BR102017020471B1 - TRANSMISSION EQUIPMENT FOR MOUNT TYPE VEHICLE - Google Patents

Abstract

TRANSMISSION EQUIPMENT FOR MOUNT TYPE VEHICLE. In a vehicle-mounted transmission apparatus, the pins (61, 62, 63, 64, 65, and 66) on the first transmission gears (m3, m4, n5, and n6) are engageable and disengageable from the pin holes (101, 102, 103, 104, 105, and 106) in the adjacent second transmission gears to change gear positions. The first transmission gears are sliding in response to angular movement of a shift spindle (47) caused by operation of a shift pedal. The invalid engagement time (TM), during which the pins and pin columns are in sliding contact, at an engine idle speed is in the range of 0ms to 40ms, which provides an improved feel for gear shifting operations and reduces hammering noise.

Description

FIELD OF TECHNIQUE

[0001] The present invention relates to a transmission apparatus for a ride-on type vehicle.

BACKGROUND TECHNIQUE

[0002] Some constant engagement multi-range gear transmissions in vehicles of the mount type include transmission gears with tooth clutches, and the number of pins and the sizes of pins and pin holes of these tooth clutches are specified for the purpose of preventing hammering noise from being produced by the pins as they hit coupling components. If the transmission gears are changed manually, then not only the hammering noise needs to be prevented, but also the required mechanical strength of the dowels has to be achieved and the user's feeling of shifting the transmission gears must be improved.

PRIOR ART DOCUMENTS PATENT DOCUMENT

[0003] Patent Document 1

[0004] Japanese Patent No. 5487065

SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0005] The present invention was developed in order to overcome the above intrinsic problems. It is an object of the present invention to provide a transmission apparatus for a vehicle of the mountable type which can reduce the hammering noise caused by the pins as they hit coupling components when the transmission gears are changed, achieve the required mechanical strength of the pins, and improve the user's feel in shifting the transmission gears.

WAYS TO SOLVE PROBLEMS

[0006] According to the present invention, there is provided a transmission apparatus for a vehicle of the mountable type, which includes: first transmission gears supported on support shafts so as to be non-rotating circumferentially and sliding axially with respect to the support shafts; and second transmission gears supported on support shafts adjacent the first transmission gears so as to be circumferentially rotatable and not axially sliding with respect to the support shafts; the first transmission gears have axially projecting pins; the second transmission gears have axially concavely defined pin holes therein and pin columns defining the pin holes; the pegs are engageable and disengageable from the peg holes to change gear positions; the first transmission gears are slippery in response to angular movement of a shift spindle caused by operation of a shift pedal; wherein an invalid engagement time during which the facing wall surfaces of the dowels and the facing wall surfaces of the dowel strings are contiguous and slide past each other at an engine idle rotation speed is in the range 0 ms (millisecond) to 40 ms, the number of the dowel strings is in the range 11 to 19, and the number of the dowel strings is in the range 11 to 19.

[0007] With the above arrangement, the invalid engagement time during which the pegs and the peg columns are contiguous and slide into each other is reduced, thus reducing the hammering noise of the pegs, making gear shifting operations smooth to provide an improved feel to the pegs. Both the dowels and the dowel columns are of a minimum size to handle torques that can be transmitted by the transmission apparatus, and the numbers of the dowels and dowel columns are increased to achieve the required mechanical strength of the dowels and dowel columns. The dowel clearance angle is reduced to reduce the hammering noise produced when the dowels engage the dowel columns and also to reduce the wobble and play caused when the dowels engage the dowel columns.

[0008] In the above arrangement, the number of pegs can be in the range of 11 to 19, and the number of peg columns can be in the range of 11 to 19.

[0009] With this arrangement, the number of dowels and the number of dowel columns are thus optimized to achieve the required mechanical strength of the dowels and dowel columns. The dowel clearance angle is reduced to reduce the hammering noise produced when the dowels engage with the dowel columns and also to reduce wobble and play caused when the dowels engage with the dowel columns.

[0010] In the above arrangement, a dowel taper angle between the line segments extending from the center of rotation of the transmission gears through the contact points on both sides of the dowels, where the dowels and the dowel columns are adjacent to each other, may be in the range of 6 degrees to 9 degrees, and a dowel column narrowing angle between the line segments extending from the center of rotation of the transmission gears through the contact points at both sides of the dowel columns where the dowel columns and the dowels are adjacent to each other can be in the range of 6 degrees to 9 degrees.

[0011] With this arrangement, the dowel narrowing angle and the dowel column narrowing angle that are in the range of 6 degrees to 9 degrees allows the numbers of dowels and the number of dowel columns to increase, so that the invalid engagement time can be decreased to make gear shifting operations smooth.

[0012] In the above arrangement, a clearance angle between the dowels and the dowel columns can be in the range of 0 degrees to 15 degrees.

[0013] With this arrangement, as the clearance angle between the pegs and the peg columns is a small angle from 0 degrees to 15 degrees, it is possible to increase the number of pegs and reduce the invalid engagement time for an improved feel for gear shifting operations.

[0014] In the above arrangement, the dowels may include inner circumferential gusset rings and dowel backplates, and the dowel posts may include outer circumferential gusset rings and dowel column backplates.

[0015] With this arrangement, the dowels include the inner circumferential gusset rings and the dowel column back plates, and the dowel columns include the outer circumferential gusset rings and the dowel column back plates. Therefore, the mechanical strength of the dowels and dowel columns is increased.

[0016] The contiguous surfaces of the pins to contact the pin columns against each other can be widened from line segments that extend from the center of rotation of the transmission gears through points of contact between the pins and the columns of pins, and the contiguous surfaces of the columns of pins to contact against the pins can be enlarged from line segments that extend from the center of rotation of the transmission gears through points of contact between the dowels and the dowel columns.

[0017] With the above arrangement, the mechanical strength of the dowel base ends of the dowels and the dowel column base ends of the dowel columns is increased for an increase in the mechanical strength of the dowels and the mechanical strength of the dowel columns.

[0018] In the above arrangement, the length from the pitch circle of the dowels and dowel columns to the dowel point ends of the dowels may be less than the length from the pitch circle of the dowels and dowel columns to the dowel base ends of the dowels, and the length from the pitch circle of the dowels and dowel columns to the dowel column ends of the dowel columns may be less than the length from the pitch circle of the dowels and dowel columns to the dowel column base ends of the dowel columns.

[0019] With this arrangement, the mechanical strength of the dowel base ends and dowel column base ends is further increased to further increase the mechanical strength of the dowels and dowel columns in their entirety.

[0020] In the above arrangement, of the contiguous surfaces of the dowels and the dowel columns that are contiguous with each other, the contiguous surfaces of any of the dowels or the dowel columns are straight while the contiguous surfaces of the others are curved as viewed along the axis of rotation of the transmission gears.

[0021] With this arrangement, of the adjoining surfaces of the dowels and dowel columns that are adjacent to each other, the adjoining surfaces of any of the dowels or dowel columns are straight while the adjoining surfaces of the others are curved. Therefore, variations in the radii of the contact points between the pins and the pin columns from the center of rotation of the transmission gears are reduced, which tends to uniform the stresses in the pins and in the pin columns.

[0022] The inflection points on the dowel columns between the curved surfaces of the dowel column base ends of the dowel columns and the adjoining surfaces thereof may be positioned radially outward from the inflection points on the dowels between the curved surfaces of the dowel end ends of the dowels and the adjacent surfaces of the dowels, and the inflection points on the dowels between the curved surfaces of the dowel base ends of the dowels s and the adjoining surfaces thereof may be positioned radially inwardly at the inflection points in the dowel columns between the dowel column tip end curved surfaces of the dowel columns and the adjoining surfaces thereof.

[0023] With this arrangement, the dowels and dowel columns can be brought closer together, making it possible to increase the numbers of dowels and dowel columns.

ADVANTAGEOUS EFFECTS OF THE INVENTION

[0024] According to the present invention, the numbers of dowels and dowel columns are increased to achieve the required mechanical strength of dowels and dowel columns. The invalid engagement time is reduced to thereby reduce the peg hammering noise, making gear shifting operations smoother to provide an improved peg feel. Both the dowels and the dowel columns are of a minimum size to handle torques that can be transmitted by the transmission apparatus, and the numbers of the dowels and dowel columns are increased to reduce the dowel gap angle to reduce the hammering noise produced when the dowels engage with the dowel columns and also to reduce the wobble and play caused when the dowels engage with the dowel columns.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a vertical cross-sectional view of an internal combustion engine incorporating a transmission apparatus for a mountable vehicle according to an embodiment of the present invention;

[0026] Figure 2 is a cross-sectional view taken along line II-II of Figure 1;

[0027] Figure 3 is an enlarged fragmentary cross-sectional view of the transmission apparatus shown in Figure 2;

[0028] Figure 4 is a side elevation view of the left side of an n5 transmission gear;

[0029] Figure 5 is a side elevation view of the right side of an n1 transmission gear;

[0030] Figure 6 is a side elevation view showing an engaged state of transmission gear n5 and transmission gear n1 in a first gear position;

[0031] Figure 7 is an enlarged fragmentary view of Figure 4;

[0032] Figure 8 is an enlarged fragmentary view of Figure 5;

[0033] Figure 9 is an enlarged fragmentary view of Figure 6;

[0034] Figure 10 is a side elevation view of the right side of an n6 transmission gear;

[0035] Figure 11 is a side elevation view of the left side of an n2 transmission gear;

[0036] Figure 12 is a side elevation view representing an engaged state of transmission gear n6 and transmission gear n2 in a second gear position;

[0037] Figure 13 is a side elevation view of the right side of transmission gear n5;

[0038] Figure 14 is a side elevation view of the left side of an n3 transmission gear;

[0039] Figure 15 is a side elevation view showing an engaged state of transmission gear n5 and transmission gear n3 in a third gear position;

[0040] Figure 16 is a side elevation view of the left side of transmission gear n6;

[0041] Figure 17 is a side elevation view of the right side of an n4 transmission gear;

[0042] Figure 18 is a side elevation view representing an engaged state of transmission gear n6 and transmission gear n4 in a fourth gear position;

[0043] Figure 19 is a side elevation view of the left side of an m3 transmission gear;

[0044] Figure 20 is a side elevation view of the right side of an m5 transmission gear;

[0045] Figure 21 is a side elevation view showing an engaged state of transmission gear m3 and transmission gear m5 in a fifth gear position;

[0046] Figure 22 is a side elevation view of the right side of an M4 transmission gear;

[0047] Figure 23 is a side elevation view of the left side of an M6 transmission gear;

[0048] Figure 24 is a side elevation view showing an engaged state of transmission gear m4 and transmission gear m6 in a sixth gear position;

[0049] Figures 25 are views representing how the shift spindle angle α, the barrel angle β and the shift pedal load F vary during the shift time T for an invalid engagement time of 0 ms;

[0050] Figures 26 are views representing how the shift spindle angle α, the barrel angle β and the shift pedal load F vary during the shift time T for an invalid engagement time of 5 ms;

[0051] Figures 27 are views representing how the shift spindle angle α, the barrel angle β and the shift pedal load F vary during the shift time T for an invalid engagement time of 10 ms;

[0052] Figures 28 are views representing how the shift spindle angle α, the barrel angle β and the shift pedal load F vary during the shift time T for an invalid engagement time of 15 ms;

[0053] Figures 29 are views representing how the shift spindle angle α, the barrel angle β and the shift pedal load F vary during the shift time T for an invalid engagement time of 30 ms;

[0054] Figures 30 are views representing how the shift spindle angle α, the barrel angle β and the shift pedal load F vary during the shift time T for an invalid engagement time of 35 ms;

[0055] Figures 31 are views representing how the shift spindle angle α, the barrel angle β and the shift pedal load F vary during the shift time T for an invalid engagement time of 40 ms;

[0056] Figures 32 are views representing how the shift spindle angle α, the barrel angle β and the shift pedal load F vary during the shift time T for an invalid engagement time of 55 ms;

[0057] Figures 33 are views representing how the shift spindle angle α, the barrel angle β and the shift pedal load F vary during the shift time T for an invalid engagement time of 75 ms;

[0058] Figures 34 are views representing how the shift spindle angle α, the barrel angle β and the shift pedal load F vary during the shift time T for an invalid engagement time of 100 ms; It is

[0059] Figures 35 are views that represent how the shift spindle angle α, the barrel angle β and the shift pedal load F vary during the shift time T for an invalid engagement time of 120 ms.

METHOD OF CARRYING OUT THE INVENTION

[0060] A transmission apparatus 30 for a ride-on type vehicle, according to an embodiment of the present invention, will be described below with reference to the drawings. The transmission apparatus 30 according to the present embodiment will be described as Invention Example 1.

[0061] The transmission apparatus 30 for a vehicle of the type to be mounted, according to the present embodiment, is applied to a constant engagement multi-range gear transmission positioned in the drive train to transmit power from an internal combustion engine E on a motorcycle, not shown, to a drive wheel thereof.

[0062] The internal combustion engine E includes an in-line two-cylinder four-stroke internal combustion engine that has two cylinders arranged in a series. The internal combustion engine E is mounted transversely on the motorcycle with its crankshaft 10 oriented laterally. In the following description, the direction in which the motorcycle moves forward is referred to as a forward direction, the direction opposite the forward direction as a backward direction, the left-hand direction when looking in the forward direction as a left-hand direction, and the right-hand direction when looking in the forward direction as a right-hand direction.

[0063] Figure 1 is a vertical cross-sectional view of the internal combustion engine E, and Figure 2 is a developed cross-sectional view of the internal combustion engine E. As shown in Figure 1, the internal combustion engine E has a drive case 1 that includes a crankcase 1c that defines therein a crank chamber CR that houses the crankshaft 10 and a transmission case 1m that defines therein a transmission chamber M that houses the transmission apparatus 3 0, crankcase 1c and gearbox 1m being integrally formed in forward and reverse directions. The unit box 1 is itself of a vertically divided structure including an upper unit box 1a and a lower unit box 1b, which divides the transmission box 1m into upper and lower transmission boxes 11m.

[0064] An integrally formed cylinder block 2, which has two cylinder bores 2c shown in Figure 2 that are arranged in a line, extends upwards from an upper portion of the upper unit box 1a and is slightly inclined forward, as shown in Figure 1. A cylinder head 3 is mounted on the cylinder block 2 and covered with a cylinder cover 4. An oil sump 5 is attached to a lower portion of the unit box 1.

[0065] As shown in Figure 2, pistons 11 are slidably fitted mutually in the respective two cylinder bores 2c in the cylinder block 2. The pistons 11 are coupled to the crankshaft 10 by respective connecting rods 12.

[0066] The cylinder head 3 has combustion chambers 13 defined therein in relation to the respective pistons 11 in the cylinder bores 2c, intake holes 14 extending backwards that are opened in the combustion chambers 13 and can be selectively opened and closed by a pair of intake valves, not shown, and exhaust ports 15 that extend forwards that can be opened and closed selectively by a pair of valves exhaust, not shown. Spark plugs, not shown, exposed to the combustion chambers 13 are mounted.

[0067] The intake valves and exhaust valves are driven by a camshaft 20 rotatably supported in the cylinder head 3 in synchronism with the rotation of the camshaft 20. As shown in Figure 2, a cam sprocket 21 is fitted over a right end 20a of the camshaft 20, and a drive sprocket 17 is fitted over the crankshaft 10 next to a portion of right end 10a thereof. A timing chain 22 is drawn around cam sprocket 21 and drive sprocket 17 to transmit power from crankshaft 10 to camshaft 20 to rotate camshaft 20 about its own axis at a turning speed that is half the turning speed of crankshaft 10.

[0068] The crankshaft 10 is rotatably supported by main bearings 18 interposed between the upper unit box 1a and the lower unit box 1b. The crankshaft 10 has a left end portion which extends through a left side wall of the crankcase 1c. An alternator 28 includes an outer rotor 28r fitted over the left end portion of the crankshaft 10 and an inner stator 28s housed in the outer rotor 28r and supported by an alternator shroud 29 which is positioned over a left hand portion of the alternator 28, the inner stator 28s having alternator generating coils 28.

[0069] As shown in Figure 1, the transmission chamber M is defined in the transmission case 1m behind the crank chamber CR of the crankcase 1c that houses the crankshaft 10 in it.

[0070] The transmission apparatus 30 housed in the transmission chamber M includes a constant engagement selective slip gear transmission. The transmission apparatus 30 includes a mainshaft 31 rotatably supported in left and right bearing portions of the upper gearbox 11m by a pair of ball bearings 32 rearward and obliquely upwards of the crankcase shaft 10 (see Figure 2), and an intermediate shaft 35 rotatably supported in and pressed between semi-arched bearing portions in the mating surfaces of the upper and lower gearboxes 11m by a ball bearing 3 6 and needle bearings 37, in a rear position of crankcase shaft 10 (see Figure 2).

[0071] As shown in Figure 2, the mainshaft 31 has a right end portion projecting from the transmission chamber M with a multi-plate friction clutch 34 mounted thereon that includes a large diameter clutch outer 34o and a small diameter clutch inner 34i. A primary speed reducer mechanism 33 includes a primary driven gear 33b co-rotatably supported on the outside of clutch 34o and a primary drive gear 33a co-rotatably supported on the right end portion 10a of the crankshaft 10 extending through a right side wall of the crankcase 1c, the primary driven gear 33b and the primary drive gear 33a being held in engagement with each other.

[0072] The inside of the clutch 34i, which serves as an output component of the friction clutch 34, which is fitted by splines to the mainshaft 31. Therefore, the rotation of the crankshaft 10 is transmitted through the primary speed reducer mechanism 33 and the friction clutch 34 to the mainshaft 31. The friction clutch 34 in the right end portion of the mainshaft 31 is covered with a right box cover 6 positioned over it in a position on the right side of friction clutch 34.

[0073] The rotation of the main shaft 31 is transmitted to the intermediate shaft 35 through an interlocking engagement between the transmission gears m1 to m6 on the drive side of the transmission apparatus 30 and the transmission gears n1 to n6 on the driven side thereof. The idler shaft 35, which serves as an output shaft of the transmission apparatus 30, has a left end portion projecting out through a left side wall of the drive case 1. An output sprocket 38 is fitted over the left end portion projecting from the idler shaft 35. A power transmission chain 39 is drawn around the output sprocket 38 and a drive sprocket on the rear wheel of the motorcycle, not shown. The output sprocket 38, the power transmission chain 39 and the driven sprocket together constitute a secondary speed reducing mechanism which transmits the power from the transmission apparatus 30 to the rear wheel.

[0074] As shown in Figure 3, the transmission apparatus 30 has a transmission gear train G disposed in the transmission chamber M. The transmission gear train G includes the six drive transmission gears m1 to m6 and the six drive transmission gears n1 to n6. The drive gears m1 to m6 providing gear ratios for the first to sixth gear positions are supported on the mainshaft 31 of the transmission apparatus 30. Of these drive gears m1 to m6, the transmission gears m1 and m2 are formed integrally with the mainshaft 31, the transmission gears m3 and m4 are fitted by splines to the mainshaft 31 so that they are axially sliding, but circumferentially not rotatable on the mainshaft 31, and transmission gears m5 and m6 are mounted on the mainshaft 31 so that they are not axially sliding, but not circumferentially rotating on the mainshaft 31.

[0075] The driven transmission gears n1 to n6 are supported on the intermediate shaft 35 in engagement with the drive transmission gears m1 to m6, respectively. Among these driven transmission gears n1 to n6, the driven transmission gears n1, n2, n3 and n4 are mounted on the intermediate shaft 35 so that they are not axially sliding, but circumferentially rotating on the intermediate shaft 35, and the driven transmission gears n5 and n6 are fitted by splines to the intermediate shaft 35 so that they are axially sliding, but not circumferentially rotating on the intermediate shaft 35.

[0076] The interlacing transmission gears m1 and n1 that provide the highest clutch ratio are arranged in a leftmost position along a left sidewall M1 of the transmission chamber M. The interlacing transmission gears m2 and n2 are arranged in a more rightmost position along a right sidewall M2 of the transmission chamber M. The gear m4 and n4 and the interlocking transmission gears m6 and n6 are arranged successively from left to right between the interlacing transmission gears m1 and n1 and the interlacing transmission gears m2 and n2. Drive gears m3 and m4 which are axially sliding and driven drive gears n5 and n6 which are axially sliding have grooves 50a, 50b, 50c and 50d defined therein for engagement with shift forks 43a, 43b, 43c and 43d of a drive gear change mechanism 40 to be described later. The drive transmission gears m3 and m4 and the driven transmission gears n5 and n6 are axially moved when the transmission gear change mechanism 40 is actuated.

[0077] The transmission gears m5 and m3 are arranged adjacent to each other on the main shaft 31. The transmission gears m4 and m6 are arranged adjacent to each other on the main shaft 31. The transmission gears m3 and m4 have pins 65 and 66 that project axially from lateral surfaces thereof, and the transmission gears m5 and m6 have columns of pins 95 and 96 arranged on lateral surfaces thereof for engagement in contact with the same dowels 65 and 66, respectively, and dowel holes 105 and 106 defined axially concavely in the side surfaces thereof by dowel posts 95 and 96 for receiving dowels 65 and 66, respectively.

[0078] When the drive gear M3 is moved axially to the left, the pins 65 engage in the pin holes 105 as the facing wall surfaces 65a of the pins 65 adjoin and slide against the facing wall surfaces 95a of the pin posts 95. When the drive gear M4 is moved axially to the right, the pins 66 engage in the pin holes 1 05 as the facing wall surfaces 66a of the dowels 66 abut and slide against the facing wall surfaces 96a of the dowel posts 96.

[0079] Transmission gears n1 and n5 are arranged adjacent to each other on the intermediate shaft 35. Transmission gears n5 and n3 are arranged adjacent to each other on the intermediate shaft 35. Transmission gears n4 and n6 are arranged adjacent to each other on the intermediate shaft 35. Transmission gears n6 and n2 are arranged adjacent to each other on the intermediate shaft 35. Transmission gears n5 and n6 have pins 61, 62, 63 and 64 projecting from the lateral surfaces thereof, and the transmission gears n1, n3, n4 and n2 have pin columns 91, 92, 93 and 94 disposed on the lateral surfaces thereof for engagement in contact with the pins 61, 62, 63 and 64, respectively, and the pin holes 101, 102, 103 and 104 defined axially concavely placed on the lateral surfaces thereof by the dowel columns 91, 92, 93 and 94 to receive the dowels 61, 62, 63 and 64, respectively.

[0080] When drive gear n5 is moved axially to the left, the dowels 61 engage with the dowel holes 101 as the facing wall surfaces 61a of the dowels 61 adjoin and slide against the facing wall surfaces 91a of the dowel columns 91. When drive gear n5 is moved axially to the right, the dowels 63 engage with the dowel holes 1 03 conforms to the facing wall surfaces 63a of the adjoining dowels 63 and slides against the facing wall surfaces 93a of the dowel posts 93. When drive gear n6 is moved axially to the left, the dowels 64 engage the dowel holes 104 as the facing wall surfaces 64a of the dowels 64 adjoin and slide against the facing wall surfaces 94a of the dowel columns pin 94. When drive gear n6 is moved axially to the right, pins 62 engage pin holes 102 along the facing wall surfaces 62a of the adjacent pins 62 and slide against the facing wall surfaces 92a of the pin posts 92.

[0081] As shown in Figures 1 and 2, the transmission gear change mechanism 40 for changing the gears of the transmission apparatus 30 includes a shift yoke shaft 41 having opposite ends fitted and supported by the left and right bearing portions 42 of the upper transmission case 11 m behind the main shaft 31. The transmission gear change mechanism 40 also includes a shift drum 45 rotatably supported on left and right bearing portions from upper gearbox 11m through bearings 46 below shift fork shaft 41.

[0082] A shift spindle 47 is rotatably supported in the left and right bearing portions of the upper gearbox 11m by the bearings 48 forward and slightly obliquely downwards from the shift drum 45.

[0083] The shift drum 45 has four shift grooves 45a, 45b, 45c and 45d defined on an outer circumferential surface thereof at axially spaced intervals, and a first shift fork 43a, a second shift fork 43b, a third shift fork 43c and a fourth shift fork 43d are axially slidably supported on the shift fork shaft 41 and have respective shift pins that engage in shift slots 45a, 45b, 45c and 45d.

[0084] The shift drum 45 is rotated around its own axis when an angular movement of the shift spindle 47 through a given angle is transmitted to the shift drum 45 by a linkage mechanism 49. A shift pedal, not shown, is operatively coupled to the shift spindle 47 through a ratchet mechanism, not shown. When the motorcycle rider operates the shift pedal (not shown) the shift spindle 47 is rotated around its own axis through a given angle in a desired direction, which rotates the shift drum 45 around its own axis through a corresponding angle.

[0085] When the shift drum 45 is thus rotated by the driver-operated shift pedal, the second shift fork 43b and the third shift fork 43c are axially moved being guided by the second shift groove 45b and the third shift groove 45c, which axially move the transmission gear m3 and the transmission gear m4 on the main shaft 31, and the first shift fork 43a and the fourth shift fork 43d are axially moved being guided by the first shift slot 45a and the fourth shift slot 45d, which axially move drive gear n5 and drive gear n6 on the intermediate shaft 35. In this way, the pins and pin holes of desired transmission gears are brought into and out of engagement, which selects a set of transmission gears to shift the transmission apparatus 30 to a desired gear position to effectively transmit power from the crankshaft 10 to the rear wheel.

[0086] The shapes of the drive transmission gears m3 to m6 and the driven transmission gears n1 to n6 of the transmission apparatus 30 and the engaged states of the transmission gears m3 to m6, and n1 to n6 in the respective gear positions are illustrated in Figures 4 to 24, and various conditions for the transmission gears are represented in Table 1 below.

[0087] The driven transmission gears n1 and n5 that engage each other in the first gear position will be described in detail below as an example of gears of the transmission apparatus 30 with reference to Figures 3 to 6. Figure 4 is a side elevation view of the left side of transmission gear n5, Figure 5 is a side elevation view of the right side of transmission gear n1, and Figure 6 is a side elevation view representing an engaged state of transmission gear n5 and gear transmission number 1 in first gear position. As shown in Figure 3, drive gears n1 and n5 are disposed adjacent to each other on idler shaft 35. When the driver operates the shift pedal to select the first gear position, the first shift fork 43a of drive gear change mechanism 40 is moved to the left, moving drive gear n5 to the left to thereby bring drive gears n1 and n5 into engagement with each other.

[0088] As shown in Figures 3 and 4, the transmission gear n5 has on its left side surface twelve angularly spaced pegs 61 that project axially therefrom along the intermediate axis 35. The pegs 61 have respective surfaces located perpendicular to the intermediate axis 35 as the facing wall surfaces 61a that face the peg columns 91.

[0089] Each of the pins 61 has two contact points P on both its sides where the pin 61 and the adjacent pin columns 91 are contiguous with each other, and the angle between two line segments extending from the center C of rotation of the transmission gear n5 through the contact points P will be referred to as the pin narrowing angle θ1. In transmission gear n5, according to the present embodiment, the pin narrowing angle θ1 is set to 7.4 degrees.

[0090] The dowel 61 has adjoining surfaces 61d respectively on both sides thereof to adjoin the dowel columns 91. The adjoining surfaces 61d are widened or angularly spaced from line segments extending from the center C of rotation of transmission gear n5 through the contact points P by an angle referred to as the dowel flare angle θ4. In drive gear n5, according to the present embodiment, the pin flare angle θ4 is set to 25 degrees.

[0091] As shown in Figures 3 and 5, the transmission gear n1 has on its right side surface twelve angularly spaced pin columns 91 projecting axially therefrom along the intermediate axis 35. The pin columns 91 have respective surfaces located perpendicular to the intermediate axis 35 as the facing wall surfaces 91a that face the pins 61 of the transmission shaft n5. The pin columns 91 define therebetween twelve angularly spaced pin holes 101 in which the pins 61 of drive gear #5 can engage.

[0092] As shown in Figure 5, each of the dowel columns 91 has two contact points P on both sides of it in which the dowel column 91 and the adjacent dowels 61 are contiguous with each other, and the angle between two line segments extending from the center C of rotation of the transmission gear 15 through the contact points P will be referred to as the dowel column narrowing angle θ2. In transmission gear n1, according to the present embodiment, the pin column narrowing angle θ2 is set to 7.4 degrees.

[0093] The dowel column 91 has adjoining surfaces 91d on both its sides to adjoin the dowels 61. The adjoining surfaces 91d are widened or angularly spaced from the line segments extending from the center C of rotation of the transmission gear n1 through the contact points P by an angle referred to as the dowel column widening angle θ5. In transmission gear n1, according to the present embodiment, the dowel column flare angle θ5 is set to 25 degrees.

[0094] As shown in Figure 6, when the dowels 61 engage the respective dowel holes 101, the dowels 61 can move in the dowel holes 101 through the clearance angle θ3. According to the present embodiment, the clearance angle θ3 is set to 14.8 degrees.

[0095] As shown in Figure 4, each of the dowels 61 on the left side surface of drive gear n5 has a length "a" from a pitch circle PC of the dowels 61 and dowel columns 91 to a dowel tip end 61b, and a length "b" from the pitch circle PC to a dowel base end 61c, the length "a" is less than the length "b", for example, the ratio a < b is satisfied. As shown in Figure 5, each of the dowel columns 91 on the right side surface of transmission gear n1 has a length "c" from the pitch circle PC to a point end of dowel column 91b, and a length "d" from the pitch circle PC to a base end of dowel column 91c, the length "c" being less than the length "d", for example, the relationship c < d is satisfied.

[0096] As shown in Figures 6 to 9, one of the contiguous surfaces 61d and 91d of the pins 61 and the pin columns 91 is curved while the other is straight as viewed along the axis of rotation of the transmission gears. According to the present embodiment, the adjoining surfaces 61d of the pegs 61 are curved, while the adjoining surfaces 91d of the peg columns 91 are straight.

[0097] Figure 7 represents an IP61a inflection point on each pin 61 of transmission gear n5 between a curved surface of the pin tip end 61b of the pin 61 and the adjoining surface 61d thereof to be adjacent to a pin column 91, and an IP61b inflection point on the pin 61 between a curved surface of the pin base end 61c of the pin 61 and the adjoining surface 61d thereof. Figure 8 shows a point of inflection IP91a on each pin column 91 of transmission gear n1 between a curved surface of the pin column tip end 91b of the pin column 91 and the adjoining surface 91d thereof for adjoining a pin 61, and an inflection point IP91b on the pin column 91 between a curved surface of the base end of the pin column 91c of the pin column pellicle 91 and adjoining surface 91d thereof.

[0098] As depicted in Figure 9, the IP91b inflection point is positioned radially outward from the IP61a inflection point, while the IP61b inflection point is positioned radially inward from the IP91a inflection point. Therefore, the pegs 61 and the peg columns 91 can be brought closer together, making it possible to increase the numbers of pegs 61 and peg columns 91.

[0099] As shown in Figure 4, drive gear n5 has an internal circumferential reinforcement ring 71 that joins the radially inward portions of the twelve pins 61. As also shown in Figure 3, drive gear n5 also has a pin back plate 81 on one side thereof opposite the side thereof from which the pins 61 protrude, the pin back plate 81 joins and reinforces the pins 61 and the inner circumferential bolster ring 71. As shown in Figure 5, drive gear #1 has an outer circumferential bolster ring 111 that joins the radially outward portions of the twelve dowel posts 91. As also shown in Figure 3, drive gear #1 also has a dowel post backplate 121 opposite the dowel posts 91, the dowel post backplate 121 joins and reinforces the dowel posts. peg 91 and outer circumferential reinforcement ring 111.

[00100] Drive gear n6 and drive gear n2 meshing with each other in the second gear position, drive gear n5 and drive gear n3 meshing with each other in the third gear position, drive gear n6 and drive gear n4 meshing with each other in the fourth gear position, drive gear m3 and drive gear m5 meshing with each other in the fifth gear position, and drive gear m4 and drive gear m6 meshing with each other in the sixth gear position will be described below.

[00101] Transmission gear N6 and transmission gear N2 that engage with each other in the second gear position are represented in figures 10 to 12. Figure 10 is a side elevation view of the N6 transmission gear, Figure 11 is a side elevation view of the left transmission gear and Figure 12 is a lateral elevation view of transmission gear N6 and 2 in second gear position. As shown in Figures 10 through 12, drive gear n6 has pins 62, an inner circumferential bolster ring 72, and a pin back plate 82, and drive gear n2 has pin posts 92, pin holes 102, an outer circumferential bolster ring 112, and a pin back plate 122. As shown in Figure 3, drive gear n6 and gear drive gear n2 are arranged adjacent to each other on idler shaft 35. When the driver operates the shift pedal to select the second gear position, the fourth shift fork 43d of drive gear change mechanism 40 is moved to the right, moving drive gear n6 to the right until drive gear n6 and drive gear n2 engage each other.

[00102] Transmission gear N5 and N3 transmission gear that engage with each other in third gear position are represented in Figures 13 to 15. Figure 13 is a lateral elevation view of the N5 transmission gear, Figure 14 is a side elevation on the left side of the N3 transmission gear and Figure 15 is a lateral elevation view of transmission gear N5 and transmission. N3 in third gear position. As shown in Figures 13 to 15, drive gear n5 has pins 63, an inner circumferential bolster ring 73, and a pin back plate 83, and drive gear n3 has pin posts 93, pin holes 103, an outer circumferential bolster ring 113, and a pin back plate 123. drive gear n3 are arranged adjacent to each other on the idler shaft 35. When the driver operates the shift pedal to select the third gear position, the first shift fork 43a of drive gear shift mechanism 40 is moved to the right, moving drive gear n5 to the right until drive gear n5 and drive gear n3 engage each other.

[00103] Transmission gear N6 and transmission gear N4 that engage with each other in fourth gear position are represented in figures 16 to 18. Figure 16 is a side elevation view of the left transmission gear, Figure 17 is a lateral elevation view of the N4 transmission gear and Figure 18 is a lateral elevation view of transmission gear N6 and 4 In fourth gear position. As shown in Figures 16 through 18, drive gear n6 has pins 64, an inner circumferential bolster ring 74, and a pin back plate 84, and drive gear n4 has pin posts 94, pin holes 104, an outer circumferential bolster ring 114, and a pin back plate 124. As shown in Figure 3, drive gear n6 and drive gear n 4 are disposed adjacent to each other on the intermediate shaft 35. When the driver operates the shift pedal to select the fourth gear position, the fourth shift fork 43d of transmission gear change mechanism 40 is moved to the left, moving transmission gear n6 to the left until transmission gear n6 and transmission gear n4 engage with each other.

[00104] M3 transmission gear and M5 transmission gear that engage with each other in the fifth gear position are represented in figures 19 to 21. Figure 19 is a lateral lift view of the left side of the M3 transmission gear, the right side of the m5 transmission gear and Figure 21 is a lateral elevation view that represents m3 transmission gear. 5 In the fifth position of gear. As shown in Figures 19 to 21, drive gear m3 has pins 65, an inner circumferential bolster ring 75, and a pin back plate 85, and drive gear m5 has pin posts 95, pin holes 105, an outer circumferential bolster ring 115, and a pin back plate 125. As shown in Figure 3, drive gear m3 and a drive gear m5 are arranged adjacent to each other on the mainshaft 31. When the driver operates the shift pedal to select the fifth gear position, the second shift fork 43b of transmission gear shift mechanism 40 is moved to the left, moving drive gear m3 to the left until drive gear m3 and drive gear m5 engage with each other.

[00105] M4 transmission gear and M6 transmission gear that engage with each other in the sixth gear position are represented in figures 22 to 24. Figure 22 is a lateral lift view of the m4 transmission gear, Figure 23 is a side elevation view of the left transmission gear and Figure 24 is a lateral elevation view that represents m4 gear and m gear. 6 in the sixth position of gear. As shown in Figures 22 through 24, drive gear m4 has pins 66, an inner circumferential bolster ring 76, and a pin back plate 86, and drive gear m6 has pin posts 96, pin holes 106, an outer circumferential bolster ring 116, and a pin back plate 126. As shown in Figure 3, drive gear m4 and a drive gear m6 are arranged adjacent to each other on the mainshaft 31. When the driver operates the shift pedal to select the sixth gear position, the third shift fork 43c of transmission gear shift mechanism 40 is moved to the right, moving drive gear m4 to the right until drive gear m4 and drive gear m6 engage each other.

[00106] The pins 62, 63, 64, 65 and 66 on the right side surface of transmission gear n6, on the right side surface of transmission gear n5, on the left side surface of transmission gear n6, on the left side surface of transmission gear m3 and on the right side surface of transmission gear m4 have a length “a” from the pitch circle PC to the ends of pin ends 62b, 63b, 64b, 65b and 66b thereof, and a length "b" from the pitch circle PC to the base ends of dowels 62c, 63c, 64c, 65c and 66c thereof, the length "a" being less than the length "b", for example, a < b.

[00107] The dowel columns 92, 93, 94, 95 and 96 on the left side surface of transmission gear n2, on the left side surface of transmission gear n3, on the right side surface of transmission gear n4, on the right side surface of transmission gear m5 and on the left side surface of transmission gear m6 have a length “c” from the pitch circle PC to the ends of ends of dowel columns 92b, 93b, 9 4b, 95b and 96b thereof, and a length "d" from the pitch circle PC to the base ends of dowel columns 92c, 93c, 94c, 95c and 96c thereof, the length "c" being less than the length "d", for example, c < d.

[00108] Since the length “b” from the pitch circle PC to the base ends of dowels 62c, 63c, 64c, 65c, and 66c is greater than the length “a” from the pitch circle PC to the ends of dowel tips 62b, 63b, 64b, 65b and 66b, and the length “d” from the pitch circle PC to the base ends of the columns 92c, 93c, 94c, 95c, and 96c is greater than the length "c" from the pitch circle PC to the ends of the ends of the dowel columns 92b, 93b, 94b, 95b and 96b, the dowels 62, 63, 64, 65 and 66 and the dowel columns 92, 93, 94, 95 and 96 have their mechanical strength increased.

[00109] In addition, the IP92b, IP93b, IP94b, IP95b and IP96b inflection points between the curved surfaces of the base ends of dowel columns 92c, 93c, 94c, 95c and 96c of dowel columns 92, 93, 94, 95 and 96 and the adjacent surfaces 92d, 93d, 94d, 95d and 96d of the dowel columns 92, 93, 94, 95 and 96 to adjoin the dowels 62, 63, 64, 65 and 66 are positioned radially outward from the inflection points IP62a, IP63a, IP64a, IP65a and IP66a between the curved surfaces of the end ends of dowel tips 62b, 63b, 64b, 65b and 66b of the pegs 62, 63, 64, 65 and 66, and the adjoining surfaces 62d, 63d, 64d, 65d and 66d of the pegs 62, 63, 64, 65 and 66 to adjoin the peg columns 92, 93, 94, 95 and 96.

[00110] In addition, the IP62b, IP63b, IP64b, IP65b and IP66b inflection points between the curved surfaces of the base ends of dowels 62c, 63c, 64c, 65c and 66c of dowels 62, 63, 64, 65 and 66, and the adjacent surfaces 62d, 63d, 64 d, 65d and 66d of the dowel posts 62, 63, 64, 65 and 66 to be adjacent to the dowel posts 92, 93, 94, 95 and 96 are positioned radially inwardly at the inflection points IP92a, IP93a, IP94a, IP95a and IP96a between the curved surfaces of the end ends of dowel posts 92b, 9 3b, 94b, 95b and 96b of the dowel posts 92, 93, 94, 95 and 96 and the adjoining surfaces 92d, 93d, 94d, 95d and 96d of the dowel posts 92, 93, 94, 95 and 96 to adjoin the dowels 62, 63, 64, 65 and 66.

[00111] Various conditions for pairs of transmission gears in the first to sixth gear positions, that is, the number of pins N, pin narrowing angle θ1, pin column narrowing angle θ2, clearance angle θ3, the existence of an internal circumferential reinforcement ring or not, the existence of an external circumferential reinforcement ring or not, whether the relation a < b is satisfied or not, whether the relation c < d is satisfied or not, flare angle dowel string angle θ4 and dowel string flare angle θ5, are shown in Table 1 below. In Table 1 below, transmission gears that are provided with an inner circumferential gusset ring and an outer circumferential gusset ring are indicated by “o”, and those not equipped with an inner circumferential gusset ring and an outer circumferential gusset ring are indicated by “x”. TABLE 1

[00112] According to the Example of the Invention 1, in each gear position, the numbers of the pins 61, 62, 63, 64, 65 and 66 and the pin columns 91, 92, 93, 94, 95 and 96 are twelve, so that the pin narrowing angle θ1 and the pin column narrowing angle θ2 are smaller than hitherto . In order to increase the mechanical strength of the pins 61, 62, 63, 64, 65 and 66 and the columns of pins 91, 92, 93, 94, 95 and 96, the transmission gears are provided with internal circumferential reinforcement rings 71, 72, 73, 74, 75 and 76 radially into the pins 61, 62, 63, 64, 65, and 66, with dowel backplates 81, 82, 83, 84, 85, and 86, with outer circumferential reinforcement rings 111, 112, 113, 114, 115, and 116 radially outward from dowel posts 91, 92, 93, 94, 95, and 96, and with dowel column 121, 122, 123, 124, 125 and 126, and the length "a" from the pitch circle PC to the dowel tip ends 61b, 62b, 63b, 64b, 65b and 66b is less than the length "b" from the pitch circle PC to the dowel base ends 61c, 62c, 6 3c, 64c, 65c and 66c, and the length "c" from pitch circle PC to dowel string nose ends 91b, 92b, 93b, 94b, 95b and 96b is less than the length "d" from pitch circle PC to dowel string base ends 91c, 92c, 93c, 94c, 95c and 96c of the dowel columns 91, 92, 93, 94, 95 and 96.

[00113] With the use of the transmission apparatus according to the present invention, experiments were conducted to measure the shift spindle angles α, the drum angles β and the shift pedal loads F during the shift time T, and their relationships are illustrated in the graphs represented in Figures 25 to 35. The relationship between the invalid engagement times TM and the shift pedal loads F supported by the shift pedal was verified. An invalid engagement time TM refers to a period of time during which the facing wall surfaces of dowels and the facing wall surfaces of dowel strings are contiguous and slide into each other when a gear change operation is performed.

[00114] In the experiments, the transmission apparatus according to the present invention was used, and data were measured a plurality of times with the use of a single gauge under conditions represented by an engine rotation speed Ne of 200 rpm, a mainshaft rotation speed of 100 rpm and manual gear shift operations. From the measured data, experimental results were extracted that indicate invalid TM engagement times of 0 ms (millisecond), 5 ms, 10 ms, 15 ms, 30 ms, 35 ms, 40 ms, 55 ms, 75 ms, 100 ms, and 120 ms. The experimental results are depicted in Figures 25 to 35 as representing the relationship between shift time T on the horizontal axis and shift spindle angle α on the vertical axis in Figures 25(a) to 35(a), the relationship between shift time T on the horizontal axis and barrel angle β on the vertical axis in Figures 25(b) to 35(b), and the relationship between shift time T on the horizontal axis and shift pedal load F on the vertical axis in Figures 25(c) ) to 35(c).

[00115] The extraction of the invalid engagement time TM will be described below with reference to Figures 29(a) to 29(c), for example. In Figure 29(b) illustrating the relationship between the change time T and the drum angle β, there is an area where even when the change time T passes, the drum angle β remains unchanged between its maximum and minimum values in the graph from start to finish of a process where the drum angle β is variable. This area represents a period of time where the facing wall surfaces of the dowels and the facing wall surfaces of the dowel strings are adjoining and sliding into each other, preventing the gear from moving further axially, and the period of time can be referred to as the invalid engagement time TM. In Figure 29(b), the TM invalid engagement time can be read as 30 ms. Experimental results were thus extracted as indicating invalid engagement times TM from the above values.

[00116] The relationship between shift time T and shift pedal load F at each invalid engagement time TM will be reviewed below with reference to Figures 25(b) and 25(c) through 35(b) and 35(c). When a gear shift operation is initiated, the shift pedal load F gradually increases until the facing wall surfaces of the dowels and the facing wall surfaces of the dowel strings make contact with each other, after which the invalid engagement time TM begins, resulting in a sharp increase in the shift pedal load F. dowel holes, ending invalid engagement time TM. Upon entry of the pins into the pin holes, the pins and the pin columns move relative to each other by a distance corresponding to the clearance angle θ3 between them, during which time the shift pedal load F is ineffective. When the dowels and the dowel columns have moved relative to each other by the distance corresponding to the clearance angle θ3, the dowels and the dowel columns are adjacent to each other and are placed in an engaged state, which results in an increase in the shift pedal load F. The gear shift operation is now terminated.

[00117] While performing the gear change operation on the transmission device, the driver or shift operator feels an increase in the shift pedal load F due to the contact between the facing wall surfaces of the pegs and the facing wall surfaces of the peg columns. Thereafter, the shift pedal load F is lost, and when the engagement between the pegs and the peg columns is completed, the shift operator feels an increase in the shift pedal load F. If the invalid engagement time TM is long, then the shift operator tends to feel the gear shift operation as if performed with a two-stage movement, and does not experience the gear shift operation as a smooth process. On the other hand, if the invalid engagement time TM is short, then the time required for the facing wall surfaces of the pegs and the facing wall surfaces of the peg columns to touch each other, which increases the shift pedal load F, is short, so that the shifter operator does not feel the gear shifting operation as performed with a two-stage movement, but feels the gearshifting operation as a smooth process, so that the quality of the gearshifting operation as felt by the shifter operator is improved.

[00118] However, insofar as the operation of the shift pedal is affected by a twist of the shift spindle and an absorption of gear shift impacts by the transmission gear, the invalid engagement time TM and the time during which the facing wall surfaces of the pegs and the facing wall surfaces of the peg columns are contiguous with each other, increasing the shift pedal load F, are not necessarily in agreement with each other.

[00119] Regarding the experimental results that indicated invalid TM engagement times of 0 ms, 5 ms, 10 ms, 15 ms, 30 ms, 35 ms, 40 ms, 55 ms, 75 ms, 100 ms and 120 ms, as represented in Figures 25 to 35, the relationship between invalid TM engagement time and gear shifting feeling was judged taking into account the relationship between shift time T and shift pedal load F.

[00120] As shown in Figures 25 to 27, according to the experimental results that indicate invalid engagement times TM of 0 ms, 5 ms, 10 ms, the time during which the shift pedal load F increases while the facing wall surfaces of the dowels and the facing wall surfaces of dowel columns are contiguous with each other is very short or virtually nil. This is due to the fact that the transmission gear shift mechanism is made up of metal components which produce a time delay in its response to gear shift operations and F shift pedal load, so the F shift pedal load hardly increases if the invalid engagement time TM is short. Therefore, in the event that the invalid engagement time TM is in the range of 0ms to 10ms, the shift operator does not feel a gear shifting operation as if performed with a two-stage movement, but feels the gear shifting operation as a smooth process. It can be seen that the range from 0 ms to 10 ms is an optimal range for the TM invalid engagement time.

[00121] As shown in Figures 28 and 29, according to the experimental results that indicate invalid engagement times TM of 15 ms and 30 ms, there is a time during which the shift pedal load F increases while the facing wall surfaces of the dowels and the facing wall surfaces of dowel columns are contiguous with each other, although the time is short. Therefore, the shift operator probably does not feel a gear change operation as performed with a two-stage movement, but feels the gear change operation as good. It can be seen that the range from 0ms to 30ms is a good range for TM invalid engagement time.

[00122] As shown in Figures 30(a), 30(b) and 30(c), according to the experimental results that indicate an invalid engagement time TM of 35 ms, the time during which the shift pedal load F increases while the facing wall surfaces of the dowels and the facing wall surfaces of the dowel columns are contiguous with each other is longer, but not very long. The shift operator is less likely to experience a gear change operation as being performed with a two-stage movement, but feels the gear change operation as preferential.

[00123] As shown in Figures 31 to 35, according to the experimental results that indicate invalid engagement times TM of 40 ms and longer, the time during which the shift pedal load F increases while the facing wall surfaces of the pegs and the facing wall surfaces of the peg columns are contiguous with each other is very long and makes the shift operator feel a gear change operation as if performed with a two-stage movement, and feels the gear change operation as unsatisfactory. In TM invalid engagement times of 40ms and longer, therefore, the shift operator feels gear shifting operations as not good. Consequently, the range from 0 ms to a time duration below 40 ms is considered a preferred range for TM invalid engagement time.

[00124] The relationship between the TM invalid engagement time duration and the shift operator's gear shift feeling is related to a time delay in the response of the metal components of the transmission gear shift mechanism to shift operations and F shift pedal load F, the speed at which the shift operator depresses the shift pedal, and a shift operator's feeling that the time during which the F shift pedal load increases is long and gear shift operations are not smooth, and does not depend on the rotational speed of the internal combustion engine E.

[00125] The shorter the TM invalid engagement time duration, the less likely that gear shift operations will be performed with a two-stage movement and the smoother the gear shift operations are felt by the shift operator. It is effective to reduce the dowel narrowing angle θ1 and the dowel column narrowing angle θ2 in order to shorten the duration of invalid engagement time TM. However, reducing the dowel taper angle θ1 and the dowel string taper angle θ2 results in a reduction in the widths of the dowels and dowel columns, posing a problem in the mechanical strength of the dowels and dowel columns. To solve this problem, the number of dowels is increased to reduce the applied load per dowel, and the annular gusset and back plate that join the dowels together are provided to increase the mechanical strength of the dowels. In addition, annular gusset and back plate are also provided which join the dowel columns together to increase the mechanical strength of the dowel columns.

♦EXPERIMENTS TO MEASURE INVALID ENGAGEMENT TIME IN GEAR CHANGING OPERATIONS UNDER GEARING CONDITIONS

[00126] Five types of transmission apparatus including the transmission apparatus according to Invention Example 1, according to the present embodiment, have been prepared, and four types of transmission apparatus according to Comparative Examples have been prepared. In each of the transmission gears, the TM invalid engagement times were measured under conditions given below in up gear shift operations and down gear shift operations for the gear positions, and the conditions for the transmission gear to keep the TM invalid engagement time in a good range were determined.

[00127] The conditions for the gear positions in relation to Examples of the Invention 1 to 5 and Comparative Examples 1 to 4 include the number of pins N, the pin narrowing angle θ1, the pin column narrowing angle θ2, the clearance angle θ3, the existence of an internal circumferential reinforcement ring or not, the existence of an external circumferential reinforcement ring or not, whether the relation a < b is satisfied or not for the dowels, whether the relationship c < d is satisfied or not for the dowel strings, the dowel string flare angle θ4 and the dowel string flare angle θ5, as depicted in Tables 2 to 4 below.

[00128] With regard to each of the transmission apparatus according to Examples of the Invention 1 to 5 and Comparative Examples 1 to 4, the invalid engagement times TM were measured at a prescribed engine cranking speed Ne of the internal combustion engine E that corresponds to an engine idle cranking speed of 1200 rpm, and the results are represented in Table 5. Since the invalid engagement time TM becomes shorter as the speed Invalid engagement times TM of engine idle speed of engine E is higher, longer invalid engagement time for internal combustion engine E can be inspected by measuring invalid engagement time TM at engine idle speed which is the lowest engine idle speed. TABLE 2 TABLE 3 TABLE 4 TABLE 5 INVALID COUPLING TIME TM

[00129] The experimental results of the Examples of the Invention of the transmission apparatus for a ride-on type vehicle according to the present invention will be described in comparison with the experimental results of the Comparative Examples. Note that the transmission apparatus for a vehicle of the mountable type according to Invention Examples 1 to 5 and Comparative Examples 1 to 4 are applied as a manual transmission apparatus for a motorcycle.

[00130] In Table 5, the TM invalid engagement times of each of the various transmission apparatuses were evaluated. These were evaluated while paying attention to gear shift operations between gear positions ranging from the first to fourth gear positions that are often used by the motorcycle when riding in the city.

[00131] In Examples of the Invention 1 to 5, the invalid engagement time TM in gear shift operations up from the first to the second gear positions, from the second to the third gear positions, and from the third to the fourth gear positions had a minimum value of 24.6 ms and a maximum value of 38.1 ms. The TM invalid engagement time in these upshift operations has been found to be in a range smaller than the 0ms to 40ms range where the shift operator perceives the shift operations to be good.

[00132] In Comparative Examples 1 to 4, the invalid engagement time TM in gear shift operations up from the first to second gear positions, from the second to third gear positions, and from the third to fourth gear positions had a minimum value of 46.0 ms and a maximum value of 131.8 ms. It has been found that the invalid engagement time TM in these up gear shift operations does not fall within a range smaller than the 0 ms to 40 ms range in which the shift operator feels the shift operations as good, but that the shift operator feels the shift operations in Comparative Examples 1 to 4 as performed with a two-stage movement, and does not experience the gear shift operations as a smooth process.

[00133] In Examples of the Invention 1 to 5, the invalid engagement time TM in gear shift operations down from the second to the first gear positions, from the third to the second gear positions and from the fourth to the third gear positions had a minimum value of 24.6 ms and a maximum value of 36.6 ms. The TM invalid engagement time in these downshift operations has been found to be in a range smaller than the 0ms to 40ms range where the shift operator perceives the shift operations to be good.

[00134] In Comparative Examples 1 to 4, the invalid engagement time TM in gear shift operations down from second to first gear positions, from third to second gear positions and from fourth to third gear positions had a minimum value of 46.8 ms and a maximum value of 161.5 ms. It has been found that the invalid engagement time TM in these downshifting operations does not fall within a range smaller than the 0ms to 40ms range in which the shifter feels the gearshifting operations as good, but that the shifter feels the shifting operations in Comparative Examples 1 to 4 as performed with a two-stage motion, and does not experience the shifting operations as a smooth process.

[00135] The relationship between the various conditions and invalid engagement time TM for these gear positions will be reviewed below. In Examples of the Invention 1 to 5, the dowel taper angles θ1 for the gear positions are generally in the range of 6 degrees < θ1 < 9 degrees. In Comparative Examples 1 to 4, the dowel taper angles θ1 are in the range of 10 degrees < θ1 < 30 degrees. The dowel neck angle θ1 has been found to be good in the range of 6 degrees to a value below 9 degrees.

[00136] In Examples of the Invention 1 to 5, the pin column narrowing angles θ2 for the gear positions are, in general, in the range of 6 degrees < θ2 < 9 degrees. In Comparative Examples 1 to 4, the dowel string taper angles θ2 are in the range of 10 degrees < θ2 < 23 degrees. It has been found that the dowel column narrowing angle θ2 is good in the range of 6 degrees to a value below 9 degrees.

[00137] In Examples of the Invention 1 to 5, the number of pins N for the gear positions is in the range of 8 < N < 19 and, in general, in the range of 11 < N < 19. In Comparative Examples 1 to 4, the number of pins N is in the range of 5 < N < 8. It was found that the range of 11 < N < 19 is a preferred range for the number of pins N, and the range of 11 < N < 15 is an optimal range for the number of N dowels.

[00138] The transmission apparatus, according to the above embodiment of the present invention, is arranged as described above and offers the following advantages.

[00139] In the transmission apparatus for a vehicle of the type to be mounted, according to the above embodiment of the present invention, since the invalid engagement time TM during which the pins 61, 62, 63, 64, 65 and 66 and the pin columns 91, 92, 93, 94, 95 and 96 are contiguous and slide into each other at an idle speed of rotation of the engine is in the range of 0 ms at a value below 40 ms, the invalid engagement time TM during which the facing wall surfaces 61a, 62a, 63a, 64a, 65a and 66a of the dowels 61, 62, 63, 64, 65 and 66 and the facing wall surfaces 91a, 92a, 93a, 94a, 95a and 96a of the dowel columns 91, 92, 93, 94, 95 and 96 are contiguous and sliding into each other is reduced to thereby reduce the hammering noise of the dowels, making gear shifting operations smoother to provide an improved feel to the dowels. Both pins 61, 62, 63, 64, 65 and 66 and pin columns 91, 92, 93, 94, 95 and 96 are of a minimum size to handle torques that can be transmitted by the transmission apparatus, and pin numbers 61, 62, 63, 64, 65 and 66 and pin columns 91, 92, 93, 94, 95 and 96 are enlarged to achieve the required mechanical strength of the dowels and dowel columns. The dowel clearance angle is reduced to reduce the hammering noise produced when the dowels engage with the dowel columns and also to reduce wobble and play caused when the dowels engage with the dowel columns.

[00140] The number of dowels 61, 62, 63, 64, 65 and 66 is in the range of 11 to 19, and the number of dowel columns 91, 92, 93, 94, 95 and 96 is in the range of 11 to 19. Therefore, the number of dowels and the number of dowel columns are thus optimized to achieve the required mechanical strength of the dowels s and dowel columns. The dowel clearance angle is reduced to reduce the hammering noise produced when the dowels engage with the dowel columns and also to reduce wobble and play caused when the dowels engage with the dowel columns.

[00141] The dowel taper angle θ1 is in the range of 6 degrees to 9 degrees, and the dowel column taper angle θ2 is in the range of 6 degrees to 9 degrees. The dowel narrowing angle θ1 and the dowel string narrowing angle θ2 are therefore small angles, which allows the number of dowels and the number of dowel columns to increase, so that the invalid engagement time TM can be decreased to make gear shifting operations smooth.

[00142] The clearance angle θ3 between the dowels 61, 62, 63, 64, 65 and 66 and the dowel columns 91, 92, 93, 94, 95 and 96 is in the range of 0 degrees to 15 degrees. As the clearance angle θ3 between the pins 61, 62, 63, 64, 65 and 66 and the pin columns 91, 92, 93, 94, 95 and 96 is a small angle, it is possible to increase the number of pins and reduce the invalid engagement time TM for an improved feel for gear changing operations.

[00143] The dowels 61, 62, 63, 64, 65 and 66 include the inner circumferential reinforcement rings 71, 72, 73, 74, 75 and 76 and the dowel back plates 81, 82, 83, 84, 85 and 86, and the dowel columns 91, 92, 93, 94, 9 5 and 96 include the outer circumferential reinforcement rings 111, 112, 113, 114, 115 and 116 and the dowel post backplates 121, 122, 123, 124, 125 and 126. Therefore, the mechanical strength of the dowel posts 61, 62, 63, 64, 65 and 66 and the dowel posts 9 1, 92, 93, 94, 95 and 96 is increased.

[00144] The contiguous surfaces 61d, 62d, 63d, 64d, 65d and 66d of the pegs 61, 62, 63, 64, 65 and 66 to be contiguous with the peg columns 91, 92, 93, 94, 95 and 96 are widened or angularly spaced from the line segments that extend from the center of rotation C of the transmission gears through the contact points P between the pins 61, 62, 63, 64, 65 and 66 and the pin columns 91, 92, 93, 94, 95 and 96 by the pin flare angle θ4, and the adjoining surfaces 91d, 92d, 93d, 94d, 95d and 96 d of the pin columns 91, 92, 93, 94, 95 and 96 to be adjacent to the pins 61, 62, 63, 64, 65 and 66 are widened or angularly spaced from line segments extending from the center C of rotation of the transmission gears through the contact points P between the pins 61, 62, 63, 64, 65 and 66 and the dowel strings 91, 92, 93, 94, 95 and 96 by the dowel string widening angle θ5. Consequently, the mechanical strength of the base ends of dowels 61c, 62c, 63c, 64c, 65c and 66c of the dowels 61, 62, 63, 64, 65 and 66 and the base ends of dowel columns 91c, 92c, 93c, 94c, 95c and 96c of the dowel columns 91, 92, 93, 94, 95 and 96 is increased, for an increase in the mechanical strength of the dowels and the mechanical strength of the dowel columns.

[00145] The length “a” from the pitch circle PC of the dowels 61, 62, 63, 64, 65 and 66 and of the dowel columns 91, 92, 93, 94, 95 and 96 to the ends of dowel tips 61b, 62b, 63b, 64b, 65b and 66b of dowels 61, 62, 63, 64, 65 and 66 is less than the length "b" from the pitch circle PC of the dowels 61, 62, 63, 64, 65 and 66 and the dowel columns 91, 92, 93, 94, 95 and 96 to the base ends of dowels 61c, 62c, 63c, 64c, 6 5c and 66c of the dowels 61, 62, 63, 64, 65 and 66, and the length "c" from the pitch circle PC of the dowels 61, 62, 63, 64, 65 and 66 and of the dowel columns 91, 92, 93, 94, 95 and 96 to the ends of ends of dowel columns 91b, 9 2b, 93b, 94b, 95b and 96b of the dowel columns 91, 92, 93, 94, 95 and 96 is less than the length "d" from the pitch circle PC of the dowels 61, 62, 63, 64, 65 and 66 and of the dowel columns 91, 92, 93, 94, 95 and 96 to the base ends of dowel columns 91c, 92c, 93c, 94c, 95c and 96c of the dowel columns 91, 92, 93, 94, 95 and 96. Consequently, the mechanical strength of the base ends of dowels 61c, 62c, 63c, 64c, 65c and 66c and the base ends of dowel columns pegs 91c, 92c, 93c, 94c, 95c and 96c is further increased to further increase the mechanical strength of pegs 61, 62, 63, 64, 65 and 66 and peg columns 91, 92, 93, 94, 95 and 96 in their entirety.

[00146] Among the contiguous surfaces of the dowels 61, 62, 63, 64, 65 and 66 and the dowel columns 91, 92, 93, 94, 95 and 96 that are contiguous with each other, the contiguous surfaces 91d, 92d, 93d, 94d, 95d and 96d of the dowel columns 91 , 92, 93, 94, 95 and 96 are straight while the adjoining surfaces 61d, 62d, 63d, 64d, 65d and 66d of pegs 61, 62, 63, 64, 65 and 66 are curved as viewed along the axis of rotation of the transmission gears. Therefore, variations in the radii of the contact points between the pins and the pin columns from the center of rotation of the transmission gears are reduced, which tends to uniform the stresses in the pins 61, 62, 63, 64, 65 and 66 and in the pin columns 91, 92, 93, 94, 95 and 96.

[00147] The IP91b, IP92b, IP93b, IP94b, IP95b and IP96b inflection points on the dowel columns 91, 92, 93, 94, 95 and 96 between the curved surfaces of the base ends of dowel columns 91c, 92c, 93c, 94c, 95c and 96c of dowel columns 9 1, 92, 93, 94, 95 and 96 and the adjoining surfaces 91d, 92d, 93d, 94d, 95d and 96d thereof are positioned radially away from the inflection points IP61a, IP62a, IP63a, IP64a, IP65a and IP66a on pegs 61, 62, 63, 64, 6 5 and 66 between the curved surfaces of the end ends of the dowels 61b, 62b, 63b, 64b, 65b and 66b of the dowels 61, 62, 63, 64, 65 and 66 and the adjacent surfaces 61d, 62d, 63d, 64d, 65d and 66d thereof and the IP61 inflection points b, IP62b, IP63b, IP64b, IP65b and IP66b on dowels 61, 62, 63, 64, 65 and 66 between the curved surfaces of the base ends of dowels 61c, 62c, 63c, 64c, 65c and 66c of dowels 61, 62, 63, 64, 65 and 66 and the adjoining surfaces 61d, 62d, 63d, 64d, 65d and 66d thereof are positioned radially inwardly at the inflection points IP91a, IP92a, IP93a, IP94a, IP95a and IP96a on the dowel columns 91, 92, 93, 94, 95 and 96 between the curved surfaces of the end ends of dowel columns s 91b, 92b, 93b, 94b, 95b and 96b of the dowel columns 91, 92, 93, 94, 95 and 96 and the adjoining surfaces 91d, 92d, 93d, 94d, 95d and 96d thereof. Therefore, the dowels 61, 62, 63, 64, 65 and 66 and the dowel columns 91, 92, 93, 94, 95 and 96 can be brought closer together, making it possible to increase the number of dowels 61, 62, 63, 64, 65 and 66 and that of the dowel columns 91, 92, 93, 9 4, 95 and 96 can be increased additionally.

[00148] Although the embodiment of the present invention has been described in detail, the present invention is not limited to the embodiment described above, but many changes and modifications can be made to it. The transmission apparatus for a ride-on type vehicle according to the present invention is not limited to being used on a motorcycle, but is widely applicable to other types of ride-on type vehicles. DESCRIPTION OF REFERENCE NUMBERS 31-^Major Shaft, 35-^Intermediate Shaft, 61-<Peg, 61a^Facing Wall Surface, 61b^Dowel Point End, 61c^Dowel Base End, 62-<Peg, 62a^Facing Wall Surface, 62b^Dowel Point End, 62c^End dowel base end, 63^ dowel, 63a^facing wall surface, 63b^dowel point end, 63c^dowel base end, 64^ dowel, 64a^dowel end face, 64b^dowel point end, 64c^dowel base end, 65^ dowel, 65a^dowel end face, 65b^Dowel Point End, 65c^Dowel Base End, 66^ Dowel, 66a^Facing Wall Surface, 66b^Dowel Point End, 66c^Dowel Base End, 71-^Inner Circumferential Reinforcement Ring, 72-^Inner Circumferential Reinforcement Ring, 73-^Inner Circumferential Reinforcement Ring, 74-^A inner circumferential reinforcement ring, 75-^inner circumferential reinforcement ring, 76^-inner circumferential reinforcement ring, 81-^bolt back plate, 82-^bolt back plate, 83^-bolt back plate, 84^-bolt back plate, 85-^bolt back plate, 86-^bolt back plate, 91-<ca column stud, 91a^Facing Wall Surface, 91b^Down Column Point End, 91c^Dowel Column Base End, 92-<Dowel Column, 92a^Dowel Column End End, 92b^Dowel Column Point End, 92c^Dowel Column Base End, 93-<Dowel Column, 93a^Super Facing wall surface, 93b^End end of dowel column, 93c^Base end of dowel column, 94-<Dowel column, 94a^Facing wall surface, 94b^End end of dowel column, 94c^Base end of dowel column, 95-<Dowel column, 95a^End of dowel column, 95b ^Dowel Column Pointed End, 95c^Dowel Column Base End, 96-<Dowel Column, 96a^Facing Wall Surface, 96b^Dowel Column Point End, 96c^Dowel Column Base End, 101^"Dowel Hole, 102-^Dowel Column, 103^"Dowel Column, 104^"Dowel Hole, 105-^Dowel Hole, 106^"Dowel Hole, 111-^Outer Circumferential Reinforcing Ring, 112-^Outer Circumferential Reinforcing Ring, 113-^Outer Circumferential Reinforcing Ring, 114^-Outer Circumferential Reinforcing Ring, 115-^Outer Circumferential Reinforcing Ring, 116-^Inframing Ring outer circumferential reinforcement, 121-^Dowel column back plate, 122-^Dowel post back plate, 123-^Dowel post back plate, 124-^Dowel post back plate, 125-^Dowel post back plate, 126-^Dowel post back plate, E^Internal combustion engine, P^Contact point, PC-<circle pitch, TM^Invalid engagement time, F-<shift pedal angle, angle^Shift spindle angle, β-^barrel angle, θl-^pin pin taper angle, θ2-^pin post taper angle, θ3-^clearance angle, θ4-^pin pin flare angle, θ5-^pin pin post flare angle, IP61a^Po Tipping Point, IP62a^Tipping Point, IP63a^Tipping Point, IP64a^Tipping Point, IP65a^Tipping Point, IP66a^Tipping Point, IP61b^Tipping Point, IP62b^Tipping Point, IP63b^Tipping Point, IP64b^Tipping Point, IP65b^Tipping Point bending point, IP66b^Tipping point, IP91a^Tipping point, IP92a^Tipping point, IP93a^Tipping point, IP94a^Tipping point, IP95a^Tipping point, IP96a^Tipping point, IP91b^Tipping point, IP92b^Tipping point, IP93b^Tipping point, IP94b^Inflection point, IP95b^Inflection point, IP96b^Inflection point, ml^Transmission gear, m2^Transmission gear, m3-•Transmission gear, m4^Transmission gear, m5-•Transmission gear, m6^Transmission gear, nl^Transmission gear, n2^Transmission gear, n3-•Eng transmission gear, n4^Transmission gear, n5-•Transmission gear, n6^Transmission gear

Claims (9)

1. Transmission apparatus for a vehicle of the mountable type, comprising: first transmission gears (m3, m4, n5, n6) supported on support shafts (31, 35) so as to be circumferentially non-rotating and axially sliding with respect to said support shafts (31, 35); and second transmission gears (m1, m6, n1, n2, n3, n4) supported on said support shafts (31, 35) adjacent to said first transmission gears (m3, m4, n5, n6) so as to be circumferentially rotatable and not axially sliding with respect to said support shafts (31, 35); said first transmission gears (m3, m4, n5, n6) have axially projecting pins (61, 62, 63, 64, 65, 66); said second transmission gears (m1, m6, n1, n2, n3, n4) have pin holes (101, 102, 103, 104, 105, 106) axially concavely defined therein and pin columns (91, 92, 93, 94, 95, 96) defining said pin holes (101, 102 , 103, 104, 105, 106); said pins (61, 62, 63, 64, 65, 66) being engageable and disengageable from said pin holes (101, 102, 103, 104, 105, 106) for changing gear positions; said first transmission gears (m3, m4, n5, n6) being sliding in response to angular movement of a shift spindle (47) caused by operation of a shift pedal; characterized by the fact that an invalid engagement time (TM) during which the facing wall surfaces (61a, 62a, 63a, 64a, 65a, 66a) of said pegs (61, 62, 63, 64, 65, 66) and the facing wall surfaces (91a, 92a, 93a, 94a, 95a, 96a) of said dowel columns (91, 92, 93, 94, 95, 96) are contiguous and slide into each other at a rotational speed from idle of the engine is in the range of 0 milliseconds to a value below 40 milliseconds. 2. Transmission apparatus for a vehicle of the mountable type, according to claim 1, characterized in that the number of said pins (61, 62, 63, 64, 65, 66) is in the range from 11 to 19, and the number of said pin columns (91, 92, 93, 94, 95, 96) is in the range from 11 to 19. 3. Transmission apparatus for a vehicle of the type to mount, according to claim 2, characterized in that a pin narrowing angle (θ1) between the line segments extending from the center (C) of rotation of the transmission gears through contact points (P, P) on both sides of said pins (61, 62, 63, 64, 65, 66), in which said pins (61, 62, 63, 64, 65, 66) and said dowel columns (91, 92, 93, 94, 95, 96) are contiguous with each other, is in the range of 6 degrees to 9 degrees; and a dowel column narrowing angle (θ2) between line segments extending from the center (C) of rotation of the transmission gears through contact points (P, P) on both sides of said dowel columns (91, 92, 93, 94, 95, 96), wherein said dowel columns (91, 92, 93, 94, 95, 96) and said dowel columns s(61, 62, 63, 64, 65, 66) are contiguous with each other, it is in the range of 6 degrees to 9 degrees. 4. Transmission apparatus for a vehicle of the type to be mounted, according to any one of claims 1 to 3, characterized in that a clearance angle (θ3) between said pins (61, 62, 63, 64, 65, 66) and said pin columns (91, 92, 93, 94, 95, 96) is in the range of 0 degrees to 15 degrees. 5. Transmission apparatus for a vehicle of the mountable type, according to any one of claims 1 to 4, characterized in that said pins (61, 62, 63, 64, 65, 66) include internal circumferential reinforcement rings (71, 72, 73, 74, 75, 76) and rear pin plates (81, 82, 83, 84, 85, 86); and said dowel posts (91, 92, 93, 94, 95, 96) include outer circumferential reinforcement rings (111, 112, 113, 114, 115, 116) and dowel post backplates (121, 122, 123, 124, 125, 126). 6. Transmission apparatus for a vehicle of the type to mount, according to any one of claims 1 to 5, characterized in that said pins (61, 62, 63, 64, 65, 66) have contiguous surfaces (61d, 62d, 63d, 64d, 65d, 66d) to be contiguous to said pin columns (91, 92 , 93, 94, 95, 96), the adjoining surfaces being widened from line segments extending from the center (C) of rotation of the transmission gears through contact points (P) between said pins (61, 62, 63, 64, 65, 66) and said pin columns (91, 92, 93, 94, 95, 96) by a dowel flare angle (θ4); and said dowel columns (91, 92, 93, 94, 95, 96) have adjoining surfaces (91d, 92d, 93d, 94d, 95d, 96d) to adjoin said dowels (61, 62, 63, 64, 65, 66), the adjoining surfaces being widened from line segments extending from the center (C) of rotation of the transmission gears through contact points (P) between said pins (61, 62, 63, 64, 65, 66) and said pin columns (91, 92, 93, 94, 95, 96) by a pin column widening angle (θ5). 7. Transmission apparatus for a vehicle of the mountable type, according to any one of claims 1 to 6, characterized in that a length (a) from a pitch circle (PC) of said pins (61, 62, 63, 64, 65, 66) and said pin columns (91, 92, 93, 94, 95, 96) to the ends of pin ends s (61b, 62b, 63b, 64b, 65b, 66b) of said pegs (61, 62, 63, 64, 65, 66) is less than a length (b) from the pitch circle (PC) of said pegs (61, 62, 63, 64, 65, 66) and of said peg columns (91, 9 2, 93, 94, 95, 96) to the dowel base ends (61c, 62c, 63c, 64c, 65c, 66c) of said dowels (61, 62, 63, 64, 65, 66); and a length (c) from the pitch circle (PC) of said dowels (61, 62, 63, 64, 65, 66) and said dowel columns (91, 92, 93, 94, 95, 96) to the ends of ends of dowel columns (91b, 92b, 93b, 94b, 95b, 96b) of said dowel columns (91, 92, 93, 94, 95, 96) is less than a length (d) from the pitch circle (PC) of said dowel columns (61, 62, 63, 64, 65, 66) and said dowel columns (91, 92, 93, 94, 95, 96) to the base ends of dowel columns (91 c, 92c, 93c, 94c, 95c, 96c) of said dowel columns (91, 92, 93, 94, 95, 96). 8. Transmission apparatus for a vehicle of the type to be mounted, according to claim 6 or 7, characterized in that, of the contiguous surfaces (61d, 62d, 63d, 64d, 65d, 66d, 91d, 92d, 93d, 94d, 95d, 96d) of said pegs (61, 62, 63, 64, 65, 66) and of said dowel columns (91, 92, 93, 94, 95, 96) which are adjacent to each other, the adjoining surfaces (91d, 92d, 93d, 94d, 95d, 96d) of any of said dowel columns (61, 62, 63, 64, 65, 66) or of said dowel columns (9 1, 92, 93, 94, 95, 96) are straight while the adjoining surfaces (61d, 62d, 63d, 64d, 65d, 66d) of the others are curved as viewed along the axis of rotation of the transmission gears. 9. Transmission apparatus for a vehicle of the type to mount, according to any one of claims 6 to 8, characterized in that the inflection points (IP91b, IP92b, IP93b, IP94b, IP95b, IP96b) in said dowel columns (91, 92, 93, 94, 95, 96) between the curved surfaces of the base ends of dowel columns (91c, 92c, 93c, 94c, 95c, 96c) of said dowel columns (91, 92, 93, 94, 95, 96) and the adjoining surfaces (91d, 92d, 93d, 94d, 95d, 96d) thereof are positioned radially away from the inflection points (IP61a, IP62a, IP63a, IP64a, IP65a, IP66a) on said dowels (61, 62, 63, 64, 65, 66) between the curved surfaces of the ends of dowel tips (61b, 62b, 63b, 64b, 65b, 66b) of said dowels (61, 62, 63, 64, 65, 66) and the tiguas (61d, 62d, 63d, 64d, 65d, 66d) thereof; and the inflection points (IP61b, IP62b, IP63b, IP64b, IP65b, IP66b) on said pegs (61, 62, 63, 64, 65, 66) between curved surfaces of the base ends of pegs (61c, 62c, 63c, 64c, 65c, 66c) of said pegs (61, 62, 63, 64, 65, 66) and the adjoining surfaces (61d, 62d, 63d, 64d, 65d, 66d) thereof are positioned radially towards the inflection points (IP91a, IP92a, IP93a, IP94a, IP95a, IP96a) on said dowel columns (91, 92, 93, 9 4, 95, 96) between the curved surfaces of end ends of dowel columns (91b, 92b, 93b, 94b, 95b, 96b) of said dowel columns (91, 92, 93, 94, 95, 96) and the adjacent surfaces (91d, 92d, 93d, 94d, 95d, 96d ) of the same.