FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13) TITLE OF THE INVENTION
Leaf Spring Assembly


APPLICANTS
TATA MOTORS LIMITED, an Indian company
having its registered office at Bombay House,
24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
INVENTORS
Mr. Udayakanth G
Mr. Jyothis Balakrishnan
both Indian nationals
of TATA MOTORS LIMITED,
an Indian company having its registered office
at Bombay House, 24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India

PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in

which it is to be performed


Field of invention
The present invention is related to the leaf spring of vehicles and more particularly it relates to leaf spring assembly with friction reduction means for reducing the inter-leaf friction.
Background of invention
Generally conventional leaf springs are stacked and clamped together with pins and clips. The stacked leaf spring having higher inter-leaf friction. In order to withstand the load, the more no. of leaves is required and leads to heavy weights. The parabolic leaf springs are also staked and fastened together. The parabolic leaf spring requires more span compared with the conventional leaf spring of the same load carrying capacity. The parabolic leaf spring also having higher winding effects.
This invention is developed to address the above said disadvantages of the prior art leaf spring arrangement.
The inter leaf friction of conventional leaf spring and the greater span and winding effect of parabolic leaf spring for the same load carrying capacity are nullified by developing this new invention.
Object of invention
The object of the present invention is to provide a leaf spring assembly with friction reduction means for vehicles.
Another object of the present invention is to provide a leaf spring assembly with friction reduction means for vehicles which nullifies the inter-leaf friction, span and winding effect.
Yet another object of the present invention is to a provide leaf spring assembly with friction reductino means for vehicles which is simple in construction.
2
-8 SEP 2009

Statement of invention
Leaf spring assembly comprises; at least two leaf springs stacked and held with spring clips ; wherein said leaf spring having plurality of grooves provided on top surfaces; a friction reduction means disposed in said groove; spacers disposed in between said leaf springs at the spring seat location.
Leaf spring assembly , in accordance with present invention, wherein said friction reduction means is plurality of balls or rollers or bushes or bars.
Leaf spring assembly , in accordance with present invention, wherein said groove is provided at overhang area of said leaf spring for disposing the said friction reduction means.
Leaf spring assembly , in accordance with present invention, wherein said balls or rollers or bushes or bars are having at least 3mm diameter.
Leaf spring assembly , in accordance with present invention, wherein said spacers are having thickness of at least 1 mm.
Leaf spring assembly , in accordance with present invention, wherein said friction reduction means are the active component in the assembly which distributes the vertical load to said leaf springs.
Leaf spring assembly , in accordance with present invention, wherein said friction reduction means rotates on its axis when there is relative movements between adjacent leaf springs.
Vehicles havings leaf spring assembly with friction reduction means as claimed in preceeding claims for reducing the inter-leaf friction of said leaf springs.
3
- 5 SEP 2009

Brief description of invention
In accordance with the present invention, leaf spring assembly comprises; at least two leaf springs stacked and held with spring clips, said leaf springs having plurality of grooves provided on top surfaces, friction reduction means disposed on said grooves, spacers disposed in between the said leaf springs at the spring seat location, said leaf springs arrangements with friction reduction means such as balls or rollers or bushes or bars (4) and spacer (5) provided therein are staked and fastened with spring clips (6). said friction reduction means (4) in between the said leaf springs avoid inter-leaf friction. The said said friction reduction means provided therein transfers the load between leaf springs in vertical direction and nullifies the inter-leaf friction.
Brief description of Drawing
Figure-01 shows top view of the leaf spring assembly with in accordance the present invention.
Figure-02 shows the cross sectional view (A-A) of leaf spring assembly with balls in accordance the present invention.
Figure-03 shows the cross sectional view (B-B) of leaf spring assembly with balls in accordance the present invention showing the details of all parts of the assembly.
Figure-04 shows the detail view (CC) of leaf spring assembly with balls in accordance the present invention. It also shows the arrangement of balls (4) in the groove present in the leaves ((1,2,3) of the spring.
Figure-05 shows the detail top view (BB) of leaf spring assembly with balls in accordance the present invention.
Figure-06 shows the Detail view (AA) of leaf spring assembly with spacers (5)
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between the leaves of the spring,in accordance the present invention.
Detailed description of invention
Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the same,
Now referring to figure -01 to 06, In accordance with the present invention, leaf spring assembly comprises; at least two leaf springs( 1,2 or 3 ) stacked and held with spring clips, said leaf springs having plurality of grooves provided on top surfaces, friction reduction means disposed in said grooves, spacers disposed in between the said leaf springs at the spring seat location, said leaf springs arrangements with friction reduction means such as balls or rollers or bushes or bars (4) and spacer (5) provided therein are staked and fastened with spring clips (6). said friction reduction means (4) in between the said leaf springs avoid inter-leaf friction. The said said friction reduction means provided therein transfers the load between leaves in vertical direction and nullifies the inter-leaf friction in longitudinal direction.
The said leaf spring having plurality of grooves at appropriate places at overhang area for disposing the friction reduction means such as balls or rollers or bushes or bars. The said balls or rollers or bushes or bars (4) provided in said grooves of said leaf springs are having at least 3mm diameter. The said spacers (5) provided in between the said leaf spring at the spring seat location are having the thickness of at least 1 mm.
The said leaf springs are stacked with friction reduction means (4) disposed in said grooves between the said leaf springs. Spacer(5) is placed in between the leaves at the spring seat and the assembly is held with the spring clips (6).
The said friction reduction means (4) provided in said groove of said leaf springs are the active component in the assembly which distributes the vertical
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load to all the leaves of the springs. In addition to the equal distribution of vertical load to all leaf springs, the said friction reduction means rotates on its axis when there is relative movements between the adjacent leaf springs.
The combination of the said spring clips (6) and the spacer plates (5) maintain an inter-leaf gap of 1mm avoiding inter-leaf friction in longitudinal direction.
The said leaf spring assembly facilitates greater load carrying capacity than the conventional leaf spring of same stiffness. The said leaf spring assembly having longer life. The number of leaves are lesser and hence lesser weight. The said leaf spring assembly having lesser span than parabolic spring of the same load carrying capacity and having decreased winding effect.
The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purpose of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included in so-far as they come within the scope of the invention as claimed or the equivalents thereof.


We Claim
1. Leaf spring assembly comprises; at least two leaf springs stacked and held with spring clips ; wherein said leaf spring having plurality of grooves provided on top surfaces; a friction reduction means disposed in said groove;, spacers disposed in between said leaf springs at the spring seat location.
2. Leaf spring assembly as claimed in claim 1, wherein said friction reduction means is plurality of balls or rollers or bushes or bars.
3. Leaf spring assembly as claimed in claim 1, wherein said groove is provided at overhang area of said leaf spring for disposing the said friction reduction means.
4. Leaf spring assembly as claimed in claim 2, wherein said balls or rollers or bars are having at least 3 mm diameter.
5. Leaf spring assembly as claimed in claim 1, wherein said spacers are having thickness of at least 1 mm.
6. Leaf spring assembly as claimed in claim 1, wherein said friction reduction means are the active component in the assembly which distributes the vertical load to said leaf springs.
7. Leaf spring assembly as claimed in claim 2 and 4, wherein said friction reduction means rotates on its axis when there is relative movements between adjacent leaf springs.
8. Vehicles havings leaf spring assembly with friction reduction means as claimed in preceeding claims for reducing the inter-leaf friction of said leaf springs.
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9. Leaf spring assembly with friction reduction means for reducing the inter-leaf friction as herein described and illustrated with reference to the accompanying description and drawings.
Dated this 8th day of September 2009
TATA MOTORS LIMITED By their Agent & Attorney

Karuna Goleria of DePENNING & DePENNING