Патент USA US2406225код для вставки
2,406,225 Patented Aug. 20, 1946 UNITED STATES PATENT OFFICE Donald W. Kelbel, Muncie, Ind., assigner to Borg- l ' Warner Corporation, Chicago, Ill., a corpora- . tion of Illinois . Application August 3, 1944, .Serial No. 547,819 2 Claims. 1 My vinvention relates to power transmissions, «and more particularly to transmissions suitable for use in automotive vehicles. i y Y It is an object of lmy-invention to provide an improved transmission which is of such con struction that a suitable number of speed ratios for driving an automotive vehicle may be ob tained with a minimum amount of gearing. It'is another object of my invention to provide an improved transmission which may be easily controlled for changing the speed ratio through the transmission. , It is a further object of my invention to pro vide an improved transmission having low and intermediate speed >ratios in which, at the will of the operator, the driven shaft may either free wheel with respect to the drive shaft or in which the two shafts may .be positively connected. It (01.74-27 0) 2 and another clutch 20 for connecting the drive shaft vIl) with the planetary gearing by means of another intermediate shaft 22. The planetary gear set I4 comprises a reaction element 24 which whenl `held stationary functions to complete ’a power train through the planetary gear set be tween the shafts I0 and I2 when either of the A'clutches I6 and 20 is engaged. A positive .type brake 26 is provided for the reaction element 24, and aÍblocker 28 allows engagement of the brake, 26 only when the reaction element is rotating in a 4direction reverse `with respect to the direction of rotation of the shaft I0. A holding mecha nism 30, adapted to be selectively operated, is provided Vfor holding the brake 26 engaged, and a -clutch 32 4comprising cam‘med interengaging teeth `is disposed between the reaction element 24 andanother element of the planetary gearing I4 to lock the elements together and to lock up the is contemplated that the transmission shall pref erably provide a direct drive ratio positively con 20 gearing for the purposeswhich will be herein after described. The reaction element 24 is mov necting the drive and driven shafts. ablel longitudinally with respect to the shaft I2 It is still another object ofthe invention to either by means of a collar 34 on the reaction _provide such a transmission which may be easily element or by means of spiral gearing 36 which controlled so that the driven shaft may drive the drive shaft at one of the lower speed ratios of 25 is apart of the planetary gear set I4 in order to the transmission for starting an internal com either engage the brake 26 >or the clutch 32. A positive typevbrake 38. is provided for the shaft bustion driving engine connected with the drive 22 and the planetary gearing for providing a re shaft. verse 'drive through the transmissionV as will be The invention consists of the novel construc « ' tions, arrangements and devices to be herein 30 hereinafter described. Referring now in particular to Figs. l and 2 after described and claimed for carrying out the for amore detailed Ydescription of the trans above stated objects and such other objects as mission, vit will be observed that the two-clutches will appear from the following description of cer I6 and 20 are positioned closely together and form tain preferred embodiments illustrated in the accompanying drawings, wherein: Fig. 1 is a longitudinal sectional View of a transmission embodying `the principles of the 35 parts-of a single clutch assembly. This assem bly comprises a. fly-wheel 4l) fixed to the shaft ` Ißat'o rotatetherewith and a rear cover plate 42` which is bolted to the fly-wheel 40. A piston .44 V,comprising annular sheet metal parts 46 and 48 Vand also a piston ring 50, held by a retainer rig. 1; e .ring '52 with respect to the parts 46 and'48, is Fig. 3 is a diagrammatic illustration of the provided within the cover plate 42. The piston transmission shown in Fig. l; _ 44 is’disposed between a Ycylindrical portion 54 Fig. 4 is a diagrammatic illustration of another formed in thecover plate 42 and a sleeve 56 dis embodiment of the invention; and Fig. 5 is a diagrammatic illustration of a third 45 posed on.. the shaft 22 and fixed with respect to thecover plate 42. A_fluid conduit 58 passing embodiment of the invention. through _the shafts I8 and 22 and the sleeve 56 Like characters of reference designate like is provided to Asupply fluid from any .suitable parts in the several views. source to the rear of the piston 44, and between Referring now to Figs. 1 to 3, and in particu lar to Fig. 3, the transmission illustrated there 50 the piston and the cover plate 42 to force the 'piston forwardly of the clutch assembly. The in comprises briefly, a drive shaft I0, a driven piston 44 acts by means of its member .48 on anshaft I2, a planetary gear set I4 connected to annular sheet metal member 60. disposed about drive the shaft l2, a centrifugal clutch I6 for the ~member 46. The member 60 has _a plurality connecting the drive shaft I0 with the planetary invention; Fig. 2 is a sectional View taken on line 2-2 of _gear set by means of an intermediate shaft I8, »of lug portions 62 each' of which passesth'rough 4 . a slot 64 provided in the side of the fly-Wheel 4|),` the arrangement being such that the member and a sheet` metal retainer member ||2`. The' member H2 holds the ring ||i| in placewith re spect to the member |48, and it has a perforated flange H4 functioning to space the members |08 and 48. The piston |66 is disposed between and is movable with respect to a cylindrical portion H6 of the member 46 and the> sleeveñíì. A fluid 69 may move longitudinally with respect to the clutch assembly. The member 160 bears on the outer edge of an annular sheet metal member 66 which is provided with lug portions 68 passing through appropriate slots lû provided in the side of the iiy-wheel fâowhereby themember 66 may also move longitudinally of the clutch assem bly. The member SS is disposed about themem.-Y ber 4S of the piston 44 and has fixed thereto, by conduit H8 extending through the sleeve 56 and the shafts H3 and 22 is provided for Vsupplying ñuid under pressure from any suitable source to >the rear of the piston lûö. A pressure plate |20 movable bythe piston iilâ is formed by the mem means of screws l2, a pressure plate 'i4 formed,` ‘ by sheet metal members ‘i6` and 7S. A plurality ' ber |S8 and an annular member |22J as shown. of springs Si? are provided in suitable cavities in ‘the side of the fly-wheel 40 'and act 0n the mem ber 66 for yieldably holding the members 66, 66 and the piston 44 at the‘rearward limit of move ment of these parts with the member 48 of the piston bearing against the cover plate 42 as shown. „ Each> of the slots E4 has a bottom 82 which functions` to limit the movement of the member SQ toward the front of the _clutch as_ sembly, and each of theslots lil is providedwith . a bottom 84| whichr functions to limit, the move ment in the same direction' or the sheet jmetal l s. The sleeve 56 has an 'annular member |24 fixed thereon ’against forward movement, and springs |26 and |28 are provided between the member .Idil and the member |24. These springs func-tion to yieldingly oppose movement of the piston |66 forwardly, and the springs, together with the springs 613, function also to oppose forward move ment of the piston 44 and its `associated parts. The clutch 2S comprises, in addition to the pres sure plate 'i4 and the pressure Vplate |20, adriven Vclutch disc i3d. The disc |3||`has a hub |32 that is splined to the shaft 22 Yso as to be non-rotat member 63. The parts of the clutch assembly so able with respect to the shaft butthe >hub may far described function so that, when iiuid under have longitudinal movement on the shaft. The pressure is admitted behind'the piston 44, the clutch 26 is engaged by applying fluid _under 'pres- ' piston, the parts 60 and E5 and the pressure sure behind the Ypiston |06 through the lconduit plate 74 are moved forward until the lugs |52 H8 to move the pistonand thereby theA pressure plate |_2il forwardly `whereby theclisc |30A igen Contact the bottoms 82 of the slots $4, ` The clutch l5, after ñuid under pressure has gaged between the pressure plates Y'|20 and 74, and been applied to the piston 44 to move the lug this engagement may take place either with the portions E2 ofthe member 6|] linto Contact with clutch v|¿6 engaged or disengaged. . , i ' Y the bottoms 'S2 of the Vslots 64, is conditioned t‘o 35 It will >be observed that the Vshaft 22 i‘s‘jour be engaged according to the speed of the shaft naled Within the housing |34 of the transmission ii). VCentrifugal weights 86 perform this func and the shaft lâ is jouinaled within the shaft 22. tion ,ofY centrifugally engaging the clutch. The The shaft iâris piloted Ywith'respect to the shaft Y member Se is provided with outwardly extend |€| by means of a bearing |36, and the Vshaft >It ' 4ing wing or lug portions 88 and each of these por- ' 40 is also piloted in the driven shaft I2, as shown. tions is provided with a notch 99 in which is re ceived an acute portion 92 o_f a weight 86, ythe arrangement being -such that the notch 'Sû‘acts as a fulcrum for the) weight, allowing the weight to move outwardly under the influence of centri fugal force due to rotation of the shaft I0, the `fly-wheel 4e, the member Bü and thereby the weights 8S.' Each of the weights is connected by means of a strut 94 with the pressure plate The shaft Yi8 has a sun ,gear |38 formed thereon, andthe shaft r22 is provided‘with a ringjgear |40, both of the gears ’|88 and |41), `_forming p-@Iîts'of `the planet gear set i4.Y rí‘he gear set i4 ,comprises` ç also planety gears |42 wliich'are in meshjwiththe sun gear |35 and planet gears- |44 which are in mesh with the planet gears |42 and with the ring gear Mt. A spiral planet gear |43 is integrally. connected with each of the gears |44, andthe la, so that as the weight V85 moves outwardly, 50 spiral gears are in mesh with a spiral sun gear the weight tends to separate the members 60 and |48 formed on the reaction element 24. The iìß?andmove the pressure plate 'i4 toward the gears |455 and |46 together fQlîmthespiral'gear ily-'wheel 4t. A washer type spring-‘95 is disposed ing Bß'hereinbefore referred to, and the reaction between the member 66' and a flange 9B on the element 24 is Vrotatably and longitudinallymov end of the member 465, and the spring'95 is thus 55 ably disposed on the driven shaft i2. The planet, so disposed as to yieldingly oppose such forward gears |42, |44 and it@ are rotatably disposed on movement of the pressure plate 'I4 dueto outward a carrier |5@ which is connected with‘theshaft `movement of. the weights 85, and as will be ap i2. >The ring gear |46 is provided with'teeth |52 parent, such movement of the pressure plate 14 on its outer periphery, and a pawl |54 carried by >is also similarly opposed by the springs 80. Y The 60 the transmission casing |34 is provided for en clutch itV comprises, in addition to theV fly-wheel gaging with the teeth M2. Y _The,pawljl54 and the Y¿it and the pressure plate 14, the driven plate teeth |52 together form the positive brakeBS for |66 which is connected by means of a vibration the ring gear |43 and the sliaftZZ.v absorbing unit |62 of any suitable construction withV a hub HB4 which is'splined to the shaft I8. .The Planetary gear set issuch thatrwhen the reaction element 24, along with its' sun gear |48, is held stationary and the shaft ’LS and its sun gear |38 are driven through the clutch'JiS, the l , Y The Weights 85 function, afterv fluid under pres surehas been appliedto the piston 44> to move'the piston and the associated parts so that the mem carrier |56 and the driven shaft l2 connected ber E3 contacts' the bottoms 82 ofthe slots B4 therewith are driven at a low ratio forward drive. lforconditioning the clutch l5, for engagement, 70 When the ring gear |45 is driven'through the tofmove the pressureplate 14 the additional dis clutch‘îû, ‘and -the reaction element 24> is held stationary, with the clutch la beingY disengaged, tance needed to engage the clutchrlß. „ , ‘ . A pistoni |36 is provided for engaging> the clutch thev oarrierji` 5|! and the shaft|2 are driven atan 2t, `'Ik'hispiston comprises a memberl lilâof` Vsheet intermediatespeed forward drive.) ,Whenbo'thof , metaL' a piston ring [l0 of va yielding'material, 75 the clutches ’l ß and 2G are :engaged and the reac-KK 2,406,225 _ Y 6 vplanet gearing I4 is locked up and the 4carrier |50 elements |64 4which are slidablydisposed in suit. -ab1e;cavities in the casing |34:- and are'adapted‘to tionv element 24 is' allowedto rotate freely,~the and the driven shaft I2 are driven at a one to `one _:fitïin a groove vI 60 in the reaction element 24 .when , ratio with respect tothe intermediate shafts I8 and 22 and the drive shaft I0. When the brake 33 is engaged to hold the ring gear |40 stationary the teeth |58 are interengag'ekîlU with the> teeth the4> elements V|64 and isprovided with cams |10 and the clutch It is engaged and the reaction ele ment 24 is released to rotate freely, the carrier |50 and the shaft I2 are driven at a low speed in on its inner surface for acting on the elements |64. The member |68 is adapted to be operated i manually or by any suitable means, and when reverse- drive. , ' The reaction element `2d: in its'movement may be controlled by a collar 34, a toothed clutch 32, a positive type brake 26, a blocker Y28 and a> re taining mechanism 3@ for holding the element |503. >A''sleeveflike'memberfl|58. is disposed’ about 10 the reaction element 24 is moved rearwardly from its position as shown in Fig. 1 to engage the teeth |58 with the teeth |55, rot-ation of the mem ber |20 will cause the cams |10 to lock the bean elements |64 in the groove |06 and thus prevent 15 any forward movement of the reaction element from longitudinal movement, all hereinbefore re 24. When the transmission is either in low or i ferred to. The collar 34 is splined on the element 24 and is fixed against longitudinal movement on intermediate speed,.with either of the clutches I0 and 20 engaged, the spiral gearing 36 acting on the element by suitable retainer rings, as shown. The brake 20 comprises stationary teeth |56 car the reaction element 24 tends to cause the latter ried by the transmission casing 134 'and brake 20 element .to be moved _forwardly'of the transmis sion to disengage the positive brake 20 when` the teeth |58 formed on the reaction element 24 and shaft i2 is allowed to drive, as when the power on adapted to mesh with the teeth |55. The blocker mechanism 23 comprises a blocker element |550 the shaft Iiì is decreased, and the'spiral gearing which is disposed on and may have limited os» 3% together with the reaction element 24 and the cillatory movement with respect to the element 24 25 brake 26 thus act as a free-wheel brake on lthe reaction element 24when> the mechanism 30 is disengaged. When the mechanism 30 is engaged, a stationary part |62, fixed with respect to the transmission casing I3Ll,.by means of a spring with the'transmission being conditioned either and which is held in friotional engagement with |63 between the collar 34 and the blo-cker element for low or intermediate forward drive, the bean |50. The blocker mechanism maybe of any suit, 30 ele-ments |64 lprevent forward movement of the reaction element 24 and thus function to prevent lable construction and is such as to prevent rear this free-wheeling action of the reaction element ward movement of the element 24 and block en 24, and the shafts |0 and I2 are .positively con gagement of the teeth |58 with the teeth |55 when nected through the gear set I4 in both speed the element is rotating' in a forward direction, ratios. that is, in the same direction as the drive shaft When the brake 35i-is engaged to condition the » |0, and the blocker mechanism allows such move ment of the element 24 and engagement of the gear set I4. for reverse drive, the reaction on the yteeth |53 with the teeth |55 when the rotation ' element 24 is in a reverse direction which tends to move the element 24 rearwardly of the trans of the element 24 is in the opposite direction. The brake 26 is engaged automatically to hold the mission to engage the brake 25. In this case, the reaction element 24 stationary when either of the collar 34 is utilized to hold the reaction element\ against such rearward movement for preventing \ clutches |B and 20 is engaged to provide a reduced speed ratio through the transmission. The spiral engagement of the brake 25. The clutch 32 comprises clutch teeth |12 on gearing 35 functions to move the reaction element 24 longitudinally of the shaft I2 either in one di 45 the carrier |50 and clutch teeth v|14 on the collar rection or in the other depending on the direc 34. The collar is splined to theV reaction element tion ofl reaction on the element 24 by the gearing. 22, and the teeth |14 are thus ñxedwith respect to the reaction element. The teeth |12 and |15 If the reaction on the element 24 is in the reverse direction, the spiral gearing urges the element are slanted or beveled, as shown, and the clutch longitudinally rearwardly of the transmission 32 may thus engage when the reaction element tending to engage the teeth |58 with the teeth 24 rotates in a forward direction with respectto |56, while if the reaction on the element 24 is in the carrier |50 but cannot engage if >the relative direction of -rotation of the element 24 is in the the opposite or forward direction, the element 24 l is urged longitudinally forwardly of the transmis opposite direction. The clutch 32 is utilized for sion. Such action by the spiral gearing is pro -Inoted by the frictional retardation of rotation of the element 24 >by thel blocker element |60 fric~tionallyA engaging with the stationary part |52. When either of the clutches `I 6 and 20 is engaged, locking up the planetary gear set|4 when it is desired to provide a connection between the shaft I2 and- the shaftV I0, with only the clutch 20 being engaged, as for starting an `internal combustion engine (not shown) connected with the shaft I0 f the reaction on the element 24 is in the reverse 60 by rotating the shaft I2. The clutch I6, in case direction and the spiral gearing urges the element the shaft I0 is not in rotation, cannot be engaged, 24 rearwardly of the transmission. On such ro as will be readily understood, sincethis clutch is tation and longitudinal movement of the element of the f» centrifugal typeactuated by rotation‘of 24, the blocker mechanism 28 allows engagement the shaft I0. When the clutch 20 is' engaged and "of the teeth |58 with the teeth IE5, and the ele the shaft I2 is rotated in the forward direction, ment 24 is thereby braked to complete a low speed the reaction on the reaction element 24 is in` a ratio drive through the transmission. When both forward direction and the spiral gearing 36 func of the clutches I6 and 20 are engaged to provide tions'to move the'element 24 forwardly of the a direct drive through the transmission,-the re transmission. Such movement of the- reaction action on the element 24 is in the forward direc 70 element 24 causes engagement of the clutch 32 tion and the tendency of the spiral gearing 35 is to lock up'the gear set I4 andxcomplete the con to pull the element 24 forwardly of the transn mission. The brake 26 is thereby disengaged, and the element 24' may thereafter rotate freely. nection from the shaft |2 to the shaft | 0. When the engine connected with the shaft I0 is started and begins `to drive, then the carrier I 50` tends- to The locking mechanism30 comprises bean-‘like 75 .rotate faster in arforward direction than the Y 2,406,225 7 Y teeth |89 eng-ageablewith.stationary teeth, |82.V reactioneiement >24 and the reactionbnitne eie-` ment 24 is .in the reverse direction, .andtheele The brake Yfor the shaft 22- may be engaged sim ment’24 'is moved rearwardly ofthe transmission -ply by moving .the sleeve |18 to ,engage theteeth andthe clutch 32`is disengaged. , y |80 with the teeth |82. This embodiment of the , .'.In' brief, the operation of the transmission illuvs~ trated in'Figs. 1..to.3'is as followsz‘ Whenit lis desired to .provide forward drive at low ratio through the transmission, the clutch I5 is con»-r e -invention operates similarly to the embodiment first .described with the exception that the brake for the reaction element 24 is engaged and dis -engaged manually. Referring to Fig. 5 of thedrawings, the em bodiment‘of the invention shown in this figure isquite similar to< that shown in Figs. 1 to 3 diiîering only from> the latter embodiment inV ditioned for. operation `by applying fluid under pressure behind thepiston 44 to move the piston and the associated> parts including the'member ‘55 to bring the lugs 62 of the latter member, -into having a different'brake structure for the reac tion element 24. The brake structure for the reaction element 24 in this embodiment'comprises ' engagement with the bottoms 82 of the slots .64. The clutch I6 is then conditioned for engagement, and `upon,increasing the speed >of the shaft I0, the weights 85 will move outwardly and will 'move the pressure plate 'i4 to engage the clutch disc It@ between the fly-wheel 4.3 and the clutch plate 14. Va one-way roller brake unit |64 which is con-Y nected in series with and is made effective by a positive type brakecomprising teeth |36 yand a’ rotationally fixed pawl '|88 adapted »to engage .The 'clutch IB, on being soengaged willdrive the shaft I8 and the'planetary gearset I ¿Land the with the teeth. A friction brakeV |90 is provided . for the reaction element 24 and is disposed in . spiral gearing 35 will cause> a reaction on the reaction element> 24 inîthe reverse direction and l. y will move r-itrearwardly of the transmission. .Such parallel with the one-way brake structure. This embodiment operates quite similarly tolthe em movementof the reaction element 24 rwill dis bodiment shown in Figs. l to 3 with the one-way engage the blccker‘rnechanism 28 and will en- -n brake unit |34 operatingsimilarly to the spiral gearing 36 and the positive'brake 26 acting on the reaction element 24. The friction brake £98 functions quite similarly to the locking mecha nism 3i) in the first embodiment of the invention and may be Vapplied to provide _a positivedrive in either low or intermediate speed bctween'the gage .the brake 2% to complete the low speed power train through the transmission. ToV shift the transmission to ‘intermediate speed, the clutch ` lâ is disengaged by draining the fluid from behind - the piston e4, and the clutch 2i! is engaged by ap-n plying' duid under‘pressure ‘to the .piston IE6 and between the piston parts |98 and 4E. Clutch 2d will then drive the planet gear set |4 through the shaft 22. The brake'Zß will remain engaged, and the intermediate speed `power train through the transmission will. be completed. It will be un drive and driven shafts. ~ I wish it to be understood that my invention is not to be limited tothe specific constructions and arrangements shown .and described except only insofar as the claims may be so limited, as it will> be apparent to those >skilled in the art derstood that 'both of these power trains are of that changes may be >made without departing the free wheeling' type due to the free wheeling' from the principles of the invention. .. action of the reaction element 24; however, both of the drives may be made positive by engaging 40 l. In a transmissionthe combination of a drive the mechanism 39,. as has been hereinbefore de shaft, a driven shaft, a planetary .gear'set con scribed. To shift the transmission to direct drive, nected to drive said driven shaft and including a the clutch It is again engaged, with the clutch sun gear, a ring gearl a first planet gear in .mesh 29 remaining `engaged, by applying duid under with said sun gear, a second planet .geargin mesh pressurebehind the piston 44. The planet gear with said first planet gearfand with Vsaid ring set I4 will be locked upand there will be a direct gear„ a third'planet gear integrally connected ,K drive between the shafts I0> and I2. The brake withfone of said first two named planet gears, and. 2_5 for the element 24 will be disengaged due to a sun `gear constituting a reaction gear vand in ' theïaction of the spiral gearing St, as has been IV claim: Vher’einbefore described. ' is held against rearward longitudinal movement by useof the collar 34, and the clutch .l5 is en gaged yto complete the low speed reverse drive. For causing rotation of the shaft _i@ by rotating the shaft I2 as for starting a driving enginethe second speed clutch 2E! is engaged, and the action of the spiral gearing 36 will engage the clutch 312 ' to lock up the planetary .gear set and complete a drive from the driven shaft I2 to the drive shaft . ' , ' ` mesh with saidr third planet gear, a clutch for connecting said drive shaft with said first Anamed sun gear to provide a power train between said vshafts at a certain speed'ratio, ’a clutch for con necting said drive shaft with said ring gear >to Y. provide a power train between said shafts at an other speed ratio, and means for braking said reaction gear to provide a reaction point for Vthe j gear set to complete both of said power trains, saidv braking vmeans comprising a one-Way roller (SO brake the inner race of which is formed on a hub of said `reaction sun gear and the outer race For reverse drive, the - brake 38 is. engaged, and the reaction element 2:? I0.. ' ' . ' Referring to Fig. 4 of the drawings, themodi ñcation therein shown differs from-the construc~ tion shown in Figs. 1 to 3 in providing a simpler positive type brake forthe reaction elementëß and in providing a somewhat different type of . positive brake for the ring gear |40 of the planet gear setV I4. The brake for the reaction element 24 in this embodiment 4of the invention comprises of which has external teeth, anon-rotatable pawl adapted to engage the teeth of said outer roller race to prevent rotation thereof and to thereby render the one-way brake effective, a brake drum connected to the hub of said reaction .sun gear, and selectively operable friction means for stop ping the rotation of said drum and for thereby braking the reaction sun gear in both ydirections ' ' ’ simply brake teeth `I'l41fixed with .respect to the .70 of rotation. reaction element and a pawl |16 which is adapted 2. In a transmission, the combinationV of a to engage -with the -teeth '|14' to hold the 'teeth drive shaft, a driven shaft, asplanetary gear set . and the reaction elementV stationary. 'The brake connected to >drive said driven shaft and includ rfor the ring gear |4|I 'for use in reverse comprises ing asun gear, a ring gear, a first planet gear y a'sleeve I'I8`splined‘to :theshaft 22 and having . in mesh with saidv sun gear, Va :second «planet gear . 2,406,225 in mesh with said first planet gear and with said ring gear, a third planet gear integrally connect ed With one of said ñrst two named planet gears, and a sun gear constituting a reaction gear and 10 ratio, land means for braking said reaction gear, to provide a reaction point for the gear set to complete both of said power trains, said braking means comprising a one-way roller brake the in ~mesh with said third planet gear, clutch 5 inner race of which is `formed on a hub of said means for connecting said drive shaft with said reaction sun gear and the outer race of which iirst named sun gear to provide a power train be has external teeth, a non-rotatable pawl adapted tween said shafts at a reduced speed ratio, the to engage the teeth of said outer roller race to initial movement of said clutch means toward prevent rotation thereof and thereby render the clutching engagement being hydraulically insti gated and the ñnal movement into clutching en gagement being responsive to a predetermined speed of rotation of the drive shaft, hydraulically operated clutch means for connecting said drive shaft with said ring gear to provide a power train between said shafts at an intermediate speed 10 one-way brake effective,a brake drum connect ed with the hub of said reaction sun gear, and selectively operable friction means for stopping the rotation of said drum and for thereby brak ing the reaction sun gear in both directions of rotation. DONALD W. KELBEL.