MXPA98006447A - Sync - Google Patents

Abstract

The present invention relates to a selectively operative synchronizer for frictionally synchronizing and positively connecting a first mounted traction for rotation about an axis of a second traction, the synchronizer comprising: a first jaw member fixed to the first traction and connectable with a second jaw member axially movable in response to its engaging movement by an axial shifting force (Fo), the second jaw member mounted for non-rotation and for axial movement relative to the second traction, a first friction member secured for rotation with the first traction and a second friction member axially movable towards frictional engagement with the first friction member to provide a synchronization torque between the tractions in response to the linking movement; a shift member for axially moving the second jaw member and the second member of friction towards di linkages in response to the force of change (Fo) applied to the member of changes; movable blocking means toward attachment in response to the linking movement of the second jaw member to prevent asynchronous attachment of the jaw members and to transmit the force of change (o) linked friction members, self-energizing first and second operative means when they are linked to react to the synchronization torsion to produce an additive force (Fa) in the direction of the change force (Fo) to increase a bonding force of the linked friction members, the first self-energizing fixed means against movement relative to the second traction, resilient means to limit a magnitude of the additive force (Fa), the improvement comprising: self-energizing means seconds fixed to a self-energizing member mounted for axial movement relative to the second jaw member, and the resilient means reacting flexibly between the self-energizing member and the second jaw member and operative to flex in response to the linking of the first and second self-energizing means to limit the additive force (Fa) in the direction of the force of change (F

Description

SYNCHRONIZER Cross Reference to Related Requests This application, which has the attorney's file number 94-rELT-154, relates to the United States Patent Applications Serial Nos.,,,,,; presented on, and having respectively the attorney's file numbers 95-rELT-217, 95-rTRN-406, 91-TRN-499, 94-rELT-247, and 97-rTRN-259, and all assigned to the transferee of this application. Field of the Invention This invention relates to a synchronizer for a transmission. BACKGROUND OF THE INVENTION It is well known that synchronizers can be used in multiple speed ratio transmissions to help change all or some of the transmission gear ratios. It is also known that the effort of change and / or the time to carry out a change can be reduced by the use of synchronizers of the self-energizing or amplification type. Since the operator's change effort is generally increased with the size of the vehicle, self-energizing synchromesers are especially useful in transmissions for heavy-duty trucks and / or in transmissions where reduced shift time and speed are preferred. / or reduced change effort. Examples of prior art synchronizers that may be relevant to the synchronizer herein may be seen by reference to U.S. Patent Nos. 5,078,245 and 5,092,439; and German Patent Publication No. 1,098,824, which are incorporated herein by reference. SUMMARY OF THE INVENTION An object of the invention is to provide a synchronizer with improved means for limiting the strength of self-energizing means. According to the invention, a synchronizer is selectively operative to frictionally synchronize and positively connect a first mounted traction for rotation about an axis of a second traction. The synchronizer includes a first jaw member fixed at the first traction and engageable with a second jaw member axially movable in response to its engaging movement by an axial force of change (F0). The second jaw member is mounted for non-rotation and for axial movement relative to the second traction. A first friction member is secured for rotation with the first traction and a second friction member is axially movable towards frictional engagement with the first friction member to provide a synchronization torque between the tractions in response to linkage movement . One change member is for axially moving the second jaw member and the second friction member towards said links in response to the change force (F0) applied to the shift member. Blocking means are movable towards linkage in response to the linking movement of the second jaw member to prevent asynchronous attachment of the jaw members and to transmit the force of change (F0) to the linked friction members. First and second self-energizing means are operative, when engaged, to react the synchronization torsion to produce an additive force (FJ in the direction of the change force (F0) to increase the bonding force of the linked friction members The first self-energizing means are fixed against movement relative to the second traction.The resilient means are for limiting the additive force (Fa) The improvement comprises that the second self-energizing means are fixed to a self-energizing member mounted for axial movement relative to the change member, and the resilient means react flexibly between the self-energizing member and the change member and being operative to flex in response to the linking of the self-energizing means to limit the additive force ( Fa) in the direction of the force of change (F0) BRIEF DESCRIPTION OF THE DRAWINGS The synchronizer of the invention is shown in the accompanying drawings, in which: Figure 1 illustrates a double action synchronizer in a neutral position and in sections along line 1-1 of Figure 2; Figure 2 illustrates the synchronizer of Figure 1 in sections along line 2-2 of Figure 1; Figure 3 illustrates an enlarged view of part of a pin component of Figures 1 and 2; Figures 4A, 4B and 4C are amplified views of a component of Figures 1 and 2; Figures 5 and 6 illustrate an amplified self-energizing component of Figures 1 and 2; and Figure 7 is a graphical representation of the axial forces and torsions acting on a shift tab of the synchronizer. The drawings are simplified omitting the background lines of the components thereof. Detailed Description of the Drawings The term "synchronizer", as used herein, will designate a clutch mechanism used to non-rotatably couple a selected engagement gear to an arrow by means of a positive clutch in which the attempted engagement is prevented. of the positive clutch until positive clutch members are brought to substantially synchro-rotation by a synchronizing friction clutch associated with the positive clutch. The term "self-energizing" or "amplification" will designate a synchronizing clutch mechanism, which includes ramps or cams or the like to increase the binding force of the synchronizing clutch relative to the synchronizing torque of the friction clutch. Looking now at the drawings, there is shown in detail a set of gears and synchronizer 10 including an arrow 12 to be mounted for rotation about a central axis 12a, axially spaced gears 14, 16, rotatably held on the shaft and secured against axial movement relative to the arrow by annular thrust members 18, 20, and a dual-action synchronizing clutch mechanism 22. The thrust members 18, 20 are axially retained in annular grooves 12b, 12c in notch teeth 13 of the arrow and are fixed against rotation relative to the arrow by a retaining pin 24 (Figure 2) disposed in a space between two of the teeth 13. The synchronizing mechanism 22 includes annular friction member portions 26, 28 and portions of limb member. jaw 30, 32 formed integrally with the gears 14, 16, jaw clutch members 34, 36 having internal notch teeth 38, 40 that slidably mate with the jaws. external notch teeth 13c formed integrally with the arrow 12 or otherwise fixed to it, a radially extending flange or shifting member 42, having opposite axially facing sides 42a, 42b, sandwiched between axially facing surfaces 34a , 36a of the jaw members 34, 36, three self-energizing members 44 further explained hereinafter, spring rollers 46, 48, annular friction members or rings 50, 52 jointly secured by three circumferentially spaced pins 54, which are they extend axially from each of the friction members and through openings 42c in the flange and three pre-energizing and neutral centering assemblies 56. Each pre-energizer assembly includes a spring 58 and a plunger 60, which reacts with defined surfaces by the pins. Also, the number of self-energizing members 44, pins 54 and sets 56 may be greater or less than that disclosed herein. The pre-energizing assemblies may be different from the type shown herein, for example they may be of the split pin type. In addition, the synchronizing mechanism may be different from the pin type; for example, the synchronizing mechanism may be of the so-called beam ring type, such as for example the one disclosed in U.S. Patent No. 5,544,727, which is incorporated herein by reference. As can easily be seen, the friction members 26, 50 and 28, 52 are matched to define friction clutches to synchronize the gears to the arrow before engagement of the jaw clutches. Cone clutches are preferred; however, other types of friction clutches can be used. The friction members 26, 28 can be fixed to the associated gears in any of several known ways. The friction members 26, 28 have internal cone friction surfaces 26a, 28c that respectively mate with external cone friction surfaces 50c, 52c. Friction surfaces 26a, 28a can be defined by any of several known friction materials fixed to the base member, for example pyrolytic carbon friction materials, such as those disclosed in U.S. Patent Nos. 4,700,823; 4,844,218; and 4,778,548. These patents are incorporated herein by reference. The pins 54 are shown in greater detail in Figure 3. Each pin includes larger diameter portions 54a having diameters slightly smaller than the diameter of the flange openings 42c, a slit portion or reduced diameter 54b, spaced between friction rings 50, 52 (midway in the present), shoulders or conical blocking surfaces 54c, 54d extending radially outwardly from the pin axis and axially away from each other at a present angle of about 45 ° relative to a plane normal to the pin axis, and preferably, but not necessarily, independent pre-energizing surfaces 54e, 54f and secondary centering surfaces, extended 54g, 54h. The slit portions, when disposed within their respective flange openings, allow limited rotation of the rigid friction pin and ring assembly relative to the flange to effect linkage of the locking pin shoulders with beveled blocking shoulders 42d, 42e defined around the eyelash openings. The pre-energizing surfaces 54e, 54f cordally intersect or remove a portion of the tapered locking shoulders 54c, 54d, are preferably (but not necessarily) flattened surfaces and form angles relative to the pin axis that are somewhat less than the angles of the pins. blocking surfaces. The centering surfaces 54g, 54h are also flattened surfaces and, as is evident from the drawings, they form angles relative to the pin axis which are substantially smaller than the angles of the blocking and pre-energizing surfaces. As disclosed in the present, the chordal extension of the flat surfaces is tangent to circles concentric to the pin axis and the arrow axis. Axial forces provided by the secondary centering surfaces must be sufficient to return the flange 42 to its neutral position in the event that such positioning has not been effected completely by the shift mechanism to move the flange. The plungers 60 are radially outwardly biased toward the pre-energizing pin and centering surfaces by the compression coil springs 58 disposed in slots 42f of the flange. The greater extension of the grooves extends, preferably but not necessarily, radially with respect to the axis of the arrow. The grooves also extend axially through the flange sides 42a, 42b, towards the flange openings 42c, and have ends 42g in their extension radially inwardly for the springs to react against. The radially inner portion of the springs can be retained by means not shown, such as pins, which extend radially outwardly from the slot ends. The plungers 60 can be formed of a sheet metal material, but are preferably formed of a forged or compacted material such as steel to provide structural rigidity and surface hardness. Each plunger 60 has a somewhat U-shaped cross section with a closed end defining a head portion having flat angled surfaces 60a, 60b to cooperate with the flat pre-energizing and centering surfaces of the associated pins 54. The side walls of each plunger have surfaces 60c60d for cooperating slidably with radially extending sidewall surfaces of the slot 42f to retain the plunger in the circumferential direction. The piston side walls also have opposite axially facing surfaces 60e to cooperate slidably with the radially extending, axially facing end surfaces 34a, 36a of the jaw members 36, 34 to retain the plunger in the axial direction .

As previously mentioned, the jaw members 34, 36 include notched internal teeth 38, 40 that slidably mate with external notch teeth 13 attached to the arrow. The external notches have involution flank surfaces 13a extending parallel to the arrow axis and mating these with the flank surfaces of the jaw member notches prevents relative rotation therebetween. Self-energizing members 44, as best seen in Figures 1, 2 and 4A-4C, each include end portions 44a, 44b, an arcuate central portion 44c with a radially inwardly facing surface 44d having a set of self-energizing ramp 45 extending radially inward from there and surfaces facing circumferentially in opposite manner 44e, 44f. The central portion 44c extends through the axially aligned opening 34b, 36b in the jaw members and through an opening 42h in a radially internal extension of the flange 42. The self-energizing member 44 is axially slidable relative to the jaw members 34, 36, and flange 42 is retained against circumferential movement relative to the flange by surfaces 44e, 44f, which closely abut in circumferentially facing shoulders 42i, 42j of flange opening 42h, and is free to rotate a limited amount in the jaw member openings 34b, 36b until the surfaces 44e, 44f contact the circumferentially facing shoulders 34c of the jaw member openings 34b, 36b. The shoulders 34c of the jaw member 34 are shown in phantom lines in Figure 2. The spring rollers 46, 48 are held in a preloaded condition against the jaw members 34, 36 by the end portions of self-energizing member 44a , 44b and anti-friction thrust sheaves 47, 49, which react against axially opposite ends of the jaw members 34, 36. The internal diameter of the thrust sheaves 47, 49 is received in annular recesses 44g, 44h in each self-energizing member 44 and axial movement towards each other is prevented by one shoulder of each recess to maintain the pre-loaded state of a spring when the other spring is compressed by self-energizing forces. Alternatively, the springs can not be pre-loaded and / or the thrust sheaves 47, 49 may not be restrained against axial movement. As will be explained hereinafter, a main function of the members 44 and the spring rollers 46, 48 is to limit the magnitude of the self-energizing additive axial force Fa provided by the ramp assembly 45. However, in the present may also retain the jaw members 34, 36 against axial movement relative to the shift tab 42. Other means may be used to axially retain the jaw members 34, 36, for example the H-shaped retaining members in the above mentioned United States Patent No. 5,092,439.

As best seen in Figures 1, 2, 5 and 6, portions of the outer arrow teeth 13 are modified to provide one or more self-energizing ramp surfaces cooperating with a similar number of ramp surfaces defined by the assembly ramp 45 of the member 44. The ramp assembly and the ramp surfaces therein extend radially inwardly between axially extending spaces between the arrow notches 13. The ramp surfaces allow limited rotation of the self-energizing member 44 and the flange 42 with respect to the jaw members 34, 36 and the arrow 12, and react to the synchronization torsion between the cone clutches and the arrow to provide the self-energizing additive axial force Fa to increase the bonding force of the cone clutch linked through the blocking shoulders by a changing force of the operator F0 applied to the flange 42, thereby increasing the synchronization torsion ion provided by the cone clutch. Ramp surfaces may be provided to increase the synchronization force for one or both gears and / or to increase the synchronization force in response to twisting in any direction, as it is found for changes at higher speed and at lower speed. More specifically, pairs of axially facing flank surfaces 13a of the notches 13 have portions removed to provide self-energizing or amplifying ramp surfaces 13b, 13c, 13d, 13e and axially extending surfaces 13f, 13g , 13h, 13i. Self-energizing or amplifying ramp surfaces 13b, 13c react respectively against self-energizing or amplifying ramp surfaces 45a, 45b on the ramp assembly 45 to provide the additive axial forces to increase or assist the gear synchronization rate 14 in response to twisting in any direction. The ramp surfaces 13d, 13e respectively react against ramp surfaces 45c, 45d to provide the axial additive forces for engagement 16 in response to the synchronization torque in either direction. The angles of the ramp surfaces can be varied to provide different magnitudes of additive axial force for changes at higher speed and lower speed and for high and low speed ratios. Also, if additive axial force is not preferred in one direction for one or more gear, the ramp surfaces may be parallel to the notch, i.e. effective ramp surfaces are not provided. The magnitude of the additive axial forces, as further explained hereafter, is also a function of the ratio of the average radii of the friction clutches and the self-energizing ramps. Accordingly, the magnitude of the additive forces for a given change force F0 applied to the shift flange 42 by a shift fork can be varied by varying the ramp angles and / or the ratio of average radii. When the flange 42 is in the neutral position of FIGS. 1 and 5, the reduced diameter portions 50b of the pins 54 are radially aligned with the associated flange openings 42c, and friction surfaces of the cone clutches are slightly spaced apart and they are held in this spaced relation by angled pre-energizing surfaces 60a, 60b of the plungers 60 acting on pre-energizing surfaces 50e, 50f of the pins 54 by the force of the springs 58. The axial force provided by the pre-energizing surfaces it is preferably sufficient to counteract any additive axial force on the flange 42 by the self-energizing ramps due to the viscous shear stress of the oil between the cone clutch surfaces. When it is desired to couple any gear to the shaft, an appropriate and not shown gear mechanism, such as that described in U.S. Patent No. 4,920,815, incorporated herein by reference, is connected to the outer periphery of the flange. 42 in a known manner to move the flange axially along the axis of the arrow 12 either to the left to engage the gear 14 or to the right to engage the gear 16. The shift mechanism can be manually moved by an operator by A link system can be moved selectively by an actuator, or it can be moved by means that automatically initiate the movement of the shift mechanism and also control the magnitude of the force applied by the shift mechanism. When the shift mechanism is moved manually, the force is proportional to the force applied by the operator to a shift lever. Whether applied manually or automatically, the force is applied to the flange 42 in an axial direction and is represented by the length of the arrow F0 in Figure 7. The initial axial movement to the right of the flange 42 by force of change of the operator F0 is transmitted to the pins by the pre-energizing surfaces 60b to effect initial frictional bonding of the cone surface 52a with the cone surface 28a. The initial bonding force on the cone surface is of course a function of the force of the springs 58 and the angles of the pre-energizing surfaces. The initial frictional link (with the condition that there is an asynchronous condition and momentarily ignoring the effect of the self-energizing cams) produces an initial force of cone clutch engagement and an initial synchronization torsion, which ensures limited relative rotation between the flange 42 and the linked friction ring, and hence movement of the reduced diameter pin portions 54b to the appropriate sides of the flange openings 42c to provide linkage of the locking pin shoulders 54c with 42d flange blocking shoulders. When the blocking shoulders are linked, the total force of change of the operator F0 on the flange 42 is transmitted to the friction ring 52 via the blocking shoulders, whereby the cone clutch is linked by the full force of change of the operator F0 to provide a resultant operator synchronization torsion T0. This operator synchronization torsion T0 is represented by the arrow T0 in FIG. 7. As the blocking shoulders are arranged at angles relative to the axial direction of the operator change force F0, they produce a counterforce or release torque, which is contrary to the synchronization torque of the cone clutch but of lesser magnitude during asynchronous conditions. Upon reaching substantial synchronism, the timing torsion falls below the unlocking torsion, whereby the blocking shoulders move the pins in concentric relation with the openings 42c to allow continued axial movement of the flange and engagement of the outer teeth jaw 36e of the jaw member 36 with jaw teeth 32a of the jaw member 32, thereby completing a shift towards the gear 16. Axial movement of the flange 42 to the left to positively synchronize and engage the gear 14 to the jaw member 36a. arrow 12 is analogous to the above, and the change is consummated when the jaw teeth 34a of the jaw member 34 mate with the teeth 30a of the jaw member 30. The jaw / jaw teeth can be configured as shown in FIGS. U.S. Patent Nos. 3,265,171 and 4,246,993, which are incorporated herein by reference. Still ignoring the effects of self-energizing ramps, the cone clutch torque provided by the force F0 is expressed by equation (1). T0 = Fc Rc μc / sin a where: Rc = mean radius of the cone friction surface, μc = coefficient of friction of the cone friction surface, and a = angle of cone friction surfaces. Looking now at the effects of the self-energizing cams, the synchronization torsion T0, due to the axial force of change F0 applied by the operator, is of course transmitted to the flange 42 by the pins 54 and is reacted to the arrow 12 through the self-energizing ramp surfaces. Self-energizing ramp surfaces, when linked, produce the additive axial force Fa acting on the flange in the same direction as the change force F0. The additive axial force Fa is applied to the friction surfaces linked through the blocking surfaces via a force path that includes the self-energizing ramp surfaces, the self-energizing member 44, any of the spring rollers 46 or 48. , and axially against the flange 42 via either of the jaw members 34, 36. The spring rollers allow sufficient axial movement of the self-energizing member 44 for the associated self-energizing ramp surfaces 45a, 45b, 45c or 45d to move it. to a force balance position at the intersection of self-energizing ramp surfaces 13b, 13c, 13d or 13e with axially extending surfaces 13f, 13g, 13h or 13i. When in this position of force balance, the maximum additive axial force Fa is limited to the force transmissible by the spring in the balance position as any further movement of the self-energizing ramp surfaces 45a, 45b, 45c, or 45d on the axially extending surfaces it does not generate additive axial force. The forces F0 and Fa are applied to the shift flange 42 in parallel and summed to provide a total force Ft, thereby further increasing the bonding force of the cone clutch to provide an additive torsion of synchronization Ta, which is added to the torsion T0 to provide a total torque Tt. The sum of the axial forces to connect the cone clutch is F0 plus Fa and the sum of the synchronization torques that are being produced by the cone clutch is T0 plus Ta, as graphically shown in figure 7. Variables and the principal equations for calculating self-energizing ramp angles can be seen with reference to U.S. Patent No. 5,092,439, previously mentioned. A pin-type synchronizer has been disclosed to illustrate the inventive material herein. The following claims are intended to cover inventive portions of the disclosed material and variations and modifications that are believed to be within the spirit of the invention.

Claims (14)

1. CLAIMS 1. A selectively operative synchronizer for frictionally synchronizing and positively connecting a first mounted traction for rotation about an axis of a second traction; the synchronizer comprising: a first jaw member fixed to the first pull and engageable with a second jaw member axially movable in response to its pivoting movement by an axial force of change, the second jaw member mounted for non-rotation and for movement axial relative to the second traction; a first friction member secured for rotation with the first traction and a second friction member axially movable towards frictional engagement with the first friction member to provide a synchronization torque between the tractions in response to the linking movement; a member of changes for axially moving the second jaw member and the second friction member toward said links in response to the change force applied to the shift member; movable blocking means toward engagement in response to the linking movement of the second jaw member to prevent asynchronous attachment of the jaw members and to transmit the force of change to the associated friction members; Self-energizing first and second operative means when they are linked to react to the synchronization torsion to produce an additive force in the direction of the change force to increase the bonding force of the linked friction members, the first self-energizing means fixed against movement relative to the second traction; resilient means to limit additive strength; the improvement comprising: the second self-energizing means are fixed to a self-energizing member mounted for axial movement relative to the shift member; and the resilient means reacting flexibly between the self-energizing member and the member of changes and operatives to flex in response to the linking of the self-energizing means to limit the additive force in the direction of the force of change.
2. 2. The synchronizer of claim 1, wherein: the shift member is in a radially extending flange; the self-energizing member includes an axially spaced portion of the flange; and the resilient means include resilient compression means interposed between the portion and the flange. The synchronizer of claim 2, wherein: the portion and the resilient compression means are positioned to retain the second jaw member against axial movement relative to the flange. The synchronizer of claim 2, wherein: the second jaw member and flange includes axially aligned openings receiving the self-energizing member for non-rotation relative thereto and to allow sliding movement of the self-energizing member relative to the eyelash . The synchronizer of claim 4, wherein: the second traction includes external notches that slidably mate with internal notches of the second jaw member; and the self-energizing member is retained in a radially inward direction by the external notches. The synchronizer of claim 5, wherein: portions of the external notches define the first self-energizing means and the second self-energizing means extend radially inwardly from the self-energizing member. The synchronizer of claim 1, further comprising: a third drive mounted for relative rotation about an axis of the second drive; a third jaw member fixed to the third drive and engageable with a fourth jaw member axially movable in response to its engaging movement by a second axial force of change, the fourth jaw member mounted for non-rotation and for axial movement relative to the second traction; a third friction member secured for rotation with the third drive, and a fourth friction member axially movable towards frictional engagement with the third friction member to provide a synchronization torque between the second and third drives in response to the linking movement; the shifting member for axially moving the fourth jaw member and the fourth friction member toward said engagement in response to the second shifting force applied to the shifting member; blocking means, moveable towards attachment in response to the linking movement of either the third or the fourth jaw member to prevent asynchronous attachment of the third and fourth jaw members and to transmit the second force of change to the third and fourth friction members fourth; third and fourth self-energizing means, operative when they are linked, to react to the synchronization torsion to produce a second additive force in the direction of the second force of change and to increase the bonding force of the third and third friction members fourth, the third self-energizing means fixed against movement relative to the second traction; the resilient means also to limit the strength of the second additive force; the self-energizing fourth quarters fixed to the self-energizing member; and the resilient means polarizing the self-energizing member axially in opposite directions and operative to flex in response to the linking of the self-energizing means to limit the additive force in the direction of the forces of change. The synchronizer of claim 7, wherein: the blocking means including a plurality of circumferentially spaced pins axially extending rigidly between the second and fourth friction members and toward a first set of openings in the flange, each of the pins having interlocking blocking shoulders with defined blocking shoulders around the associated opening; first and second self-energizing means, operative when they are linked to react to the synchronization torsion to produce an additive force in the direction of the force of change and to increase the bonding force of the linked friction members, the first fixed self-energizing means against movement relative to the second traction; resilient means to limit additive strength; the improvement comprising: the second self-energizing means fixed against movement relative to the self-energizing member mounted for non-rotation and for axial movement relative to the flange; and the resilient means polarizing the self-energizing member axially in opposite directions and operative to flex in response to the linking of the self-energizing means to limit the additive force in the direction of the bi-directional change force. The synchronizer of claim 7 or 8, wherein: the shift member is a radially extending flange having opposing axially facing sides positioned between the second and fourth jaw members. The synchronizer of claim 9, wherein: the self-energizing member includes first and second portions axially spaced respectively from the first and second sides of the flange; and the resilient means include first and second resilient compression means interposed respectively between the first and second portions and the first and second sides of the flange. The synchronizer of claim 10, wherein: the first and second portions and the resilient compression means are positioned to retain the second and fourth jaw members against axial movement relative to the flange. The synchronizer of claim 9, wherein: the second and fourth jaw members and the flange each include axially aligned openings receiving the self-energizing member for non-rotation relative thereto and to allow sliding movement of the self-energizing member. energizing relative to the tab. The synchronizer of claim 12, wherein: the second traction includes external notches that slidably mate with internal notches of the second and fourth jaw members; and the self-energizing member is retained in a radially inward direction by the external notches. The synchronizer of claim 13, wherein: portions of the outer notches define the first and second self-energizing means, and the second and fourth self-energizing means extend radially inwardly of the self-energizing member.