FORM2
THE PATENTS ACT 1970
39 OF 1970
&
THE PATENT RULES 2003
COMPLETESPECIFICATION
(SEE SECTIONS 10 & RULE 13)
1. TITLEOF THE INVENTION “TWO-SPEED GEARBOX ASSEMBLY FOR ELECTRIC VEHICLES”

2. APPLICANTS (S)
(a) Name:
(b) Nationality:
(c) Address:

Varroc Engineering Limited
Indian
L-4, Industrial Area,
Waluj MIDC, Aurangabad-431136,
Maharashtra, India

3. PREAMBLETOTHEDESCRIPTION
COMPLETESPECIFICATION
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
The present disclosure in general relates to electric vehicles, and more specifically, to a two speed gearbox for an electric vehicle, with a centrifugal clutch and a free wheel unit. 5
BACKGROUND
Electric automobiles generally include multiple gears to realize different speeds or rotations
per minute (RPMs). Generally, gear shifting in such automobiles is performed by using
10 various mechanisms such as Continuous Variable Transmission (CVT) mechanisms.
However, CVT systems usually include usage of belts and pulleys for realizing gear transmission, which results in considerable loss of power when the vehicle operates at a high speed.
15 Therefore, a need exists for a transmission system that is compact, light in weight, more
efficient and optimizes power consumption when the vehicle operates at high speeds.
SUMMARY
20 This summary is provided to introduce a selection of concepts, in a simplified format, that
are further described in the detailed description of the disclosure. This summary is neither intended to identify key or essential inventive concepts of the disclosure and nor is it intended for determining the scope of the disclosure.
25 In an embodiment of the present disclosure, a two-speed gearbox that uses a centrifugal
clutch in an electric vehicle is disclosed. In an embodiment, a first gear is engaged at a lower speed with a freewheel unit engaged while a second gear is engaged at a higher speed with the freewheel unit disengaged. However, when the vehicle reaches a certain higher speed, the centrifugal clutch is engaged, and one or more centrifugal actuators are automatically

activated. Additionally, the vehicle may also operate in a reverse gear where a third gear is engaged with another freewheel unit engaged.
In an embodiment, a gearbox assembly for an electric vehicle is disclosed. The gearbox
5 assembly comprises a motor shaft coupled to a motor of the electric vehicle and a first gear
assembly; a centrifugal clutch assembly unit; and a flywheel unit. The first gear assembly is
configured to be engaged, at a first lower speed of the motor shaft, with the freewheel unit in
an engaged position, thereby transmitting, via an output gear, torque to a transmission unit
of the electric vehicle. The centrifugal clutch assembly is configured to engage with a second
10 gear assembly at a second higher speed of the input shaft with the freewheel unit in a
disengaged position.
According to one or more embodiments, the gearbox assembly comprises at least one
centrifugal actuator. The at least one centrifugal actuator is configured to be engaged when
15 the centrifugal clutch assembly is engaged with the second gear assembly, and when the
electric vehicle is operating at the second higher speed.
According to one or more embodiments, the first gear assembly is configured to be engaged
with the first freewheel unit at a first gear ratio. The centrifugal clutch assembly is configured
20 to be engaged with the second gear at a second gear ratio, while the first gear ratio is higher
than the second gear ratio.
According to one or more embodiments, the first gear ratio is 3.3:1, and the second gear ratio is 2.7:1.
25
According to one or more embodiments, the centrifugal clutch assembly comprises at least one shoe made of a frictional material; at least one arm; and at least one spring. The at least one arm is configured to move due to a centrifugal force and the at least one shoe is configured to transmit torque for movement of the electric vehicle, and wherein a tension in
30 the at least one spring automatically retracts the arm when the centrifugal force is reduced.
3

According to one or more embodiments, the gearbox assembly comprises a third reverse gear, wherein the third reverse gear is configured to be engaged with another freewheel unit of the gearbox assembly.
5 According to one or more embodiments, a method of operating a gearbox assembly for an
electric vehicle is described. The method comprises engaging a first gear assembly, at a first
lower speed of an motor shaft, with a freewheel unit in an engaged position, wherein the
motor shaft is coupled to a motor of the electric vehicle and the first gear assembly, and
wherein the engagement of the first gear assembly transmits, via an output gear, torque to a
10 transmission unit of the electric vehicle. The method further comprises engaging a centrifugal
clutch assembly with a second gear assembly at a second higher speed of the motor shaft with the freewheel unit in a disengaged position.
According to one or more embodiments, the gearbox assembly comprises at least one
15 centrifugal actuator, wherein the method comprises engaging the at least one centrifugal
actuator when the centrifugal clutch assembly is engaged with the second gear assembly, and when the electric vehicle is operating at the second higher speed.
According to one or more embodiments, the first gear assembly is configured to be engaged
20 with the first freewheel unit at a first gear ratio. The centrifugal clutch assembly is configured
to be engaged with the second gear at a second gear ratio. The first gear ratio is higher than the second gear ratio.
According to one or more embodiments, the method further comprises engaging a third
25 reverse gear, wherein the third reverse gear is configured to be engaged with another
freewheel unit of the gearbox assembly.
To further clarify advantages and features of the present disclosure, a more particular
description of the disclosure will be rendered by reference to specific embodiments thereof,
30 which is illustrated in the appended drawings. It is appreciated that these drawings depict
4

only typical embodiments of the disclosure and are therefore not to be considered limiting of its scope. The disclosure will be described and explained with additional specificity and detail with the accompanying drawings.
5 BRIEF DESCIPTION OF THE DRAWINGS
These and other features, aspects, and advantages of the present disclosure will become better
understood when the following detailed description is read with reference to the
accompanying drawings in which like characters represent like parts throughout the
10 drawings, wherein:
Figure 1 illustrates a graphical representation of torque with respect to vehicle speed, in accordance with an embodiment of the present disclosure.
15 Figure 2A illustrates an exemplary two-speed gearbox, in accordance with an embodiment
of the present disclosure.
Figure 2B illustrates a centrifugal clutch assembly, in accordance with an embodiment.
20 Figure 2C illustrates another centrifugal clutch assembly 200C, in accordance with an
embodiment.
Figure 3 illustrate a gear arrangement associated with the two-speed gearbox, according to an exemplary embodiment of the present disclosure. 25
Figures 4A-4B illustrate a centrifugal clutch assembly 400 associated with the two-speed gearbox, in accordance with an embodiment.
Figures 5A-5B illustrates a freewheel unit associated with the two-speed gearbox, according
30 to an exemplary embodiment of the present disclosure.
5

Figures 6A-6B illustrate flowcharts describing aspects of a method of gear transmission, according to an embodiment of the present disclosure.
Figure 7A-7B illustrate a reverse gear mechanism in the two-speed gearbox, according to an
5 exemplary embodiment of the present disclosure.
Further, skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and may not have been necessarily drawn to scale. For example, the flow charts illustrate the method in terms of the most prominent steps involved to help to improve
10 understanding of aspects of the present disclosure. Furthermore, in terms of the construction
of the device, one or more components of the device may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the embodiments of the present disclosure so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in
15 the art having benefit of the description herein.
DETAILED DESCRIPTION OF DRAWINGS
For the purpose of promoting an understanding of the principles of the disclosure, reference
20 will now be made to the embodiment illustrated in the drawings and specific language will
be used to describe the same. It will nevertheless be understood that no limitation of the scope
of the disclosure is thereby intended, such alterations and further modifications in the
illustrated system, and such further applications of the principles of the disclosure as
illustrated therein being contemplated as would normally occur to one skilled in the art to
25 which the disclosure relates. Unless otherwise defined, all technical and scientific terms used
herein have the same meaning as commonly understood by one of ordinary skilled in the art to which this disclosure belongs. The system, methods, and examples provided herein are illustrative only and not intended to be limiting.

The term “some” as used herein is defined as “none, or one, or more than one, or all.”
Accordingly, the terms “none,” “one,” “more than one,” “more than one, but not all” or “all”
would all fall under the definition of “some.” The term “some embodiments” may refer to no
embodiments or to one embodiment or to several embodiments or to all embodiments.
5 Accordingly, the term “some embodiments” is defined as meaning “no embodiment, or one
embodiment, or more than one embodiment, or all embodiments.”
The terminology and structure employed herein is for describing, teaching and illuminating
some embodiments and their specific features and elements and does not limit, restrict or
10 reduce the spirit and scope of the claims or their equivalents.
More specifically, any terms used herein such as but not limited to “includes,” “comprises,”
“has,” “consists,” and grammatical variants thereof do NOT specify an exact limitation or
restriction and certainly do NOT exclude the possible addition of one or more features or
15 elements, unless otherwise stated, and furthermore must NOT be taken to exclude the
possible removal of one or more of the listed features and elements, unless otherwise stated with the limiting language “MUST comprise” or “NEEDS TO include.”
Whether or not a certain feature or element was limited to being used only once, either way
20 it may still be referred to as “one or more features” or “one or more elements” or “at least
one feature” or “at least one element.” Furthermore, the use of the terms “one or more” or “at least one” feature or element do NOT preclude there being none of that feature or element, unless otherwise specified by limiting language such as “there NEEDS to be one or more . . . ” or “one or more element is REQUIRED.” 25
Unless otherwise defined, all terms, and especially any technical and/or scientific terms, used herein may be taken to have the same meaning as commonly understood by one having an ordinary skill in the art.

Reference is made herein to some “embodiments.” It should be understood that an
embodiment is an example of a possible implementation of any features and/or elements
presented in the attached claims. Some embodiments have been described for the purpose of
illuminating one or more of the potential ways in which the specific features and/or elements
5 of the attached claims fulfil the requirements of uniqueness, utility and non-obviousness.
Use of the phrases and/or terms such as but not limited to “a first embodiment,” “a further embodiment,” “an alternate embodiment,” “one embodiment,” “an embodiment,” “multiple embodiments,” “some embodiments,” “other embodiments,” “further embodiment”,
10 “furthermore embodiment”, “additional embodiment” or variants thereof do NOT necessarily
refer to the same embodiments. Unless otherwise specified, one or more particular features and/or elements described in connection with one or more embodiments may be found in one embodiment, or may be found in more than one embodiment, or may be found in all embodiments, or may be found in no embodiments. Although one or more features and/or
15 elements may be described herein in the context of only a single embodiment, or alternatively
in the context of more than one embodiment, or further alternatively in the context of all embodiments, the features and/or elements may instead be provided separately or in any appropriate combination or not at all. Conversely, any features and/or elements described in the context of separate embodiments may alternatively be realized as existing together in the
20 context of a single embodiment.
Any particular and all details set forth herein are used in the context of some embodiments
and therefore should NOT be necessarily taken as limiting factors to the attached claims. The
attached claims and their legal equivalents can be realized in the context of embodiments
25 other than the ones used as illustrative examples in the description below.
Embodiments of the present disclosure will be described below in detail with reference to the accompanying drawings.
8

Figure 1 illustrates a graphical representation of torque with respect to vehicle speed, in accordance with an embodiment of the present disclosure.
The power generation in an internal combustion (IC) engine is limited and it cannot produce
5 sufficient torque to drive a vehicle initially. To rectify this problem, the embodiments
presented herein introduce gearboxes in IC engines. In an embodiment, the gearbox is designed such a way it can shift the torque as per the vehicle requirement.
However, in case of an electric vehicle, its motor can produce sufficient torque to drive the
10 vehicle initially and can generate enough RPM to achieve required speed. However, to
increase the performance of the vehicle, a two-speed gearbox along with an automated shifting mechanism needs to be developed to shift the gear from low to high speed or vice versa, as per design requirements.
15 In manual shifting, the IC engine creates noise and vibration when the engaged gear reached
its maximum RPM limit. Consequently, the driver may feel the vibration and shift the gear to a higher ratio to achieve speed. However, in an electric motor, this phenomenon is not achievable because noise and vibration is not present. Therefore, in a lower gear, the driver may press the accelerator paddle unknowingly, which may draw more current and overload
20 the entire system, which is not recommended.
To solve this problem, the embodiments presented herein disclose a two-speed gearbox with
an automatic shifting mechanism. The disclosed automatic gearbox includes an automatic
transmission in which the rotation of an input/motor shaft causes the engagement of a
25 centrifugal clutch assembly, which further drives a constant mesh gear assembly.
Accordingly, the output shaft rotational speed increases which further disengages the initial gear reduction through the free wheel unit.
Figure 2A illustrates an exemplary two-speed gearbox 200 that includes a centrifugal clutch
30 (not shown), in accordance with an embodiment. Centrifugal force is a force which acts on a
9

rotating body when viewed from a rotating frame of reference. It acts in a direction away from the center of rotation of the body. In an embodiment, the centrifugal clutch is implemented as per this principle. For example, a weight is attached with a spring to a rotating arm. When a motor speed increases, the weights move outward due to the centrifugal 5 force and engage with a rotating clutch drum to act as a single unit.
According to an embodiment of the present disclosure, when the vehicle starts moving, a high torque is provided with an initial gear arrangement. When the vehicle achieves a predetermined velocity, the centrifugal clutch is engaged with another gear and the associated 10 lower gear ratio provides high speed automatically.
Figure 2B illustrates a centrifugal clutch assembly 200B, in accordance with an embodiment. One or more key components of centrifugal clutch assembly include a hub (201), flyweights (202), springs (203), linings (204), and a housing (205). Further, in the centrifugal clutch 15 assembly, a drum is connected to the input shaft (motor shaft) while one or more shoes are connected to the output shaft (transmission shaft), as explained hereinafter. When the motor spins, the centrifugal force causes the weights inside the clutch to move outward. As the rotational speed increases, so does the outward force acting on these weights.
20 In an embodiment, the mass of each shoe (used interchangeably with “frictional material” and associated terms in the present disclosure) of centrifugal clutch assembly 200B may be determined in the following manner.
Let
25 m = Mass of each shoe,
n = Number of shoes
r = Distance of centre of gravity of the shoe from the centre of the spider
R = Inside radius of the pulley rim
N = Running speed of the pulley in r.p.m
30 ω = Angular running speed of the pulley in rad / s = 2 π N / 60 rad/s
10

ω1 = Angular speed at which the engagement begins to take place μ = Coefficient of friction between the shoe and rim.
∴ Net outward radial force (i.e., centrifugal force) with which the shoe presses against
10 the rim at the running speed

We know that the centrifugal force acting on each shoe at the running speed, Pc = m.ω2.r 5 Since the speed at which the engagement begins to take place is generally taken as 3/4th of the running speed, therefore the inward force on each shoe exerted by the spring is given by,

and the frictional force acting tangentially on each shoe, F = μ (Pc - Ps)
••• Frictional torque acting on each shoe = F × R = μ (Pc - Ps) R
15 and total frictional torque transmitted, T = μ (Pc - Ps) R × n = n.F.R
From this expression,
the mass of the shoes (m) may be evaluated.
20 Similarly, the size of each shoe may be determined in the following manner:
Let l = Contact length of the shoes,
b = Width of the shoes,
R = Contact radius of the shoes. It is same as the inside radius of the rim of the pulley,
θ = Angle subtended by the shoes at the centre of the spider in radians, and
25 p = Intensity of pressure exerted on the shoe. In order to ensure reasonable life, it may

∴ Area of contact of the shoe = l . b
11
be taken as 0.1 N/mm2.

and the force with which the shoe presses against the rim = A × p = l.b.p Since the force with which the shoe presses against the rim at the running speed is (Pc – Ps), therefore,
l.b.p = Pc – Ps
5 From this expression, the width of shoe (b) may be obtained.
2.3.3. Dimensions of the spring The load on the spring is given by

10 The dimensions of the spring may be obtained as usual.
Figure 2C illustrates another centrifugal clutch assembly 200C, in accordance with an embodiment. The components of the assembly 200C are described hereinbelow:
1. Clutch housing: A centrifugal clutch housing is a casing that encloses and protects
15 the components of a centrifugal clutch mechanism, facilitating its operation and preventing
damage to internal parts.
2. Frictional material: The frictional material of a centrifugal clutch is the substance or
material used on the clutch shoes or pads to create friction against the clutch drum or housing.
20 This frictional material allows the clutch to engage and transfer power smoothly from the
engine to the transmission system as engine speed increases.
3. Arm assembly: The arm of a centrifugal clutch is a lever-like component that extends
from the clutch hub and holds the clutch shoes or pads. As engine speed increases, centrifugal
25 force causes the arms to swing outward, pushing the clutch shoes against the clutch drum or
housing. This action engages the clutch, allowing power transfer from the engine to the transmission system.

4. The housing plate of a centrifugal clutch is a protective cover or casing that encloses
the clutch assembly's internal components, such as the clutch shoes, springs, and arms. It provides structural support and helps contain the moving parts of the clutch mechanism.
5 5. Needle roller bearing for smooth rotational operation of the assembly with shaft.
6. Transmission plate: It’s an assembly part which helps to hold the assembly on the
shaft and secure the assembly in its position.
10 In an embodiment, the materials may be chosen as per below table 1:

Sl No Part name Materials
1 Shaft 20MnCr5
2 Gearbox casing ADC 12
3 Bearing SKF std.
4 Gears 20MnCr5
5 Clutch Assembly Composite
6 Freewheel unit Composite
7 Fasteners SS, Zinc plating
Table 1 Figure 3 illustrates a gear arrangement 300 associated with the two-speed gearbox 200,
15 according to an embodiment of the present disclosure. In a first transmission, the first gear
pair 302a-302 is activated to provide the maximum gear ratio to provide high torque. When the vehicle reaches a certain speed, one or more actuators (not shown) are activated automatically due to the centrifugal force and engage second gear pair 304a-304b. The vehicle speed, thus, increases due to a lower gear ratio. The working mechanism of first gear
20 pair 302a-302b and second gear pair 304a-304b is explained in detail hereinafter.

In an embodiment of the present disclosure, the first gear ratio may correspond to 3.3:1, while second gear ratio may correspond to 2.7:1.
Figures 4A-4B illustrate a centrifugal clutch assembly 400 associated with the two-speed
5 gearbox 200, in accordance with an embodiment. Due to high speed of the vehicle, the
centrifugal actuators activate and engage the gear housing automatically. In an embodiment,
the centrifugal clutch assembly 400 includes a friction material 402, at least one arm 404 and
at least one spring 406. The arm 404 moves due to a centrifugal force and the friction material
402 generates sufficient friction to transmit the torque. The spring tension of the spring 406
10 helps to retract the arm 404 when centrifugal force is reduced.
Figures 5A-5B illustrate a freewheel unit 500 associated with the two-speed gearbox 200,
according to an exemplary embodiment of the present disclosure. In mechanical or
automotive engineering, a freewheel unit or overrunning clutch is a device in a transmission
15 that disengages the driveshaft from the driven shaft when the driven shaft rotates faster than
the driveshaft. In an embodiment, the freewheel device may include two saw-toothed, spring-loaded discs pressing against each other with the toothed sides together, somewhat like a ratchet.
20 Rotating in one direction, the saw teeth of the drive disc lock with the teeth of the driven disc,
making it rotate at the same speed. If the drive disc slows down or stops rotating, the teeth of the driven disc slip over the drive disc teeth and continue rotating, producing a characteristic clicking sound proportionate to the speed difference of the driven gear relative to that of the (slower) driving gear.
25
In another embodiment, a more sophisticated and rugged design of freewheel unit 500 may include spring-loaded steel rollers inside a driven cylinder. Rotating in one direction, the rollers lock with the cylinder making it rotate in unison. Rotating slower, or in the other direction, the steel rollers just slip inside the cylinder.

Figures 6A-6B illustrate flowcharts describing different aspects of a method of gear transmission, according to an embodiment of the present disclosure.
As illustrated in Figure 6A, when the first gear is engaged, gear [3] which is fixed on a shaft
5 of the vehicle, is directly connected to a motor (not shown) of the vehicle. Therefore, in initial
condition, when the motor starts rotating, the gear [3] starts to rotate and transmits the power
to a next gear [4] of the gear pair [3]-[4] (corresponds to 302a-302b, as explained above).
The torque transmitted to gear [4] is transmitted to a freewheel unit [5], which engages the
output shaft [2] and transmits the same torque to the output shaft [2]. This happens due to the
10 difference in gear ratios. The output torque received in gear [6] then multiplies, as per vehicle
requirements and is transmitted to the transmission unit. Each of the input/motor shaft [1] and the output shaft [2] are supported by bearings at both ends.
As illustrated in Figure 6B, when the second gear is engaged and the motor speed increases,
15 the torque requirement reduces because the vehicle is already in motion. When the motor
speed reaches as per designed RPM, the centrifugal clutch [9] engages the gear [7], which is mounted on a ball bearing and transmits the torque to the attached gear [8]. The gear [8] is mounted to the shaft and transmits the torque due to comparatively low gear ratio from the first gear. Consequently, the vehicle can achieve much higher speed. 20
As the power starts flowing from the second gear pair, the first gear pair need to dis-engage to avoid teeth breakage, and therefore, a freewheel unit [5] is incorporated in the system which able to free the first gear when the second gear is engaged.
25 In an exemplary embodiment, the first gear pair [3]-[4] is engaged when the input/motor shaft
[1] is rotating at a speed of less than 2500 rotations per minute (RPM), while the second gear pair [7]-[8] is engaged when the input/motor shaft is rotating at a speed of more than 2500 RPM.

In operation, when the vehicle is in starting condition or in very low speed, the input/motor
shaft rotates the first gear pair/set. The freewheel unit, which can rotate only in one direction,
is engaged and transmit the power to the output shaft. When the vehicle speed increases, the
increased RPM helps the centrifugal clutch to engage the second gear. As the speed of second
5 gear is always greater than the first gear unit, the freewheel unit is disengaged and starts to
rotate freely and act as a bearing.
Figure 7A illustrates a reverse gear mechanism 700 in the two-speed gearbox 200, according
to an exemplary embodiment of the present disclosure. In the illustrated assembly of the
10 reverse gear mechanism 700 with a reverse freewheel unit 704, a gear 702 with higher ratio
gear arrangement helps the gear engaged in reverse direction.
Figure 7B illustrates corresponding a method to implement the reverse gear mechanism 700,
in accordance with an embodiment. A third gear pair may be used to implement the reverse
15 gear mechanism 700 by engaging the freewheel unit 704. The torque generated is then
transmitted to the output shaft to realize the reverse movement of the vehicle.
In operation, one gear set is attached in opposite direction. When the motor rotates in forward
direction, the other freewheel unit mounted on reverse gear acts as a bearing. But when the
20 motor changes the rotation direction, the other freewheel unit is engaged and start to transmit
power in reverse direction.
The present disclosure is directed towards an automatic transmission gearbox with
centrifugal clutches which operate automatically as motor speed (RPM) increases in electric
25 vehicles. The automatic gearbox model consists of a gear assembly with two different gear
ratios and a centrifugal clutch unit to engage and disengage the gear, whenever required. The disclosed gearbox overcomes disadvantages of Continuous variable Transmission (CVT) system by replacing belt and pulleys with centrifugal clutches and gear assembly, which is more compact and avoids loss of power when operating at high speed. Also, the disclosed

gearbox is light in weight, efficient, reliable, less cycle time consuming, and economical for manufacturing.
While specific language has been used to describe the present subject matter, any limitations
5 arising on account thereto, are not intended. As would be apparent to a person in the art,
various working modifications may be made to the method in order to implement the
inventive concept as taught herein. The drawings and the foregoing description give
examples of embodiments. Those skilled in the art will appreciate that one or more of the
described elements may well be combined into a single functional element. Alternatively,
10 certain elements may be split into multiple functional elements. Elements from one
embodiment may be added to another embodiment.

We Claim:
1. A gearbox assembly for an electric vehicle, the gearbox assembly comprising:
a motor shaft coupled to a motor of the electric vehicle and a first gear
assembly;
5 a centrifugal clutch assembly unit; and
a flywheel unit,
wherein the first gear assembly is configured to be engaged, at a first lower
speed of the motor shaft, with the freewheel unit in an engaged position, thereby
transmitting, via an output gear, torque to a transmission unit of the electric vehicle;
10 and
wherein the centrifugal clutch assembly is configured to engage with a second gear assembly at a second higher speed of the input shaft with the freewheel unit in a disengaged position.
15 2. The gearbox assembly as claimed in claim 1, comprising at least one centrifugal
actuator, wherein:
the at least one centrifugal actuator is configured to be engaged when the
centrifugal clutch assembly is engaged with the second gear assembly, and when the
electric vehicle is operating at the second higher speed. 20
3. The gearbox assembly as claimed in claim 1, wherein:
the first gear assembly is configured to be engaged with the first freewheel unit at a first gear ratio;
the centrifugal clutch assembly is configured to be engaged with the second
25 gear at a second gear ratio, and
the first gear ratio is higher than the second gear ratio.
4. The gearbox assembly as claimed in claim 3, wherein the first gear ratio is 3.3:1, and
the second gear ratio is 2.7:1.

5
10

5. The gearbox assembly as claimed in claim 1, wherein the centrifugal clutch assembly
comprises:
at least one shoe made of a frictional material;
at least one arm; and
at least one spring;
wherein the at least one arm is configured to move due to a centrifugal force and the at least one shoe is configured to transmit torque for movement of the electric vehicle, and wherein a tension in the at least one spring automatically retracts the arm when the centrifugal force is reduced.
6. The gearbox assembly as claimed in claim 1, comprising:
a third reverse gear, wherein the third reverse gear is configured to be engaged with another freewheel unit of the gearbox assembly.

15 7. A method of operating a gearbox assembly for an electric vehicle, the method
comprising:
engaging a first gear assembly, at a first lower speed of an motor shaft, with
a freewheel unit in an engaged position, wherein the motor shaft is coupled to a motor
of the electric vehicle and the first gear assembly, and wherein the engagement of the
20 first gear assembly transmits, via an output gear, torque to a transmission unit of the
electric vehicle; and
engaging a centrifugal clutch assembly with a second gear assembly at a second higher speed of the motor shaft with the freewheel unit in a disengaged position. 25
8. The method as claimed in claim 7, wherein the gearbox assembly comprises at least one centrifugal actuator, wherein the method comprises:
engaging the at least one centrifugal actuator when the centrifugal clutch
assembly is engaged with the second gear assembly, and when the electric vehicle is
30 operating at the second higher speed.
19

9. The method as claimed in claim 8, wherein:
the first gear assembly is configured to be engaged with the first freewheel
unit at a first gear ratio;
5 the centrifugal clutch assembly is configured to be engaged with the second
gear at a second gear ratio, and
the first gear ratio is higher than the second gear ratio.
10. The method as claimed in claim 9, comprising:
10 engaging a third reverse gear, wherein the third reverse gear is configured to
be engaged with another freewheel unit of the gearbox assembly.
Dated this 30th Day of March, 2024
Varroc Engineering Limited