FORM 2 THE PATENT ACT 1970
&
The Patents Rules, 2003 COMPLETE SPECIFICATION
1. TITLE OF THE INVENTION
IMPROVEMENT IN DRUM GEAR SHIFTER
2. APPLICANT
(a) NAME: ADVIK HI-TECH PVT LTD
(b) NATIONALITY: Indian Company
Gat No. 357/99, Chakan Talegaon Road, Village Kharabwadi, Chakan,
(c) ADDRESS: Tal. Khed, Pune -410501, Maharashtra
India
2. PRREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed

IMPROVEMENT IN DRUM GEAR SHIFTER
FIELD OF INVENTION
[001] The present invention relates to a gear shifter for road vehicles. More specifically, the present invention is related to a gear shifter with star detent having integrated and modular cam pins.
BACKGROUND OF INVENTION
[002] Related Art: The transmission assembly of an internal combustion engine of two wheeled vehicles such as a motorcycle is generally comprised of a clutch, a gearbox containing gear train and a drive mechanism connecting the gear box to the wheel. The gear train has multiple gear ratios with the ability to switch between them as the speed of the vehicle varies. [003] Ordinarily, upon getting actuation the gears shift from one stage to another by a gear shift lever. The gear shift lever supports plurality of gears on parallel shafts in a gearbox enabling selecting one of the several gear ratios through a shift fork.
[004] The gearbox as known in prior art comprises a star shaped detent on the end of the shift drum. It further includes metal pins striking out of the star shaped detent and a bolt to attach the star shape detent to the drum shift. When the gear shift lever is pressed by the operator, it rotates the shift shaft, which in turns moves the gear lever. The gear (ratchet pawl) lever pushes on the pin to

rotate the drum gear and to select/switch gear. The bolt generally has a collar
like shape at the top end that is pushed by the gear lever.
[005] In existing design, if the collar of bolt gets crack or distort, then pins will
be fell down and will leave the transmission in inoperable condition. Further, the
material and process cost of such assembly is very high because of the number
of components and investment is inventory.
[006] Detailed Description of prior art: Referring to FIG. 1, the existing
drum gear shifter (100) is shown. The existing drum gear shifter (100) includes a
shift drum (102), a plurality of circumferentially distributed gear pins
corresponding to the star detent.
[007] Therefore, the challenge is to design an improved drum gear for the
transmission of an internal combustion engine accommodating a star shaped
detent with minimum engine assembly design alterations and capable to be
accommodated with any two wheeled vehicle.
SUMMARY OF THE INVENTION {008] The present invention is directed to overcome one or more problems as set forth above. Accordingly, a drum gear shift is provided. The drum gear shift comprises a star detent adapted to arrange over a first end of the shift drum; a plurality of circumferentially distributed gear pins corresponding to the star detent, wherein at least three gear pins are integrated with the star detent and are arranged axially to be supported by the shift drum; further wherein at least two modular gear pins are adapted to axially housed in between the star detent and the shift drum thereby interlocking the star detent and the shift drum, and a gear

lever arranged to exert load on the at least two gear pins at a time to rotate the shift drum for selecting different gears.
[009] In an aspect of the present invention, the star detent is preferably a star-shaped plate having five vertices and the plurality of circumferentially distributed gear pins are arrange equidistantly in between the ten edges. [010] It is an object of the present invention to provide an integrated star cam pin type gear shifter capable of being operated without creating any noise. [Oil] It is an object of the present invention to provide an integrated star cam pin type gear shifter capable of eliminating cracking failure. The chance of cracking failure can be reduced by increasing the strength of the star by changing the material.
[012] Further objects of the present invention will be cleared by considering the detailed description of the embodiments.
BRIEF DESCRIPTION OF DRAWINGS
[013] FIG. I illustrates a drum shift with star detent as disclosed in the prior
art;
[014] FIG. 2 illustrates a drum shift with star detent in accordance with an
embodiment of the present invention;
[015] FIG. 3 illustrates a star detent in accordance with an embodiment of the
present invention, and
[016] FIG. 4 illustrates a drum shift with star detent and stopper pin in released
in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS
[017] Embodiments of the present invention provide an integrated star cam pin type gear shifter. As shown in FIG. 2, a drum gear shift (200) includes a shift drum (202) and a star detent (204) adapted to arrange over a first end of the shift drum (202). The drum gear shift (200) further includes a plurality of circumferentially distributed gear pins (208) and (210) corresponding to the star detent (204), wherein at least three gear pins (210) are integrated with the star detent (204) and are arranged axially to be supported by the shift drum (202). [018] In the embodiment of the present invention, the two modular gear pins (208) are adapted to axially housed in between the star detent (204) and the shift drum (202) thereby interlocking the star detent (204) and the shift drum (202). [019] In a further embodiment of the present invention, a gear lever arranged to exert load on the two circumferentially distributed gear pins at a time to rotate the shift drum (202) for selecting different gears.
[020] Further, in another embodiment of the present invention a lever grip bolt (212) is arranged in the center of star detent (204) and extended to a central slot (214) of shift drum (202) for supporting rotation of the shift drum (202). [021] In an embodiment of the present invention, the shift drum (202) is preferably of cylindrical shape, having a first side, a second side that are axially opposite to each other and an interior in between the first side and the second side.
[022] As depicted in FIG. 2 and FIG. 3, the three integrated gear pins (210) are sintered to integrate with the star detent (204) and two modular gear pins (208)

are housed in matching axially grooves (216) given on the surface of the star decent (204) and the shift drum (202).
[023] As depicted in FIG. 4, a central groove (214) is given on the shift drum (202) to receive a bolt (212) initially received by a groove (218) of star detent (204). In the embodiment, the bolt (212) is a preferably a standard and/or Allen bolt adapted to have matching diametric and/or thread specification with the central groove (214) of shift drum and the groove (218) of star detent (204). [024] Further, in an embodiment of the present invention, the two modular gear pins (208) are made of steel material. In other embodiments, they can be of any suitable material like iron, aluminum and/or mixed alloy etc. [025] In embodiment of the present invention, the modular gear pins (208) are preferably configured circumferentially opposite to each other on the star detent (204) and the shift drum (202). The star detent (204) is preferably a star-shaped plate having five vertices and the plurality of circumferentially distributed gear pins (208) and (210) are arrange equidistantly in between the ten edges. [026] In an embodiment of the present invention, the gear lever is preferably a ratchet type gear lever.

WE CLAIM:
1. A drum gear shift comprising:
a shift drum;
a star detent adapted to arrange over a first end of the shift drum;
a plurality of circumferentially distributed gear pins corresponding to the star detent, wherein at least three gear pins are integrated with the star detent and are arranged axially to be supported by the shift drum; further wherein at least two modular gear pins are adapted to axially housed in between the star detent and the shift drum thereby interlocking the star detent and the shift drum;
a gear lever arranged to exert load on the at least two gear pins at a time to rotate the shift drum for selecting different gears.
2. The drum gear shift as claimed in claim 1, further comprising a lever grip bolt arranged in the center of star detent and extended to a central slot of shift drum for supporting rotation of the shift drum.
3. The drum gear shift as claimed in claim 1, wherein the shift drum is preferably of cylindrical shape, having a first side, a second side that are axially opposite to each other and an interior in between the first side and the second side.
4. The drum gear shift as claimed in claim 1, wherein the at least three gear pins are sintered to integrate with the star detent.
5. The drum gear shift as claimed in claim 1, wherein the at least two modular gear pins are housed in matching axially grooves given on the surface of the star decent and the shift drum.

6. The drum gear shift as claimed in claim 1, wherein the at least two modular gear pins are housed in matching axially grooves given on the surface of the star decent and the shift drum.
7. The drum gear shift as claimed in claim 1, further comprising a central groove to receive a bolt initially received by a groove of star detent.
8. The drum gear shift as claimed in claim 6, wherein the bolt is a preferably a standard and/or Allen bolt adapted to have matching diametric and/or thread specification with the central groove of shift drum and the central groove of star detent.
9. The drum gear shift as claimed in claim 1, wherein the at least two modular gear pins are preferably made of steel material.
10. The drum gear shift as claimed in claim 1, wherein the at least two modular gear pins are preferably configured circumferentially opposite to each other on the star detent and the shift drum.
11. The drum gear shift as claimed in claim 1, wherein the star detent is preferably a star-shaped plate having five vertices and the plurality of circumferentially distributed gear pins are arrange equidistantly in between the ten edges.