WO2018017654A1

WO2018017654A1 - Independent block with integration of inhibitor system for double engagement and independent detent rails

Info

Publication number: WO2018017654A1
Application number: PCT/US2017/042756
Authority: WO
Inventors: Carlos A. FONTANA
Original assignee: Eaton Corporation
Priority date: 2016-07-20
Filing date: 2017-07-19
Publication date: 2018-01-25

Abstract

Openings in the end block of a gear shift assembly are connected to one another via passageways. Shift rails include an end having first and second surfaces, and an outer surface at a radial distance that is greater than a radial distance of the first and second surfaces. The assembly includes circular objects positioned within passageways of the end block, such that the circular objects are loosely in contact with one another and with the first and second flats of each shift rail. When one of the shift rails is repositioned axially during a manual gear shift, two of the circular objects that are in contact respectively with the first and second surfaces engage against the outer surface of the shift rail, forcing the circular objects within the passageways to engage against each other, preventing any of the other shift rails from being able to shift axially.

Description

INDEPENDENT BLOCK WITH INTEGRATION OF INHIBITOR SYSTEM FOR DOUBLE ENGAGEMENT AND INDEPENDENT DETENT RAILS

TECHNICAL FIELD

[0001] The technical field is generally related to multi-rail shifting mechanisms of manual compound transmissions, and particularly, a gear selection system within the manual compound transmission.

BACKGROUND

[0002] Manual compound transmissions are used for various vehicle applications. Such compound transmissions typically comprise a multiple speed main section containing a plurality of gears for various range and load gearing configurations.

[0003] Manual compound transmissions are generally positioned within a driveline adjacent a primary drive unit with at least one rotating drive shaft. These compound transmissions generally include a shifter or gear selector that extends from the transmission for interaction with an operator. The compound transmission may include a rotating and sliding assembly that is configured to engage a desired gear set when an operator moves the shifter or gear selector. Specifically, in a manual compound transmission an operator, through the gear selector, selects an appropriate gear by pushing or pulling the shift lever to a desired shift gate. A rail selector fixed to the main shift rail is configured to translate the movement of the shift lever to the shift forks. The rail selector is fixed to the main shift rail by a roll pin that extends through a central location of the rail selector. The action on the shift lever causes a set of shift rails to move at least one shift fork, which causes a shift collar to slide over the appropriate rotating gear to synchronize and activate a desired gear range.

[0004] Shift quality is an important factor for manual compound transmissions when selecting the desired gear range. There are many factors affecting shift quality, such as, but not limited to shift force, notches from bumps and detents, nibble, and precision of the rotating and sliding components, such as, but not limited to end stop feel and lash. Nibble may be defined as a form of partial clash following a successful synchronizing action. It may result from a speed differential generated during the period between indexing and final engagement of the teeth for the desired gear.

Unfortunately, the previously discussed factors affecting shift quality are typically transmitted directly through the rotating components and shift rails, as the previous designs included shift components that were fixed directly to the shift rail. These factors are transmitted directly through the components, through the shift lever and ultimately to the operator.

[0005] Shift quality is important to provide the operator with the appropriate feedback through the shift lever indicating that the compound transmission is engaged in the appropriate gear set while preventing a mis- shift or other misalignment that may potentially damage or shorten the life of the transmission. The shift quality is also important for preventing fatigue and possible injury to the operator, as feedback carried through the shift lever may result in damage to the hand, wrist, arm or shoulder of an operator. Moreover, if shift engagement feedback is not provided to the operator, the operator may not know or sense that the gear is properly engaged before releasing a clutch.

[0006] In addition, shift rail involuntary movement may occur that could result in simultaneous gear engagement, thereby potentially impairing the long-term life of the gears and other components within the transmission. That is, although a particular gear may be selected and engaged, inadvertent shifting of gears can occur wherein one shift rails moves at least partially in an engagement direction to cause at least partial and simultaneous engagement of a second gear.

[0007] Therefore, it is desirable to provide a manual compound transmission system that allows for reduced simultaneous gear engagement while also providing a force feedback to the operator so that the operator can physically sense successful gear engagement.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 is a perspective view, of an exemplary manual transmission with a shift rail assembly;

[0009] FIG. 2 is a view of the rail assembly of FIG. 1 and showing a cutaway view of an end block,

[0010] FIG. 3 is an enlarged view of the end block of FIG. 2, but not as a cutaway;

[0011] FIG. 4 is a close-up perspective view of a cutaway of the end block of FIG. 3;

[0012] FIG. 5 is an exemplary end of a shift rail illustrating flat surfaces;

[0013] FIG. 6 is an end view of shift rails, balls, pins, and springs with all shift rails in an unengaged arrangement; and

[0014] FIG. 7 is an end view of shift rails, balls, pins, and springs with one shift rail in an enga arrangement.

DETAILED DESCRIPTION

[0015] Referring now to the discussion that follows and also to the drawings, illustrative approaches to the disclosed systems and methods are shown in detail. Although the drawings represent some possible approaches, the drawings are not necessarily to scale and certain features may be exaggerated, removed, or partially sectioned to better illustrate and explain the present disclosure. Further, the descriptions set forth herein are not intended to be exhaustive or otherwise limit or restrict the claims to the precise forms and configurations shown in the drawings and disclosed in the following detailed description.

[0016] Reference in the specification to "an exemplary illustration" and "example" or similar language means that a particular feature, structure, or characteristic described in connection with the exemplary approach is included in at least one illustration. The appearances of the phrase "in an illustration" or similar type language in various places in the specification are not necessarily all referring to the same illustration or example.

[0017] According to various exemplary illustrations described herein, a system and method are disclosed. Specifically, an independent block for an exemplary shift mechanism of a compound manual transmission is disclosed. The compound manual transmission includes an input shaft and an output shaft, the input shaft may be configured to engage a prime mover (not shown). The compound manual transmission includes a main shaft, a countershaft and a plurality of gears configured within a transmission housing. The main shaft may be configured between the input shaft and the output shaft, which may be configured at a rear of the compound manual transmission. The main shaft may include a first plurality of gears configured about the main shaft and in rotative alignment with a second plurality gears configured on the countershaft. The shafts and gears are typically referred to as a rotating assembly.

[0018] A shift lever (not shown) may extend on a shift bar housing, which may be attached to an upper section of the compound transmission housing. The shift bar housing may be configured to position shift rails in proximity to the rotating assembly via a disclosed independent block, thereby slidably connecting the shift lever and a shift fork (not shown) to the rotating assembly. A connection between the shift lever and the rotating assembly allows for an operator to select a desired gear set as the lever may be directly connected to the gears within the compound

transmission. Through movement of the shift rails, the shift fork may engage a synchronizer for meshing the selected gear set, which helps to prolong the life of the compound transmission and minimize nibble that may be associated with gear changing. A plurality of shift rails is connected together by a support block and an end block for relative longitudinal sliding movement. A cross slide can be moved laterally such that selector tangs engage any one of the desired shift rails.

[0019] In operation, an operator positions the shift lever to select a predetermined gear set. To initiate a shifting operation, the shift lever is first moved in the lateral direction to select one of the shift rails for axial or longitudinal movement in order to engage one of the gears. Lateral movement of the cross slide causes selector tangs provided thereon to become laterally aligned with a selected one of the shift rails. Then the shift lever is subsequently moved in a longitudinal direction, the selected one of the shift rails to be moved longitudinally therewith.

[0020] Referring to FIG. 1 a compound manual transmission 100 is illustrated. The transmission 100 may comprise an input shaft 102 and an output shaft 104 (not visible), input shaft 102 may be configured to engage a prime mover (not shown), while output shaft 104 may include a yoke or other engagement mechanism for engaging a driven member. Compound manual transmission 100 includes a countershaft 106 and a plurality of gears 108, 110 configured about shafts 102, 104. A main shaft 112 may include a first plurality of gears 108 configured about main shaft 112 and rotatably aligned with a second plurality of gears 110 configured on countershaft 106. Input shaft 110, output shaft 112, main shaft 112 and countershaft 106 may be supported by a housing 114 through a plurality of bearings (not shown). Compound manual transmission 100 includes a shift bar assembly 116.

[0021] Shift bar assembly 116 of FIG. 1 is illustrated in FIG. 2 as a gear shift assembly 116.

Assembly 200 includes a support block 202 and an end block 204. End block 204, incidentally, is shown as a cutaway in order that internal components therein can be illustrated. In reality, however, end block 204 contains the internal components that are visible in the cross-section or cutaway that is visible in FIG. 2. FIG. 3, on the other hand, illustrates end block 204 which contains balls, springs, and other components that are visible in the cutaway view of end block 204 in FIG. 2.

[0022] Referring still to FIG. 2, a main rail 206 and four shift rails 208, 210, 212, and 214 are shown. A shift lever 216, shown only in part, is operable to engage the main rail 206 and shift rails 208-214 to selectively engage gears 108, 110 of compound manual transmission 100, and as is understood within the art. In doing so, shift rails 208-214 are caused to move axially and it is desirable that only one of shift rails 208-214 move axially, while the others remain stationary.

[0023] Referring to FIG. 4, an end view 400 of end block 204 of both FIGS. 2 and 3 is illustrated. As mentioned, however, the components visible in end view 400 are in fact contained within end block 204, as illustrated in FIG. 3. End view 400 includes main rail 206 of FIG. 2, as well as shift rails 208-214 that are passing through openings or holes in the end block 204. During operation and in order to shift and selectively engage gears 108, 110, and as commonly understood within the art, shift rails 208-212 are selectively and individually caused to move in an axial direction 402. That is, one of shift rails 208-214 is caused to move in axial direction 402 while the others of shift rails 208- 214 remain stationary. However, as mentioned above, in the absence of the mechanism discussed herein, shift rail involuntary movement may occur that could potentially result in simultaneous gear engagement. Thus, if one of shift rails 208-214 is engaged as intended, and another of shift rails 208-214 inadvertently becomes engaged, then long-term performance may be impaired to the gears or other components within the transmission.

[0024] Accordingly, the disclosed mechanism prevents any such inadvertent simultaneous gear engagement. That is, as will be further described, the disclosed mechanism forces a modest interference fit between components when one of the shift rails 208-214 is axially engaged, which prevents inadvertent movement of the others of shift rails 208-214. More specifically, according to the disclosure and referring now to FIGS. 4 and 5, each shift rail 208-214 includes two flats at an end that causes a slight or modest interference to occur between components when one of the shift rails 208-214 is repositioned in the axial direction 402. In one example the slight or modest interference fit may be a line-line or nominal fit between components such that interference occurs due to overlapping tolerance bands for which components are designed. In another example the slight or modest interference fit may be up to one or a few thousands of an inch interference, such that parts may need to be pressed together to overcome the slight interference. Regardless, as will be described, the interference fit that would result is precluded due to the engagement of

components as described herein.

[0025] FIG. 5 shows rail 208 that corresponds also to shift rail 208 of FIG. 4. Shift rail 208 includes an end 500 as shown, that is positioned within end block 204 of FIG. 4. Shift rail 208 of FIG. 5 also illustrates a first surface 502 and a second surface 504 that is orthogonal to first surface 502. In the illustrated examples, first and second surfaces 502, 504 are illustrated as flat surfaces. However, it is contemplated that the surfaces may not be flat but may be simply surfaces that are at a radial distance from a center of rail 208, and extend approximately parallel along a central axis of shift rail 208, as will be further described. Surfaces 502, 504 also adjoin one another and are approximately transverse to one another. As can be seen in end view 400 of FIG. 4, each of shift rails 210-214 also includes two surfaces that are approximately orthogonal to one another and as adjoining surfaces that extend approximately parallel with a central axis of their respective shift rail, as in shift rail 208. Accordingly, in the illustrated approach, each of shift rails 208-214 is configured to engage with the others of shift rails 208-214 to prevent their inadvertent axial movement when one of shift rails 208-214 is engaged, as illustrated and discussed herein.

[0026] Referring again to FIG. 4, each of shift rails 208-214 is positioned between a series of balls and spring mechanisms that cause the shift rails 208-214 to interact with one another, to prevent their inadvertent motion, after one of shift rails 208-214 is axially repositioned. Further, although the following is described with balls as circular elements or objects that roll and compress against one another during engagement, it is contemplated that other shapes, such as cylinders, may also be employed so long as their outer surfaces roll and engage against one another, according to the disclosure. Further, when described as balls it is contemplated that the balls are spherical balls. A first set 404 of four balls and a second set 406 of four balls are positioned along a passageway defined by an axis 408 between shift rail 208 and shift rail 214. A pin 410 and a pin 412 are also positioned within the passageway along axis 408 and between first set 404 of balls and second set 406 of balls, as shown. As with shift rail 208, the end of shift rail 214 is positioned axially in line with first and second sets of balls 404, 406, as well as pin 410 and pin 412. In addition, a ball 414 and a ball 416 are each positioned in contact with two of the respective sets of balls 404, 406. That is, ball 414 is positioned to contact two of balls 404, and ball 416 is positioned to contact two of balls 406. Ball 414 is also positioned so that it can contact shift rail 210 and ball 416 is positioned so that it can contact shift rail 212.

[0027] Further, balls 418 and 420 are also positioned transverse to each of the balls 414 and 416, and balls 418, 420 are positioned to engage respective surfaces 422, 424 as well. Balls 418, 420 are provided in another passageway along a second axis 426 between shift rails 210, 212, with spring elements 428, 430 likewise positioned between balls 418, 420 and along second axis 426. Second axis 426 in one example is approximately parallel with first axis 408. It is contemplated, however, that first and second axes 408, 426 need not be approximately parallel with one another, although if not parallel then vertical positions between components such as rails 210, 212 may not be the same. A spring element 432 is positioned within this passageway and over respective ends of first and second pins 410, 412. Each of spring elements 428, 430, and 432 exerts an expansive or outward force on their respective balls and along their respective axis. FIG. 4 also illustrates a ball 434 and a ball 436 that press against surfaces, as illustrated, on each of shift rails 208 and 214, respectively. Springs 438 and 440 provide expansive or outward forces that press against respective balls 434 and 436, sufficient to prevent shift rails 208, 214 from inadvertent axial movement due to their engagement with the surfaces of their respective rails.

[0028] During the axial movement of one of shift rail 210 and 212, compression of springs 428, 430 causes an increased compression force between shift rails 210 and 212, which thereby reduces the propensity of the other shift rail 210, 212 to also shift axially. That is, springs 428, 430 provide sufficient force against balls 418, 420 such that their respective surfaces 422, 424 are axially engaged when one of shift rails 210, 212 is axially repositioned.

[0029] The shift rails, balls, and pins are shown in FIG. 4 in their "unengaged" position. That is, each of shift rails 208-214 is positioned at approximately the same axial location such that none of the rails, balls, or pins are engaged tightly against one another and no interference between components occurs. Moreover, each of shift rails 208-214 is positioned such that the surfaces of each of shift rails 208-214 in general contact with the balls that are next to the surfaces. The same "unengaged" arrangement is shown in FIG. 6 as well, in an end view 600. The illustrated components of FIG. 6 are in reality contained within an end block, such as end block 204.

However, in order to better illustrate and describe operation of the components, end block 204 is not included in FIG. 6.

[0030] Elements identified in the previous figures are also identified in FIG. 6. The unengaged arrangement of FIG. 6, as will be further described, corresponds to the position and interaction of all the components when all shift rails 208-214 are positioned in a neutral position, such that none of the gears within the transmission is engaged. That is, the arrangement of FIG. 6 is described as unengaged, because all components are in a relatively neutral position such that any one of rails 208-214 may be moved axially during a gear shift. All of the shift rails 208-214 are positioned axially such that the surfaces of each of the shift rails 208-214 is positioned in loose contact with the corresponding balls.

[0031] When one of shift rails 208-214 is moved axially, then the balls, springs, and pins engage as a system that forces the components together, preventing any of the other shift rails 208-214 from inadvertent engagement. As mentioned, shift rail 208 is illustrated in FIG. 5 and is described as having flat surfaces 502 and 504. As can be seen in both FIGS. 4 and 6, however, the other shift rails 210-214 also include flat surfaces as well. For the sake of illustration, system operation is described with respect to the axial motion of shift rail 208, but it will be evident that system operation is similar for axial motion of any of shift rails 208-214.

[0032] Thus, for operation particular to the axial motion of shift rail 208, it can be seen that ball 434 is maintained in loose contact with surface 504 by the operation of spring 438. Also, one of balls 404, identified in FIG. 6 as ball 602, is also maintained in slight contact with surface 502. Thus, in this position, balls 404 are in slight but loose contact with one another, as well as balls 406. In addition, balls 414, 416, 418, 420, and 604 (identified as one of balls 406) are all in slight but loose contact with respective surfaces of their respective shift rails. [0033] In operation, in this described example, shift rail 208 is moved in axial direction 402. In so doing, ball 602 traverses along a "line of contact" 506, as seen in FIG. 5, from a first contact location 508, along line of contact 506, along a detent or ramp 510 that is formed between surface 502 and an outer circumference 512 of shift rail 208, to a second contact location 514. Ramp 510 in one example is not a step, but is abrupt enough in the change from surface 502 to circumference 512 to cause an abrupt motion in response to short axial travel, of perhaps 1/8" or less, to cause an abrupt shift in the location of ball 602. As can be seen in FIG. 6, therefore, as shift rail 208 moves axially 402, ball 602 rides from a first radial distance 516 at first location 508 (shown in FIG. 5 and clearly at a smaller distance than a radius of shift rail 208 that is defined by outer circumference 512), to second location 514 that is at the outer circumference 512. The motion of shift rail 208, and therefore the movement of ball 602 along line of contact 506, causes ball 602 to shift to the right in FIG. 6. The movement of ball 602 therefore pushes balls 404, pins 410 and 412, and balls 406 to all move to the right as well. As such, any clearance or looseness 606 that may have existed between ball 604 and the surface of shift rail 214 is consumed, and ball 604 is caused to press against the surface of shift rail 214.

[0034] Further and as mentioned, although surfaces 502, 504 are described and illustrated as flat surfaces, it is contemplated that any surface profile for surfaces 502, 504 may suffice, such that surfaces 502, 504 shift in radial location from first radial distance 516 at first location 508 to outer circumference 512 at second location 514. In fact, it is further contemplated that each of rails need not necessarily be cylindrical in shape, as illustrated. Rather, the disclosed system functions for other surface shapes or profiles as well, so long as first radial distance 516 at first location 508 is less than outer circumference 512 at second location 514. Accordingly, the axial shift of each or shift rails 208-214, and in the example shown of shift rail 208, causes movement of the balls in contact therewith to shift due to the change in radial dimension between first location 508 and second location 514.

[0035] In addition, the movement of balls 404 and 406 to the right also causes an upward motion of respective balls 414 and 416. That is, ball 414 moves upward or is at least constrained from any downward movement, and caused to contact the flat of shift rail 210. Likewise, ball 416 moves upward or is at least constrained from any downward movement to contact the flat of shift rail 212. That is, clearances are designed in the unengaged position of all the rails, such that a small total amount of play or clearance (perhaps a few thousandths of an inch in total) occurs between balls 404, between balls 406, between ball 414 and balls 404, and between ball 416 and balls 406. In addition, there is a minor amount of clearance in the overall system of balls, springs, and pins, such that each of balls 434, 602, 414, 418, 420, 416, 436, and 604 are each only loosely in contact with each of their respective flats of each respective shift rail 208-214. Accordingly, when one of shift rails 208-214 is repositioned axially, then this loose contact between all the components is consumed, preventing one of the other shift rails 208-214 from being repositioned axially.

[0036] The position of the components, after the axial movement of shift rail 208, is shown in FIG. 7. Accordingly, when shift rail 208 is axially shifted, ball 602 therefore contacts the outer diameter 512 of shift rail 208, and at second location 514. Ball 434 is similarly in contact with outer circumference 512 of shift rail 208, as well. Thus, balls 434 and 602 are shown as engaged against circumference 512 of shift rail 208. However, because only shift rail 208 has shifted axially, balls 414 and 418 are positioned against the flats of shift rail 210, balls 420 and 416 are positioned against the flats of shift rail 212, and balls 604 and 436 are positioned against the flats of shift rail 214. Thus, the axial movement of shift rail 208 forces all of the balls, pins, and springs as described to tighten up against one another and against the flats of the respective shift rails 210, 212, 214. As such, shift rails 210, 212, and 214 are prevented from any axial movement because respective clearances have been consumed and none of rails 210, 212, and 214 can move. In other words, the balls, springs, and pins are designed having clearances collectively therebetween such that, when one of shift rails 208, 214, such as shift rail 208, moves axially 402, the clearances are consumed. This axial movement causes the parts to mildly compress against one another, and there is no remaining clearance left such that another of the shift rails 210-214 can be moved axially because any such movement would cause an interference fit between the components.

[0037] Further, as mentioned the same action occurs if another of the shift rails 210-214 is moved axially 402 instead of shift rail 208. As also mentioned, each of shift rails 210-214 include two flats as well. Thus, if another of shift rails 210-214 is moved axially, then the respective balls ride up from a flat, along a ridge, to an outer circumference of the shift rail. As such, any of shift rails 208- 214, when moved axially 402, causes the others of the shift rails 208-214 to engage in the same fashion, preventing inadvertent movement of the other shift rails 208-214

[0038] Thus, a transmission having a main shaft and a countershaft 100 includes a gear shift assembly 200. The gear shift assembly 200 includes a main rail 206, and an end block 204 having a plurality of openings passing therethrough. The openings are connected to one another via a plurality of passageways within the end block 304. The gear shift assembly 200 includes a plurality of shift rails 208-214. Each shift rail 208-214 includes an outer surface 512 as defined about a central axis that extends along its length, and an end 500 that includes a first flat surface 502 that extends parallel with the central axis, and a second flat surface 504 that extends parallel with the central axis. The outer surface 512 is at a radial distance that is greater than the radial distance 516 of the first and second flat surfaces. A plurality of balls 404, 406, 414, 416, 418, 420, 434, and 436 are positioned within the plurality of passageways, such that balls 404, 406, 414, 416, 418, 420, 434, and 436 are loosely in contact with one another 404, 406, 414, 416, 418, 420, 434, and 436 and loosely in contact with the first and second flats 502, 504 of each shift rail 208-214. When one of the shift rails 208-214 is repositioned axially 402 during a manual gear shift of the transmission 100, two balls 404, 406, 414, 416, 418, 420, 434, and 436 that are in contact respectively with the first and second flat surfaces 502, 504 of the shift rail that is repositioned engage against the outer surface 512 of the shift rail that is repositioned, forcing the plurality of balls 404, 406, 414, 416, 418, 420, 434, and 436 within the plurality of passageways to engage against each other, preventing any of the other shift rails 208-214 from being able to shift axially 402

[0039] Thus, some balls 404, 406 of the plurality of balls 404, 406, 414, 416, 418, 420, 434, and 436 are positioned along the first axis 408 and between the ends 500 of the first two of the shift rails 208, 214, and some of balls 418, 420 of the plurality of balls 404, 406, 414, 416, 418, 420, 434, and 436 are positioned along the second axis 426 and between the ends 500 of the second two of 210, 212 of the shift rails. One ball 414 is in contact with two balls 404 that are positioned along the first axis 408, and another ball 416 is in contact with two other balls 406 that are positioned along the first axis 408. [0040] Ball 414 is in contact with a flat surface 502 of shift rail 210, and ball 416 is in contact with a flat surface 502 of the of the other shift rail 212. At least one spring 432 is positioned within the first passageway and between the balls 404, 406 therein, causing an outward force against the balls 404 and 406, forcing the balls 404 and 406 against the ends of the first two of the shift rails 208, 214.

[0041] Another spring 428, 430 is positioned within the second passageway and between the balls 418, 420 therein, causing an outward force against the balls 418, 420, forcing the balls 418, 420 against the ends 500 of the second two of the shift rails 210, 212. A first pin 410, 412 is positioned within spring 432, and one or more springs 428, 430 are positioned between rails 210, 212. When one shift rail 208-214 is repositioned axially 402, the plurality of balls 404, 406, 414, 416, 418, 420, 434, and 436 engage each other such that if the any other of the shift rails 208-214 were to shift axially 402 then an interference fit would occur between the balls 404, 406, 414, 416, 418, 420, 434, and 436 and any other of the shift rails 208-214.

[0042] With regard to the processes, systems, methods, heuristics, etc. described herein, it should be understood that, although the steps of such processes, etc. have been described as occurring according to a certain ordered sequence, such processes could be practiced with the described steps performed in an order other than the order described herein. It further should be understood that certain steps could be performed simultaneously, that other steps could be added, or that certain steps described herein could be omitted. In other words, the descriptions of processes herein are provided for the purpose of illustrating certain embodiments, and should in no way be construed so as to limit the claimed invention.

[0043] Accordingly, it is to be understood that the above description is intended to be illustrative and not restrictive. Many embodiments and applications other than the examples provided would be apparent upon reading the above description. The scope of the invention should be determined, not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. It is anticipated and intended that future developments will occur in the technologies discussed herein, and that the disclosed systems and methods will be incorporated into such future embodiments. In sum, it should be understood that the invention is capable of modification and variation.

[0044] All terms used in the claims are intended to be given their broadest reasonable

constructions and their ordinary meanings as understood by those knowledgeable in the technologies described herein unless an explicit indication to the contrary in made herein. In particular, use of the singular articles such as "a," "the," "said," etc. should be read to recite one or more of the indicated elements unless a claim recites an explicit limitation to the contrary.

[0045] Reference in the specification to "one example," "an example," "one approach," or "an application" means that a particular feature, structure, or characteristic described in connection with the example is included in at least one example. The phrase "in one example" in various places in the specification does not necessarily refer to the same example each time it appears.

[0046] The present disclosure has been particularly shown and described with reference to the foregoing illustrations, which are merely illustrative of the best modes for carrying out the disclosure. It should be understood by those skilled in the art that various alternatives to the illustrations of the disclosure described herein may be employed in practicing the disclosure without departing from the spirit and scope of the disclosure as defined in the following claims. It is intended that the following claims define the scope of the disclosure and that the method and apparatus within the scope of these claims and their equivalents be covered thereby. This description of the disclosure should be understood to include all novel and non-obvious

combinations of elements described herein, and claims may be presented in this or a later application to any novel and non-obvious combination of these elements.

[0047] Moreover, the foregoing illustrations are illustrative, and no single feature or element is essential to all possible combinations that may be claimed in this or a later application. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. The invention may be practiced otherwise than is specifically explained and illustrated without departing from its spirit or scope. The scope of the invention is limited solely by the following claims.

Claims

CLAIMS What is claimed is:

1. A transmission having a main shaft and a countershaft, comprising:

a gear shift assembly that includes:

a main rail;

an end block having a plurality of openings passing therethrough, wherein the openings are connected to one another via a plurality of passageways within the end block;

a plurality of shift rails, each shift rail having:

an outer surface as defined about a central axis;

an end that includes a first surface that extends parallel with the central axis, and a second surface that extends parallel with the central axis, the outer surface at a radial distance that is greater than a radial distance of the first and second surfaces; and

a plurality of circular objects positioned within the plurality of passageways, such that circular objects are loosely in contact with one another and loosely in contact with the first and second surfaces of each shift rail;

wherein, when one of the shift rails is repositioned axially during a gear shift of the transmission, two circular objects that are in contact respectively with the first and second surfaces of the shift rail that is repositioned engage against the outer surface of the shift rail that is repositioned, forcing the plurality of circular objects within the plurality of passageways to engage against each other, preventing any of the other shift rails from being able to shift axially.

2. The transmission of claim 1, wherein:

the plurality of passageways includes a first passageway extending along a first axis, and a second passageway extending along a second axis that is approximately parallel with the first axis; ends of a first two of the shift rails pass through openings in the end block that are aligned with the first axis; and

ends of a second two of the shift rails pass through openings in the end block that are aligned with the second axis.

3. The transmission of claim 2, wherein:

some of the circular objects are positioned along the first axis and between the ends of the first two of the shift rails; and

some of the circular objects are positioned along the second axis and between the ends of the second two of the shift rails.

4. The transmission of claim 3, further comprising a first additional circular object that is in contact with two of the circular objects that are positioned along the first axis, and a second additional circular object that is in contact with two other of the circular objects that are positioned along the first axis, wherein the first additional circular object is in contact with one of the first and second surfaces of one of the second two shift rails, and the second additional circular object is in contact with one of the first and second surfaces of the other of the second two shift rails.

5. The transmission of claim 3, wherein at least one spring is positioned within the first passageway and between the circular objects therein, causing an outward force against the circular objects, forcing the circular objects against the ends of the first two shift rails, and wherein another spring is positioned within the second passageway and between the circular objects therein, causing an outward force against the circular objects, forcing the circular objects against the ends of the second two shift rails.

6. The transmission of claim 1, wherein when the one shift rail is repositioned axially, the plurality of circular objects engage each other such that if another of the shift rails were to shift axially then an interference fit would occur between the balls and the another shift rail.

7. The transmission of claim 1, wherein the outer surface of each of the plurality of shift rails is cylindrical.

8. The transmission of claim 1, wherein the first and second surfaces are flat.

9. The transmission of claim 1, wherein the plurality of circular objects are spherical balls.

10. The transmission of claim 1, wherein when the one shift rail is repositioned axially, the two circular objects pass along a line of contact from a first contact location on respective first and second surfaces to a second contact location on the outer surface, consuming clearance between at least the plurality of balls.

11. A method of assembling a gear shift assembly for a transmission, the method comprising: providing an end block having a plurality of holes passing therethrough, wherein the holes are connected to one another via a plurality of passageways within the end block;

positioning a plurality of shift rails within holes of the end block, each shift rail having: an outer surface as defined about a central axis;

positioning a plurality of balls within the plurality of passageways, such that balls are loosely in contact with one another and loosely in contact with the first and second flats of each shift rail; repositioning one of the shift rails during a manual gear shift of the transmission, causing two balls that are in contact respectively with the first and second surfaces of the shift rail that is repositioned to engage against the outer surface of the shift rail that is repositioned; and

forcing the plurality of balls within the plurality of passageways to engage against each other, preventing any of the other shift rails from being able to shift axially.

12. The method of claim 11, wherein the plurality of passageways each includes a first passageway extending along a first axis, and a second passageway extending along a second axis; further comprising:

positioning ends of a first two of the shift rails pass through holes in the end block that are aligned with the first axis; and

positioning ends of a second two of the shift rails pass through holes in the end block that are aligned with the second axis.

13. The method of claim 12, further comprising:

positioning some balls of the plurality of balls along the first axis and between the ends of the first two of the shift rails; and

positioning some of balls of the plurality of balls along the second axis and between the ends of the second two of the shift rails.

14. The method of claim 13, further comprising positioning a first additional ball that is in contact with two balls along the first axis, and positioning a second additional ball that is in contact with two other balls along the first axis.

15. The method of claim 14, wherein the first additional ball is in contact with a surface of one of the second two of the shift rails, and the second additional ball is in contact with a surface of the other of the second two of the shift rails.

16. The method of claim 13, further comprising positioning at least one spring within the first passageway and between the balls therein, causing an outward force against the balls, forcing the balls against the ends of the first two of the shift rails.

17. The method of claim 16, further comprising positioning another spring within the second passageway and between the balls therein, causing an outward force against the balls, forcing the balls against the ends of the second two of the shift rails.

18. The method of claim 17, wherein the first and second surfaces are flat.

19. The method of claim 11, further comprising shifting the rail is axially, and engaging the plurality of balls against each other such that if the any other of the shift rails were to shift axially then an interference fit would occur between the balls and the any other of the shift rails.

20. The method of claim 11, wherein the outer surface of each of the plurality of shift rails is cylindrical.