Rear swingarm configuration for motorcycles

Abstract

Configuration of the rear swingarm for motorcycles, wherein the motor scooter (2) comprises a power unit (5), wherein a rear swingarm (6) is pivotably arranged at the rear end of the power unit (5), wherein the power unit (5) comprises a cylinder section (51) and a transmission section (52), and the transmission section (52) comprises a crankshaft (54) and a continuously variable belt drive system (56) driven via the crankshaft (54), and the continuously variable belt drive system (56) comprises a drive wheel (561), a driven wheel (562), and a drive belt (563) connected to the drive wheel (561) and the driven wheel (562), and the center of the driven wheel (562) is provided with a drive shaft (564) through which a reduction gear (55) can be driven, and the reduction gear (55) has an output shaft (57) connected with an output wheel (571). is equipped, can drivewherein the rear swingarm (6) has a first pivot connection section (61) and a second pivot connection section (62) and is provided with a rear wheel axle (63) and a rear wheel (RW) and a rear wheel drive wheel (7) are rotatably arranged on the rear wheel axle (63), and a transmission part (8) is arranged between the rear wheel drive wheel (7) and the output wheel (571), wherein the rear swingarm (6) is pivotably arranged on the transmission section (52) by means of the first pivot connection section (61) and the second pivot connection section (62), characterized in that the drive shaft (564) passes through the first pivot connection section (61) of the rear swingarm (6) and the rear swingarm (6) uses the axis center (Y) of the drive shaft (564) as the center point for pivoting up and down and the output shaft (57) is coaxial with the axis center (Y),wherein the first pivoting connection section (61) is located in a gearbox housing (53) and between a reduction gearbox chamber (53b) and a continuously variable belt drive system (53c), both of which are housed in the gearbox housing.

Description

Technical field of the invention

[0001] The present invention relates to a rear swing arm configuration for motorcycles, and more particularly to a rear swing arm configuration for motorcycles that allows the rear swing arm to be shifted toward the front of the body, thereby shortening the wheelbase between the front wheel and the rear wheel and thus shortening the length of the scooter. State of the art

[0002] Document JP H10-316 077 A describes a pivot shaft mounting structure for a motorcycle with a rear arm structure supported on a pivot portion to allow up-and-down movement. The side frames are equipped with pivot parts (10) over which a pivot shaft (11) is guided. The lateral ends of the pivot shaft (11) are fixed to the lateral pivot parts (10) with independent fastening mechanisms. This design minimizes axial compressive or tensile forces on the pivot shaft. In addition, the front end of a rear arm structure (14) is rotatably supported on the pivot shaft, enabling smooth rotation.

[0003] Document FR 1 138 812 A relates to motorcycles, bicycles, or tricycles that use a continuous transmission system driven by a trapezoidal belt. Traditionally, in such systems, the drive pulleys for the belt are mounted directly on the motor shaft. The prior art proposes a novel arrangement in which the drive pulley for the trapezoidal belt and the clutch mechanism are mounted coaxially on an intermediate shaft. This shaft is positioned parallel to both the motor shaft and the pulley shaft. This design reduces the protrusion of the motor shaft and improves the symmetry and balance of the overall system.

[0004] Fig. 1 shows a scooter with a rear swing arm as disclosed in patent TW I359766 B “Structure of a scooter”. In this patent, one side of the crankshaft 12 of the engine unit 11 of the scooter 1 is connected to a continuously variable belt transmission system 13 driven by the crankshaft 12, wherein the driven shaft 131 of the continuously variable belt transmission system 13 is connected to a reduction and clutch system 14 driven by the driven shaft 131, and thus the reduction and clutch system 14 can drive the output shaft 15, wherein the output shaft 15 is provided with a drive wheel 151, and the drive wheel 151 drives the drive wheel 171 arranged on the rear wheel 17 by means of a belt-like transmission part 16, wherein the rear wheel 17 is pivotally arranged at the rear end of a rear swing arm 18 and the front end of the rear swing arm 18 is pivotally arranged on the outside of the output shaft 15.

[0005] In the transmission configuration of patent I359766 "Structure of a Motor Scooter," the crankshaft 12, the driven shaft 131, the output shaft 15, the rear swing arm 18, and the rear wheel 17 are arranged sequentially from the front of the body to the rear of the body. This increases the wheelbase between the front and rear wheels 17. More specifically, the transmission configuration of patent TW I359766 B "Structure of a Motor Scooter" causes the body length of the scooter 1 to increase. The scooter 1 therefore becomes longer in length.

[0006] How to provide a rear swingarm configuration for motorcycles that shortens the wheelbase between the front and rear wheels of a scooter and thus shortens the length of the scooter is of great importance to motorcycle manufacturers and represents an important research direction. Object of the inventionProblems to be solved by the invention

[0007] The main object of the present invention is to provide a rear swingarm configuration for motorcycles that can overcome the drawback resulting from the increase in the wheelbase between the front and rear wheels and thus the increase in the overall body size of the conventional scooter with a rear swingarm. This object is solved by independent claim 1. Further advantageous embodiments of the invention are specified in the dependent claims. Technical means

[0008] According to the above description, the technical means consists in providing a configuration of the rear swing arm for motorcycles, wherein the scooter comprises a power unit, wherein a rear swing arm is pivotally arranged at the rear end of the power unit, and the power unit comprises a cylinder section and a transmission section, wherein the transmission section comprises a crankshaft and a continuously variable belt transmission system drivable via the crankshaft, and the continuously variable belt transmission system comprises a drive wheel, a driven wheel, and a drive belt connected to the drive wheel and the driven wheel, wherein the center of the driven wheel is provided with a drive shaft through which a reduction gear can be driven, wherein the reduction gear can drive an output shaft provided with an output gear,The rear swing arm has a first pivot connection portion and a second pivot connection portion and is provided with a rear wheel axle. A rear wheel and a rear drive wheel are rotatably mounted on the rear wheel axle, and a transmission part is arranged between the rear drive wheel and the driven wheel. The rear swing arm is pivotally mounted on the transmission portion by means of the first pivot connection portion and the second pivot connection portion, and the drive shaft is passed through the first pivot connection portion of the rear swing arm. The rear swing arm uses the axis center of the drive shaft as the center point for pivoting up and down, and the driven shaft is coaxial with the axis center. In this way, the rear swing arm can be displaced toward the front of the body.which shortens the wheelbase between the front and rear wheels and thus allows the scooter to be shortened in length. Technical effects of the invention

[0009] Technical effect achieved by the technical means: The technical means described above allows the rear swing arm to be moved towards the front of the body, thereby shortening the wheelbase between the front and rear wheels and thus making it possible to shorten the length of the scooter. Brief description of the drawings Fig. Figure 1 shows a schematic plan view of the rear swing arm of a conventional scooter; Fig. 2 shows a schematic side view of the scooter according to the invention; Fig. 3 shows a sectional view of the power unit of the scooter according to the invention; Fig. Figure 4 shows a sectional view of the power unit and the rear swing arm of the scooter according to the invention; Fig. 5 shows an exploded view of the connection cover of the power unit of the scooter according to the invention. Detailed description of the preferred embodiment

[0010] It will be Fig. 2. The scooter 2 includes a vehicle frame unit 3, a seat cushion 4 arranged on the vehicle frame unit 3, and a power unit 5.

[0011] It will be Fig. 2. In the following description, when the rider is sitting on the scooter 2, the left side refers to the left-hand side with respect to the rider, and the right side refers to the right-hand side. A head tube section 31 is pivotally mounted on the front of the vehicle frame unit 3, a steering mechanism 32 is mounted above and connected to the head tube section 31, and a lowered tube section 33 is mounted on the head tube section 31 toward the rear of the body and connected thereto. A pair of footrest tube sections 34, which are mounted on the left and right and extend toward the rear of the body and run approximately horizontally, are mounted below and connected to the lowered tube section 33, and a footrest cross tube 341 is mounted between the end of the lowered tube section 33 and the pair of footrest tube sections 34, which are mounted on the left and right.arranged and connected to these two, wherein a side frame section 35 extends towards the rear of the body from the respective footrest tube section 34, wherein the respective side frame section 35 has a step-up segment 351 adjacent to the respective footrest tube section 34 and an extension segment 352 located at the rear section of the body, wherein a support tube 353 is arranged between the step-up segment 351 and the extension segment 352 of the respective side frame section 35, and an extension piece 354 is extended from the point where the respective step-up segment 351 adjoins the respective footrest tube section 34 towards the rear of the body, wherein a front fork unit A, consisting of a front shock absorber, is rotatably arranged below the head tube section 31 and a front wheel FW is pivotally arranged at the lower end of the front fork unit A.

[0012] It will be Fig. 2. An approximately flat footboard P is arranged on the approximately horizontally extending footrest tube sections 34 of the vehicle frame unit 3. The flat footboard P can form a footboard section for the driver to rest his feet on. In the interior space provided between the approximately horizontally extending footrest tube sections 34 arranged on the left and right, a fuel tank is housed for storing the fuel injected in the form of fuel jets provided to the power unit 5. The power unit 5 is connected to the vehicle frame unit 3 and is located on the fuel tank T towards the rear of the body.

[0013] It will be Fig. 2. A seat cushion 4, on which the driver can sit, is arranged above the extension segments 352 of the side frame sections 35. A luggage box C is arranged on the extension segments 352 of the side frame sections 35 below the seat cushion 4. The power unit 5 is arranged on the support tubes 353 and the extension pieces 354 of the side frame sections 35, with the power unit 5 being non-pivotally attached to the vehicle frame unit 3.

[0014] It is based on the Fig. 2 and Fig. 3. The power unit 5 comprises a cylinder section 51 and a transmission section 52, wherein the cylinder section 51 extends slightly inclined towards the front of the body and partially from the riser segments 351 of the side frame sections 35 to the outside, ie the section of the cylinder section 51 extending towards the front of the body extends more towards the front of the body than the riser segments 351 of the side frame sections 35. The cylinder section 51 has, from the front to the rear of the body, in succession a cylinder head cover 511, a cylinder head 512 and a cylinder body 513, wherein one end of the cylinder body 513 (i.e.the end facing toward the rear of the body) is connected to the transmission section 52 and the cylinder head 512 is connected to the end of the cylinder body 513 remote from the transmission section 52 and the cylinder head cover 511 covers the other end of the cylinder head 512 remote from the cylinder body 513.

[0015] It is based on the Fig. 2 and Fig. 3. The transmission section 52 is connected to the cylinder body 513 of the cylinder section 51 and is located at the end remote from the cylinder head 512. In the transmission section 52, the transmission case 53 consists of at least a right case body 52a and a left case body 52b (when driving, the left side refers to the left-hand side with respect to the driver, and the right side refers to the right-hand side; the same applies below). The transmission case 53 includes a crankshaft chamber 53a for accommodating a crankshaft 54, a reduction gear chamber 53b for accommodating a reduction gear 55, and a belt-type continuously variable transmission system chamber 53c formed by covering the right case body 52a with the outer cover 52c. A belt-type continuously variable transmission system 56 is disposed in the belt-type continuously variable transmission system chamber 53c.

[0016] It is based on the Fig. 2 and Fig. 3. The crankshaft 54, located in the crankshaft chamber 53a of the transmission case 53, is connected to a piston 542 via a connecting rod 541 and projects into the cylinder body 513 so that the piston 542 can be pushed by the fuel energy generated by the operation of the cylinder portion 51 to drive the crankshaft 54 ​​to rotate. The two sides of the crankshaft 54 ​​extend toward the transmission case 53, and one end (on the left side) is connected to an engine part E (generator, etc.), and the other end (on the right side) projects into the chamber of the belt-type continuously variable transmission system 53c and is connected to the belt-type continuously variable transmission system 56, so that the belt-type continuously variable transmission system 56 can be operated via the crankshaft 54.

[0017] It is based on the Fig. 2, Fig. 3 and Fig. 4. The continuously variable belt transmission system 56 includes a drive gear 561 driven by the crankshaft 54, a driven gear 562 driven by the drive gear 561, and a drive belt 563 arranged between the drive gear 561 and the driven gear 562. After the drive gear 561 is driven by the crankshaft 54, the driven gear 562 is driven to rotate at a continuously variable speed by the drive belt 563. A drive shaft 564 is arranged at the center of the driven gear 562. The drive shaft 564 projects into the reduction gear chamber 53b via the chamber of the continuously variable belt transmission system 53c, so that the reduction gear 55 located in the reduction gear chamber 53b can be operated by the drive shaft 564. An output shaft 57 can be driven by the reduction gear 55, the output shaft 57 and the input shaft 564 being coaxial.The output shaft 57 protrudes from the gear housing 53, specifically from the left housing body 52b, via the reduction gear chamber 53b. The output shaft 57 protrudes from the left housing body 52b and is connected to an output gear 571.

[0018] It is based on the Fig. 2, Fig. 3 and Fig. 4. A first support piece 58 and a second support piece 59 are arranged on two sides of the transmission case 53. More specifically, the first support piece 58 is locked to the right case body 52a, and the second support piece 59 is locked to the left case body 52b. A rear swing arm 6 is pivotally arranged between the first support piece 58 and the second support piece 59, a first pivot connecting portion 61 and a second pivot connecting portion 62 are provided on two sides of the front end of the rear swing arm 6, and a rear wheel RW is pivotally arranged at the rear end of the rear swing arm 6 via a rear wheel axle 63. The first pivot connecting portion 61 of the rear swing arm 6 is pivotally connected to the first support piece 58, that is, the output shaft 57 is passed through the second pivot connecting portion 62 and the second support piece 59.Thus, the second pivot connecting portion 62 of the rear swing arm 6 is pivotally connected to the second support piece 59, the second pivot connecting portion 62 being located between the output gear 571 of the transmission portion 52 and the transmission case 53, so that the rear swing arm 6 uses the axis center Y of the drive shaft 564 as the center point for swinging up and down, and the output shaft 57 is coaxial with the axis center Y and is swung up and down synchronously with the rear wheel RW. A rear wheel drive gear 7 is arranged on the rear wheel RW, wherein the rear wheel drive gear 7 is connected by means of a transmission part 8 (a belt or a chain) to the output gear 571 located on the output shaft 57, so that the transmission part 8 is driven by the output gear 571 located on the output shaft 57 so that it moves the rear wheel drive gear 7, thus driving the rear wheel RW for synchronous rotation.Another thing worth mentioning is that since the drive shaft 564 is passed through the first pivot connecting portion 61 and the first support piece 58, and the first pivot connecting portion 61 of the rear swing arm 6 and the first support piece 58 are located between the reduction gear chamber 53b of the transmission case 53 and the belt-type continuously variable transmission system chamber 53c, the overall configuration of the power unit 5 and the rear swing arm 6 can be made more compact.

[0019] It is based on the Fig. 3, Fig. 4 and Fig.5. A connecting cover 9 is arranged between the rear portion of the transmission section 52 and the outer cover 52c, namely, between the right housing body 52a and the outer cover 52c. More specifically, the connecting cover 9 is arranged on and locked to the outer cover 52c. The connecting cover 9 is provided with a through-hole 91, the inner periphery of the through-hole 91 being provided with a stepped receiving portion 92, and the receiving portion 92 being provided with a dust cover 93. The first pivot connecting portion 61 of the rear swing arm 6 is inserted through the through-hole 91.More specifically, the dust protection ring 93 is located between the outer periphery of the first pivot connection portion 61 of the rear swing arm 6 and the inner periphery of the through hole 91, and further, the dust protection ring 93 is located between the connection cover 9 and the outer periphery of the first pivot connection portion 61. Since the dust protection ring 93 is located between the first pivot connection portion 61 and the through hole 91, moisture or dust from the outside can be effectively prevented from entering the first pivot connection portion 61 and the chamber of the belt-type continuously variable transmission system 53c, to prevent the bearing of the first pivot connection portion 61 from being corroded by moisture or dust from the outside, and thus to ensure the pivotability of the rear swing arm 6 and the operability of the belt-type continuously variable transmission system 56.

[0020] The main effect of the present invention is explained below: In that the motor scooter 2 comprises a power unit 5, wherein a rear swing arm 6 is pivotally arranged at the rear end of the power unit 5, and in that the power unit 5 comprises a cylinder section 51 and a transmission section 52, and the transmission section 52 comprises a crankshaft 54 ​​and a continuously variable belt transmission system 56 drivable via the crankshaft 54, and the continuously variable belt transmission system 56 comprises a drive wheel 561, a driven wheel 562, and a drive belt 563 connected to the drive wheel 561 and the driven wheel 562, and the center of the driven wheel 562 is provided with a drive shaft 564 through which a reduction gear 55 can be driven, and the reduction gear 55 can drive an output shaft 57 provided with an output gear 571,and that the rear swing arm 6 has a first pivot connection section 61 and a second pivot connection section 62 and is provided with a rear wheel axle 63, and a rear wheel RW and a rear-wheel drive gear 7 are rotatably arranged on the rear wheel axle 63, and a transmission part 8 is arranged between the rear-wheel drive gear 7 and the driven gear 571, and that the rear swing arm 6 is pivotally arranged on the transmission section 52 by means of the first pivot connection section 61 and the second pivot connection section 62, and the drive shaft 564 is passed through the first pivot connection section 61 of the rear swing arm 6, and the rear swing arm 6 uses the axis center Y of the drive shaft 564 as the center for pivoting up and down, and the driven shaft 57 is coaxial with the axis center Y, the rear swing arm 6 can be displaced toward the front of the body,which shortens the wheelbase between the front wheel FW and the rear wheel RW and thus shortens the length of the scooter 2.

[0021] The second advantageous effect of the present invention will be explained below: Because the output shaft 57 is coaxial with the drive shaft 564 and the output shaft 57 is passed through the second pivot connecting portion 62 of the rear swing arm 6, the rear swing arm 6 can use the axis center Y of the drive shaft 564 as the center for swinging up and down and the output shaft 57 can be coaxial with the axis center Y, whereby the scooter 2 can be shortened in length.

[0022] The third advantageous effect of the present invention will be explained below: By virtue of the fact that in the transmission section 52, the gear case 53 consists of at least a right case body 52a and a left case body 52b, and the gear case 53 is provided with a first support piece 58, and the first pivot connecting section 61 of the rear swing arm 6 is pivotally connected to the first support piece 58, it can be ensured that the rear swing arm 6 uses the axis center Y of the output shaft 57 as the center for pivoting up and down, and the axis center Y is coaxial with the input shaft 564.

[0023] The fourth advantageous effect of the present invention will be explained below: By providing the first pivotal connecting portion 61 of the rear swing arm 6 and the first support piece 58 between the reduction gear chamber 53b of the transmission case 53 and the belt-type continuously variable transmission system chamber 53c, the overall configuration of the power unit 5 and the rear swing arm 6 can be made more compact.

[0024] The fifth advantageous effect of the present invention will be explained below: Because the second pivoting connecting portion 62 of the rear swing arm 6 is pivotally connected to the second support piece 59 and the second pivoting connecting portion 62 is located between the output gear 571 of the transmission portion 52 and the gear case 53, the rear swing arm 6 can use the axis center Y of the drive shaft 564 as the center for swinging up and down and the output shaft 57 can be coaxial with the axis center Y.

[0025] The sixth advantageous effect of the present invention will be explained below: By covering one side of the gear case 53 with an outer cover 52c to form a chamber of the continuously variable belt transmission system 53c, and disposing the continuously variable belt transmission system 56 of the transmission section 52 in the chamber of the continuously variable belt transmission system 53c, and by disposing a connecting cover 9 between the chamber of the continuously variable belt transmission system 53c and the first pivot connecting section 61, and by providing the connecting cover 9 with a through hole 91 through which the drive shaft 564 of the transmission section 52 can be inserted, the operability of the reduction gear 55 and the continuously variable belt transmission system 56 can be ensured.

[0026] The seventh advantageous effect of the present invention is explained below: By providing the connecting cover 9 with a through hole 91 through which the drive shaft 564 of the transmission section 52 can be inserted, the functionality of the reduction gear 55 and the continuously variable belt transmission system 56 can be ensured.

[0027] The eighth advantageous effect of the present invention will be explained below: By providing the inner circumference of the through hole 91 with a stepped receiving portion 92 and the receiving portion 92 with a dust protection ring 93, moisture or dust from the outside can be effectively prevented from entering the first pivot connecting portion 61 and the chamber of the continuously variable belt transmission system 53c, to prevent the bearing of the first pivot connecting portion 61 from being corroded by moisture or dust from the outside, and thus to ensure the pivotability of the rear swing arm 6 and the operability of the continuously variable belt transmission system 56.

[0028] The ninth advantageous effect of the present invention will be explained below: By locking the connecting cover 9 with the outer cover 52c, moisture or dust from the outside can be effectively prevented from entering the first pivot connecting portion 61 and the chamber of the belt-type continuously variable transmission system 53c, to prevent the bearing of the first pivot connecting portion 61 from being corroded by moisture or dust from the outside, and thus to ensure the pivotability of the rear swing arm 6 and the operability of the belt-type continuously variable transmission system 56.

[0029] The tenth advantageous effect of the present invention will be explained below: By providing the dust protection ring 93 between the connection cover 9 and the first pivoting connecting portion 61 of the rear swing arm 6, moisture or dust from the outside can be effectively prevented from entering the first pivoting connecting portion 61 and the chamber of the belt-type continuously variable transmission system 53c, to prevent the bearing of the first pivoting connecting portion 61 from being corroded by moisture or dust from the outside, and thus to ensure the pivotability of the rear swing arm 6 and the operability of the belt-type continuously variable transmission system 56.

Claims

[1] Configuration of the rear swing arm for motorcycles, wherein the scooter (2) comprises a power unit (5), wherein a rear swing arm (6) is pivotally arranged at the rear end of the power unit (5), wherein the power unit (5) comprises a cylinder section (51) and a transmission section (52), and the transmission section (52) comprises a crankshaft (54) and a continuously variable belt transmission system (56) drivable via the crankshaft (54), and the continuously variable belt transmission system (56) comprises a drive wheel (561), a driven wheel (562) and a drive belt (563) connected to the drive wheel (561) and the driven wheel (562), and the center of the driven wheel (562) is provided with a drive shaft (564) through which a reduction gear (55) can be driven, and the reduction gear (55) has an output shaft (57) connected to a driven gear (571),wherein the rear swing arm (6) has a first pivot connection section (61) and a second pivot connection section (62) and is provided with a rear wheel axle (63), and a rear wheel (RW) and a rear wheel drive gear (7) are rotatably arranged on the rear wheel axle (63), and a transmission part (8) is arranged between the rear wheel drive gear (7) and the driven gear (571), wherein the rear swing arm (6) is pivotally arranged on the transmission section (52) by means of the first pivot connection section (61) and the second pivot connection section (62), , characterized byin that the drive shaft (564) is passed through the first pivoting connection section (61) of the rear swing arm (6), and the rear swing arm (6) uses the axis center (Y) of the drive shaft (564) as the center point for swinging up and down, and the output shaft (57) is coaxial with the axis center (Y), wherein the first pivoting connection section (61) is located in a gear housing (53) and between a reduction gear chamber (53b) and a continuously variable belt transmission system (53c), both of which are accommodated in the gear housing. [2] The configuration of the rear swing arm for motorcycles according to claim 1, wherein the output shaft (57) is coaxial with the drive shaft (564) and the output shaft (57) is passed through the second pivot connecting portion (62) of the rear swing arm (6). [3] The configuration of the rear swing arm for motorcycles according to claim 1, wherein the transmission portion (52) includes at least a right case body (52a) and a left case body (52b) to form the transmission case, and the transmission case (53) is provided with a first support piece (58), and the first pivot connecting portion (61) of the rear swing arm (6) is pivotally connected to the first support piece (58), wherein the transmission case (53) is further provided with a second support piece (59), and the second pivot connecting portion (62) of the rear swing arm (6) is pivotally connected to the second support piece (59). [4] The configuration of the rear swing arm for motorcycles according to claim 3, wherein the rear swing arm (6) and the first support piece (58) are located in the transmission case (53) and between the reduction gear chamber (53b) and the chamber of the continuously variable belt transmission system (53c) disposed therein. [5] The configuration of the rear swing arm for motorcycles according to claim 3, wherein the second pivotal connecting portion (62) of the rear swing arm (6) is pivotally connected to the second support piece (59), and the second pivotal connecting portion (62) is located between the output gear (571) of the transmission portion (52) and the transmission case (53). [6] The configuration of the rear swing arm for motorcycles according to claim 3, wherein one side of the transmission case (53) is covered with an outer cover (52c) to form a chamber of the continuously variable belt transmission system (53c), and the continuously variable belt transmission system (56) of the transmission section (52) is arranged in the chamber of the continuously variable belt transmission system (53c), a connecting cover (9) is arranged between the chamber of the continuously variable belt transmission system (53c) and the first pivot connecting section (61). [7] The configuration of the rear swing arm for motorcycles according to claim 6, wherein the connecting cover (9) is provided with a through hole (91) through which the drive shaft (564) of the transmission section (52) can be passed. [8] The configuration of the rear swing arm for motorcycles according to claim 7, wherein the inner periphery of the through hole (91) is provided with a step-shaped receiving portion (92) and the receiving portion (92) is provided with a dust protection ring (93). [9] The configuration of the rear swing arm for motorcycles according to claim 6, wherein the connecting cover (9) is locked to the outer cover (52c). [10] The configuration of the rear swing arm for motorcycles according to claim 8, wherein the dust protection ring (93) is located between the connecting cover (9) and the first pivot connecting portion (61) of the rear swing arm (6).

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