TECHNICAL FIELD

[0001] The present subject matter relates to a transmission assembly for a powertrain. More particularly, the present subject matter relates to a multi range transmission assembly for a powertrain.

BACKGROUND OF THE INVENTION

[0002] Over the last few years, with the induction of new powertrain technologies concomitantly, substantial attention has been paid to compact powertrain delivering optimum power. To this end, much attention has also been paid to the design and development of an engine and a transmission. Typically, the engine and transmission are mounted in the vehicle as a single unit.

[0003] Generally, a vehicle contains in its powertrain a series of different gear ratios which can be selected according to the requirement. The gears are arranged with their axis aligned to their respective shafts and are communicatively connected to achieve power transmission. Such systematic assembly of the gears along with the other components to run the vehicle is known as the powertrain.

[0004] The above information disclosed in this background section is only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.

BRIEF DESCRIPTION OF DRAWINGS

[0005] The Non-limiting and non-exhaustive embodiments of the invention are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified. It should be appreciated that the following figures may not be drawn to scale.

[0006] Descriptions of certain details and implementations follow, including a description of the figures, which may depict some or all of the embodiments described below, as well as a discussion of other potential embodiments or implementations of the inventive concepts presented herein. An overview of embodiments of the invention is provided below, followed by a more detailed description with reference to the drawings.

[0007] The above and other features, aspects and advantages of the subject matter will be better understood with regard to the following description, appended claims and accompanying drawings where:

[0008] Figure 1 illustrates a perspective view of a powertrain with a transmission assembly, in accordance with an embodiment of the present subject matter.

[0009] Figure 2 illustrates an exploded view of the powertrain with a transmission assembly, in accordance with an embodiment of the present subject matter.

[00010] Figure 3 illustrates an exploded view of a transmission assembly with where few parts being omitted from the figure, in accordance with an embodiment of the present subject matter.

[00011] Figure 4 illustrates a perspective view of the transmission assembly, where cover member being omitted from the figure, in accordance with an embodiment of the present subject matter.

[00012] Figure 5 illustrates a cut section side view of the transmission assembly in a low range position, in accordance with one embodiment of the present invention.

[00013] Figure 6 illustrates a cut section side view of the transmission assembly in a high range position, in accordance with one embodiment of the present invention.

[00014] Figure 7 illustrates a perspective view of the shifting drum in the transmission assembly, in accordance with one embodiment of the present invention.

[00015] Figure 8 shows a cut section view wherein the mode of operation of the transmission assembly and the respective position of invention features being shown, wherein few parts are omitted from the figure, in accordance with one embodiment of the present invention.

[00016] Figure 9 shows the architecture of a transmission assembly wherein figure 9a shows meshing relationship of gears during Low Torque (High Speed range) mode Figure 9b shows meshing relationship of gears during High torque (Low speed range) mode and wherein few parts are omitted from the figure, in accordance with one embodiment of the present invention. [00017] Figure 10 shows a side view of the powertrain as an alternate embodiment.

DETAILED DESCRIPTION OF THE INVENTION

[00018] Generally, a transmission-based mechanical machine’s performance is based on a wide range of performance criteria which includes quantitative features like top speed, acceleration, gradeability etc. But there are several other aspects related to vehicle performance which includes refinement in torque transmission, drivability or driving pleasure. Therefore, it is always a challenge for design engineers to have a right trade-off between several performance features involving wide range of transmission ratios for a given powertrain under varying conditions. This wider range of transmission ratios leading to a more refined powertrain employed in a vehicle having a high torque and a high speed which is desirable.

[00019] Conventionally, in the powertrains, there is a problem of low torque at low speeds. For example, when the vehicle is climbing a gradient on the road or heavy load is to be pulled, there is requirement of a lot of torque at the drive wheels to pull the vehicle, and the powertrain may not be able to provide the same efficiently. Further, moving at low speeds with less torque results in loss of fuel economy or range. Whereas, at higher speeds, a predetermined transmission ratio restricts speed at which the vehicle can travel and hence results in loss of fuel economy or range. Therefore, the powertrain may not be able to provide sufficient torque and the prime mover may get stalled / switched off. Hence, a trade-off between torque requirement and fuel economy or speed range is a difficult challenge since at higher torque requirements, the fuel economy or speed range drops which is undesirable. In this regard, there are various transmission mechanisms with many modes of switching like manual or automatic are known in the art.

[00020] The manual transmission system allows driver to select different speed ratio or gear ratio manually. Hence some special driving skills are required to operate this type of gear box specifically in dense traffic conditions. Further, it is known in the art to introduce a greater number of stages in order to get more power from the powertrain, for example by adding more gears of desired sizes to obtained more torque or speeds at different gear ratios. However, this leads to an increase in transmission losses and weight. Further, this increases the overall size of the powertrain, which changes the layout of the vehicle. To solve this problem, it is known in the art to provide auxiliary units. These auxiliary unit is connected to the powertrain using a linkage mechanism. It is observed that the auxiliary unit is positioned near a differential of the vehicle. More specifically, the auxiliary unit being detachably attached to the differential. The auxiliary unit increases the overall length of the vehicle as the unit is positioned inline to the differential. Further, it increases the overall weight and cost of the vehicle. As in the auxiliary unit, the device comprises a pair of casings which enclose a plurality of gears and shafts. Further, these continuously rotating gears require lubrication. Therefore, it is essential to observe desirable lubricant level in the auxiliary unit in addition to the main transmission unit. However, it is cumbersome for the user to check the lubricant level and/or conduct maintenance as the auxiliary unit is not easily accessible. Further, this unit being positioned near to the differential may reduce the ground clearance of the vehicle. Ground clearance is essential, especially for vehicles running day and night on unmetalled roads. In addition to the above, it is also observed that the auxiliary unit is operated by a shifting mechanism which includes a plurality of wires and linkages. This leads to decreased reliability as a greater number of parts are involved in the shifting and dedicated wires travel from said auxiliary device to handle bar assembly. It is observed that wire and/or linkages tends to break due to prolonged use and exposure to environmental conditions. Thus, there is a need to provide extended gear ratios for a varying driving-conditions requiring broader range of torque and speed.

[00021] To this end, there is a need to provide a transmission assembly for a powertrain that will meet the above requirements and also of “compactness, cost effectiveness, accessibility, serviceability, while providing a broader power range with more gear ratios without significantly increasing the number of parts. The aforementioned disadvantages of the prior arts are solved by the present invention which provides an improved transmission assembly. The transmission assembly is advantageously used striving to meet customer expectations by providing a low cost and efficient transmission assembly. [00022] According to one embodiment of the present invention, it is the object of the present invention to provide a transmission assembly, which is compact, having lesser parts, capable of being easily manufactured, assembled and serviced, efficient, durable, and configured to provide more power ranges.

[00023] According to one embodiment, it is yet another object of the present invention to provide a transmission assembly comprising a housing assembly, a primary transmission unit comprising a plurality of shafts, a plurality of gears mounted on the said shafts that enable transfer of a torque from the one or more of said shafts to the another one or more of the said shafts in a predetermined one or more gear ratios. The said transmission assembly comprises a secondary transmission unit which further comprises at least one secondary shaft and at least a pair of secondary gears. The secondary transmission unit is operably connected to the primary transmission unit and configured to transmit said torque thereby enabling at least twice the number of said predetermined one or more gear ratios; said secondary transmission unit and primary transmission unit are assembled substantially inside said housing assembly. The present invention provides a high torque (H) and low torque mode (L). For example, in a standard three-speed gear box providing predetermined gear ratios 1, 2 and 3, one can achieve six different primary gear ratios by introducing an auxiliary unit (in this case being referred to as a secondary transmission unit). This unit has at least a pair of secondary (output) gears, in addition to idler gears for achieving gear ratios in the secondary unit and a shifting assembly.

[00024] The shifting assembly of the secondary transmission unit includes, a shifting drum, a plurality of shifting forks and an actuating member. In one embodiment said actuating member is a dog clutch. The pair of gears of secondary unit are installed on an output shaft (primary output shaft in one embodiment and secondary output shaft in another embodiment). The pair of output gears, referred herein as secondary gears, are meshed with idler gears in the secondary transmission unit and are operably connected to the primary gears on the primary shaft. Thus, the actuating member, when engaged with low torque secondary gears from the secondary unit, provides LI, L2 and L3 as gear ratio/ transmission ratio for the respective primary gears selected from the primary transmission unit. Similarly, when the actuating member engages with the High torque gear of secondary transmission unit, it gives Hl, H2, H3 as gear ratio. Therefore, a multiple ranges of transmission ratios are obtained in the disclosed invention. Similarly, if the primary transmission unit has five gears originally providing gear ratios 1, 2, 3, 4 and 5, the corresponding gear ratios obtained when said primary transmission unit is operated in the present transmission assembly, ten (10) gear ratios (L1-L5 and Hl to H5) corresponding to the high torque and low torque mode of the secondary transmission unit would be achieved. Thus, the present invention enables higher number of gear ratios (ten in this example) without substantially increasing the number of gears. Similarly, a skilled person can come up with three output gears in the secondary transmission unit to obtain thrice the number of pre-determined ratios originally obtained from the conventional primary transmission unit.

[00025] According to another aspect of the present invention, in the transmission assembly, the primary transmission unit comprises a clutch assembly and primary shifting assembly that are capable of shifting the plurality of primary gears on the plurality of shafts in said primary transmission unit to achieve the said predetermined gear ratios. Also, the secondary transmission unit comprises an actuating member (for example, a dog clutch which can be either manual/automatic/semi-automatic) and a secondary shifting assembly which is capable of shifting the plurality of secondary gears on the secondary shafts by engaging the actuating member to achieve said plurality of gear ratios.

[00026] According to an embodiment of the present invention, in the said transmission assembly, the primary shifting assembly and the secondary shifting assembly are installed on the same axis of rotation in the said housing assembly.

[00027] According to another embodiment of the present invention, in the said transmission assembly, the primary transmission has at least one output shaft having plurality of primary output gears mounted thereon to transmit the torque and the said primary output shaft extends into the secondary transmission unit. The secondary transmission unit comprises a first secondary gear and a second secondary gear wherein said first and secondary gears are output gears and are mounted on said primary output shaft extending into the secondary transmission unit. Skilled person will appreciate that in this embodiment, both the transmission units are disposed closely to facilitate the primary output shaft extending into the secondary transmission unit.

[00028] The secondary transmission unit comprises a first secondary shaft which has a set of idler gears mounted thereon. The first secondary gear, when engaged by said actuating member, delivers a first set of said predetermined gear ratios. Also, the second secondary gear, when engaged by said actuating member, delivers a second set of said predetermined gear ratios.

[00029] In another embodiment instead of the primary output shaft extending into the secondary transmission unit, the secondary transmission has a second secondary shaft wherein said second secondary shaft has the first and second secondary (output) gears mounted thereon. Said first and second secondary gear get shifted using said actuating member slidably mounted on said second secondary shaft to derive the same set of primary gear ratios as described above.

[00030] According to an embodiment of the present invention, the said transmission assembly comprises a gear position switch capable of detecting position of said one or more primary gears and plurality of secondary gears simultaneously in the said primary transmission unit and the secondary transmission unit.

[00031] According to an embodiment of the present invention, in the transmission assembly, the said secondary shifting assembly comprises a shifting drum capable of shifting a plurality of forks. The said plurality of shifting forks is operably connected to the said actuation members slidably mounted on the said one or more output shafts (extended primary output shaft in one embodiment or second secondary shaft in another embodiment). The said plurality of actuation member is configured to laterally slide on the said secondary shafts to engage said first and second secondary gears. Also, in another aspect of the invention, the said shifting drum comprises grooves and a guideway whereby a stopper means is capable of sliding over the guideway and locking into the said grooves to arrest the rotation of the shifting drum at the positions corresponding to engagement of first secondary gear and second secondary gear. [00032] According to an embodiment of the present invention, in the transmission assembly, the said elastic member is a preloaded spring and the said stopper means is a spherical member capable of snug fitting into said grooves.

[00033] According to an embodiment of the present invention, in the said transmission assembly, one end of the spring is connected to the spherical member and another end is rigidly attached to the said housing assembly.

[00034] According to an embodiment of the present invention, in the transmission assembly, a load of said preloaded spring can be adjusted using a bolt mechanism mounted on said housing assembly.

[00035] The present subject matter is further described with reference to accompanying figures. It should be noted that the description and figures merely illustrate principles of the present subject matter. Various arrangements may be devised that, although not explicitly described or shown herein, encompass the principles of the present subject matter. Moreover, all statements herein reciting principles, aspects, and examples of the present subject matter, as well as specific examples thereof, are intended to encompass equivalents thereof.

[00036] The foregoing disclosure is not intended to limit the present disclosure to the precise forms or particular fields of use disclosed. As such, it is contemplated that various alternate embodiments and/or modifications to the present disclosure, whether explicitly described or implied herein, are possible in light of the disclosure. Having thus described embodiments of the present disclosure, a person of ordinary skill in the art will recognize that changes may be made in form and detail without departing from the scope of the present disclosure. Thus, the present disclosure is limited only by the claims.

[00037] In the foregoing specification, the disclosure has been described with reference to specific embodiments. However, as one skilled in the art will appreciate, various embodiments disclosed herein can be modified or otherwise implemented in various other ways without departing from the spirit and scope of the disclosure. Accordingly, this description is to be considered illustrative and is for the purpose of teaching those skilled in the art the manner of making and using various embodiments of the disclosure. It is to be understood that the forms of disclosure shown and described herein are to be taken as representative embodiments. Equivalent elements, materials, processes or steps may be substituted for those representatively illustrated and described herein. Moreover, certain features of the disclosure may be utilized independently of the use of other features, all as would be apparent to one skilled in the art after having the benefit of this description of the disclosure. Expressions such as “including”, “comprising”, “incorporating”, “consisting of’, “have”, “is” used to describe and claim the present disclosure are intended to be construed in a nonexclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural.

[00038] Further, various embodiments disclosed herein are to be taken in the illustrative and explanatory sense, and should in no way be construed as limiting of the present disclosure. All joinder references (e.g., attached, affixed, coupled, connected, etc.) are only used to aid the reader's understanding of the present disclosure, and may not create limitations, particularly as to the position, orientation, or use of the systems and/or methods disclosed herein. Therefore, joinder references, if any, are to be construed broadly. Moreover, such joinder references do not necessarily infer those two elements are directly connected to each other.

[00039] Additionally, all numerical terms, such as, but not limited to, “first”, “second”, “third”, “primary”, “secondary”, “main” or any other ordinary and/or numerical terms, should also be taken only as identifiers, to assist the reader's understanding of the various elements, embodiments, variations and/or modifications of the present disclosure, and may not create any limitations, particularly as to the order, or preference, of any element, embodiment, variation and/or modification relative to, or over, another element, embodiment, variation and/or modification.

[00040] It will also be appreciated that one or more of the elements depicted in the drawings/figures can also be implemented in a more separated or integrated manner, or even removed or rendered as inoperable in certain cases, as is useful in accordance with a particular application. Additionally, any signal hatches in the drawings/figures should be considered only as exemplary, and not limiting, unless otherwise specifically specified. [00041] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The invention will be described taking a five-speed transmission assembly as an example through the specification.

[00042] Figure 1 illustrates a perspective view of a powertrain (100) with a transmission assembly (101), in in accordance with an embodiment of the present subject matter.

[00043] Figure 2 illustrates an exploded view of the powertrain (100) with a transmission assembly (101), in accordance with an embodiment of the present subject matter. A frontward direction F and a rearward direction R are shown along a line segment. The transmission assembly (101) is extending from the rear direction R to the front direction F. as shown. The transmission assembly (101) includes a housing assembly (102), a set of idle gears (107D), a gear position switch (109; See Figure 3), and a secondary shifting assembly (106). The idler gears (107D) are mounted on first secondary shaft (104Sf). A pair of secondary gears (107H, 107L) are also provided shown to be mounted on a second secondary shaft (104Ss) operably connected to primary transmission unit’s primary output shaft (not shown). In another embodiment, instead of the second secondary shaft (104Ss), the first and second secondary gears (107L and 107H) are mounted on the primary output shaft (103s; Figure 3, Figure 8). A housing assembly 102 comprises left hand side and right hand side portions which substantially encloses the primary and secondary transmission units. Further, the gear position switch (109) is operatively connected to said idle gears (107D), the first and secondary gears (107H, 107L) and said primary transmission assembly to sense the gear positions for indicating to the user. Furthermore, the gear position switch (109) being supported by said housing assembly (102) helps to select and indicate user’s selected mode. The housing assembly (102) includes a housing cover (102C).

[00044] Figure 3 illustrates an exploded view of a transmission assembly with where few parts being omitted from the figure, in accordance with an embodiment of the present subject matter. Figure 4 illustrates a perspective view of the transmission assembly, where cover member being omitted from the figure, in accordance with an embodiment of the present subject matter. For sake of brevity, Figure 3 and Figure 4 will be discussed together. The said pair of idler gears (107D) being rotatably supported by the housing assembly (102) (as shown in Figure 3) through a pair of bearings. This shows idler gears (107D) mounted on the first secondary shaft (also known as idler shaft). Also shown is the primary output shaft (103s) extending out of the primary transmission unit (not shown) into the secondary transmission unit (shown in exploded view). The first and second secondary gears (107 and 107H) are mounted in this embodiment on the extended primary output shaft (103S) as shown in Figure 4. The gear position switch (109) on the transmission assembly is used to sense the appropriate range selection. Figure 3 and 4 also show shifting assembly (106) comprising shifting drum (110) and shifting forks. In one aspect of the invention shifting assembly also shows pulley mechanism having shifting pulley (106P) for actuating the shifting drum(HOO). The shifting pulley (106P) has circular grooves where a string or wire or other pulling means (not shown) can be attached. The pulling means is stretched upon shifting of a shifting lever (not shown) by a user, for example a driver of a vehicle, which then rotates the pulley (106P) clockwise or anticlockwise direction to rotate the secondary shifting drum (110) which in turn shifts the first secondary gear (107L) or second secondary gear (107H) using shifting forks (111) and actuating member (108; Figure 5, 6, 8, 9).

[00045] Figure 5a illustrates a cut section side view of the transmission assembly in a low range position (high torque), in accordance with one embodiment of the present invention. Figure 5b illustrates a side view of the transmission assembly in a low range position (high torque) where a housing cover being omitted from the figure, in accordance with one embodiment of the present invention. For sake of brevity, Figure 5a and Figure 5b will be discussed together. The stage of the secondary transmission unit (104) and the primary transmission unit (106) for gear ratio selection in the low speed range position (High Torque) is shown. In this stage, the user caused the pulley (106P) to rotate the shifting drum (110) in a first direction, causing the shifting forks to move and engage the actuating member (108) with second secondary gear (107H). While the shifting drum (110) is rotating the stopper means (200) slides over a guideway provided on the periphery of the shifting drum (110) and upon reaching the desired point where the second secondary gear (107H) is engaged, the stopper means (200) locks into stopper groove (200G). This arrests the further rotation of the shifting drum (110) in either direction to ensure there is no unwanted shifting unless the user actuates the shifting drum (110) again by exerting force on the pulley (106P). The second secondary gear being (107H) delivers first set of primary gear ratios (107H1, 107H2, 107H3) which have higher output of torque or the low speed range in combination with the predetermined gear ratios (1, 2, 3) outputted from the primary gears via the primary output shaft (103S).

[00046] Similarly, Figure 6 illustrates a cut section side view of the transmission assembly in a high speed range position, in accordance with one embodiment of the present invention. Figure 6b illustrates a side view of the transmission assembly in a high range position (low torque) where a housing cover being omitted from the figure, in accordance with one embodiment of the present invention. For sake of brevity, Figure 6a and Figure 6b will be discussed together. The stage of the secondary transmission unit ( 104) and the primary transmission unit (106) for gear ratio selection in the High range position (High Speed) is shown. In this stage, the user caused the pulley (106P) to rotate the shifting drum (110) in a second direction, causing the shifting forks (111) to move and engage the actuating member (108) with the first secondary gear (107L). The stopper means (200) moves out of the stopper groove (201) allowing shifting drum (110) to rotate in the second direction. While the shifting drum (110) is rotating in the second direction, the stopper means (200) slides over a guideway provided on the periphery of the shifting drum (110) and upon reaching the desired point where the first secondary gear (107L) is engaged, the stopper means (200) locks into another stopper groove (200G). This arrests the further rotation of the shifting drum (110) in either direction to ensure there is no unwanted shifting unless the user actuates the shifting drum (110) again by exerting force on the pulley (106P). The first secondary gear (107L) being smaller in size compared to the second secondary gear (107H) delivers a second set of primary gear ratios (107L1, 107L2, 107L3) which have lower output of torque or the higher speed range in combination with the predetermined gear ratios (1, 2, 3) outputted from the primary gears via the primary output shaft (103S).

[00047] Figure 7 illustrates a perspective view of a shifting drum (110) having stopper grooves (200G) in the transmission assembly (101), in accordance with one embodiment of the present invention. A stopper means (200) and an elastic member (201) with preloaded force and fixedly mounted from the housing assembly (102). As explained for Figure 5 and 6 above, the lock means (200) is able to snug fit into said stopper grooves (200G) to arrest the rotation of the shifting drum (110) upon completion of shifting operation in one direction. The elastic member (201) exerts sufficient force so as to keep the stopper means (200) stuck into said stopper groove (200G) unless the user enables the elastic member (201) to compress and release the stopper means (200) from the stopper groove (200G) in the next shifting operation. The diameter of the elastic member (201) is configured to receive a bolt for adjusting the preload. In one embodiment the elastic member (201) is a pre-loaded spring. In one embodiment, the stopper means (200) is a spherical ball made of metal and fixedly mounted to the elastic member (201).

[00048] Also, there is a follower being provided on the top portion of a plurality of shifting forks (111) which follows the groove (HOG) which moves the shifting forks (111). One end of the shifting forks (111) having the follower is slidably disposed into said cam groove (110G) being provided on the periphery of the shifting drum (110). Another end of the shifting forks is connected to the actuating member(108). Cam grooves (100G), as known in the art, are provided in substantially ‘S’ shape configuration on the periphery of the shifting drum. This way, when the shifting drum (110) rotates, the shifting fork (111) move linearly thereby moving the actuating member (208) linearly.

[00049] Figure 8 shows a cut section view wherein the mode of operation of the transmission assembly (101) and the respective position of invention features being shown, wherein few parts are omitted from the figure, in accordance with one embodiment of the present invention. It shows one of the stages of gear ratio (disclosed in figure as High speed/Low Torque range) achieved during the interaction of the components in the transmission assembly (101), in accordance with one embodiment of the present invention. It shows the shifting assembly (106) interaction with the other components during the High range and low range for transmission. Figure 8 depicts the placement of the secondary shifting drum (110) in line with the primary shifting drum (103D) where the shifting fork (111) is responsible for shifting the actuating member ( 108) being engaged with the first secondary gear ( 107L) . This actuation leads to the operable connectivity and transmission of torque between the plurality of primary gears (103G) of the primary transmission unit (103) and the secondary gears (107H and 107L) of the secondary transmission unit (104). In this embodiment also, the primary output shaft (103S) has the primary gears (103G) mounted thereon while said primary output shaft (103S) extends into the secondary transmission unit. The first secondary gear (107L) and the second secondary gear (107H) are mounted on said extended portion of said primary output shaft (103S).

[00050] Figure 9 shows the architecture of the transmission assembly (??) wherein figure 9a shows meshing relationship of gears during Low Torque (High Speed range) mode Figure 9b shows meshing relationship of gears during High torque (Low speed range) mode and wherein few parts are omitted from the figure, in accordance with one embodiment of the present invention. The figure 9 shows the pre-determined gear ratios (1, 2, 3, n) being transmitted from the primary transmission unit (103). The number of predetermined gear ratios from the primary transmission unit (103), like in any conventional transmission unit, could range from ‘ 1 to n’ depending on number of gears chosen by the designer of the transmission unit as per requirement. The ‘n’ number depicts the maximum number of gear ratios from any given primary transmission unit (103) for example, 5 or 6 etc. The first and second secondary gears (107L and 107H) are mounted on the extended primary output shaft (103S). On the left hand side drawing in Figure 9, the first secondary gear (107L) is engaged by the actuating member (108) while being meshed with the idler gears (107D). Said first secondary gear (107L) being smaller in size delivers first set of primary gear ratios (107L1, 107L2, 107L3, 107Ln) with higher speed/ lower torque. On the right hand side drawing in Figure 9, the second secondary gear (107H) is engaged by the actuating member (108) while being meshed with the idler gears (107D). Said second secondary gear (107H) delivers second set of primary gear ratios (107H1, 107H2, 107H3, 107Hn) with lower speed/ higher torque.

[00051] In one embodiment, the actuating member (108) is a dog clutch.

[00052] Figure 10 shows an alternate arrangement of the components of the transmission assembly in such a manner that the primary transmission unit (103) and the secondary transmission unit (104) have their shifting drums not aligned on the same axis. This means that the secondary shifting assembly (106) of the secondary transmission unit (104) is kept offset from the primary transmission unit (103).

[00053] According to the architecture described herein in various embodiments, one of the primary efficacies of the present invention is the optimum operation of the transmission due to wider range of torque and speed available to a user.

[00054] According to the above architecture, one of the primary efficacies of the present invention is the flexibility to switch between high torque mode and high-speed mode improves the vehicle performance as user can select the modes based on powertrain operating conditions or environmental/ road conditions. All of the above advantages and various other as understood by a skilled person, are achieved without significantly altering the power train size and without significantly increasing number of parts adding bulk and maintenance requirements.

[00055] The above-described embodiments, and particularly any “preferred” embodiments, are possible examples of implementations and merely set forth for a clear understanding of the principles of the invention. 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.

List of Reference

100 Powertrain

101 Transmission assembly

102 Housing assembly

102C Housing assembly cover

103 Primary transmission unit

103D Primary Shifting Assembly

103S primary Shafts/primary output shaft

103G Plurality of Primary Gears

104 Secondary transmission unit

104Sf First Secondary Shaft 104Ss Second Secondary Shaft

105 Primary shifting drum

106 Secondary Shifting Assembly

106P Shifting Pulley 107L First Secondary Gear

107H Second Secondary Gear

107D Idler Gear

108 Actuating member

109 Gear position switch 110 Secondary Shifting Drum

HOG Cam grooves

111 Plurality of shifting forks

200 Stopper Means

200G Stopper Grooves 201 Elastic member /Pre-loaded spring