DESC:Technical Field
[0001] The present subject matter described herein generally relates to a gear shift linkage assembly for a motorcycle.
Background
[0002] Typically, a motorcycle gear shift linkage assembly includes a gear shift link member connected to a gear shift shaft, a connecting member connecting said gear shift link member to a gear shift lever. The gear shift linkage assembly is used for manually shifting gears by using the foot to shift the position of the gear shift lever so that the desired drive gears or the neutral position in a gear box is engaged. Particularly, the desired drive gears or the neutral position in the gear box is engaged by either lifting up or pushing down the gear shift lever. Thus, the gear shift lever serves as the contact point for manual shifting with foot. A change in drive gear positions is achieved due to transfer of motion from the gear shift lever to the gear shift shaft through said connecting member and said gear shift link member.
[0003] The above described gear shift linkage assembly typically has at least two fixed attachments. Whereas, the gear shift lever is fixedly attached to a frame member at one end, the gear shift link member located on the gear shift shaft is fixedly attached thereto by means of a fastener. Typically, fastening to the gear shift shaft is performed on a left hand side of said gear shift link member and adjacent to a magneto cover. However, assembly of said gear shift link member to the gear shift shaft proves to be cumbersome when the size of the magneto cover increases, causing it to protrude outwards and closer towards the gear shift link member. Typically, such a problem is experienced in motorcycles with higher engine capacity, where, in order to meet higher power requirements, a higher diameter/width magneto has to be provided, causing a shift in the position of the pulser coil, and thereby resulting in increased size of the magneto cover.
[0004] Moreover, conventional gear shift linkage assemblies also make use of multiple ball joints for enhanced ergonomics. Use of multiple ball joints not only leads to increase in number of parts and therefore increase in complexities during manufacturing process, but also leads to significantly higher manufacturing costs. There is therefore a need to decrease the number of parts used in the gear shift linkage assembly, while ensuring ease of assembly. Also, one or more tools have to be used to assemble said gear shift link member to the gear shift shaft, which decreases overall convenience during assembly. The gear shift linkage assembly thus assembled should be ergonomically optimized for providing comfort to a rider while shifting gears.
Summary of the Invention
[0005] The present invention has been made in view of the above circumstances.
[0006] It is an object of the present invention to provide a gear shift linkage assembly which aids in ensuring good fitment flexibility.
[0007] It is another object of the present invention to provide a gear shift linkage assembly whose installation is easy and convenient, and which involves reduced assembly man hours.
[0008] It is yet another object of the present invention to provide a gear shift linkage assembly which can be retro fitted onto any motorcycle.
[0009] It is still another object of the present invention to provide a gear shift linkage assembly which involves the use of reduced number of parts.
[0010] It is one more object of the present invention to provide a gear shift linkage assembly which aids in ensuring good rider ergonomics based on individual requirements.
[0011] Thus, the present subject matter discloses a gear shift linkage assembly for a motorcycle. The gear shift linkage assembly as per the present invention is connected to a transmission system of said motorcycle and allows a rider to manually select different gears during the course of riding. Particularly, the gear shift linkage assembly includes a gear shift lever pivotally connected to a connecting member at a first end thereof, and a gear shift link member fixedly connected at its upper end to a gear shift shaft of said transmission system, and pivotally connected at its lower end to a second end of said connecting member. Operation of said gear shift lever causes corresponding movement of said gear shift link member, whose connection with the gear shift shaft causes said gear shift shaft to rotate in a selected direction, thereby causing a selection of a desired gear. In other words, motion of the gear shift lever is transferred to the gear shift link member through the connecting member for selection of the desired gear. In order to ensure that said gear shift link member is surely seated on the gear shift shaft, said link member is fastened to the same by means of a fastener.
[0012] As per an aspect of the present invention, said connecting member is directly detachably attached to said gear shift link member at its second end. Providing a detachable connection with the gear shift link member permits adjustment of said link member at any time before final assembly. For example, said link member can be adjusted so that fastening to the gear shift shaft may be performed from a side which is away from the magneto cover, thereby easing access to said link member. Moreover, the direct detachable attachment performed as per the present invention does not involve the use of additional tools for assembly of said link member to the gear shift shaft. The present invention therefore contemplates a direct detachable attachment of said connecting member with said gear shift link member.
[0013] Further, as per another aspect of the present invention, the first end of said connecting member is threaded. Rotation of said gear shift lever along said first end of said connecting member allows adjustment to overcome variation in position of said gear shift lever with respect to the connecting member and said gear shift link member. Thus, the present invention also contemplates allowance for fitment flexibility in case of misalignments in engine or frame assembly.
[0014] Summary provided above explains the basic features of the invention and does not limit the scope of the invention. The nature and further characteristic features of the present invention will be made clearer from the following descriptions made with reference to the accompanying drawings.

Brief Description of Drawings
[0015] The above and other features, aspects, and advantages of the subject matter will be better understood with regard to the following description and accompanying drawings where:
[0016] FIG.1 illustrates a side view of a vehicle including a gear shift linkage assembly in accordance with an embodiment of the present invention.
[0017] FIG.2 illustrates a body frame of said vehicle to which at least a portion of said gear shift linkage assembly is attached in accordance with an embodiment of the present invention.
[0018] FIG.3 illustrates an exploded view depicting mounting of said gear shift linkage assembly to a gear shift shaft of a transmission assembly of said vehicle in accordance with an embodiment of the present invention.
[0019] FIG.4a illustrates arrangement of said gear shift linkage assembly for enabling shifting of a gear shift lever therein in accordance with an embodiment of the present invention.
[0020] FIG.4b illustrates arrangement of said gear shift linkage assembly for enabling gear shifting in a direction different than that indicated in FIG.4a.
Detailed Description of the Preferred Embodiments
[0021] Exemplary embodiments detailing features of the gear shift linkage assembly, in accordance with the present invention will be described hereunder with reference to the accompanying drawings. Various aspects of different embodiments of the present invention will become discernible from the following description set out hereunder. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the invention. Further, it is to be noted that terms “upper”, “lower”, “right”, “left”, “front”, “forward”, “rearward”, “downward”, “upward”, “top”, “bottom” and like terms are used herein based on the illustrated state or in a standing state of the motorcycle with a driver riding thereon unless otherwise elaborated. Furthermore, a longitudinal axis refers to a front to rear axis relative to said vehicle, while a lateral axis refers to a side to side, or left to right axis relative to the vehicle. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.
[0022] With reference to FIG.1, a description is made of an entire schematic structure of a motorcycle 10. The motorcycle 10 includes a body frame 11 to support different parts of said motorcycle 10. A head pipe 12 is provided at a front end of the body frame 11. The head pipe 12 supports a steering shaft (not shown) rotatably in a certain range. In an upper portion of the head pipe 12, a handlebar 20 is rotatably integrally connected to the steering shaft. The handlebar 20 is used to steer the motorcycle 10 and is connected to a front wheel 21 through the steering shaft. An upper portion of the front wheel 21 is covered by a front fender 22 which prevents mud and water from getting deflected towards the steering shaft. Further, a front fork assembly 23 is supported partially on the front fender 22 and is connected to the front wheel 21.
[0023] In a front portion of the body frame 11 a fuel tank 24 is arranged immediately behind the handlebar 20 and is disposed over an internal combustion engine, hereinafter ‘engine’ 25. A seat 30 is placed behind the fuel tank 24. The seat 30 includes a front rider portion and rear pillion portion.
[0024] For the safety of the rider and in conformance with the traffic rules, a headlamp unit 31 and a turn signal lamp unit 32 is provided in a front portion of the motorcycle 10. The headlamp unit 31 and the turn signal lamp unit 32 are housed in a headlamp housing assembly 33.
[0025] Suspension systems are provided for comfortable steering of the motorcycle 10 on the road. The front fork assembly 23, which forms the front suspension system, serves as rigidity component just like the body frame 11. The front fork assembly 23 clamped to the head pipe 12 through an upper bracket 12a and a lower bracket 12b is capable of being moved to the left and right. Further, a rear suspension system, which is a hydraulic damped arrangement, is connected to the body frame 11. The rear suspension system comprises of at least one rear suspension preferably on a left hand side of the motorcycle 10. However, in a motorcycle with two rear suspensions, the same may be disposed on the left side and the right side respectively of said motorcycle.
[0026] The engine 25 is mounted to a front lower portion of the body frame 11 by means of a first engine mounting bracket 25a (shown in FIG.2). The engine 25 is equipped with an exhaust system that includes an exhaust pipe (not shown) connected to the engine 25 and a muffler (not shown) connected to the exhaust pipe. The muffler (not shown) extends rearwards along the right side of a rear wheel 35.
[0027] Power from the engine 25 is transmitted to the rear wheel 35 through a transmission assembly 26, so as to drive and rotate the rear wheel 35. Particularly, speed change is achieved by operation of a gear shift linkage assembly 40 which is operatively connected to a gear shift shaft 26d (shown in FIG.2) of said transmission assembly 26.
[0028] Thus, power from the engine 25 is transmitted to the rear wheel 35 rotatably supported at a rear end of a swing arm 45. A rear fender 50 for covering an upper side of the rear wheel 35 is mounted to a rear portion of body frame 11 to prevent mud and water splashed by the rotating rear wheel 35 from entering the muffler, the engine 25 and other parts disposed close by.
[0029] A detailed description of the body frame 11 is made with reference to FIG.2. As may be seen, the body frame 11 includes the head pipe 12, a down tube 13 extending downwards and rearwards from said head pipe 12, at least a main tube 14 extending rearwards from said head pipe 12, a pair of rear tubes 15 extending rearwards from a portion of said main tube 14, a pair of side tubes 16 extending inclinedly downwardly and forwardly from said pair of rear tubes 15. Particularly, the body frame 11 forms the skeleton of the motorcycle 10 and provides rigidity to the motorcycle. More particularly, at least the pair of rear tubes 15 and the pair of side tubes 16 form a rear portion of the body frame 11 and contribute to rigidity thereof. Further, the rear portion of the body frame also includes a frame member 17 to which a footrest member 18 is supported.
[0030] In a front portion of the body frame 11, the engine 25 is supported. Particularly, said engine 25 is supported to the down tube 13 by means of the first engine mounting bracket 25a. Further, to a lower portion of the main tube 14, a sprocket cover 26a is attached to a crankcase 25c of said engine 25.
[0031] The transmission assembly 26 (shown in FIG.1) includes a gearbox containing gear train and a drive mechanism connecting the gear box to the rear wheel 35. Particularly, the gear train includes a gear shift shaft 26d, and a plurality of gears, each having a varying gear ratio.
[0032] Typically, operation of the gear shift linkage assembly 40 results in shifting between said plurality of gears, thereby enabling in attaining varying riding speeds. As illustrated in FIG.2, whereas one end of said gear shift linkage assembly 40 is connected to said gear shift shaft 26d, another end of said linkage assembly 40 is connected to the frame member 17 supporting a footrest member 18. Particularly, as may be seen in FIG.2, said one end of the gear shift linkage assembly 40 connected to said gear shift shaft 26d lies adjacent to a magneto cover 27 attached to the crankcase 25c.
[0033] FIG.3 illustrates an exploded view depicting installation of said gear shift linkage assembly 40 to the gear shift shaft 26d. The gear shift linkage assembly 40 as per the present embodiment includes a gear shift lever 40a, a connecting member 40b, and a gear shift link member 40c. Particularly, while one end of the gear shift lever 40a is fixedly connected to the frame member 17 by means of a fastener (shown in FIG.2), other end of the gear shift lever 40a is pivotally connected to a first end 40ba of the connecting member 40b by means of a banjo joint. More particularly, said pivotal connection is made to the first end 40ba, which is a threaded end of said connecting member 40b. Further, a second end 40bb of the connecting member 40b is directly detachably attached to a lower end of the gear shift link member 40c. In the present embodiment, said second end 40bb of the connecting member 40b is provided as a bent end, and includes an attachment hole 40bc. Further, a split pin 40d is used to secure said second end 40bb to the lower end of the gear shift link member 40c through said attachment hole 40bc. Thus, pivotal connection of said gear shift link member 40c with said second end 40bb of the connecting member 40b is achieved by detachable attachment therewith. Thus, as the assembly of said connecting member 40b with said gear shift link member 40c merely involves the use of the split pin 40d, the need for additional assembly tools is eliminated, thereby easing assembly operations and reducing assembly man hours. Further, an upper end of the gear shift link member 40c is fixedly connected to the gear shift shaft 26d. Attachment to said gear shift shaft 26d involves firstly disposing the upper end of the gear shift link member 40c over the gear shift shaft 26d extending outwards from the transmission case 26a, followed by fastening said gear shift link member 40c to the gear shift shaft 26d.
[0034] As may be seen in FIG.3, an attachment orifice 40ca is provided on the gear shift link member 40c. Particularly, in the present embodiment said attachment orifice 40ca is provided as a plain hole capable of receiving a fastener such as a bolt. In an implementation, said gear shift link member 40c is disposed in a manner so that said attachment orifice 40ca faces a side which is away from the magneto cover 27. Therefore, fastening of the gear shift link member 40c to the gear shift shaft 26d is enabled to be performed from the side facing away from the magneto cover 27, thereby easing installation of said gear shift linkage assembly 40. Particularly, assembly of the gear shift link member 40c, in a manner so as to ensure orientation of the attachment orifice 40ca in the side away from the magneto cover 27 is achieved due to a provision of detachable attachment with the second end 40bb of the connecting member 40b. In another implementation, said attachment orifice 40ca may be provided on both sides of said link member 40c and said link member 40c may be fastened to said gear shift shaft 26d using a bolt and a nut.
[0035] Providing a means for direct detachable attachment of said gear shift link member 40c to the connecting member 40b enables one to change the orientation of the attachment orifice 40ca towards the side away from the magneto cover 27 or a side towards said magneto cover 27 by simply flipping the gear shift link member 40c. For example, the gear shift link member 40c may be flipped before attachment to the connecting member 40b, so that the attachment orifice 40ca faces the side away from the magneto cover 27 to avoid interference by the magneto cover 27 during assembly. Further, in case where size of the sprocket cover 26a increases, orientation of said attachment orifice 40ca may be changed to face the magneto cover 27. Thus, providing a direct detachable attachment allows an existing gear shift link member 40c to be used without the need to make any changes therein. Therefore, the gear shift linkage assembly 40 as per the present embodiment can be retro fitted onto any motorcycle, including those with a higher capacity engine and consequently having a higher diameter magneto without design change in said link member. Moreover, in the present embodiment since a regular banjo joint over the second end 40bb of the connecting member 40b is eliminated, number of parts used in the present gear shift linkage assembly 40 is less, consequently reducing manufacturing costs.
[0036] Manual operation of said gear shift lever 40a by foot or toe causes corresponding movement of said gear shift link member 40c, whose connection with the gear shift shaft 26d causes said gear shift shaft 26d to rotate in a selected direction, thereby causing a selection of desired gear ratio. In other words, motion of the gear shift lever 40a is transferred to the gear shift link member 40c through the connecting member 40b for selection of desired gear ratios.
[0037] In order to ensure good riding ergonomics, it is essential to ensure that the gear shift lever 40a is easily accessible to the rider. Since gears have to be shifted frequently while riding, ideally the rider should be able to reach said shift lever comfortably with his foot under all riding conditions. Adjustment of the gear shift lever 40a on the threads provided in the first end 40ba of the connecting member 40b enables height adjustment of the gear shift lever 40a. Moreover, adjustment of the gear shift lever 40a on said threads also aids in fitment flexibility of said gear shift lever 40a with respect to the connecting member 40b and the gear shift link member 40c, and in compensating for misalignments in the engine or frame assembly.
[0038] Further, as may be seen in FIG.4a and FIG.4b, the gear shift linkage assembly 40 as per the present invention also allows both upshifting and downshifting of the gear shift lever 40a. In FIG.4a and FIG.4b, arrow mark represented by ‘A’ denote direction in which load has to be applied by foot, while arrow mark represented by ‘B’ denote input rotational direction. Arrow mark denoted by ‘C’ denotes output rotational direction. As may be seen, the present invention is adapted to be used in motorcycles where upshifting and/or downshifting of the gear shift lever is involved and in motorcycles where unidirectional shifting of the gear shift lever is involved. For example, FIG.4a denotes a case where the position of the gear shift link member 40c with respect to that of the connecting member 40c is such that downshifting is capable of being performed, whereas FIG.4b denotes a case where the position of the gear shift link member 40c with respect to that of the connecting member 40b is such that upshifting is capable of being performed. In other words, since the connecting member 40b is adapted to be directly detachably attached with the gear shift link member 40c, reversal in position of the gear shift link member 40c with respect to the connecting member 40b is capable of being achieved easily so as to allow change in direction of shifting. Thus, the existing gear shift linkage assembly 40 may be used to change direction of shifting without involving major design changes thereto.
[0039] Thus, the gear shift linkage assembly as per the present invention not only facilitates easy installation but also aids in maintaining good rider ergonomics.
[0040] While the present invention has been shown and described with reference to the foregoing preferred embodiments, it will be apparent to those skilled in the art that changes in form, connection, and detail may be made therein without departing from the spirit and scope of the invention as defined in the appended claims.
,CLAIMS:I/We Claim:
1. A gear shift linkage assembly (40) for a motorcycle (10), said motorcycle (10) comprising a body frame (11) to which an internal combustion engine (25) is supported, and a magneto cover (27) attached to a crankcase (25c) of said engine (25);
wherein said gear shift linkage assembly (40) includes a gear shift lever (40a) pivotally connected to a connecting member (40b) at a first end (40ba) of said connecting member (40b), and a gear shift link member (40c) fixedly connected at its one end to a gear shift shaft (26d) provided in a gearbox of said engine (25), and pivotally connected at its other end to a second end (40bb) of said connecting member (40b);
characterized in that, said pivotal connection of said gear shift link member (40c) with said second end (40bb) of the connecting member (40b) is established by direct detachable attachment with said connecting member (40b) at said second end (40bb).
2. The gear shift linkage assembly (40) as claimed in claim 1, wherein said second end (40bb) of said connecting member (40b) is a bent end and includes an attachment hole (40bc) for direct detachable attachment with said gear shift link member (40c).
3. The gear shift linkage assembly (40) as claimed in claim 2, wherein said connecting member (40b) is directly detachably attached to said gear shift link member (40c) using a split pin (40d) passing through said attachment hole (40bc).
4. The gear shift linkage assembly (40) as claimed in claim 1, wherein said gear shift link member (40c) is fixedly connected to said gear shift shaft (26d) through an attachment orifice (40ca) using a fastener.
5. The gear shift linkage assembly (40) as claimed in claim 3 or claim 4, wherein said direct detachable attachment of said gear shift link member (40c) to said connecting member (40b) allows said attachment orifice (40ca) of said gear shift link member (40c) to face either a side away from said magneto cover (27) or face a side toward said magneto cover (27).
6. The gear shift linkage assembly (40) as claimed in claim 1, wherein said first end (40ba) of said connecting member (40b) is a threaded end.
7. The gear shift linkage assembly (40) as claimed in claim 1, wherein said gear shift lever (40a) is pivotally connected to said connecting member (40b) at said first end (40ba) using a banjo joint.
8. The gear shift linkage assembly (40) as claimed in claim 1, wherein said gear shift lever (40a) is adapted to be upshifted as well as downshifted for causing gear shift.
9. A motorcycle (10) including said gear shift linkage assembly (40) as claimed in claims 1-8.