FORM 2
THE PATENT ACT, 1970,
(39 OF 1970)
&
THE PATENTS RULE, 2003
COMPLETE SPECIFICATION
(SEE SECTION 10; RULE 13)
"RIGID DEAD AXLE FOR A MOTOR VEHICLE"
MAHINDRA & MAHINDRA LIMITED
AN INDIAN COMPANY, R&D CENTER,
AUTOMOTIVE SECTOR,
89, M.I.D.C., SATPUR,
NASHIK-422 007,
MAHARASHTRA, INDIA.
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES AND ASCERTAINS THE NATURE OF THIS INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED

FIELD OF INVENTION:
The present invention is related to dead axles used on motor vehicles. More particularly the present invention is related to the rigid dead axle adapted to be used with light and medium motor vehicles / trucks that are driven by a rear wheel drive.
BACKGROUND OF THE PRESENT INVENTION:
Conventionally rigid axles for leaf / coil spring suspension are designed with either of the following configurations.
(i) rigid axle with integrated differential mechanism and live wheel ends
(ii) rigid axle with dead wheel ends without power input
These conventional axles does not permit to package the engine between the wheels and external driveline, whereas the present invention permits to package the engine between wheels and an external driveline.
US patent No. 5054575 discloses dead axle suspension for a pair of driven wheels including a lateral guide wherein chassis and body are supported upon a dead axle the latter of which is of a light weight and rigid construction so as to permit a lower positioning of the chassis relative to the ground and in such a way as to eliminate lateral displacement of the dead axle relative to the chassis and wherein the aft end of the roll axis of the suspension is either horizontal or displayed vertically above a horizontal line passing through the point of articulation of the suspension to the chassis to eliminate the tendency of the dead axle to oversteer the vehicle as it moves vertically relative to he chassis.
The prior art considers only differential at the rear axle and the engine is packaged at the front axle. Nevertheless it does not teach anything regarding a vehicle where full powerpack is packaged between the wheels at the rear

axle. Whereas the present invention provides a solution for such vehicle packaging.
OBJECTIVES OF THE PRESENT INVENTION:
The main object of the present invention is to provide a novef rigid dead axle which is rugged and robust in nature.
Another object of the present invention is to provide a novel rigid dead axle that enables to packaging of engine-transaxle between the wheels.
Still another object of the present invention is to overcome the ride and handling issues (such as straight line stability, driveability and handling) during the rugged use of the vehicle.
STATEMENT OF INVENTION
Accordingly the invention provides a rigid dead axle for a motor vehicle comprises a hollow tube made of three section consisting of end section, middle section and intermediate section; a spring bracket and axle brackets welded at each of the said end section of the said hollow tube; a resting platform to rest leaf spring of the suspension system is provided to the said spring bracket; an arrangement with the said axle bracket having housing for mounting a bearing, hub and spindle assembly; wheel ends mounted to the said spindle assembly such a that the said arrangement enables locating an engine compartment/transaxle packaged at centre line of vehicle in alignment with the said axle bracket; and a drive line connected between the said engine and wheel ends.

BRIEF DESCRIPTION OF THE FIGURES:
The objects and features of the present invention will be more clearly understood from the following description of the invention taken in conjunction with the accompanying drawings, in which,
Figure 1 shows the perspective view of rigid dead axle for a motor vehicle in accordance with the present invention.
Figure 2 shows schematic view of rigid dead axle mounted on the vehicle.
DETAILED DESCRIPTION OF THE INVENTION:
Referring to Figure 1, the rigid dead axle (4) comprises of a hollow tube (1) of a suitable material, spring bracket (2), and axle bracket (3). The hollow axle tube (1) is made of three sections (A, B & C) as shown in figure. The spring bracket (2) and axle bracket (3) are welded or fitted permanently by suitable means to section 'A' of an axle tube (1). The specially made spring bracket (2) provides resting platform to the leaf springs (5) of the suspension system. The axle bracket (3) provides a rigid mounting to the wheel ends (6) comprising of bearing, hub and spindle assembly. Owing to the packaging and process feasibility the bearing carrier can be integrated with the axle bracket (3).
Referring to figure 2, the rigid dead axle (4) is packaged with springs (5), wheel ends (6), engine compartment (7) and driveline (8). The rigid dead axle (4) with live wheel ends (6) and external driveline (8) enables the design of vehicle with rigid axle and engine transaxle between the wheels. The design of the components can be moderated to package the changing system requirements of suspension, engine and driveline.
The rigid axle (4) in the form of tube gives a rigid link to the left and right hand suspension of the vehicle. The axle tube (1) is subjected to high loads that come during the suspension travel in extreme conditions. It is designed to

have enough strength to sustain the subjected stresses. The alignment of section 'B' with section 'C or section 'D' is possible at any angle in the range of zero degree to 90 degrees. However, the most optimized alignment of section 'B' with section 'A' or section 'C ranges from 10 degree to 35 degree to sustain the subjected stress during the ride and rugged use of the vehicle.
The cross section of the axle tube (1) is circular or triangular, square or hexagonal or combination of thereof with suitable reinforcement fulfilling the technical requirements (load sustainability) and packaging conditions under the body of a vehicle. The rigid dead axle (4) is manufactured by permanently welding its components or hydro-forming or casting or forging or combination of thereof adhered to the manufacturability convenience.
The rigid dead axle (4) as described in the present invention is comfortably suited to the vehicle having coiled spring suspension system provided coiled spring housing bracket is provided over the spring bracket (2). Thus, the design of rigid dead axle (4) is flexible to accommodate different type of suspension packaging requirements.
Wheel ends (6) are the conventional mechanism of rotating spindle/hub for power transfer to the wheels. The inside bearing mechanism is decided from subjected loads and life expectancy. Typically the design will be rotating spindle type and stationary bearing carrier. The wheel-ends will perform the following functions-
o Assembly of wheels and axle.
o Power transfer from driveline to wheels.
o Friction free rotation of wheels.
Engine compartment (7) also termed as power-pack is typically placed at the centre line of the vehicle or at a suitable offset as per vehicle architecture. The size of the power-pack is crucial for the feasibility of use of this type of axle. The axle should not foul with the power pack in all the position of the suspension travel. This can be confirmed by the centre link extension or three link mechanism for the axle path analysis.

The driveline (8) transfers power from engine/transaxle to the wheel ends (6). The driveline (8) can be a constant velocity joint or a suitable slider mechanism that can ensure uniform power transfer at variable suspension travel.
For vehicles like load carriers or off-road vehicles having similar requirement, this design of axle will enable to packaging of engine-transaxle between the wheels. There is no alternate technology available for an Rigid-axle that can be packaged with an engine, external driveline and springs.
It is to be understood that the present invention is not limited in its application to the details of the construction and to the arrangements of the components as mentioned in the above description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, the terminologies used herein are for the purpose of description and should not be regarded as limiting.
ADVANTAGES OF THE PRESENT INVENTION:
• The rigid dead axle is rugged and robust in nature.
• The rigid dead axle is easily matchable / suitable to off-road vehicles.

WE CLAIM:
1. A rigid dead axle for a motor vehicle comprises a hollow tube made of three section consisting of end section, middle section and intermediate section; a spring bracket and axle brackets welded at each of the said end section of the said hollow tube; a resting platform to rest leaf spring of the suspension system is provided to the said spring bracket; an arrangement with the said axle bracket having housing for mounting a bearing, hub and spindle assembly and the wheel ends mounted to the said spindle assembly such a that the said arrangement enables locating an engine compartment/transaxle packaged at centre line of vehicle in alignment with the said axle bracket; and a drive line connected between the said engine and wheel ends.
2. A rigid dead axle as claimed in claim 1 wherein the alignment between the said intermediate section and end section is possible at any angle in range zero degree to 90 degree.
3. A rigid dead axle as claimed in claim 2 wherein the alignment between the said intermediate section or end section is optimized from 10 degree to 35 degree to sustain the subjected stress during the ride and rugged use of vehicle.
4. A rigid dead axle as claimed in claims 1 to 3 wherein said hollow tube is having cross section of circular or triangular, square or hexagonal or combination of thereof with suitable reinforcement fulfilling the technical requirements (load sustain ability) and packaging conditions under the body of a vehicle.
5. A rigid dead axle as claimed in claims 1 to 4 wherein said axle is manufactured by permanently welding its components or hydro-forming or casting or forging or combination thereof adhered to the manufacturability convenience.
6. A rigid dead axle as claimed in claims 1 to 5 wherein the said driveline is a constant velocity joint or a suitable slider mechanism having uniform power transfer at variable suspension travel.

7. A rigid dead axle as claimed in claims 1 to 6 wherein the different type of suspension packaging is accommodated to the said spring bracket.
8. A rigid dead axle as claimed in claim 7 wherein the said different type of suspension system is coiled spring suspension system.