FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION Automatic Crown Wheel And Pinion Identification System
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
INVENTOR
SONAWANE NILESH BHIMRAJ
An Indian National
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 relates to a rear axle differential housing and more particularly it relates to automatic crown wheel pinion identification system.
BACKGROUND OF INVENTION
Correct crown wheel & pinion assembly is very important in differential housing of axle. This assembly decides the output speed of axle. During assembly of differential housing crown wheel & pinion interchanges from one model to another. After doing assembly of differential housing it is very difficult to identify type of crown wheel & pinion fitted inside the axle. This is done with the help of measuring the out put speed of brake drum of axle. On assembly line after assembly of differential housing, axle is tested for differential action. On this inspection station input drive is provided by using electric motor.
One of the method used for measuring the speed of brake drum of axle is by using digital tachometer with reflector arrangement. In this arrangement, Reflector is required to be fixed on the rotating portion of every job. So cost of reflector is involved because it comes with digital tachometer. Sticking reflector is an additional activity which requires human intervention. Moreover the cost of tachometer and reflector is high. Additionally this arrangement is not programmable for certain speed limit and number of output signals.
OBJECTS OF THE INVENTION
The main object of the present invention is to provide automatic crown wheel and pinion identification system.
Another object of the present invention is to provide automatic crown wheel and pinion identification system which is fitted on inspection station for differential housing assembly.

Another object of the present invention is to provide automatic crown wheel and pinion identification system which eliminates additional inspection work or process after assembly.
Yet another object of the present invention is to provide automatic crown wheel and pinion identification system which can be used without disassembling the differential housing of the axle.
STATEMENT OF INVENTION
Automatic crown and pinion wheel identification system in a rear axle differential housing of a vehicle comprising; an inspection platform for inspecting the crown wheel and pinion arrangement; sensor means for detecting the speed of brake drum of said axle; control means for counting electrical pulses generated by said sensor means; display means for displaying the speed of the crown wheel; wherein said sensor means is mounted such that the sensor beam focuses on brake drum stud and said sensor means is capable of generating electric pulses during the interception of its sensor beam by said brake drum stud during rotation which are counted by said control means to detect speed of said brake drum of said rear axle.
The said system containing said sensor which is a photo electric sensor, said control means is programmable logic controller for counting pulses per unit time and for comparing it with predefined values; said control means comprises a first electrical signal means for indicating that said measured speed is equal to speed of selected first gear ratio; said first electrical signal means is a green lamp; said control means comprises a second electric signal means and a hooter means as an alarm for indicating that measured speed is not equal to speed of selected first gear ratio, thereby indicating the presence of a second gear ratio of crown wheel and pinion inside said differential housing; said second electrical signal means is a red lamp; said display means is a digital display for visual indication of brake drum speed of axle; said system is non contact type speed measurement system and said system is connected with constant speed electrical motor for rotating the input pinion.

A method for identifying the type of crown wheel and pinion fitted inside a differential housing of a rear axle in a vehicle comprising the steps of:
rotating a constant speed electrical motor to provide constant speed of rotation to crown wheel and pinion of a first gear ratio and thereby to a brake drum; detecting speed of rotation of said brake drum by sensor means; determining and displaying output speed of said brake drum per unit time; comparing said output speed with predetermined speed; and audibly and/or visibly indicating whether or not measured speed is equal to speed of selected first gear ratio.
The method for identifying the type of crown wheel and pinion fitted inside a differential housing of a rear axle in a vehicle wherein said sensor is photoelectric sensor; wherein said step of indicating through a first electric signal means that said measured speed is equal to speed of selected first gear ratio; wherein said step of indicating through a second electric signal means and hooter means that said measured speed is not equal to speed of selected first gear ratio thereby indicating the presence of a second gear ratio of crown wheel and pinion inside said differential housing; wherein said sensor means generates optical beams which are intercepted by the continuous rotation of said brake drum, said number of interceptions being counted by a control means to detect speed of said brake drum of said rear axle.
BRIEF DESCRIPTION OF INVENTION
in accordance with the present invention, automatic crown and pinion wheel identification system comprises; inspection platform (9) for inspecting the crown wheel and pinion arrangement, sensor means (8) for detecting , mounting means for sensor means, control means (14), first electrical signal means (15) provided on said Programmable Logic Controller, second electrical signal means (16) provided on said programmable logic controller, hooter means provided therein (17), display means provided for displaying the speed of the brake drum, wherein said sensor means for detecting the crown wheel and pinion is mounted on the mounting means

which is installed on the said platform (9) such a way that sensor beam focuses on brake drum stud (11) ,said control means (14) is connected to said sensor means (8) so that rotation of brake drum of axle enables to detect the speed of the axle.
BRIEF DESCRIPTION OF DRAWINGS
Figure-01 shows Isometric view of the system
Figure-02 shows sensor mounting arrangement
Figure-03 shows front view of the system
Figure-04 show top view of the system
Figure-05 shows crown wheel and pinion for first gear ratio.
Figure-06 shows crown wheel and pinion for second gear ratio.
DETAILED DESCRIPTION OF THE 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, Automatic crown wheel and pinion identification system comprises; inspection platform (9) for inspecting the crown wheel and pinion arrangement, sensor means (8) for detecting stud , mounting means for providing sensor means, control means (14), first electrical signal means (15) provided on said control means , second electrical signal means (16) provided on said control means, hooter means provided therein (17), display means provided for displaying the speed of the brake drum, wherein said sensor means is mounted on the mounting means for detecting the stud, in turn detecting type of crown wheel and pinion. Said mounting means is installed on the said platform (9). Said crown wheel and pinion is fitted inside differential housing (1) of axle (7) which is mounted on said station (9) and said control means (14) is connected to the said sensor means (8) such that rotation of brake drum (13) of axle (7) enables to detect the speed of the brake drum of said axle. The said sensor is photoelectric sensor. The said control means (14) is

programmable logic controller for counting pulses for unit time and for comparing it with predefined values. The said display means is digital display used for visual indication of speed of brake drum of said axle. The said control means having first and second electrical signal which is green and red lights for indicating correct and incorrect job respectively. Said control means also includes hooter for alarm purpose. The said automatic crown wheel and pinion identification system is non contact type speed measurement system.
The said automatic crown wheel and pinion identification system is connected with constant speed electrical motor (12) for rotating the input pinion.
The setup has been prepared for measurement of axle output speed with non contact type measurement method & identifies type of crown wheel & pinion fitted inside the differential housing (1) of axle (7). The input rotation speed (Nl) of pinion is same because it is connected to constant speed electrical motor (12), this will give fixed output speed (N2) for crown wheel (3) & pinion (4). As crown wheel (3) & pinion (4) of first gear ratio interchanges to crown wheel (5) & pinion (6) of second gear ratio, it gives different output speed. In this system output speed measured & compared with predetermined speed so that the type of crown wheel & pinion fitted inside the differential housing (1) of axle (7) can be identified.
The said photoelectric sensor (8) has been mounted on inspection station (9) in such a way that it focuses the optical beam (10) on break drum stud (11) of said axle. When input motor (12) gives rotation to the pinion (4) this will cause the output break drum (13) rotation by transferring motion through crown wheel (3). Then the photoelectric sensor (8) gives electrical pulses because it's optical beam (10) is intercepted by break drum stud (11). These pulses are counted by counter of Programmable Logic Controller (14) for unit time.
Output brake drum speed = I/P Pinion Speed X Gear Ratio


Therefore G = N2/N1
Number of pulses counted = Number of Studs X Number of Break Drum Revolutions (N2)
Then these pulses divided by number of stud gives pulse of rotation for unit time.
Number of output revolutions (N2) = Number of pulses counted /
Number of studs
This gives output speed of brake drum (13) per unit time this speed is compared with predetermined speed ranges programmed in Programmable Logic Controller. After comparison if measured speed is equal to speed of selected first gear ratio then Programmable Logic Controller gives electrical signal to green lamp (15) which means that it is correct model. If it is not equal to selected first gear ratio speed then it gives electrical signal to red lamp (16) & hooter (17) which means there is second gear ratio of crown wheel (5) & pinion (6) inside the differential housing. During rotation of axle break drum (13) Programmable Logic Controller gives electrical signal to electrical display (18) which shows output speed of brake drum of said axle (7). This visual indication gives information about speed. So that type of pinion fitted inside the differential axle can be identified easily.
BENEFITS OVER EARLIER STATUS
1) Identifies type of crown wheel & pinion fitted inside the differential housing.
2) Gives visual indication of correct & incorrect type of crown wheel & pinion.
3) It is low cost indirect speed measurement system
4) Time saving in rework of incorrect axle.
5) Pinion identification is done by non contact type speed measurement method.
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. An automatic crown and pinion wheel identification system in a rear axle
differential housing of a vehicle comprising;
An inspection platform for inspecting the crown wheel and pinion arrangement;
Sensor means (8) for detecting the speed of brake drum of said axle;
control means (14) for counting electrical pulses generated by said sensor
means;
display means (18) for displaying the speed of the crown wheel;
wherein said sensor means (14) is mounted such that the sensor beam focuses on brake drum stud and said sensor means is capable of generating electric pulses during the interception of its sensor beam by said brake drum stud during rotation which are counted by said control means (14) to detect speed of said brake drum of said rear axle.
2. The system as claimed in claim 1, wherein said sensor is photoelectric sensor.
3. The system as claimed in claim 1, wherein said control means is a programmable logic controller for counting pulses per unit time and for comparing it with predefined values.
4. The system as claimed in claim 1, wherein said control means comprises a first electrical signal means for indicating that said measured speed is equal to speed of selected first gear ratio.
5. The system as claimed in claim 4, wherein said first electrical signal means is a green lamp.
6. The system as claimed in claim 1, wherein said control means comprises a second electric signal means and a hooter means as an alarm for indicating that measured speed is not equal to speed of selected first gear ratio, thereby

indicating the presence of a second gear ratio of crown wheel and pinion inside said differential housing.
7. The system as claimed in claim 6, wherein said second electrical signal means is a red lamp.
8. The system as claimed in claim 1, wherein said display means is a digital display for visual indication of brake drum speed of axle.
9. The system as claimed in claim 1 to 8, wherein said system is a non contact type speed measurement system.
10. The system as claimed in claim 1, wherein said system is connected with a constant speed electrical motor for rotating the input pinion.
11. A method for identifying the type of crown wheel and pinion fitted inside a
differential housing of a rear axle in a vehicle comprising the steps of:
rotating a constant speed electrical motor to provide constant speed of rotation to crown wheel and pinion of a first gear ratio and thereby to a brake drum;
detecting speed of rotation of said brake drum by sensor means;
determining and displaying output speed of said brake drum per unit time;
comparing said output speed with predetermined speed; and
audibly and/or visibly indicating whether or not measured speed is equal to speed of selected first gear ratio.
12. The method as claimed in claim 11, wherein said sensor is photoelectric sensor.
13. The method as claimed in claim 11, wherein said method comprises the step of indicating through a first electric signal means that said measured speed is equal to speed of selected first gear ratio.

14. The method as claimed in claim 11, wherein said method comprises the step of indicating through a second electric signal means and hooter means that said measured speed is not equal to speed of selected first gear ratio thereby indicating the presence of a second gear ratio of crown wheel and pinion inside said differential housing.
15. The method as claimed in claim 12, wherein said sensor means generates optical beams which are intercepted by the continuous rotation of said brake drum, said number of interceptions being counted by a control means to detect speed of said brake drum of said rear axle.
16. An automatic crown wheel & pinion identification system substantially as herein described with reference to accompanying drawings.
Dated this 29th day of December 2008