US2923389A

US2923389A - Change speed gearing

Info

Publication number: US2923389A
Application number: US637105A
Authority: US
Inventors: Charles M Perkins
Original assignee: Fuller Manufacturing Co
Current assignee: Fuller Manufacturing Co
Priority date: 1954-06-17
Filing date: 1957-01-30
Publication date: 1960-02-02
Anticipated expiration: 1977-02-02

Description

Feb. 2, 1960 c. M. PERKINS CHANGE SPEED GEARING Original Filed June 17, 1954 3 Sheets-Sheet 1 w: 6 an O E E 6 \nml.w ww vm mm mm o 5 u no a W mm c 6: am V11 3 mm m. m BN1. 0 HH mm 0 93 m h g w 8 mm 2. 9 w 4 o N I m Q.

INVENTOR. 0mm. 5 M. PA

WW 6M4 91% HTTOHNEYS Feb. 2, 1960 c. M. PERKINS 2,923,389

CHANGE SPEED GEARING Original Filed June 17, 1954 5 Sheets-Sheet 2 INVENTOR.

[HR/H55 M. P w BY Feb. 2, 1960 c. M. PERKINS 2,923,389

CHANGE SPEED GEARING Original Filed June 17, 1954 3 Sheets-Sheet 5 AB INVENTOR.

(fin/e4 55 M. Pram/v5 7 zrmamw JMJ\VJ 12% 6 ATTOR/VEYS States CHANGE SPEED GEARING Charles M. Perkins, Kalamazoo, Mich;, assignor, by mesne assignments, to Fuller Manufacturing Company, a corporation of Delaware Claims. (Cl. 192-53) This invention relates to a gearing structure for alternately driving two coaxial, adjacent gears from a third coaxial gear adjacent to'one of said two coaxial gears and, more particularly, relates to a synchronizing structure for such a gearing assembly; This applicationis a division of my co-pending.application,.Serial.No. 437,337, filed June 17, 1954, and entitled Change Speed Gearing, now Patent No. 2,794,348.

In certain types of change speed gearing arrangements, it is necessary to alternately drive two coaxial, adjacent gears from a third gear, which is coaxial with, and adjacent to, one of said two coaxial gears. It is a particular problem with such an arrangement to provide a synchronizer structure, which operates effectively and which is of simple and durable construction. While a number of such arrangements, including forms of synchronizer structures, have been suggested, it has been found that these arrangements are not completely satisfactory, usually because they are unduly complex and, therefore, are expensive to manufactue and difficult to maintain in proper operating condition.

Accordingly, it is a principal object of this invention to provide a gear structure as set forth above ,.having an improved and simplified synchronizer arrangement.

- It is a further object of this invention to provide a gearing structure, as aforesaid, in which the synchronizer structure consists of a minimum number of parts,- and which is inexpensive to manufacture and easy to maintainin proper operating condition.

' It is a further object of thisinvention to provide a gearing. structure, as aforesaid, ,in which .oneof a pair .of coaxial, adjacent gears is. coupled to athird coaxial, adjacent gear by sliding movement of a clutch member, and including a synchronizer structure between the gears in said pair, which synchronizer will be effective, regardless of which one of said pair of gears is to be coupled to said third gear, and which will act in a simple and reliable manner.

Other objects and purposes of this invention will be apparent to persons acquainted with devices of this general type upon a' reading of the following disclosure an a study of the accompanying drawings.

In the drawings:

Figure 1 is a general view in central section of apparatus embodying the invention. i

Figure 2 illustrates a section taken on the line II-II of Figure 1. 1

Figure 3 is a partially schematic, sectional view taken on the line III-III of Figure l.

Figure 4 is a sectional view taken on the line IVIV of Figure 3.

Figure 5 is a view of a portion of Figure 1, redrawn on an enlarged =scale.

I Figure 6 is a diagrammatic view illustrating the position of the gears, through which driving is accomplished, in one operating position of the mechanism.

Figure 7 is a diagrammatic view illustrating another position of the gears, through which driving is accomatent ice plished, in another operating position of the mechanism. 1 Figure .8 is a diagrammatic view of the tooth pattern of the synchronizer unit, shown in one operating position.

Figure 9 .is a view .similar to Figure 8, showing the tooth pattern of the synchronizer unit in another operating position. 1

- a General Description In meeting the objects and purposes above set forth, I have provided a pair of coaxial shafts, one of 'said shafts being driven and the other being mounted for driving connection to said driven shaft. A pair of gears are mounted on said other, or driving, shaft, one of said pair of gears being fixed to said drivingv shaft for rotation therewith and the other of said pair of. gears being rotatable with respect to said driving shaft. A third gear is fixed to said driven shaft and is adapted to be selectively coupled to one of said pair of gears by a clutch sleeve, said clutch sleeve surrounding the adjacent ends of said shafts. A synchronizing ring is positioned between the gears of said pair and has balk teeth thereon for synchronizing the speeds of rotation of a selected one of said pair of gears and the clutch sleeve before they are brought into meshing engagement, regardless of which gear of said pair is selected to be meshed with said sleeve.

Detailed Description Turning now to the drawings in more detail, and referring. first to Figure 1,. there is shown gearing which, for convenience in reference, may be termed the main gear group 1 and the supplementary gear group 2, although itwill be apparent from the following description that these gear groups are actually intimately related to each other and not truly separable in their functions. While the main gear group may be largely similar to any one of many standard types, a brief description of the particular form herein shown for illustrative' purposes will be given in the interest of completeness. 1

Said main gear group 1 includes a housing 3, having aligned openings at either end thereof for the reception of. the bearings 4 and 6. Bearing 6 supports one end of an intermediate shaft 7, the other end of which is supported within the supplementary gears, as explained further. hereinbelow.. The inner-(rightward) endof said intermediate. shaft 7 has afirst countershaft, drivinggear 8 formed thereon, said gear having a bearing 9 contained concentrically therein, holding the leftward end of the main shaft 11. A point near the rightward end of said mainshaft 11 is supported by the bearing 4. The extreme rightward end of said main shaft is connected in any suitable manner to the apparatus to be driven by the transmission. The bearing 4 is retained in position by a ,cap 12. The bearing 6 is held in place by the nut 10. A point near the leftward end of said main shaft is provided with the splines 13, to which the sleeve 14 is fitted. Said sleeve 14 is externally provided with clutch teeth 16, capable of meshing with internal clutch teeth 17 provided on the gear 8. A gear 19 is mounted on, and for rotation with respect to, theshaft 11 and is provided with external teeth 21 and with internal teeth 22.' The teeth 23 on the sleeve 14 are provided for meshing with said internal teeth 22. I

The gear 24 is mounted on, and for rotation with respect to, the shaft 11 and carries both thedrive teeth 26 and the clutch teeth 27. A sleeve 28 is splined for rotation with, but horizontal sliding with respect to, the shaft 11 and includes internal clutch teethengageable with the clutch teeth 27. A gear 31 is provided with external drive teeth 32 and with clutch teeth 33, also engageable with the internal teeth of the sleeve- 28. Said gear 31 is mountedon; and for rotation with respect to,

the shaft 11. A sleeve gear 34 is slidablysplined onto the shaft 11 for rotation therewith and horizontal sliding with respect thereto, and includes internal clutch teeth engageable with the clutch teeth 36 of the gear 37, said gear 37 being mounted rotatably with respect to the shaft 11 and being provided, also, with external drive teeth 38.

The sleeve 14 is axially moved by the shift fork 41, which in turn is movable by the shift rod 42 (Figures 1 and 3), and the sleeve 28 is movable by the shift fork 43, which is mounted on, and movable by, the shift rod 44. The sliding gear 34 is moved by the shift fork 46, which is mounted on, and movable by, the shift rod 47. Each of said shift rods is operated in the usual manner by a shift lever, of which the lower end is indicated at 48.

Said housing 3 also contains further coaxial openings, within which are received the

bearings

51 and 52. A countershaft 53 is supported within these bearings and extends forwardly (leftwardly) of the forward end of the housing 3 for purposes appearing hereinafter. Splined to the countershaft 53 is the gear 54, a power take-off gear 56, a gear 57 and a gear 58. The reverse pinion 59 is, in this instance, formed on the countershaft 53, as are also the

pinions

61 and 62.

The gear 54 is in constant mesh with the gear 8, the gear 57 is in constant mesh with the gear 19 and the gear 58 is in constant mesh with the gear 24. The reverse pinion 59 is in constant mesh with the gear 71 (Figures 3- and 4) on the reverse countershaft 72 and the pinion 61 is in constant mesh with the gear 31. The pinion 62 is in constant mesh with the gear 37.

The reverse countershaft 72 supports a sliding gear 73, which is axially movable through conventional means by the shift rod 74 (Figure 3) into and out of mesh with both clutch teeth 75, extending from the reverse countershaft 72, and the main shaft gear 34.

It will be understood, of course, that the'above de- A scribed specific apparatus is only illustrative of the invention and that many other types of main gearing arrangements may be substituted therefor.

Turning now to the supplementary gear group 2, there may be provided a housing 81, which is connected in any convenient manner (by means not shown) to the forward end of the housing 3 of the main gear group 1. The housing 81 has an opening for receiving a bearing 82, which bearing is positioned coaxially with the bearing 6. Within said bearing 82 is supported the rearward end of a drive shaft 83, the forward end thereof being connected to any convenient drive means, such as the driven side of a clutch assembly. The clutch element 84 is formed on the rearward end of the drive shaft 83 and said clutch element is provided with axially elongated splines 86 for reasons appearing hereinafter. A bearing 87 is provided concentrically within the clutch element 84 for supporting the forward end of the intermediate shaft 7 coaxially with, but in a rotatable relationship with, the drive shaft 83. A second countershaft driving gear 88 is provided adjacent the rearward wall of the housing 81 and is supported on, and rotatably with respect to, the shaft 7 by the bearings 89 and 91 (Figures 1 and-). The forward end of the gear 88 is provided with clutch teeth 92 (Figure 5 only) and with a tapered, or friction, surface 93, for purposes appearing hereinafter.

The gear 116 is fastened to the leftward end of the shaft 53 for rotation therewith and, in this particular embodiment, is held in position by the nut 117. Said gear 116 is in constant mesh with the gear 88.

The rnain transmission housing 3 is preferably closed by a removable cover 118, to which the shift lever support housing 119 is fastened in a conventional manner. The auxiliary housing 81 is closed by any convenient cover plate, not shown. A clutch element 94 is positioned between the clutch element 84 and the gear 88 and is splined to the shaft 7 for rotation therewith. Said clutch element 94 includes a tapered, or friction, surface 85 and clutch teeth 95. A synchronizing ring 97 encircles the tapered surfaces 93 and and has internally tapered surfaces and 96 to correspond with each thereof. Said synchronizing ring has external balk teeth 98 (Figures 5, 8 and 9), which are arranged in two rows A and B, as explained hereinafter in more detail. A sleeve 99 is provided with a first row of internal clutch teeth 101 engaging the splines 86 of the clutch element 84, and said sleeve also has a second row of internal clutch teeth 102 engaging, in the position of the apparatus as shown in Figures 5 and 8, both the clutch teeth 92 and row A of the balk teeth 98. A fork 103 is provided for shifting the sleeve 99 in a conventional manner.

Turning now to the details of the

teeth

92, and 98, attention is directed primarily to Figures 8 and 9. In Figure 8, the position of the balk teeth 98 of the synchronizing ring 97 is shown by the single-line, shaded areas. The position of the

teeth

101 and 102 on the sleeve 99 is shown by the crossed-lined, shaded areas. Individual balking teeth are indicated at 106, 107, 108 and 109. Theright-hand row A of said teeth 98 are equally spaced circumferentially from each other and are spaced a multiple of the spacing of the teeth 102. The left-hand row B of said teeth 98 are likewise equally spaced circumferentially from each other and are spaced at multiple of the spacing of the teeth 95, this spacing being, of course, equalto the spacing of the teeth 102. However, the teeth of the row A are spaced circumferentially from the teeth of the row B a distance which is a multiple of the spacing of the teeth 102 plus a-distance sufficient to secure effective blocking, such as one-quarter or one-half of the thickness of the teeth 102. The teeth 98 are individually of such circumferential dimension that they can slide snugly, but easily, between the teeth 102. The teeth of the row A are chamfered at approximately a 20 degree angle at their leftward ends, and the teeth of the row B are similarly chamfered at their rightward ends. Those of the teeth 102, which lie in a first circumferential direction, downwardly as appearing in Figure 8, from, and immediately adjacent to, each of the teeth in row B of the teeth 98, are chamfered at their leftward ends, as indicated by the teeth 111 and 112, to cooperate with the chamfer on the said adjacent teeth of row B. Those of said teeth 102, which lie in a second circumferential direction, upwardly as appearing in Figure 8, from, and immediately adjacent to, each of the teeth of said row A of the teeth 98, are chamfered at their rightward ends, as shown by the teeth- 113 and 114, to cooperate with the chamfer on said adjacent teeth of row A.

A spring 115 (Figure 2) is atfixed to the synchronizing ring 97 to bear against the radially inward surfaces of the teeth 102. This effects axial urging of the synchronizing ring in the direction of movement of the sleeve 99 at the beginning of a shifting operation, and thereby effects an initial engagement of the synchronizing ring 97 with one of the friction surfaces 93 or 85. Thus, there is secured a fully guided passageway for the movable clutch teeth 102 in all of their several positions.

Operation With power applied to the drive shaft 83, the clutch element 84 is caused to rotate. With the parts in the position as shown in Figures 1 and 5, rotation of the clutch element '84 acts through the-sleeve-99 and the teeth 92 to rotate the gear 88. This effects rotation of the gear 116, which rotates the countershaft 53. Rotation of said countershaft 53 rotates all of the gears mounted for rotation with said countershaft and rotates each of the gears mounted on the main shaft, which are in constant mesh with the several gears and pinions on the countershaft. With the sleeve 99 in its leftward position,

rotation of the clutch element 84 will actthrough said sleeve to rotate the clutch element 94 and, through it, rotate the shaft 7. This effects rotation of the gear 8. Thus, instead of the conventional, half-step, auxiliary transmission utilizing four gears and a clutch mechanism, the apparatus of the invention requires supplementary elements involving only two gears and a clutch mechanism. Further, because of the changed relationship of these parts, all of the supplementary elements may be normally received within aspace usually not more than one-half of the axial distance required for an auxiliary,

transmission of the conventional type. 1

,Figures 6 and7 schematically show the arrangement of thegears during the two operative positions of the supplementaryelements. 7 It will be recognized that, in either position of the supplementary elements, the shift lever 48 may be actuated to place any of the gears within the main housing 3 in any desired connection, so that the full shifting range may be had in either position of the supplementary elements and the selection of the shifting ratios within the main housing is not dependent upon the operation of the supplementary elements. n

In more detail, it may be assumed first that the supplementary elements are in the position indicated schematically in Figure 6, namely, with the sleeve 99 in a leftwardgposition so that its internal teeth 102 engage the teeth 95 of the clutch element 94. Thus, power istransmitted at a one-to-one ratio to the gear 8. With the sleeve 14 in its neutral position and the sleeve gear 34 in its rightward position, power is transmitted from the gear 8 to the gear 54, thence to the countershaft 53, to the pinion 62, to the gear 37, to the sleeve gear 34, and finally to the main shaft 11. This is the lowest position. Now, without changing the position of the gears within the main housing 3, the sleeve 99 is moved rightwardly into the position shown in Figures 1 and 7. This connects the power delivered at the clutch element 84 through the clutch element 94, through the gears 88 and116, to the countershaft 53. While the gear 8 now idles, this is the same, insofar as power relationships are concerned, as though the gear 8 were being driven at a slightly higher ratiothan previously inasmuch as the gear 88, by which the countershaft is now being driven, is larger than the gear 8.- Thus, the power ratio decreases one-half step and the speed ratio increases correspondingly. This is the second lowest position.

For the third gear position, the sleeve 99 is returned to its leftward position (Figure 6) and the sleeve 34 is moved leftwardly into itsneutral position. The shift lever is now operated to movethe sleeve, 28 rightwardly to ga clutch eethfil ftm gear 31... andthepower is, now transmitted from thecountershaftto said gear, 31

and to the main shaft 11,, Next, while the gears within the main housing 3 are left in the position just indicated, the sleeve 99 may be moved rightwardly and the countershaft driven at a speed one-half step greater than that associated with said third position, and the fourth position is thereby attained. This series may be repeated through the leftward position of the sleeve 28 by which the gear 24 is locked to themain shaft 11, the rightward position of the sleeve 14 by which the gear 19 is locked to the main shaft 11, and the leftward position of the sleeve 14 by which a direct drive is attained between the shaft 7 and the main shaft 11. a In this latter case, movement of the sleeve 99 into its rightward position effects adriving of the gear 8 by the gear 54 and functions as an overdrive. In the foregoing description, it has been assumed that the gears within the main housing 3 are not supplied with synchronizers, but it will be appreciated that they may be so supplied, if desired, without changing the nature of the invention.

Attention is now directed to the synchronizer shown in connection with the auxiliary gears. With the clutch teeth 102 in the position shown in Figures 1, 5 and 8, it will be assumed that the sleeve 99 is to be moved leftwardly to connect the clutch element, 84 with the clutch element 94. As the teeth 102 of said sleeve 99,move-leftwardly, since the teeth 98 in row A are between the teeth 102, the teeth 98 in row Bare positively aligned in a position-tocontact the balkingsurfaces; ontheteeth 102. For example, the face 121 of the"tooth.-111..will strike, the face 122 of the tooth .106 and thereby arrestfurther movement of the sleeve 99 ,leftwardly solong as the teeth102 are moving in one circumferential direction, downwardlyv as appearing inFigure 8 and indicated by the arrow, at a rateslower than the corresponding move-. ment of the teeth 95. The gear ratio relationships, in this embodiment, between the gear 88 and the-clutchelee; ments 94 and 84 are such that they gear 88is always going slower than the clutch element, 94, regardless of which, way the sleeve 99 is positioned or moving. Of course, where the ratios are such that the supplementary elements function asan overdrivesplit of the maingears (the present embodiment constituting. an, underdrive .split), then .the gear 88,will always be, going. faster thanthe clutch element 94, regardless of the position of thesleeve 99. In such case, of course, the angles-of the contacting blocking faces will be reversed, Initial leftward movement of the sleeve, 99 will act through the springllS to move the synchronizingring 97 .into. light engagement with the friction surface As the teeth .102 meet the teeth 98 of row B, the synchronizing ring 97 will be further urged leftwardlyv and its innersurface 96 will press more firmly against the adjacent surface 85 of the clutch element 94 to synchronize its'speed with that of the teeth 102 in a'known manner. As soon as the speeds of the teeth 95 and the teeth 102 are Synchronized and cross each other, reversal of the torque acting on synchronizing ring 97- occurs and, instead of being urged downwardly as appearing in Figure 8 becauseof the frictional engagement-thereof with :the clutch element 94,' the synchronizing ring 97 and teeth 98 are urged upwardly with respect to teeth 95 by said teeth 102 as said teeth 102 slide off the teeth 98. .When the teeth 102 have slid off teeth 98, the frictional engagement between the synchronizing ring 97 and the clutch element--94 lessens and said clutch element ,speeds up withrespect to the synchronizing ring 97 so thatqteeth 95 move downwardly as appearing in Figure8 with respect to teeth 98. The teeth 95 move with respect to teeth 98 only ,so far as to become aligned with teeth 98 as shown in solid lines in Figure 9 at which time the continued leftward pressure on said sleeve 99 will cause the teeth 102 to move, into the position'shown in solid lines in Figure 9.,;. 1 s.

l Upon ,moving the sleeve 99 from its leftward position to its rightward ,p0sition,; the,action;.starts. withl thesparts inqthe position. shown in solid lines in Figure "9. In this position, the left-hand row B of the teeth 98- are engaged between the teeth 102 and, hence, the right-hand row of the teeth 98 are in'blocking position. As the teeth 102 move rightwardly, theyassume the position shown in broken lines in. Figure 9 and are blocked until the rotation of said teeth 102 and that of teeth 92 are substantially synchronized. When such occurs, continuing rightward pressure on said teeth 102 .will moveblocking teeth 98 and teeth 92. downwardly,' as appearing inFigure 9, with respect to teeth 102 since the teeth 98in row A are lockedby the friction surfaces and 93 to rotation at; the same speed as the teeth 92 when. the parts are then in the position shown in broken lines in Figure 8. Continuing rightward pressure-on the sleeve 99, then moves the parts into the position shown in solid lines in Figure 8 and the shift is completed.

. l I It will berecognized in the shifting of the supplementary elements that, with the clutch disconnected, .the synchronizer unit used therewith needs only to change the speed of rotationtof the drive shaft 83, to bring the clutch element 84 into synchronism with either the clutch element 94 or the gear 88. Since this is a relatively small shaft and, hence, possessed of low inertia, a relatively smallsynchronizer is adequate to effect this result, and even a small synchronizer will provide the necessarysyn- 7. chronism within an extremely. short period of time. The shift of. the supplementary gears may thus be accomplished very quickly.

Accordingly, a device has been provided meeting the objects and purposes set forth her'einabove.

While a particular embodiment of the invention has been selected for illustrative purposes herein, it will be apparent to persons acquainted with apparatus of this general type that many variations may be made from the particular form herein shown and that the claims should berconstrued as including such variations, excepting as said claims by their own terms expressly require otherwise.

I claim: I

l. A change gear set, comprising in combination: a driving element, having splines thereon; a shaft coaxial with, and axially spaced from, said driving element; a first'driven element fixed to said shaft for rotation therewith; a second driven element mounted on, and rotatable with respect to, said shaft and having the same tooth spacing and pitch diameter as said first driven element; a sleeve encircling said driving element and having first and second rows of internal clutch teeth thereon, said first row of internal clutch teeth being in constant, but slidable, mesh with the splines of said driving element, and said second row of internal clutch teeth being engageable alternately with the teeth of said first driven element and the teeth of said second driven element; a balking ring positioned between said first and second driven elements and frictionally engageable with alternate ones thereof upon being axially urged toward same, balking teeth on said balking ring arresting movement of 'said second row of internal clutch teeth from one of said driven elements toward the other thereof until the driven elements are rotating in substantial synchronism with each other.

2. A change gear set, comprising in combination: a driving shaft having a gear thereon, said gear having external teeth; a driven shaft coaxial with, and axially spaced from said driving shaft; a first gear having external clutch teeth and fixed to said driven shaft for rotation therewith; a second gear having external clutch teeth and being mounted on said driven shaft for rotation with respect thereto, said external clutch teeth on said first and second gears on said driven shaft having substantially the same tooth spacing and pitch diameter; a clutch sleeve encircling said driving shaft and said driven shaft, said sleeve has first and second axially spaced, circumferentially extending rows of internal clutch teeth thereon, said first row of internal clutch teeth being axially slidable with respect to, but being in constant mesh with, the teeth of said gear on said driving shaft,-said second row of internal clutch teeth being engageable alternatively with the clutch teeth of said first and secondgears on said driven shaft; a synchronizing ring coaxial with said shafts and positioned between said first and second gears on said driven shaft and being alternatively frictionally engageable therewith upon being urged axially towardsarne; said synchronizing ring has-two axially spaced, circumferentially extending rows of external balk teeth, the balk teeth' in each of said rows being circumferentially spaced from the balk teeth in the other row a distance equal to a multiple plus a fraction of the spacing of adjacent teeth in said second row of internal clutch teeth, the adjacent axial ends of the balk teeth in the respective rows being tapered in respectively opposite circumferential directions, the teeth in said second row of internal clutch teeth which are engageable with said balk teeth have tapered axial ends for matingly engaging the tapered ends of said balk teeth, said balk teeth being adapted to arrest movement of said second row of internal clutch teeth from one of said gears on said driven shaft toward the other thereof until said second row of internal clutch teeth and the clutch teeth of said other gear arerotating in substantial synchronism with each other.

3.? Synchronizing mechanism for-- use in shifting a toothed clutch ring from engagement with a first toothed clutch element into engagement with a second toothed clutch element, said clutch ring, first clutch element and second clutch element being coaxial and one of said clutch elements rotating faster, prior to synchronization in a selected circumferential direction than the other, the combination comprising: a synchronizing ring coaxial with said clutch ring and said first and second clutch elements, said synchronizing ring being positioned between said first and second clutch elements and being alternatively frictionally engageable therewith, said synchronizing ring being drivingly engaged by said clutch ring and being mounted for movement circumferentially with respect to said clutch ring, said synchronizing ring having first and second axially spaced, circumferentially extending rows of balk teeth mounted thereon and fixed against relative circumferential movement with respect to each other and with respect to said synchronizing ring, the balk teeth in each of said rows being circumferentially spaced from the balk teeth in the other row a distance equal to a multiple plus a fraction of the spacing of adjacent teeth on said clutch ring, the adjacent axial ends of the balk teeth in the rows being tapered in respectively opposite circumferential directions, the teeth on the clutch ring engageable with said balk teeth having tapered axial ends for matingly engaging the tapered ends of said balk teeth, said clutch ring as it moves from engagement with one clutch element to the other passing through one row of balk teeth to the other row whereupon the teeth of said clutch ring having tapered ends contact the correspondingly tapered ends of said balk teeth in said other row.

4. Synchronizing mechanism for use in shifting a toothed clutch ring from engagement with a first toothed clutch element into engagement with a second toothed clutch element, said clutch ring, first clutch element and second clutch element being coaxial and one of said clutch elements rotating faster prior to synchronization in a selected circumferential direction than the other, the combination comprising: a synchronizing ring coaxial with said clutch ring and said first and second clutch elements, said synchronizing ring being positioned between said first and second clutch elements and being alternatively frictionally engageable therewith, said synchronizing ring being drivingly engaged by said clutch ring and being mounted for movement circumferentially with respect to said clutch ring, said synchronizing ring having first and second axially spaced, circumferentially extending rows of balk teeth mounted thereon and fixed against relative circumferential movement with respect to each other and with respect to said synchronizing ring, the balk teeth in each of said rows being circumferentially spaced from the balk teeth in the other row a distance equal to a multiple plus a fraction of the spacing of adjacent teeth on said clutch ring, said clutch ring as it moves from engagement with one clutch element to the other clutch element passing through one row of balk teeth to the other row of balk teeth whereupon at least some of the teeth in said clutch ring contact the ends of said balk teeth in said other row.

5. A change gear set comprising in combination: a driving element having splines thereon; a driven shaft coaxial with and'axially spaced from said driving element; a first driven element fixed to said shaft for rotation therewith; a second driven element coaxial with said shaft and having the same tooth spacing and pitch diameter as said first driven element; a-sleeve encircling said driving element and having first and second rows of internal clutch teeth thereon, said first row of internal clutch teeth being in driving relationship with the splines of said driving element and said second row of internal clutch teeth being engageable alternately with the teeth of said first driven element and the teeth of said second driven element; a balking ring positioned between said first and seconddriven elements and frictionally engageable with alternate ones thereof upon being axially urged toward same; balking teeth on said balking ring arresting movement of said second row of internal clutch teeth from one of said driven elements toward the other thereof until the driven elements are rotating in substantial syn- 5 chronism with each other.

References Cited in the file of this patent UNITED STATES PATENTS Buchanan Sept. 6, 1938 Flinn Oct. 10, 1944 Schultze Oct. 30, 1951 Wolfe Apr. 21, 1953