate, like the spring ring 380 of FIG. 7. A ball race 692 may be positioned over the spring ring 684 in the groove 680. Like the spring ring 684, the ball race 692 may also include a cut or a slit to make the ball race 692 a non-continuous circular member to allow for installation in the groove 680. A plurality of balls 698 may be positioned on the ball race 692 between the inner race 620 and the ball race 692. The outer periphery of the inner ring 603 may also include one or more circumferential grooves (not

shown) to reduce the build-up of a hydrodynamic oil film between the inner race 620 and the inner ring 603.

[0079] The clutch 600 is adjustable between different modes of operation depending on whether the pressurized chamber 678 is pressurized or de-pressurized. Particularly, when the chamber 678 is de-pressurized, the clutch 600 is operable in a first mode (i.e., the "no-lock" mode) in which there is little or no drag force between the brake ring 672 and the control member 664, allowing the inner race 620 to remain stationary relative to the outer race 615 and the slipper surface 624 to be spaced from the outer surface 628 of the inner ring 603 by the balls 698, thereby allowing the inner race 620, the plurality of rollers 644, the outer race 615, and the control member 664 to rotate with the outer ring 611.

[0080] When the chamber 678 is pressurized, the resilient brake arm 670 is moved toward the control member 664, causing the brake ring 672 to impart a frictional drag force on the control member 664, and the clutch 600 is operable in another mode (i.e., either the "one-way lock" mode or the "full-lock" mode, depending on which slot 702, 706 the projection 668 is positioned) in which the inner race 620 rotates about the central axis 609 relative to the outer race 615. With reference to FIG. 9, the pressurized chamber 681 and the resilient disk 679 are operable to move the projection 668 along the central axis 609 relative to the outer and inner races 615, 620 to a first position (shown in FIG. 10) to operate the clutch 600 in the one-way lock mode (i.e., in which the projection 668 is positioned within the slot 702), and to a second position against the bias of the spring 677 to operate the clutch 600 in the full-lock mode (i.e., in which the projection 668 is positioned within the slot 706).

[0081] The clutch 600 may be locked on demand by pressurizing the chamber 678.

Since the projection 668 on the control member 664 is positioned within the slot 676 in the inner race 620, the braking torque on the control member 664 is also transferred to the inner race 620 to cause the inner race 620 to rotate about the central axis 609 relative to the outer race 615 and cause the rollers 644 to jam against the ridges on the respective bearing surfaces 636, 640, as described above with reference to the clutch 10 of FIGS. 1-4. The inner race 620, the ball race 692, the spring ring 684, and the balls 698 may then be displaced radially inwardly to allow the inner surface 624 to engage the outer surface 628 of the inner ring 603 to lock together the inner ring 603 and the outer ring 611. It is to be understood that other methods and other controllable

friction devices for creating drag force between the brake ring 672 and the control member 664 (e.g., electromagnetic coils) can also be substituted for the pressurized chamber 678.

[0082] Like the clutch 300 of FIG. 7, the clutch 600 will remain locked after the chamber

678 is de-pressurized (illustrated in FIG. 9), and the clutch 600 will not unlock until the torque carried through the clutch 600 reverses.

[0083] Although all of the illustrated embodiments of the clutches 10, 200, 300, 500, 600 includes the bearing 102 positioned between the inner race 30 and the input member 14, alternative embodiments of the clutch 10 in which the inner race 30 is fixed for rotation with the input member 14 and the outer race is configured as the "slipper" may include the bearing 102 positioned between the outer race 26 and the output member 22. Additionally, those skilled in the art understand that the input and output members of a clutching device can be reversed, and as such the terms "input" and "output" as used in the above description are to provide a frame of reference relative to the illustrated embodiments and are not intended to be limiting. Further, although the clutches 200, 300, 500 include the balls 298, 398 positioned between the inner races 220, 320, 520 and the input members 204, 304, 504 alternative embodiments of the clutches 200, 300, 500 in which the inner races 220, 320, 520 are fixed for rotation with the input members 204, 304, 504 and the outer races 216, 316, 516 are configured as the "slippers" may include the balls 298, 398, 598 positioned between the outer races 216, 316, 516 and the output members 212, 312, 512.

[0084] Various features of the invention are set forth in the following claims.