FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)


TITLE OF THE INVENTION An Improved Test Rig For Assessing Strength Of Body Shell Of A Vehicle
APPLICANTS
TATA MOTORS LIMITED, an Indian Company
(laving its registered office at Bombay House,
24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
INVENTORS
Atul Date, Madhav Argulkar,
And Sachin Lam bate
All are Indian Nationals
0i TATA MOTORS LIMITED an Indian company
(laving its registered office at Bombay House,
24 Honii Mody Street, Hutatma Chowk,
PREAMBLE TO THE DESCRIPTION
The follow 'nS specification particularly describes the invention and the manner in which it is to be performed.


FIELD OF INVENTION
This invention relates to a test rig used for assessing strength of vehicle body structure and more particularly it relates to an improved test rig for assessing strength of body shell of a vehicle and specially side doors of a vehicle.
BACKGROUND OF INVENTION
Body shell structure of a motor vehicle is tested on a test rig for assessment of its mechanical properties, such as strength, stiffness etc. The test rig consists of a plunger connected to an actuator. The bodyshell is positioned against this plunger. The bodyshell is loaded by the plunger. A load sensor is fitted between the actuator and the plunger to measure load applied to the bodyshell structure. The plunger is provided with guides to ensure appropriate orientation and linear movement of the plunger against the bodyshell during the test. The plunger is rigidly connected to the guides and load sensor. During the test, the plunger experiences a non uniform reaction force from the bodyshell structure and the guides, load sensor and actuator experience bending moments. Depending on their magnitude, the bending moments results into undesirable permanent deformations in the guide, load sensor and the actuator. These undesirable deformations damage the load sensor, actuator and the guides which require repair or replacement.
OBJECTS OF INVENTION
The main objective of the present invention is to provide an improved test rig for assessing strength of body shell of a vehicle.
Another object of the present invention is to provide an improved test rig for assessing strength of body shell of a vehicle which limits the bending moments on the loading plunger and the load sensor.

STATEMENT OF INVENTION
An improved test rig for assessing strength of body shell of a vehicle comprises; a loading plunger for loading the vehicle structure, load sensor for measuring the load applied, guide rods for maintaining the direction and position of the loading plunger, actuator to push the said loading plunger against the vehicle structure, a pressure plate to push the loading plunger, wherein said pressure plate comprises a spherical ball or a cylindrical pin for pressing said loading plunger.
A test rig, in accordance with this invention, wherein said load sensor is provided between said actuator and said loading plunger.
A test rig, in accordance with this invention, wherein said load sensor is provided behind said actuator.
A test rig, in accordance with this invention, wherein said test rig comprises plunger retaining bolts provided between said pressure plate and the said loading plunger to facilitate movement of said plunger in opposite direction after completion of the test.
A test rig, in accordance with this invention, where in said test rig comprises a cage to hold the said spherical ball or cylindrical pin in place.
A test rig, in accordance with this invention, wherein said pressure plate comprises cavity to suit the size of said spherical ball or cylindrical pin.
A test rig, in accordance with this invention, wherein said pressure plate comprises hole having predetermined size in relation to the size of said bolts.
A test rig, in accordance with this invention, wherein said Plunger retaining bolts (6) having predetermined strength are provided between the said pressure plate (5)

and the said loading plunger (2) which rupture in case of excessive bending moment and disconnect the load sensor and actuator from the loading plunger.
BRIEF DESCRIPTION OF INVENTION
In accordance with the present invention, a test rig for assessing strength of a body shell of a vehicle comprises; a loading plunger for loading the vehicle structure, load sensor for measuring the load applied, guide rods for maintaining the direction and position of the loading plunger, actuator to push the said loading plunger against the vehicle structure.
Said guide rods are positioned or oriented to be parallel to the direction of movement of the said loading plunger to maintain the direction and location of the said loading plunger against the vehicle structure.
The said loading plunger is pushed or pressed by the said load sensor through a spherically shaped ball.
The plunger retaining bolts provided between the said load sensor and the said plunger are selected of a predetermined strength in order to fail in case of excessive bending moment and disconnect the load sensor and actuator from the loading plunger.
BRIEF DESCRIPTION OF DRAWINGS
Figure-01 shows the vehicle body shell structure positioned against the test rig Figure-02 shows the details of the constructional features of the test rig Figure-03 shows an alternate design of the test rig wherein the load sensor is provided behind the actuator.

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 & 02, in accordance with this invention,
The vehicle structure (1) is positioned against the loading plunger (2) of the test
rig for assessment the strength of its side door.
The test rig comprises; a loading plunger (2) for applying load on the vehicle structure, spherical ball (3), pressure plate (5), load sensor (7) for measuring the load applied , actuator (8) to push the said loading plunger against the vehicle structure and plunger guides (9) for maintaining the direction and position of the loading plunger.
Said guide rods are positioned or oriented to be parallel to the direction of movement of the said loading plunger to maintain the direction and location of the said loading plunger against the vehicle structure
The said actuator (8) pushes the said loading plunger on the vehicle structure through load sensor (7), pressure plate (5) and spherical ball (3).
The said load sensor can be positioned in two ways.
In first position, said load sensor (7) is disposed between said pressure plate (5) and said actuator (8). In second position, said load sensor (7) is placed behind the said actuator (8)
This loading arrangement is termed as "loading link". The said loading plunger (2) is guided throughout the process by the plunger guides (9). The said plunger

guides (9) also ensure desired position of the loading plunger against the actuator axis.
It! such test the loading plunger receives non uniform reaction from the vehicle bodyshell structure. Such non uniform reaction results in bending of the loading 'ink.
In order to ensure the centre of rotation of this bending, a spherical ball (3) is Provided between the said plunger (2) and said pressure plate (5) due to which the said loading plunger (2) always tilts about the centre of the sphere. It is also Possible to use a cylindrical pin in place of the spherical ball.
Plunger retaining bolts (6) are provided between the said pressure plate (5) and the said loading plunger (2) to facilitate movement of the said plunger in opposite direction after completion of the test.
Ball cage (10) is provided to retain the said spherical ball (3) at its place. The said bail cage (10) is supported on the said bolts (6).
The said bolts (6) pass through holes (11) provided on said pressure plate (5). The clearance between the bolt shank and the said through hole decide the extent of the tilt of said plunger during testing.
Any further tilt of said plunger will generate lo^d on the said bolts (6). The strength of said bolt (6) are selected such that tney rupture in case the load exceeds a predetermined load. The said arrangem^nt provides the safeguard to the loading link from overloading.
The foregoing description is a specific embodiment 0f tne present invention. It should be appreciated that this embodiment is described for purpose of illustration orily, 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 insofar as they come within the scope of the invention as claimed or the equivalents thereof.

WE CLAIM
1. An improved test rig for assessing strength of body shell of a vehicle
comprising
a loading plunger for loading the vehicle structure;
at least one load sensor for measuring the load applied;
plurality of guide rods to guide the loading direction and position of the loading plunger;
an actuator to push the loading plunger against the vehicle structure;
a pressure plate linked with loading plunger for advancing loading plunger through a spherical ball or a cylindrical pin;
wherein the improved test rig assesses the strength of the body shell of the vehicle without undesirable permanent deformation of the entire test
rig-
2. A test rig as claimed in claim 1, wherein said load sensor is provided between said pressure plate and said actuator.
3. A test rig as claimed in claimed in claim 1, wherein said load sensor is provided behind said actuator.
4. A test rig as claimed in claim 1, wherein plunger retaining bolts are provided between said pressure plate and said loading plunger to facilitate movement of said plunger in opposite direction after completion of the test.
5. A test rig as claimed in claim 1 and 4, where in said pressure plate is provided with cavity to suit the size of said spherical ball or cylindrical pin and holding means to hold the said spherical ball or cylindrical pin in place.

6. A test rig as claimed in claim 1 and 6, wherein said pressure plate is provided with plurality of holes having predetermined size in relation to the size of said retaining bolts for facilitating tilting of the loading plunger.
7. A test rig as claimed in claim 1 and 4, wherein said Plunger retaining bolts having predetermined strength are provided between said pressure plate and said loading plunger to disconnect the said load sensor and said actuator from said loading plunger after failure of the said retaining bolts in case of excessive bending moment there by avoiding undesirable permanent deformation of major components of the test rig.
8. A test rig for assessing strength of body shell of a vehicle as herein described substantially with reference to accompanying drawings.
Dated this 3 lsl day of December 2008