FORM – 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
Title:
DRIVETRAIN LAYOUT AND VEHICLE ARCHITECTURE OF A MOTOR GRADER
Applicant:
MAHINDRA & MAHINDRA LIMITED
GATEWAY BUILDING, APOLLO BUNDER,
MUMBAI – 400001,
MAHARASHTRA, INDIA.
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED. 2

FIELD OF INVENTION
The present invention relates to motor grader used in civil engineering. In particular, the present invention relates to an improved drivetrain and new vehicle architecture to facilitate the use of commonly available drivetrain in a new “mini grader” category under motor graders. More particularly, the present invention relates to such a mini grader with an improved drivetrain layout configured without tandem axles and the new vehicle architecture thereof.
BACKGROUND OF THE INVENTION
Grading operation in civil engineering and landscape architectural construction is performed for ensuring a level base, or a base having a specified slope for subsequently constructing, e.g. the foundation, the base course for roads or railways, or for improving the landscapes and/or gardens, or surface drainage. Such earthworks developed for these purposes are normally called as sub-grade or finished contouring.
These graders are commonly used in the construction and maintenance of dirt roads and gravel roads. In the construction of paved roads, these graders are used to prepare the base course to create a wide flat surface for placing asphalt thereon.
The graders can produce inclined surfaces for providing cant or camber to roads. These graders are also used for producing drainage ditches with shallow V-shaped cross-sections on either side of highways in some countries. Therefore, a grader is commonly also referred to as a road grader, a blade, a maintainer, or a motor grader, and it is a construction machine with a long blade used to create a flat surface during the grading process.
The drivetrain of a motor grader is the set of components delivering power to the driving wheels thereof. This does not include the engine generating the propulsive power. Whereas the powertrain includes both the engine or motor and the drivetrain.
The drivetrain couples the engine producing the power to the driving wheels of the grader consuming this mechanical power. This coupling involves physically linking the two components, which are normally at opposite ends of the grader and thus require a long propeller shaft or drive 3

The different operating speed of the engine and wheels have also to be matched by using a correct gear ratio. With the change in grader speed, the ideal engine speed should remain approximately constant for an efficient operation and therefore, the gear ratio should also be changed manually, automatically or by means of an automatic continuous variation.
DISADVANTAGES OF THE PRIOR ART
The conventional motor graders have the following disadvantages:
1. The drivetrain of the motor grader includes a very costly drivetrain and an independent suspension system.

2. These drivetrains make the motor grader manufacturers very much dependent on the suppliers, because of the availability of a very limited number of drivetrains suppliers all over the world.

3. Due to this very costly drivetrain, the total motor grader cost also becomes very high and thus it is not feasible to be used for small construction projects, where the budget for capital investment is limited, e.g. in rural road projects, particularly in Indian rural road projects etc.

Generally, the costs of the mini motor graders are in range of Rupees 50-70 Lakhs. This is quite high for low-revenue applications of mini grader prevalent in Indian context.
Therefore, there is an existing need for a low-cost mini grader equipped with the improved drivetrain layout and vehicle architecture. This also presents a new category product particularly suitable for Indian markets.
Such improved drivetrain layout and vehicle architecture for the improved motor grader configuration is very suitable Bill-Of-Material (BOM) Cost targets for the present applicants ever expanding and competitive manufacturing facilities.
OBJECTS OF THE INVENTION
Some of the objects of the present invention - satisfied by at least one embodiment of the present invention - are as follows: 4

An object of the present invention is to provide an improved drivetrain and vehicle architecture of a new category of motor grader configured without tandem axles.
Another object of the present invention is to provide an improved drivetrain and vehicle architecture of a motor grader, which includes a cost-efficient drivetrain.
Still another object of the present invention is to provide an improved drivetrain and vehicle architecture of a motor grader, which does not require an independent suspension.
Yet another object of the present invention is to provide an improved drivetrain and vehicle architecture of a motor grader, which can be used even for low-capital smaller projects.
Still further object of the present invention is to provide an improved drivetrain and vehicle architecture of a motor grader, which can be configured from a commonly available drivetrain.
Yet further object of the present invention is to provide an improved drivetrain and vehicle architecture of a motor grader, which therefore reduces the dependency on high-cost and complex drivetrain manufacturers and suppliers.
These and other objects and advantages of the present invention will become more apparent from the following description, when read with the accompanying figures of drawing, which are however not intended to limit the scope of the present invention in any way.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a motor grader with an improved drivetrain and vehicle architecture; the motor grader comprises:
• a propulsion unit;

• a driver’s cabin and/or canopy;

• a chassis assembly mounting the propulsion unit and the driver’s cabin and/or canopy, the chassis assembly supported on the twin-axle wheels;
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• a grader unit disposed forward of the chassis assembly and including a mainframe assembly with a single axle wheel assembly fitted under the front end thereof;

• a steering system to steer the single-axle or the articulation in the mainframe assembly or a combination of both;

wherein the propulsion unit mounted on the chassis is configured with a pivoting structure configured at the front end of the chassis and an oscillation structure configured at the rear end and disposed rearward of the rear axle of the motor grader; the single axle grader unit includes a pivoting structure configured at the rear end of the mainframe assembly, complementary to the pivoting structure of the propulsion unit and an oscillation structure configured at the front end of the mainframe assembly and disposed forward of the single axle wheel assembly.
In accordance with the present invention, the pivoting structure of propulsion unit comprises a pair of pivoting brackets configured at the front end of the chassis and disposed between the chassis cross-members, the pivoting brackets include a through holes each, through which a horizontal pivot pin passes to be tightened by means of a fastening mechanism to assemble the chassis assembly to the complementary pivoting structure of the mainframe.
In accordance with the present invention, the pair of pivoting brackets extend longitudinally from a transverse member joined between the chassis cross-members at the front end of the chassis.
In accordance with the present invention, the oscillation structure comprises a swivel pin inserted through the two oscillation brackets to facilitate oscillation between these in order to negotiate the lateral ground undulations in a plane transverse to the motor grader direction of movement.
In accordance with the present invention, the complementary pivoting structure of the single axle grader unit comprises a pivoting end configured at the rear end of the mainframe.
In accordance with the present invention, a through hole is configured through the pivoting end of the mainframe and passing in a transverse direction with respect to the motor grader. 6

In accordance with the present invention, the oscillation structure configured at the front end of the mainframe assembly comprises a first oscillation bracket fixed under the rear end of the chassis assembly and a second oscillation bracket fixed on the rear axle at the rear side thereof, and a swivel pin inserted through these oscillation brackets to facilitate oscillation between the chassis assembly and the rear axle with wheels in order to negotiate the lateral ground undulations in a plane transverse to the motor grader direction of movement.
In accordance with the present invention, the propulsion unit comprises the engine assembly and the transmission couples to each other by means of an engine-transmission coupling mounted under the chassis assembly via a front and rear propeller shafts each respectively, for facilitating to generate traction necessary for the propulsion of the motor grader on the ground for grading operation.
In accordance with the present invention, the pivoting structure of the propulsion unit and the complementary pivoting structure of the mainframe assembly of the grader unit are joined by means of a horizontal pivot pin of a fastening mechanism passing transversely therethrough and allowing the mainframe assembly to pivot in a longitudinal vertical plane with respect to the propulsion unit for facilitating a pivoting up and down movement of the motor grader on an undulating ground.
In accordance with the present invention, each oscillation structure comprises a swivel pin longitudinally inserted through each pair of oscillation bracket to facilitate an oscillation between the oscillation brackets of the respective pair of oscillation bracket to facilitate the motor grader in negotiating the lateral ground undulations in a plane transverse to the direction of movement of the motor grader.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The present invention will be briefly described with reference to the accompanying drawings:
Figure 1a shows a perspective view of the conventional motor grader with three axles and a drive train assembly for compensating for the undulations of the ground by using rear tandem axles.
Figure 1b shows a perspective view of the drive chain assembly equipped with a transmission for the motor grader of Figure 1a. 7

Figure 1c shows a side view of the internal construction of the drive chain assembly fitted between the tandem axles.
Figure 2 shows a perspective view of the conventional motor grader (shown in the background) equipped with the chassis and the mainframe assembly oscillating about the forward axle (middle axle of the motor grader) of the twin rear tandem axles.
Figure 3 shows a motor grader 100 with three axles fitted with wheels, however without tandem axles and having an improved drivetrain mechanism and vehicle architecture configured in accordance with the present invention.
Figure 4a to 4c show the different positions of the motor grader equipped with the new drivetrain mechanism and having vehicle architecture configured in accordance with the present invention with different axles disposed above undulations in ground.
Figure 5 shows a side view of the new drivetrain layout and vehicle architecture in accordance with the present invention configured for the motor grader of Figure 3.
Figure 6 shows a top view of the propulsion unit layout showing different components thereof mounted on the chassis of the motor grader of Figure 3.
Figure 7a shows a perspective view of the chassis assembly and the mainframe assembly of the motor grader of Figure 3.
Figure 7b shows a detailed side view of the chassis assembly and the mainframe assembly of the motor grader of Figure 3.
Figure 8 shows a detailed perspective view of the pivoting structure at the forward end of the chassis assembly for pivoting the mainframe in a longitudinal vertical plane of the motor grader.
Figure 9 shows a detailed perspective view of the oscillation structure fitted under the rear end of the chassis assembly for oscillating the rear axle wheels to negotiate ground undulations in a transverse direction.
Figures 10a and 10b show a detailed front view of the oscillation structure fitted near the front end of the mainframe assembly for oscillating the front axle wheels to negotiate ground undulations in a transverse direction.
Figure 11a shows a detailed perspective view of the chassis structure seen from the left side and depicts different components thereof. 8

Figure 11b shows a detailed perspective view of the chassis structure seen from the right side and depicts different components thereof.
Figure 12a shows a detailed perspective rear view of the propulsion unit of the motor grader of Figure 3.
Figure 12b shows a detailed perspective rear view of the chassis assembly of the motor grader of Figure 3, as seen from below and depicting the oscillation structure fitted at the rear end of the chassis.
Figure 13 shows a detailed enlarged view of the transmission assembly of the motor grader of Figure 3, disposed inline with backhoe loader.
Figure 14 shows a detailed enlarged view of the engine assembly of the motor grader of Figure 3, disposed inline with backhoe loader.
DETALED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1a shows a perspective view of the conventional motor grader 10 with three axles, a front axle 12 and a pair of tandem axles 14, 16 at the rear and with a blade 18 in between the front axle 12 and middle axle 14. The motor grader 10 was equipped with a drive train assembly for operating the chain drive for compensating for the undulations of the ground by means of this tandem axle construction. The tandem axles fitted with wheels 14, 16 to support the engine 20 and operator’s cab/canopy 30. The tandem axles fitted with wheels 14, 16 are located close to each other for imparting a greater weight bearing capacity than a single axle at the rear to support much heavier engine 20 and operator’s cab 30. A drive train assembly 40 fitted between the tandem axles 14, 16 is described in more details with reference to Figures 1b, 1c and the chassis assembly 60 and the mainframe assembly 70 are described in more details with reference to Figure 1d below.
Figure 1b shows a perspective view of the drive train assembly equipped with a transmission for the motor grader of Figure 1a. Tandem axles 14, 16 are disposed on either sides of the hydraulic motor and carrying wheels which cover the ground thereunder.
Figure 1c shows a side view of the internal construction of the drive chain assembly fitted between the tandem axles. Tandem axles 14, 16 are disposed on either sides of the hydraulic motor driving one dual sprocket 13, 15 each on either side thereof (Fig. 1c), which carry chains C1, C2 and C3, C4 respectively. The hydraulic motor 9

can be driven in both directions as marked by double-arrows in order to properly negotiate the undulating ground by means of drive chain mechanism of the tandem axles 14, 16. The drive chains C1, C2 and C3, C4 facilitate the movement of motor grader (not shown) 10 by transferring torque to the tandem axles 14 and 16 respectively. The hydraulic motor 17 enables the drivetrain assembly to absorb any undulation of the ground and allows the motor grader 10 to travel on any topography.
Figure 2 shows a schematic view of the chassis and the mainframe assembly of the conventional motor grader 10 (shown in the background) oscillating about the middle axle or the forward axle of the twin rear tandem axles. The blade 80 is shown disposed between the front axle 12 and the forward axle 14 of the tandem axles. Here, the rear tandem axles jointly act as an independent suspension and the front axle can oscillate about this middle axle (shown by RED arrow C) for allowing the motor grader 10 to travel on any topography. The centrally pivoted construction of the drive chain mechanism enables it to absorb any undulation of the ground by facilitating the movement of the wheels in up and down direction and independent of each other and thereby allows the motor grader 10 to travel on any topography. Thick red double-sided arrows depict the movement of the tandem axles 14, 16.
Figure 3 shows a motor grader 100 with the new drivetrain layout and vehicle architecture configured in accordance with the present invention. This drivetrain layout and vehicle architecture does not require tandem axles. The encircled portion A represents a propulsion unit for traction generation and consists of a front axle 112, a middle axle 114, a rear axle 116 (both not tandem axles) fitted with wheels. The axles 114, 116 supports the engine assembly 120 and operator’s cab/canopy 130 and these axles 114, 116 are located substantially closer to each other for imparting a greater weight bearing capacity (than a lighter single axle configuration at the rear) and thereby to support much heavier engine 120 and operator’s cab 130. Here, it is possible for motor grader 100 to absorb ground undulations very effectively even without the tandem rear axles. The mould board assembly/blade 180 is disposed between the front axle 112 and the middle axle 114. Similarly, the encircled portion B represents a grading unit, which includes an improved chassis assembly 160 and an improved mainframe assembly 170.
Figure 4a shows the position of the motor 100 grader equipped with the drivetrain mechanism and having vehicle architecture configured in accordance with the present invention is travelling in direction Tr. So, when its front axle wheels 112 pass over a substantial undulation U1 present in the ground surface GL, the rear axle wheels 116 are resting on the ground level GL and the front axle wheels 112 are 10

positioned raised on this undulation U1 and therefore, the middle axle wheels 114 remain off the touching position of the ground GL. In fact, motor grader is travelling in the direction Tr not along the ground level GL, but along the inclined level AL1.
Figure 4b shows the motor grader 100, when its middle axle wheels 114 pass over a substantial undulation U2 present in the ground surface GL. Here, the front axle wheels 112 and rear axle wheels 116 are resting on the ground level GL and the middle axle wheels 114 are positioned raised on this undulation U2 and therefore, the middle axle wheels 114 remain off the touching position of the ground GL. Although travelling in the direction Tr, the motor grader 100 is not positioned exactly along the ground level GL but is inclined thereto.
Figure 4c shows the motor grader 100, when its rear axle wheels 116 pass over a substantial undulation U3 present in the ground surface GL. Here, the front axle wheels 112 and middle axle wheels 114 are resting on the ground level GL and the rear axle wheels 116 are positioned raised on this undulation U3 and therefore, the rear axle wheels 116 remain off the touching position of the ground GL. In fact, motor grader 100 is travelling in the direction Tr, not along the ground level GL, but along the inclined level AL2.
Figure 5 shows the propulsion unit of the new drivetrain layout and vehicle architecture of the motor grader depicted in Figure 3. The propulsion unit includes an engine assembly 120, a transmission unit 150 and an engine-transmission coupling unit 140. Here, the rear twin axles 114, 116 are not acting in tandem.
Figure 6 shows a top view of the propulsion unit 140 layout showing engine assembly 120, transmission unit 150 and engine-transmission coupling unit 140 mounted on the chassis 160 of the motor grader 100 of Figure 3. It also depicts an engine cooling package (e.g. radiator) 152, rear-axle 116, middle axle 114. The chassis 160 includes a front end 162 and a rear end 164.
Figure 7a shows a perspective view of the superstructure of the motor grader 100 including chassis assembly 160 and mainframe assembly 170 of the motor grader 100 of Figure 3. A pivoting structure including a pivot pin 166 for mainframe assembly 170 (marked encircled as C) is configured at the front end 162 of the chassis assembly 160. This pivoting structure is described in more details with reference to Figure 8 below. An oscillation structure 190 (marked encircled as D) is also configured at the rear end 164 of the chassis assembly 160. This oscillation structure 190 is described in more details with reference to Figure 9 below. 11

Figure 7b shows a detailed side view of the chassis assembly 160 and the mainframe assembly 170 of the motor grader 100 of Figure 7a. The chassis 160 includes a pivoting structure including a pivot pin 166 at the front end 162 thereof and an oscillation structure 190 at the rear end 164 thereof. A front axle oscillation pivot 175 formed longitudinally in a transverse bracket 178 fitted to the front axle 112. Therefore, the combination of the front axle swivel pin 175, middle axle pivoting structure including a pivot pin 166 and rear axle oscillation structure 190 form the key structures of the present invention. With this new vehicle architecture, the motor grader 100 can handle any ground undulation by allowing the vehicle to orient the front axle 112 and the rear axle 116 to take a common ground plane GL, whereas the middle axle 114 remains displaced from the ground level AL1, GL, AL2 (see Figures 4a to 4c) to accommodate any undulations (U1, U2, U3) present in the ground topography during the movement of the motor grader 100.
Figure 8 shows a detailed perspective view of the pivoting structure at the forward end of the chassis assembly for pivoting the mainframe in a longitudinal vertical plane of the motor grader. It includes a bracket 168 for pivoting mainframe assembly 170 at the front end 162 of the chassis assembly 160 by means of a horizontal pivot pin 166 for allowing the motor grader 100 to effectively and efficiently negotiate the undulating ground during the motor grader operation.
Figure 9 shows a detailed perspective view of the oscillation structure fitted under the rear end of the chassis assembly for oscillating the rear axle wheels to negotiate ground undulations in a transverse direction. It includes an oscillation structure 190 fitted under the rear end 164 of the chassis assembly 160 to oscillates the rear axle 116 with wheels about a pin 165 to oscillate the wheels with respect to chassis 160.
Figure 10a shows a detailed front view of the oscillation structure fitted near the front end of the mainframe assembly for oscillating the front axle wheels to negotiate ground undulations in transverse direction appearing on LHS while moving forward. It depicts the front axle 112 is depicted tilted with respect to the chassis 160 due to the swiveling thereof about the longitudinal pivot pin 166 due to the presence of undulation under the left side wheel (on the RHS in figure) of the front axle 112. The range of oscillation is configured to be ± 50 with respect to the horizontal plane of chassis assembly 160.
Figure 10b shows a detailed front view of the oscillation structure fitted near the front end of the mainframe assembly for oscillating the front axle wheels to negotiate ground undulations in a transverse direction appearing on RHS while moving forward. 12

It depicts the front axle 112 is depicted tilted with respect to the chassis 160 due to the swiveling thereof about the longitudinal pivot pin 166 due to the presence of undulation under the right side wheel (on the LHS in figure) of the front axle 112. The range of oscillation is configured to be ± 50 with respect to the horizontal plane of chassis assembly 160.
Figure 11a shows a detailed perspective view of the structure of the chassis 160 as seen from the left side thereof and depicts the rear end 164 and front end 162 fitted with a pivoting bracket 168 for transversely fixing the horizontal pivot pin 166 for connecting the mainframe assembly 170 (not shown) to the chassis assembly 160.
Figure 11b shows a detailed perspective view of the structure of the chassis assembly 160 fitted with pivoting bracket 168 as seen from the right side thereof.
Figure 12a shows a detailed perspective rear view of the propulsion unit including the engine assembly 120, transmission 150 and an engine-transmission coupling 140 mounted on the chassis assembly 160, which in turn is equipped with an oscillation structure 190 configured with an swivel pin 192 disposed at rear end 164 thereof.
Figure 12b shows a detailed perspective rear view of the chassis assembly as seen from below and depicting the oscillation structure fitted at the rear end of the chassis. The chassis 160 is mounted with a chassis oscillation structure 190, which can oscillate about the swivel pin 192 in order to allow the front axle 112 with the wheels thereof to negotiate the undulations of the ground.
Figure 13 shows a detailed enlarged view of the transmission assembly 150 swiveling mounted on the chassis assembly 160 by means of a set of mounting brackets 152, 154 and disposed in-line with backhoe loader (not shown).
Figure 14 shows a detailed enlarged view of the engine assembly 120 mounted on the chassis assembly 160 by means of an engine mounting bracket 122 and disposed in-line with backhoe loader (not shown).
WORKING OF THE INVENTION:
When the motor grader 100 moves forward on the ground having undulating topography, the rear and middle axles 114, 116 supporting the chassis 160 oscillates about the oscillation structure 190 fitted at the rear end of the motor grader 100. The mainframe assembly 170 of the motor grader 100 pivots about the pivot pin 166 in 13

the pivoting bracket 168 to move in a vertical plane depending on the surface being travelled on by the wheels of the front axle 112, which move up and down according to the ground undulations faced in the longitudinal directions due to varying topography thereof. Another oscillation structure 175-178 is also provided near the front axle wheels, which facilitate these wheels to negotiate the lateral ground undulations as well (see Figures 10a-10b).
Therefore, the combination of the front axle oscillation structure having the swivel pin 175, middle axle pivoting structure having the pivot pin 166 and rear axle oscillation structure having the swivel pin 175 constitute the key features of the present invention. By this new vehicle architecture, the motor grader 100 can handle the ground undulation both in longitudinal and transverse directions by allowing the vehicle to suitably orient the front axle 112 and the rear axle 116 to take a common ground plane GL, while the middle axle 114 is displaced upwards or downwards from the ground level AL1, GL, AL2 (see Figures 4a to 4c) to accommodate any such undulations (U1, U2, U3) present in the ground topography during the movement of the motor grader 100.
TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE
The motor grader with the new drivetrain layout and vehicle architecture proposed in accordance with the present invention has the following technical and economic advantages:
• Requires no tandem axles.
• Cost-effective construction.
• Does not require an independent suspension.
• Particularly useful for low-capital smaller projects.
• Configurable from a commonly available drivetrain.
• Removes dependency on high-cost and complex drivetrain manufacturers and suppliers.
• Integrated chassis assembly, simple oscillation and pivoting structure and motor grader attachment.
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• Facilitates the motor grader to effectively negotiating undulations or changes in ground topography both in longitudinal and transverse directions by means of a combination of oscillation and pivoting structures.

The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments.
It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. The description provided herein is purely by way of example and illustration. The various features and advantageous details are explained with reference to this non-limiting embodiment in the above description in accordance with the present invention. The descriptions of well-known components and manufacturing and processing techniques are consciously omitted in this specification, so as not to unnecessarily obscure the specification.
Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
Although the embodiments presented in this disclosure have been described in terms of its preferred embodiments, a person skilled in the art may make innumerable changes, variations, modifications, alterations and/or integrations in terms of materials and method used to configure, manufacture and assemble various constituents, components, subassemblies and assemblies, in terms of their size, shapes, orientations and interrelationships without departing from the scope and spirit of the present invention.
The numerical values given of various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher or lower than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the disclosure unless there is a statement in the specification to the contrary. 15

Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, shall be understood to implies including a described element, integer or method step, or group of elements, integers or method steps, however, does not imply excluding any other element, integer or step, or group of elements, integers or method steps.
The use of the expression “a”, “at least” or “at least one” shall imply using one or more elements or ingredients or quantities, as used in the embodiment of the disclosure in order to achieve one or more of the intended objects or results of the present invention.
While considerable emphasis has been placed on the specific features of the preferred embodiment described here, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiments without departing from the principles of the invention. 16

We claim:
1. A motor grader with an improved drivetrain layout and vehicle architecture; the motor grader comprises:

• a propulsion unit;

• a driver’s cabin and/or canopy;

• a chassis assembly mounting the propulsion unit and the driver’s cabin and/or canopy, the chassis assembly supported on the twin-axle wheels;

• a grader unit disposed forward of the chassis assembly and including a mainframe assembly with a single axle wheel assembly fitted under the front end thereof; and

• a steering system to steer the single-axle or the articulation in the mainframe assembly or a combination of both;

wherein the propulsion unit mounted on the chassis is configured with a pivoting structure configured at the front end of the chassis and an oscillation structure configured at the rear end and disposed rearward of the rear axle of the motor grader; the single axle grader unit includes a pivoting structure configured at the rear end of the mainframe assembly, complementary to the pivoting structure of the propulsion unit and an oscillation structure configured at the front end of the mainframe assembly and forward of the single axle wheel assembly.
2. Motor grader as claimed in claim 1, wherein the pivoting structure of propulsion unit comprises a pair of pivoting brackets configured at the front end of the chassis and disposed between the chassis cross-members, the pivoting brackets include a through holes each, through which a horizontal pivot pin passes to be tightened by means of a fastening mechanism to assemble the chassis assembly to the complementary pivoting structure of the mainframe.

3. Motor grader as claimed in claim 2, wherein the pair of pivoting brackets extend longitudinally from a transverse member joined between the chassis cross-members at the front end of the chassis.
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4. Motor grader as claimed in claim 2, wherein the oscillation structure comprises a swivel pin inserted through the two oscillation brackets to facilitate oscillation between these in order to negotiate the lateral ground undulations in a plane transverse to the motor grader direction of movement.

5. Motor grader as claimed in claim 1, wherein the complementary pivoting structure of the single axle grader unit comprises a pivoting end configured at the rear end of the mainframe.

6. Motor grader as claimed in claim 5, wherein a through hole is configured through the pivoting end of the mainframe and passing in a transverse direction with respect to the motor grader.

7. Motor grader as claimed in claim 1, wherein the oscillation structure configured at the front end of the mainframe assembly comprises a first oscillation bracket fixed under the rear end of the chassis assembly and a second oscillation bracket fixed on the rear axle at the rear side thereof, and a swivel pin inserted through these oscillation brackets to facilitate oscillation between the chassis assembly and the rear axle with wheels in order to negotiate the lateral ground undulations in a plane transverse to the motor grader direction of movement.

8. Motor grader as claimed in claim 1, wherein the propulsion unit comprises the engine assembly and the transmission couples to each other by means of an engine-transmission coupling mounted under the chassis assembly via a front and rear propeller shafts each respectively, for generating traction necessary for the propulsion of the motor grader on ground for grading operation.

9. Motor grader as claimed in anyone of the claims 1 to 8, wherein the pivoting structure of the propulsion unit and the complementary pivoting structure of the mainframe assembly of the grader unit are joined by means of a horizontal pivot pin of a fastening mechanism passing transversely therethrough and allowing the mainframe assembly to pivot in a longitudinal vertical plane with respect to the propulsion unit for facilitating a pivoting up and down movement of the motor grader on an undulating ground.
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10. Motor grader as claimed in anyone of the claims 1 to 9, wherein each oscillation structure comprises a swivel pin longitudinally inserted through each pair of oscillation bracket to facilitate an oscillation between the oscillation brackets of the respective pair of oscillation bracket to facilitate the motor grader in negotiating the lateral ground undulations in a plane transverse to the direction of movement of the motor grader.