A saddle-type vehicle having primary and secondary power-transmission units

Abstract

The present invention relates to a saddle-type vehicle. The vehicle comprises a crankshaft (102), a primary power transmission unit (106) and a secondary power transmission unit (108). The primary power transmission unit (106) is housed in a crankcase (100) and configured to operably connect the crankshaft (102) and the clutch shaft (104) rotatably supported in the crankcase (100). The secondary power transmission unit (108) is operably connected to the clutch shaft (104) and a rear wheel shaft (110) of a rear wheel (112) of the vehicle.

Description

[0001] TITLE OF INVENTION:

[0002] A SADDLE-TYPE VEHICLE

[0003] FIELD OF THE INVENTION

[0004]

[0001] The present invention relates to a vehicle. More particularly, the present invention relates to a transmission layout of a saddle type vehicle.

[0005] BACKGROUND OF THE INVENTION

[0006]

[0002] In conventional two wheeled saddle type vehicle, also referred to as “vehicle” hereinafter for brevity, more particularly scooter type vehicle, a significant challenge arises when attempting to accommodate different wheel sizes while maintaining the same internal combustion engine or engine displacement (CC). Unlike motorcycles, wherein a chain drive is used to connect an engine’s cranks shaft to a rear wheel, scooters typically have an engine that is directly connected to the rear wheel via a continuously variable transmission (CVT) system. This direct connection introduces multiple design constraints when changing the wheel size of the vehicle based on different height requirement of the vehicle in different countries. When increasing the wheel size in a scooter, it necessitates a change in the centre distance (CD) between the crankshaft and the wheel shaft. This is because a rear wheel shaft of the rear wheel of the vehicle is directly linked to the CVT system, and any increase in wheel size affects the entire drivetrain configuration. Additionally, larger wheels can interfere with the crankcase due to clearance limitations. As a result, maintaining the same engine configuration while changing wheel sizes is often not feasible.

[0007]

[0003] A key challenge in the prior arts is change in distance between the crankshaft and the rear wheel shaft of the rear wheel of the vehicle. The increase in wheel size leads to an increase in required centre distance between the crankshaft and the rear wheel shaft. Unlike motorcycles, where different wheel sizes can be accommodated by adjusting the chain length, scooter engines are directly connected to the wheel, requiring modifications to the crankcase and transmission layout as a majorcomponents of the CVT system are configured within the crankcase. Changing the wheel size also impacts ground clearance and engine orientation. Altering the frame height and vehicle orientation can affect engine positioning, and a change in engine angle due to mounting constraints can lead to lubrication issues, improper oil return, and potential failures in drainage systems. Furthermore, a larger wheel may require changes to the crankcase, variator cover, and clutch system to maintain proper alignment. Such modifications increase the number of unique parts, driving up costs and development time.

[0008]

[0004] In the internal combustion engines of the scooter type vehicle, components of the CVT system is enclosed in the crankcase left portion or the crankcase right portion. The crankcase portion which accommodates the components of the CVT system is extend rearwards. A centre distance between the crankshaft and the clutch shaft depends on the wheel size of the vehicle. As a portion of the rear wheel of the vehicle is located behind the lateral protruded portion of the crankcase connecting the crankcase left portion and the crankcase right portion, thus the wheel size affects the crankcase left portion and the cover variator / transmission covers used to cover the CVT components from outside. Change in size of the wheel in different countries requires change in size of the crankcase left portion and the variator cover of the vehicle.

[0009]

[0005] Developing different crankcases and transmission covers / variator covers for each wheel size increases part variety and complexity, leading to additional design, validation, and production processes, extending project timelines and raising costs. Existing solutions to accommodate different wheel sizes in scooters typically involve development of new crankcases, transmission covers / variator covers, and clutch systems specific to each wheel configuration. This results in increased manufacturing complexity and part proliferation, making it an inefficient solution for manufacturers aiming to standardize their product lines. In the know solutions use of differentcrankcases, clutch systems and transmission covers / variator covers for different wheel size vehicles are recommended but is highly undesirable.

[0010]

[0006] In view thereof, there is a need-felt to overcome at least the above-mentioned disadvantages of the prior art.

[0011] SUMMARY OF THE INVENTION

[0012]

[0007] In one aspect of the present invention, a vehicle is disclosed. The vehicle comprises a crankshaft of an internal combustion engine of the vehicle, a primary power transmission unit and a secondary power transmission unit. The crankshaft and a clutch shaft are rotatably supported in a crankcase of the internal combustion engine. The primary power transmission unit is housed in the crankcase. The primary power transmission unit is configured to operably connect the crankshaft and the clutch shaft supported by the crankcase. The secondary power transmission unit is configured to operably connect the clutch shaft and a rear wheel shaft of the rear wheel of the vehicle.

[0013]

[0008] In an embodiment, the crankcase is formed of a first crankcase portion that can be configured on a left side of the engine and a second crankcase portion that can be configured on a right side of the engine. The primary power transmission unit is housed in the first crankcase portion and the clutch shaft is rotatably is supported in the first crankcase portion.

[0014]

[0009] In an embodiment, the secondary power transmission unit comprises a drive sprocket and a driven sprocket. The drive sprocket and the driven sprocket are operably connected to each other. The drive sprocket is connected to the clutch shaft and the driven sprocket is mounted on the rear wheel shaft of the rear wheel.

[0015]

[0010] In an embodiment, the vehicle comprises one or more brackets. The one or more brackets are adapted to support the crankcase on the rear wheel of the vehicle.

[0016]

[0011] In an embodiment, the one or more brackets comprises a first bracket and a second bracket. The first bracket is adapted to be connected to the first crankcase portion of the crankcase and the rear wheel shaft of the vehicle. The second bracket isadapted to be connected to the second crankcase portion of the crankcase and the rear wheel shaft of the vehicle.

[0017]

[0012] In an embodiment, each of the one or more brackets comprises a mounting bore and a mounting unit. The mounting unit is configured in the mounting bore. The mounting unit comprises at least a bearing, a dust seal member, and a circlip to enable mounting of the one or more brackets on the rear wheel shaft of the vehicle.

[0018]

[0013] In an embodiment, each of the one or more brackets comprises one or more mounting arms.

[0019]

[0014] In an embodiment, the first bracket is adapted to support a left shock absorber and the second bracket is adapted to support a right shock absorber and a muffler of the vehicle.

[0020]

[0015] In an embodiment, the primary power transmission unit is a continuously variable transmission.

[0021]

[0016] In another aspect of the present invention, a crankcase for an internal combustion engine for a vehicle is disclosed. The crankcase is adapted to house a primary power transmission unit and support a clutch shaft and a crankshaft. The clutch shaft is operably connected to the crankshaft through the primary power transmission unit and to a rear wheel shaft of a rear wheel of the vehicle through a secondary power transmission unit. The secondary power transmission unit is configured to operably connect the clutch shaft to the rear wheel shaft of the rear wheel.

[0022]

[0017] In an embodiment, the crankcase comprises one or more mounting provisions to connect with one or more brackets. The one or more brackets are adapted to mount the crankcase to the rear wheel of the vehicle. The crankcase comprises a first crankcase portion and a second crankcase portion. The primary power transmission unit is housed in the first crankcase portion and the clutch shaft is supported in the first crankcase portion .BRIEF DESCRIPTION OF THE DRAWINGS

[0023]

[0018] Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.

[0024] Figure 1 illustrates a schematic view of a scooter type vehicle of prior art. Figure 2 illustrates an internal combustion engine with a transmission system configured in a rear part of the vehicle, in accordance with an embodiment of the present invention.

[0025] Figure 3 illustrates an exploded view of an internal combustion engine and the transmission system of the vehicle, in accordance with the embodiment of the present invention.

[0026] Figure 4a illustrates a top perspective view of a second bracket, in accordance with the embodiment of the present invention.

[0027] Figure 4b illustrates a perspective view of the second bracket, in accordance with the embodiment of the present invention.

[0028] Figure 4c illustrates a front view of the second bracket, in accordance with the embodiment of the present invention.

[0029] Figure 4d illustrates a rear view of the second bracket, in accordance with the embodiment of the present invention.

[0030] Figure 5a illustrates a top perspective view of a first bracket, in accordance with the embodiment of the present invention.

[0031] Figure 5b illustrates a perspective view of the first bracket, in accordance with the embodiment of the present invention.

[0032] Figure 5c illustrates a front view of the first bracket, in accordance with the embodiment of the present invention.Figure 5d illustrates a rear view of the first bracket, in accordance with the embodiment of the present invention.

[0033] DETAILED DESCRIPTION OF THE INVENTION

[0034]

[0019] Various features and embodiments of the present invention here will be discernible from the following further description thereof, set out hereunder.

[0035]

[0020] Figure 1 illustrates a schematic view of a scooter type vehicle 10 of prior art. In the prior arts, continuously variable transmission (CVT) system 12 is used to transmit power of an internal combustion engine to a rear wheel shaft of a rear wheel of the vehicle 10. More particularly, power from the internal combustion engine is transmitted through the crankshaft to components of the CVT system, which usually comprises a primary (drive) pulley and a secondary (driven) pulley connected by a belt or chain. The drive pulley is operably connected to the crankshaft of the internal combustion engine 101 and the driven pulley is connected to the rear wheel shaft, which in turn drives the rear wheel. In other words, the transmission system of the prior art is directly connected to the rear wheel shaft of the rear wheel of the vehicle 10.

[0036]

[0021] Figure 2 illustrates an internal combustion engine 101 with a transmission system configured in a rear part of the vehicle, in accordance with an embodiment of the present invention. Figure 3 illustrates an exploded view of an internal combustion engine 101 and the transmission system of the vehicle, in accordance with the embodiment of the present invention.

[0037]

[0022] As shown, in the vehicle 150 of the present invention, a crankshaft 102 is connect to a a clutch shaft 104 via a primary power transmission unit 106, and the clutch shaft 104 is connected to a rear wheel shaft 110 of the rear wheel 112 of the vehicle 150 via a secondary power transmission unit 108. Thus, to transmit power of the internal combustion engine 101 to the rear wheel shaft 110 of the rear wheel 112 of the vehicle, the present invention utilizes the primary power transmission unit 106 and the secondary power transmission unit 108. The primary power transmission unit106 is housed in a crankcase 100 of the vehicle. The primary power transmission unit 106 is configured to operably connect the crankshaft 102 of the internal combustion engine 101 and the clutch shaft 104. Both the crankshaft 102 and the clutch shaft 104 are rotatably supported by the crankcase 100 of the vehicle. The crankcase 100 of the vehicle 150 is typically formed of a first crankcase portion 100L, for instance a left crankcase portion, configured on a left side of the internal combustion engine 101, when viewed from a rear-front direction of the vehicle, and a second crankcase portion 100R, for instance a right crankcase portion configured on a right side of the internal combustion engine 101 when viewed from the rear-front direction of the vehicle,. The first crankcase portion / left crankcase portion 100L and the second crankcase portion / right crankcase portion 100R are detachably connected to the each other. In a non-limiting example, as shown in Figure 3, the primary power transmission unit 106 is housed in the first crankcase portion 100L of the crankcase 100. Also, both the crankshaft 102 and the clutch shaft 104 are supported in the first crankcase portion 100L of the crankcase 100. However, this should not be construed as limiting and second crankcase portion 100R of the crankcase 100 can also be utilized to house the primary power transmission unit 106 and support the crankshaft 102 as well as clutch shaft 104. In a non-limiting example, the primary power transmission unit 106 is continuously variable transmission (CVT) system with the crankshaft 102 being operably connected to a drive pulley 104a of the CVT system 12 and the clutch shaft 104 being operably connected to the driven pulley 104b of the CVT system 12. Figure 3 also illustrates a transmission cover / variator cover. The transmission cover / variator cover 134 is a protective component that covers the first crankcase portion 100L and the primary power transmission unit 106 from dirt, debris and moisture, and helping to manage heat or prevent fluid leaks. The transmission cover / variator cover 134 protects the first crankcase portion 100L and the primary power transmission unit 106 from external damage while keeping the same enclosed and lubricated.

[0023] The secondary power transmission unit 108 is configured to operably connect the clutch shaft 104 and the rear wheel shaft 110 of the rear wheel 112 of the vehicle. The secondary power transmission unit 108 comprises a drive sprocket 118 and a driven sprocket 120 operably connected to each other. In a non-limiting example, the drive sprocket 118 and the driven sprocket 120 are connected to each other by means of a belt 121. In a non-limiting example, the drive sprocket 118 and the driven sprocket 120 are connected to each other by means of a chain. However, this should not be construed as limiting and the drive sprocket 118 and the driven sprocket 120 connected to each other by now known or later developed means are well within the scope of the present invention. The drive sprocket 118 of the secondary power transmission unit 108 is connected to the clutch shaft 104 and the driven sprocket 120 of the secondary power transmission unit 108 is connected to the rear wheel shaft 110 of the rear wheel 112 of the vehicle. The vehicle 150 of the present invention further comprises one or more brackets 114, 116 to support the crankcase 100 on the rear wheel shaft 110 of the vehicle. In a non-limiting example, as shown in Figure 3, the vehicle 150 of the present invention comprises a first bracket 114 also referred to as a left bracket, configured on a left side of the vehicle 150 in a rear-front direction and a second bracket 116 also referred to as a right bracket, configured on a right side of the vehicle 150 in the rearfront direction. The first bracket / left bracket 114 is adapted to connect the first crankcase portion 100L of the crankcase 100 to the rear wheel shaft 110 of the vehicle, i.e. the first bracket / left bracket 114 is adapted to be connected to the first crankcase portion 100L of the crankcase 100 as well as the rear wheel shaft 110 of the vehicle. Similarly, the second bracket 116 is adapted to connect the second crankcase portion 100R of the crankcase 100 to the rear wheel shaft 110 of the vehicle, i.e. the second bracket 116 is adapted to be connected to the second crankcase portion 100R of the crankcase 100 as well as the rear wheel shaft 110 of the vehicle.

[0038]

[0024] Each of the one or more brackets 114, 116 comprises one or more portions including a first portion 128 and one or more arms 130 extending from the first portion128. The first portion 128 of each of the bracket 114, 116 comprises a mounting bore 132 (shown in Figure 4 and 5) and a mounting unit configured inside the mounting bore 132. The first portion 128 is connected to the rear wheel shaft 110 of the vehicle. In a non-limiting example, the mounting unit comprises at least one bearing and a dust seal member 133, a circlip to enable mounting of the brackets 114, 116 on the rear wheel shaft 110 of the rear wheel 112 of the vehicle. The bearing allows rotation of the rear wheel shaft 110 of the rear wheel 112 with respect to the brackets 114, 116. The dust seal member 133 is configured to prevent entry of dust in the bearing and the first portion 128 of the brackets 114, 116. For instance, the dust seal member 133 can be dust seal nut 133. As shown in Figure 3, the first portion 128 of the first bracket 114 and the first portion 128 of the second bracket 116 are mounted on the rear wheel shaft 110 of the vehicle. The one or more arms 130 extend from the first portion 128 and comprise one or more mounting portions M1-M5 (shown in Figure 4 and Figure 5). The one or more mounting portions M1-M5 are provided to connect the one or more brackets 114, 116 to the crankcase 100 and optionally to one or more other components of the vehicle. For example, the one or more mounting portions M4-M5 provided on the first bracket 114 are used to connect the first bracket 114 to the first crankcase portion 100L and to a left shock absorber 122 of the vehicle. It is to be understood that mounting sections will be provided on the first crankcase portion 100L as well as left shock absorber 122 for mounting of the first bracket 114 onto the first crankcase portion 100L as well as left shock absorber 122. In a non-limiting example, the mounting portions M4-M5 as well as mounting sections comprise mounting holes which can be aligned and fastened with one or more now known or later developed fasteners.

[0039]

[0025] Similarly, the one or more mounting portions Ml -M3 provided on the second bracket 116 are used to connect the second bracket 116 to the second crankcase portion 100R, a right shock absorber 124 and a muffler 126 of the vehicle. It is to be understood that mounting sections Ml -M3 will be provided on the second crankcase portion 100R,right shock absorber 124 and the muffler 126 for mounting of the second bracket 116 onto the right crankcase portion 100R, right shock absorber 124 and the muffler 126. In a non-limiting example, the mounting portions Ml -M3 as well as mounting sections comprise mounting holes which can be aligned and fastened with one or more now known or later developed fasteners.

[0040]

[0026] Figure 4a illustrates a top perspective view of a second bracket 116, in accordance with the embodiment of the present invention. Figure 4b illustrates a perspective view of the second bracket 116, in accordance with the embodiment of the present invention. Figure 4c illustrates a front view of the second bracket 116, in accordance with the embodiment of the present invention. Figure 4d illustrates a rear view of the second bracket 116, in accordance with the embodiment of the present invention.

[0041]

[0027] As shown, the second bracket 116 comprise the first portion 128 and plurality of arms 130 extending from the first portion 128. The plurality of arms 130 can be connected with each other. The plurality of arms 130 comprises a first set of mounting portions Ml, a second set of mounting portions M2 and a third set of mounting portions M3. The mounting portions can be provided on a front surface of the second bracket 116 and / or the rear surface of the second bracket 116. The rear surface is the surface of the second bracket R facing the rear wheel 112 of the vehicle. The front surface is the surface opposite the rear surface . The first set of mounting portions Ml is used to connect the second bracket 116 to the second crankcase portion 100R. The second set of mounting portions M2 is used to connect the second bracket 116 to the right shock absorber 124. The third set of mounting portions M3 is used to connect the second bracket 116 to the muffler 126.

[0042]

[0028] Figure 5a illustrates a top perspective view of a first bracket 114, in accordance with the embodiment of the present invention. Figure 5b illustrates a perspective view of the first bracket 114, in accordance with the embodiment of the present invention. Figure 5c illustrates a front view of the first bracket 114, in accordance with theembodiment of the present invention. Figure 5d illustrates a rear view of the first bracket 114, in accordance with the embodiment of the present invention.

[0043]

[0029] As shown, like the second bracket 116, the first bracket 114 also comprises the first portion 128 and plurality of arms 130 extending from the first portion 128. The plurality of arms comprises a fourth set of mounting portions M4 and a fifth set of mounting portions M5. The mounting portions can be provided on a front surface of the first bracket 114 and / or the rear surface of the first bracket 114. The rear surface is the surface of the first bracket 114 facing the rear wheel 112 of the vehicle. The front surface is the surface opposite the rear surface . The fourth set of mounting portions M4 is used to connect the first bracket 114 to the first crankcase portion 100L. The fifth set of mounting portions M5 is used to connect the first bracket 114 to the left shock absorber 122.

[0044]

[0030] The claimed features of the present invention as discussed above are not routine, conventional, or well understood in the art, as the claimed features enable the following solutions to the existing problems in conventional technologies. Specifically, the technical problem of separate crankcases, clutch systems, transmission layouts and engine configurations for different wheel sizes, is solved by present invention.

[0045]

[0031] The present invention accommodates various wheel sizes in the vehicle while maintaining a common crankcase, transmission system and engine configuration resulting in optimization of development costs, reduction in part complexity, and enhancement in manufacturing efficiency of the vehicle.

[0046]

[0032] In the present invention, the transmission system is divided in two parts i.e. the primary power transmission unit and the secondary power transmission unit. However, only the primary power transmission unit is accommodated in the first crankcase portion. In other words, the secondary power transmission unit is not accommodated in the first crankcase portion. Any change in length of the transmission system due to change in wheel size will cause change in length of the secondary power transmission unit. In other words, any change in the first crankcase portion and the transmissioncover / variator cover is prevented. In addition, only by changing size of the brackets, same crankcase and other components can be mounted on the rear wheel shaft. Therefore, wheel having different sizes can be accommodated in vehicle only by changing size of brackets without the need of changing the crankcase and transmission / variator cover. Thus, change in the wheel size will not affect the first crankcase portion and the cover variator / transmission covers. The present invention, therefore, prevents the need for different crankcases and transmission / variator covers for different sizes of rear wheel, thereby, decreasing part variety and complexity associated with the manufacture of vehicle having different sizes of rear wheel. This results in decreased manufacturing complexity and part proliferation, making it an efficient solution for manufacturers aiming to standardize their product lines.

[0047]

[0033] The present invention is simple, reliable as well as cost-effective.

[0048]

[0034] While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.

[0049] List of Reference Numerals

[0050] 10-vehicle

[0051] 12- CVT system

[0052] 100- crankcase

[0053] 100L- first crankcase portion

[0054] 100R- second crankcase portion

[0055] 102- crankshaft

[0056] 104- clutch shaft

[0057] 104a- drive pulley

[0058] 104b- driven pulley

[0059] 106- primary power transmission unit108- secondary power transmission unit 110- rear wheel shaft

[0060] 112- rear wheel

[0061] 114- first bracket

[0062] 116- second bracket

[0063] 118- drive sprocket

[0064] 120- driven sprocket

[0065] 121- belt

[0066] 122- left shock absorber

[0067] 124- right shock absorber

[0068] 126- muffler

[0069] 128- first portion of bracket

[0070] 130- arms of bracket

[0071] 132- mounting bore

[0072] 133- dust seal member

[0073] 150-vehicle

[0074] 134- transmission cover / variator cover Ml - first set of mounting portions M2- second set of mounting portions M3- third set of mounting portions M4- fourth set of mounting portions M5- fifth set of mounting portions

Claims

1. WE CLAIM:

1. A vehicle (150) comprising:a crankshaft (102) of an internal combustion engine 101 of the vehicle, the crankshaft (102) being rotatably supported in a crankcase (100), the crankcase (100) being adapted to rotatably support a clutch shaft (104);a primary power transmission unit (106) being housed in the crankcase (100), the primary power transmission unit (106) being configured to operably connect the crankshaft (102) and the clutch shaft (104); anda secondary power transmission unit (108), the secondary power transmission unit (108) being configured to operably connect the clutch shaft (104) and a rear wheel shaft (110) of a rear wheel (112) of the vehicle.

2. The vehicle (150) as claimed in claim 1 , wherein the crankcase (100) being formed of a first crankcase portion (100L) and a second crankcase portion (100R), the primary power transmission unit (106) being housed in the first crankcase portion (100L) and the clutch shaft (104) being rotatably supported in the first crankcase portion (100).

3. The vehicle (150) as claimed in claim 1, wherein the secondary power transmission unit (108) comprises a drive sprocket (118) and a driven sprocket (120) operably connected to each other, the drive sprocket (118) being connected to the clutch shaft (104) and the driven sprocket (120) being mounted on the rear wheel shaft (110) of the rear wheel (112).

4. The vehicle (150) as claimed in claim 2, comprising one or more brackets (114, 116), the one or more brackets (114, 116) being adapted to support the crankcase (100) on the rear wheel shaft (110) of the vehicle.

5. The vehicle (150) as claimed in claim 4, wherein plurality of brackets (114, 116) comprises a first bracket (114) and a second bracket (116), the first bracket (114) being adapted to be connected to the first crankcase portion (100L) of the crankcase (100) and the rear wheel shaft (110) of the vehicle, and the second bracket (116) being adapted to be connected to the second crankcase portion (100R) of the crankcase (100) and the rear wheel shaft (110) of the vehicle.

6. The vehicle (150) as claimed in claim 4, wherein each of plurality of brackets (114, 116) comprises a mounting bore (132) and a mounting unit configured in the mounting bore (132), the mounting unit including at least a bearing, a dust seal member (133), and a circlip to enable mounting of the of the respective brackets on the rear wheel shaft (110).

7. The vehicle as claimed in claim 4, wherein each of plurality of brackets (114, 116) comprises one or more mounting arms (130).

8. The vehicle (150) as claimed in claim 5, wherein the first bracket (114) being adapted to support a left shock absorber (122), and the second bracket (116) being adapted to support a right shock absorber (124) and a muffler (126) of the vehicle.

9. The vehicle (150) as claimed in claim 1, wherein the primary power transmission unit (106) being a continuously variable transmission.

10. A crankcase (100) for an internal combustion engine 101 of a vehicle (150), the crankcase (100) adapted to house a primary power transmission unit (106) and support a clutch shaft (104), the clutch shaft (104) operably connected to a crankshaft through the primary power transmission unit (106) and to a rear wheel shaft (110) of a rear wheel (112) through a secondary power transmission unit (108), the secondary power transmission unit (108) being configured to operablyconnect the clutch shaft (104) to the rear wheel shaft (110) of the rear wheel (112) of the vehicle.

11. The crankcase (100) as claimed in claim 10, comprising one or more mounting sections to connect with a plurality of brackets (114, 116), the plurality of brackets (114, 116) being adapted to mount the crankcase (100) to the rear wheel shaft (110), and wherein crankcase (100) comprises a first crankcase portion (100L) and a second crankcase portion (100R), the primary power transmission unit (106) being housed in the first crankcase portion (100L) and the clutch shaft (104) being supported in the first crankcase portion (100L).

Images