CA1072367A - Manually shiftable planetary gearset - Google Patents

Abstract

ABSTRACT

A power transfer mechanism incorporating a planetary or epicyclic gearset which may be shifted manually between high and low range conditions for direct drive and reduction ratio drive modes. The ring and planet gears are unloaded in the direct drive mode, thus avoiding vibration and wear commonly experienced when running locked-up. The mechanism may be incorporated in a multiple path drive system comprising a transfer case disposed between a source of input torque and a pair of drive axles, wherein torque is transferred directly to one drive axle and automatically to the other drive axle, when required, through a double-acting overrunning clutch.

Description

This invention relates generally to a power transfer mechanism incorporationg a planetary gearset.
In recent years, there have been many improvements in drive trains, including improvements relating to planetary gearing for establishing paths ~or the transfer of power in high and low range modes. Some such planetary gearsets are shifted by engaging and disengaging friction elements manually, hydraulically, electrically, or by some other suitable means. Other planetary gearsets are shifted - 10 by engaging and disengaging clutches. Normally, this is done by sliding sleeves into and out of dental engagement with various elements for establishing high and low range modes. This requires considerable space and a large number of parts within the assembly. The planetary gear-sets may be provided with ring gears which are moved into and out of engagement with planet or sun gears for establishing the various modes. However, in these ` ` arrangements, the system is generally loaded when running ; in the locked-up condition, thus causing vibration and - 20 excessive wear.
According to the present invention, there is provided a planetary gear assembly including a sun gear, and a slidable sub-assembly~ The sub-assembly includes a carrier, a ring gear and a plurality of planet gears in meshing relationship with the sun and ring gears. The sub-assembly is slidable to a first position engaging the carrier with the sun gear for rotation therewith, and to a second position grounding the ring gear.
More specifically, an improved planetary gearset ~- 30 of the present invention includes a planet carrier and sb/ ~
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ring gear which slide as a unit to provide direct drive through engagement oE the sun gear with the planet carrier, and to provide reduction ratio drive through engagement of the ring gear with the case. Power input is to the sun gear. Power output is from the carrier.
Output may be from one end of the carrier or, if the torque is to be split, from both ends of the carrier.

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In direc~ drive, the carrier meshes with the sun gear~ transmitting power without loading the planet and ring gears, thus avoiding vibratory wear commonly experienced ' when running in the locked-up condition. In reduction drive, the carrier and ring gear assembly is moved to disengage the carrier from the sun gear and to ground the ring gear by locking it to a stationary member. In neutral, the carrier is disengaged from the sun gear but remains engaged with output elements, and the ring gear is disengaged from the stationary member. An additional shift position may be provided, if desired, to disengage the carrier from the ~`
output elements and establish a towing mode.

The improved planetary gearset may be incorporated in a four~wheel drive transfer case for use between a prime mover and a pair o~ drive axles. The mechanism includes a transfer case adaptable for transferring torque from the input to one output directly and to another output through an overrunning clutch.

In the accompanying drawings:
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FIGURE 1 is a sectional view showing details of the torque transfer case including the improved planetary gearset in the high range position for establishing direct drive to a rear output coaxial with the input and to a front output offset therefrom;

FIGURE 2 is a partial sectional view on an enlarged scale showing details of the planekary gearset in -the low range position providing reduc~ion ra~io drive;

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FIGURE 3 ls a partial sec~ional vie~ on an enlarged scale showing details of the planetary gearset in the neutral position;

FIGURE 4 is a partial sectional view on an enlarged `~ scale showing details of the planetary gearset in the towing position;

FIGURE 5 is a sectional view on an enlarged scale, ` taken along the line 5-5 of FIGURE 1, showing details of the : overrunning clutch; and :' FIGURE 6 is a sectional view, similar to FIGURE 1, showing details of the torque transfer case in a configuration wherein both outputs are offset from the input.
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`- While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will be described herein in detail a preferred embodiment with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to this ; embodiment.

` Referring now to the drawings in greater detail, there is sho~n generally a torque transfer case 10 particularly adapted for use in an automo~ive vehicle incorporating a four-wheel drive system. Torque transfer case 10 is suitable for tr~nsmitting torque from a prime mover through a plurality ~- of drive axle assemblies to drive front and rear pairs of traction wheels.

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075099-A-WG 107Z3fi^~

Torque transfer case 10 includes a first housing section 12 which supports bearings 14, 16 and 18. Torque transfer case 10 also includes a second housing section 20 suitably secured to housing section 12 and aligned by a plurality of dowels 22 or the like. Housing section 20 supports bearings 24, 26 and 28.

A sleeve 30 is journalled in bearings 14 and 24.
Sleeve 30 includes an annular extension 32 which defines ~outwardly facing teeth 34. A bearing 36 is located inwardly of annular extension 32.

A rear output or propeller shaft 38 is journalled in bearing 26 and extends into transfer case lO; Output shaft 38 defines outwardly facing teeth 40, and is provided with an axial bore 42 in which a bearing 44 is located.

An input shaft 46 extends into transfer case 10 and is journalled in bearing 36. Input shaft 46 defines an end portion 48 received in axial bore 42 of output shaft 38 and journalled in bearing 44. A spline 50 is defined by input shaft 46 between bearings 36 and 44. Input shaft 46 is adapted to receive torque, for example, from an associated txansmission of an automotive vehicle. It should be understood that input shaft 46 may be the output shaft of such a transmission.

A first sprocket 52 is secured to sleeve 30 for rotation therewith. A second sprocket 54 defines an interior pocket 56. Sprocket 54 includes a flange 58 which deines a plurality of openings 60 extending therethrough and spaced ~75099-A-WG
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around its periphery to communica~e pocket 56 with the exterior ther~of. Sprocket 54 also includes an annular ext~nsion 62. Also forming a portion of sprocket 54 is a flange 64 including an annular extension 66. Flange 64 is secured to sprocket 54 by means of a locking ring 68 or the like. Sprocket assembly 54 is journalled in bearings 18 and 28. A suitable chain 69 couples sprockets 52 and 54. Sprocket 52, chain 69 and sprocket 54 form a chain drive train.
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A front output or propeller shaft 70 is journalled in bearing 16 and extends into transfer case 10. Output shaft 70 defines an upstanding flange 72 having an annular extension 74 within pocket 56 of sprocket assembly 54.
Extension 74 defines an outer clutch race 76 of cylindrical configuration.

A stub shaft 78 is secured to extension 62 of sprocket assembly 54 for rotation therewith. An annular element or cam 80 is splined to stub shaft 78. Cam 80 is within pocket 56 defined by sproc~et assembly 54 and defines an inner clutch race 82 comprising a plurality of facets or ramp surfaces.

An annular roller cage 84 supports a plurality of rollers 86, one of which is associated with each facet of inner race 82. ~xtension 74, cam 80, cage 84, and rollers 86 form a double-acting o~errunning clutch 88.

Cage 84 defines a plurality o fingers 90 extending through openings 60 in flange 58. An annular wear ring 92 is pressed into housing section 20 in opposed relationship to fingers 9G. A plurality of drag shoes 94 are provided, 075099-A-WG 10'~23~t~

each engaged by a inger 90 for rotation therewith. Drag shoes 94 are in frictional contact with wear ring 92, and may be spring biased ~oward this frictional contact. As a result, balanced radial drag forces are developed which cause a relative drag effect on roller cage 84.

Turning now to a detailed description of the manually shiftable planetary gearset, attention is directed in particular to FIGURES 1, 2, 3 and 4. FIG~RE 1 shows the planetary gearset 100 in its high range position for establishing direct drive. FIGURE 2 shows the low range position for establishing reduc~ion ratio drive, FIGURE 3 shows the neutral position, and FIGURE 4 shows the optional towing position.

Planetary gearset 100 includes a sun gear 102 defining teeth 194 on the exterior thereof. Sun gear 102 is secured to input shaft 46 by means of spline 50 for rotation therewith. As so secured, teeth 104 are in alignment with teeth 34 on extension 32 of sleeve 30. A planet carrier 106 includes a pair of end sections 108 and 110 secured for movement together. Sections 108 and 110 support a plurality of shafts 112, one of which is shown in the drawings, spaced in an annular configuration. End section 108 supports an oil collector 109 and defines inwardly facing teeth 114 in alignment with teeth 34 and 104 for engagement therewith.
Similarly, end section 110 defines inwardly facing teeth 116 in alignment with teeth 40 on output shaft 38 :Eor engagement.

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Each shaft 112 carries a pair of spaced bearings ~ 118 and 120 between end sections lG8 and 110. Journalled on !
: each pair of bearings 118 and 120 is a planet gear 122.
Planet gears 122 define outwardly facing teeth 124 in mesh : with teeth 104 of sun gear 102.
' , A ring gear 126 is supported out~ardly of end section 108 of planet carrier 106. A pair of spaced locking rings 127 is provided to carry ring gear 126 with planet carrier 106, without hindering rotation of ring gear 126.
Ring gear 126 defines inwardly facing teeth 128 in mesh with teeth 124 of planet gears 122.

- An annular element 130 is secured to housing section 20. Element 130 defines outwardly facing teeth 132 in alignment with teeth 128 of ring gear 126, It should be understood that element 130 may be ormed as an integral part of housing secti.on 20 if desired.
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With particular reference to FIGURE 1, planetary . gearset 100 is in its high range position establishing the .; direct drive mode. Teeth 114 are in mesh with teeth 104 and teeth 34, thereby engaging planet carriex 106 with both sun ~ gear 102 and sleeve 30. Teeth 116 are in mesh with teeth `~ 40, thereby engaging planet carrier 106 with outpu~ s~aft 38. Planet gears 122 are in mesh with both sun gear 102 and ring gear 126.

-' , 1~72367 Torque is received by input shaft 46 and is transEerred through sun gear 102 and planet carrier 106 directly to sleeve 30 and output shaft 38. In this direct drive mode, the planet and ring gears are unloaded, thereby avoiding vibration and wear commonly experienced when running in the locked-up condition, especially in heavy-duly vehicles.

With particular reference to FIGURE 2, planetary gearset 100 is in its low range position establishing the reduction ratio drive mode. It is apparent that planet carrier 106 is slidable and carries therewith ring gear 126 and planet gears 122, all as a unit. Suitable means, not shown, engages end section 110 to slide planet carrier 106 leftwardly to a position where teeth 114 remain in mesh with teeth 34 but not with teeth 104, and t~eth 116 remain in mesh with teeth 40. Teeth 128 are in mesh with teeth 132, thereby effectively grounding ring gear 126 by locking it to housing section 20. Planet gears 122 remain in mesh with both sun gear 102 and ring gear 126. In this position, ring gear 126 acts as a reaction mem~er, and planet gears 122 planetate. As planet carrier 106 is engaged with both sleeve 30 and output shaft 38, torque received by input shaft 46 is transferred through planetary gearset 100 to provide reduction ratio torque to sleeve 30 and output shaft 38.

FIGURE 3 shows planetary gearset 100 in its neutral position. Planet carrier 106 has been slid to a position .:

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~etween the high and low range positions, where teeth 114 are not in mesh with teeth 10l~, thereby disengaging planet carrier 106 from sun gear 102. Teeth 128 are not in mesh with teeth 132, thereby disengaging ring gear 126 ~rom housing section 20. In this mode, it is apparent that planetary gearset 100 will freewheel without transmitting torque to either sleeve 30 or output shaft 38.

The optional towing position is shown in FIGURE 4.
Planet carrier 106 has been slid rightwardly beyond the high range position to move teeth 114 and 1167 respectively, out of mesh with teeth 34 and 4~. This disengages planet carrier 106 from both sleeve 30 and output shaft 38, which are thus free to rotate without causing damage to an automatic transmission, for example, , In one preferred form of the invention, output shaft 38 may be connected to a rear drive axle assembly of an associated vehicle. Output shaft 70 may be connected to the ront drive axle assembly of an associated vehicle.

Output shaft 70 normally rotates faster than output shaft 38. This is inherent when the vehicle is turning, since the front wheels travel through a larger radius than do the rear wheels. For straight movement, this may be accomplished by providing front and rear axles having slightly different gear ratios, front wheels slightly smaller than rear wheels, or by in~lati.ng the front tires to a pressure slightly less than that in the rear tires. Other suitable means may be provided for causing output shaft 70 normally to overrun output shaft 38.
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~7~367 Sleeve 30 and output shaft 38 rotate together.
Torque is transmitted from sleeve 30 through the chain drive train to drive stub shaft 78 and cam 80. Annular extension 74 rotates with output sha~t 70. Thus, under normal conditions, annular element 74 and outer clutch race 76 rotate faster than cam 80 and inner clutch race 82. Roller cage 84 is rotated, and fingers 90 carry drag shoes 94. Due to the frictional engagement of drag shoes 94 with housing section 20, balanced radial forces are developed which result in a relative drag effect on roller cage 84. This reLative drag effect is developed without any axial forces acting on -roller cage 84, and thus there is no tendency for roller cage 84 to bind.

With re~erence to FIGURE 5~ assume cam 80 is rotating in the clockwise direction. Extension 74 also is rota~ing in the clockwise direction, but at a slightly faster speed. The drag effect on roller cage 84 causes rollers 86, in effect, to rotate relatively in the counterclockwise direction. Rollers 86 tend to wedge ~e-tween inner race 82 and outer race 76 so as to engage clutch 88. However, due to the fact that extension 74 is overrunning cam S0, a force is developed which acts on rollers 86 such that they will be carried in the clockwise direction, reIati~ely, away from their engaged position. Thus, the relative rotation between extension 74 and cam 80 prevents engagement of clutch 88.
As a result, torque is transerred to output shaft 38 but not to output sha~t 70. In this condition, the operation is essentially that of a conventional two-wheel drive vehicle.

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If the rear wheels lose traction, output shaf~ 38 will speed up. This will be re~lected in stub shaft 78, which rotates with output shaft 3g. I~hen stub shaft 78, and cam 80, are rotating at the same speed as extension 74, the drag effect on roller cage 84 will cause rollers 86 to wedge between inner race 82 and outer race 76. When this takes place, torque will be transferred both to output shaft 38 and through clutch 88 to output shaft 70. In this condition7 the operation is essentially that of a conventional four-wheel drive vehicle in locked-up mode.

When the rear wheels regain traction, output shaft 70 will again overrun output shaft 38 and stub shaft 78.
Rollers 86 will be carried away from their engaged position toward a freewheeling position, thereby disengaging clutch 88 and restoring the vehicle to the two-wheel drive condition.
Thus, it will be seen that the transfer case provides for establishment of four-wheel drive automatically as required, and for establishment of two-wheel drive automatically when four-wheel drive is not required. This automatic engaging and disengaging feature is provided when the vehicle is moving in either the forward or reverse direction; that is, whèn output shafts 38 and 70 are rotating in either the cloclcwise or counterclockwise direction.

This automatic engaging and disengaging ~eature is provided when planetary gearset 100 is in either the direct drive mode or the reduction ratio drive mode. In either case, torque input is to sun gear 102, and torque output is from planet carrier 106. In the single offset configuration shown in FIGURE 1, the torque is split, some transerred directly to rear output shaft 38, and some through sleeve 30, .

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the chain drive train and clutch 88 to front output shaft 70. Of course,neither output shaEt receives torque when planetary gearset 100 is in either the neutral or towing position.

Turning now to the configuration shown in FIGURE
6, torque transfer case 10 may be modified so as to provide double offset output shafts. Housing section 20 is replaced by housing section 220 which is suitably secured to housing section l2 and aligned by dowels 22 or the like. A sleeve 222 is secured to housing section 220 by a pin 224 or the like. Sleeve 222 defines an end portion 226 of reduced diameter on which sun gear 102 is maintained in axial alignment. Sleeve 222 has a smooth outer surface, and thus is not engaged by teeth 116 in any position of planet carrier 106. A shortened input shaft 246 replaced input shaft 46.

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A rear output or propeller shaft 238 replaces output shaft 38 and stub shaft 78, and is journalled in a relocated bearing 26 so as to extend into torque transfer case 10. Output shaft 238 is splined to extension 62 of sprocket assembly 54 to receive torque from the chain drive train. Cam 80 is splined to output shaft 238 such that cam 80 is rotatable with output shaft 238. This is all that is required to complete modification of the torque trans~er case.
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In the configuration shown in FIGURE 6 the torque is not split in planetar~ gearset 100, but rather is transferred from input shaft 246 to sun gear 102 and from end section 108 of planet carrier 106 through sleeve 30 and the chain , ' .

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~' ' drive train to output shaft 238. Operation of clu-tch 88 is the same as in the configuration shown in FIGURE 1, and torque will not be transferred to output shaft 70 until output shaft 238 speeds up so as to approach synchronization with output shaft 70. At this time, clutch 88 will engage automatically. This takes place when planetary gearset 100 is in either the high or low range position. Of course, no torque will be transferred from planet carrier 106 when planetary gearset 100 is in either the neutral or towing position.

It should be noted that operation of the transfer case will be the same when the vehicle is moving in either the forward or reverse direction; that is, wi~h rotation of shafts 238 and 70 in the clockwise or counterclockwise direction.

The simplicity of this mechanism is apparent. It will be seen that a transfer case has been provided which normally drives one output shaft to provide conventional two-wheel drive of an associated vehicle. I~hen required, a double-acting overrunning clutch engages automatically to provide drive to both output shafts so as to establish four-wheel drive. When four-wheel drive is no longer required, the clutch automatically disengages and the system reverts to conventional two-wheel drive.

The transfer case is adaptable to either of two configurations. In one con~iguration the input and one output are coaxial and the other output is offset therefrom, ~ 236'~

:. Assembly in either configuration is simple, as most of the parts are interchangeable. In either configuration, high speed-low torque or low speed-high ~orque modes may be established by a planetary gearset having a manually slidable planet carrier. The gearset includes a sun gear as the input element and a planet carrier as the output element.
Direct drive is established through toothed engagement o~
the sun gear with the planet carrier, and reduction ratio drive is provided through toothed engagement of the reaction ring gear with the case. In direct drive, the planets and ring gear are lmloaded, thus avoiding vibratory wear commonly experienced when running heavy-duty vehicles in the locked-up condition.

Claims (17)

WHAT WE CLAIM IS:

1. In power transmission apparatus especially adapted for driving a motor vehicle having front and rear ground engaging wheels, said apparatus including a rotary input member adapted for connection to a source of power and rotary output means adapted for connection to said ground engaging wheels, said rotary output means including a pair of spaced primary rotary members coupled to each other for synchronous rotation and providing a driving connection for said rear wheels, and an auxiliary rotary member providing a driving connection for said front wheels, said auxiliary member being coupled to one of said primary members by a clutch arranged to permit overrunning of said auxiliary member with respect to said one primary member and to prevent overrunning of said one primary member with respect to said auxiliary member, and means arranged for transmission of power between said rotary input member and said rotary output means selectively in a plurality of drive conditions;
the improvement wherein said power transmission means comprises a planetary gear assembly including an input sun gear adapted to be driven by the source of power, and a sub-assembly adapted to establish driving relationships with said rotary output means in said drive conditions, said sun gear being in engagement with said rotary input member, and said sub-assembly including an output carrier, a ring gear, and a plurality of planet gears in meshing relationship with said sun and ring gears, said sub-assembly being slidable to a first position wherein said carrier is in engagement with said sun gear and said rotary output means and wherein said ring gear is not locked, and to a second position wherein said carrier is disengaged from said sun gear and is in engagement with said rotary output means and wherein said ring gear is locked.

2. In a torque transfer assembly including a housing, an input shaft and a pair of output shaft supported for rotation in said housing, means coupling said input shaft with said output shafts for transfer of torque thereto, and means for selectively establishing high speed-low torque and low speed-high torque transferring modes; the improvement wherein said mode establishing means comprises a planetary gear assembly including a sun gear in driven relationship with said input shaft, and a sub-assembly, said sub-assembly having a carrier, at least one planet gear in mesh with said planet gear, said sub-assembly being movable between a high speed-low torque position wherein said carrier is engaged with said sun gear and is in driving relationship with at least one of said output shafts and wherein said ring gear is not locked to said housing, and a low speed-high torque position wherein said carrier is not engaged with said sun gear and is in driving relationship with at least one of said output shafts and wherein said ring gear is locked to said housing.

3. The invention of Claim 2, wherein said driving relationship is established by said carrier being engaged with one of said output shafts directly and with the other of said output shafts through said coupling means.

4. The invention of Claim 2, wherein said driving relationship is established by said carrier being engaged with both of said output shafts through said coupling means.

5. The invention of Claim 2, wherein said sub-assembly has a plurality of planet gears in mesh with said sun and ring gears.

6. A planetary gear assembly comprising a sun gear, and a slidable sub-assembly, said sub-assembly including a carrier, a ring gear, and a plurality of planet gears in meshing relationship with said sun and ring gears, said sub-assembly being slidable to a first position engaging said carrier with said sun gear for rotation therewith, and to a second position grounding said ring gear.

7. The invention of Claim 6, said carrier meshing with said sun gear in said first position for effecting engagement therewith.

8. In combination, a stationary member, a planetary gearset including a sun gear, and a slidable sub-assembly, said sub-assembly having a carrier, a plurality of planet gears meshing with said sun gear, and a ring gear meshing with said planet gears, said sub-assembly being slidable to a first position wherein said carrier is engaged with said sun gear for rotation therewith and said ring gear is not locked to said stationary member, and to a second position wherein said carrier is not engaged with sun gear and said ring gear is locked to said stationary member.

9. The invention of Claim 8, said sub-assembly being slidable to a third position wherein said carrier is disengaged from said sun gear and said ring gear is disengaged from said stationary member.

10. In combination, a stationary member, a rotatable input member, at least one rotatable output member, and a planetary gearset including a sun gear rotatable with said input member, a carrier slidable relative to said sun gear, a plurality of planet gears slidable with said carrier, said planet gears meshing with said sun gear, and a ring gear slidable with said carrier, said ring gear meshing with said planet gears, said carrier being slidable to a first position wherein said carrier is engaged with said sun gear and output member for rotation therewith and said ring gear is disengaged from said stationary member, to a second position wherein said carrier is disengaged from the sun gear and is engaged with said output member for rotation therewith and said ring gear is locked to said stationary member, and to another position wherein said carrier is disengaged from said output member and said ring gear is disengaged from said stationary member.

11. The invention of Claim 10, said carrier being engaged with said sun gear for rotation therewith in said other position.

12. The invention of Claim 10, said first position being between said second and other positions.

13. In combination, a stationary member, a rotatable input member, at least one rotatable output member, and a planetary gearset including a sun gear rotatable with said input member, a carrier slidable relative to said sun gear, a plurality of planet gears slidable with said carrier, said planet gears meshing with said sun gear, and a ring gear slidable with said carrier, said ring gear meshing with said planet gears, said carrier being slidable to a first position wherein said carrier is engaged with said sun gear and output member for rotation therewith and said ring gear is unlocked from said stationary member, to a second position wherein said carrier is disengaged from the sun gear and is engaged with said output member for rotation therewith and said ring gear is locked to said stationary member, to a third position wherein said carrier is disengaged from said sun gear and is engaged with said output member for rotation therewith and said ring gear is unlocked from said stationary member, and to a fourth position wherein said carrier is disengaged from said output member and said ring gear is disengaged from said stationary member.

14. The invention of Claim 13, said carrier being engaged with said sun gear for rotation therewith in said fourth position.

15. The invention of Claim 13, said third position being between said first and second positions.

16. The invention of Claim 13, said first position being between said third and fourth positions.

17. The invention of Claim 13, said third position being between said first and second positions and said first position being between said third and fourth positions.