FORM 2
THE PATENT ACT 1970 (as amended)
[39 OF 1970]
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
[See Section 10 and Rule 13]
TITLE: “A VARIABLE RATIO BRAKE PEDAL MECHANISM OF A VEHICLE AND METHOD THEREOF”
Name and address of the Applicant:
TATA MOTORS LIMITED, an Indian company having its registered office at
Bombay house, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400 001, Maharashtra,
INDIA.
Nationality: INDIAN
The following specification particularly describes the invention the manner in which it is to be performed.

TECHNICAL FIELD
Embodiments of the present disclosure relates to a brake pedal mechanism of a vehicle, more particularly the embodiments relate to a variable ratio brake pedal mechanism of the vehicle.
BACKGROUND OF DISCLOSURE
Vehicles, in particular automotive vehicles, include a brake system for controlling the movement of the vehicle. Conventional brake systems include a brake pedal for transmitting a braking force from the vehicle operator to the wheels of the vehicle. The brake pedal is operatively coupled to a brake booster via a push rod. The brake booster is operatively connected to a master cylinder, and the master cylinder is operatively connected to a braking mechanism via brake lines. The braking mechanism is coupled to a wheel of the vehicle and applies the force to the wheel to slow down the rotational movement of the wheel.
Various factors influence the overall efficiency of the brake system. Examples of some of these factors include the size of the brake booster, the master cylinder diameter and radius of the tires, the brake pad material and the pedal lever ratio. At the same time, the brake system must comply with regulatory requirements regarding braking distance and the amount of force required to slow down the vehicle.
As shown in FIG. 1 the conventional pedal mechanism includes a pedal arm, and an upper end of the pedal arm is pivotally mounted to a support bracket. The support bracket is fixedly mounted to the vehicle. A pedal pad is mounted to a lower end of the pedal arm for depression by the driver's foot. The brake booster push rod is attached to the pedal arm at a location between the pedal pad and the pivot point at the upper end of the pedal arm.
The feel and effectiveness of the braking action experienced by the operator can be varied by changing the “pedal ratio”. Pedal lever ratio refers to the geometric relationship between the levers that make up the brake pedal assembly. The “pedal ratio” is expressible as a ratio a/b, where “a” is the distance between the pivot point for the pedal

arm and the actuation point on the pedal pad, and “b” is the distance between the pivot point and the booster rod attachment point. In general, the lower the value of the pedal ratio, the greater the distance the brake rod pivot point and booster push rod travel, relative to the distance travelled by the pedal pad. A high pedal ratio can be effective, but the long pedal travel results in a “spongy” feel to the brakes. Conversely, a low pedal ratio can provide good brake feel with shorter pedal travel but lead to higher pedal effort. Further, in the conventional brake pedal mechanism the brake pedal ratio remains constant throughout the brake pedal operation.
In light of forgoing discussion, it is necessary to provide a brake pedal mechanism with variable pedal ratio to have good brake pedal feel, less brake pedal travel and moderate pedal effort.
STATEMENT OF THE DISCLOSURE
Accordingly, the present disclosure provides a variable ratio brake pedal mechanism of a vehicle comprises: a support bracket, a pedal arm, wherein an upper end of said pedal arm is pivotally mounted to said support bracket at a first pivot point and a pedal pad is mounted to a lower end of said pedal arm, a first link having an upper end and a lower end, movably connected to the pedal arm at the first pivot point through its upper end, an intermediate link having an upper end and a lower end, pivotally connected to the lower end of the first link through its upper end, and a bell crank lever having an upper end, center area of pivot and a lower end, wherein upper end of the bell crank lever is pivotally connected to the lower end of the intermediate link and lower end of the bell crank lever is pivotally connected to a pivotable rod of brake booster, wherein, the bell crank lever is pivotally mounted to the support bracket at a second pivot point through its centre area of pivot for transmitting rotation motion from intermediate link to the brake booster for operating the brake in variable pedal ratio, and also provides for a method of assembling a variable ratio brake pedal mechanism of a vehicle, said method comprising acts of, mounting a support bracket on firewall of the vehicle, mounting a pedal arm pivotally to the support bracket at a first pivot point, connecting a first link having an upper end and a lower end movably to the pedal arm at a first pivot point through its

upper end, connecting an intermediate link having an upper end and a lower end pivotally to the lower end of the first link through its upper end, and connecting a bell crank lever having an upper end, center area of pivot and a lower end, pivotally to the lower end of the intermediate link, the support bracket and a pivotable rod of brake booster respectively, wherein, the upper end of the bell crank lever is pivotally connected to the lower end of the intermediate link and lower end of the bell crank lever is pivotally connected to a pivotable rod of brake booster, and the bell crank lever is pivotally mounted to the support bracket at a second pivot point through its centre area of pivot for transmitting rotation motion from intermediate link to the pivotable rod of the brake booster for operating the brake in variable pedal ratio.
SUMMARY OF THE DISCLOSURE
The shortcomings of the prior art are overcome and additional advantages are provided through the provision of system as claimed in the present disclosure.
Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.
One embodiment of the present disclosure provides a variable ratio brake pedal mechanism of a vehicle. The mechanism comprises: a support bracket, a pedal arm pivotally mounted on support bracket at first pivot point. A first link having an upper end and a lower end, movably connected to the pedal arm at the first pivot point through its upper end. An intermediate link having an upper end and a lower end, pivotally connected to the lower end of the first link through its upper end. The mechanism further comprises, a bell crank lever having an upper end, center area of pivot and a lower end. The upper end of the bell crank lever is pivotally connected to the lower end of the intermediate link and lower end of the bell crank lever is pivotally connected to a pivotable rod of brake booster. And the bell crank lever is pivotally mounted to the support bracket at a second pivot point through its centre area of pivot for transmitting rotation motion from intermediate link to the brake booster for operating the brake in variable pedal ratio.

In an embodiment of the present disclosure, at least one preloaded torsion spring is mounted coaxially at each of the first pivot point and second pivot point respectively for retracting the first link and bell crank lever to their original position when brake pedal arm is released.
In an embodiment of the present disclosure, plurality of spring stoppers are provided in predetermined location of support bracket and first link for supporting first tangential leg and a second tangential leg of the torsion spring mounted coaxially at first pivot point and plurality of spring stoppers are provided in predetermined locations of bell crank lever and support bracket for supporting first tangential leg and a second tangential leg of the torsion springs mounted coaxially at second pivot point.
In an embodiment of the present disclosure, the first link, the intermediate link the bell crank lever and the pivotable rod of the brake booster forms rotary pair with each other.
In one embodiment of the present disclosure, the rotation motion of the intermediate link and angular motion of the bell crank lever creates variable brake pedal ratio.
Another embodiment of the present disclosure relates to a method of assembling a variable ratio brake pedal mechanism of a vehicle. The method follows steps of mounting a support bracket on firewall of the vehicle, then mounting a pedal arm pivotally to the support bracket at a first pivot point. Connecting a first link having an upper end and a lower end movably to the pedal arm at a first pivot point through its upper end and connecting an intermediate link having an upper end and a lower end pivotally to the lower end of the first link through its upper end. Then, connecting a bell crank lever having an upper end, center area of pivot and a lower end, pivotally to the lower end of the intermediate link, the support bracket and a pivotable rod of brake booster respectively. The upper end of the bell crank lever is pivotally connected to the lower end of the intermediate link and lower end of the bell crank lever is pivotally connected to a pivotable rod of brake booster, and the bell crank lever is pivotally mounted to the support bracket at a second pivot point through its centre area of pivot for transmitting

rotation motion from intermediate link to the pivotable rod of the brake booster for operating the brake in variable pedal ratio.
In an embodiment of the present disclosure, mounting at least one preloaded torsion spring coaxially at each of the first pivot point and second pivot point retracting the first link, intermediate link and bell crank lever to their original position when brake pedal arm is released.
In an embodiment of the present disclosure, mounting plurality of plurality of spring stoppers in predetermined location of support bracket and first link for supporting first tangential leg and a second tangential leg of the torsion spring mounted coaxially at first pivot point, and mounting plurality of spring stoppers in predetermined locations of bell crank lever and support bracket for supporting first tangential leg and a second tangential leg of the torsion springs mounted coaxially at second pivot point.
The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
OBJECTIVES OF THE DISCLOSURE
One object of the present disclosure is to provide brake pedal mechanism which has a variable brake pedal ratio to improve brake pedal feel.
One object of the present disclosure is to provide a brake pedal mechanism which has a variable brake pedal ratio to meet customer satisfaction with less pedal travel and with moderate pedal effort.
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
The novel features and characteristic of the disclosure are set forth in the appended claims. The disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the

accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which:
FIG. 1 illustrates a side view of conventional brake pedal mechanism.
FIG. 2 illustrates a side view of variable ratio brake pedal mechanism according to present disclosure.
FIG. 3 illustrates a perspective view of variable ratio brake pedal mechanism according to present disclosure.
FIG. 4 illustrates a graph showing a comparison between constant pedal ratio and variable pedal ratio.
FIGS 5a-5c illustrates working principle of variable ratio brake pedal mechanism.
The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAILED DESCRIPTION
The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristic of the disclosure, both as to its organization and method of

operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.
To overcome the drawbacks mentioned in the background the present disclosure provides a brake pedal mechanism with variable pedal ratio to meet customer satisfaction with less pedal travel and with moderate pedal effort.
As an exemplary embodiment FIGS.2 and 3 illustrates side view and perspective view of the variable ratio brake pedal mechanism of the vehicle. The variable ratio brake pedal mechanism (200) comprises a support bracket (201) mounted on firewall of the vehicle for supporting the brake pedal mechanism (200). The support bracket (201) comprises a mounting face (201a) and two spaced apart side arms (201b) extending from opposing edges of said mounting face (201a). A pedal arm (202) having an upper end (202a) and lower end (202b) is pivotally mounted on the support bracket (202) at first pivot point (A) through its upper end (202a) using a suitable means. And a pedal pad (202b) is mounted to a lower end of said pedal arm (202) for actuating the brake pedal arm (202) by the driver/user. A first link (203) having an upper end (203a) and a lower end (203b) is pivotally mounted to the pedal arm (202) at a first pivot point (A) through its upper end (203a) and said first link (203) forms a rolling pair with pedal arm (202). In the first pivot point (A) pivoting means is rotatbly connected to a support bracket (201), the pedal arm (202) and first link (203) are hinged to the pivoting means, such that the when the pedal arm (202) moves the first link (203) rotates. A preloaded torsion spring (208) with first tangential leg (208a) and a second tangential leg (208b) is mounted coaxially at the first pivot point (A) for retracting the pedal arm (202) and the first link (203) to their original position when the brake pad is released. The variable ratio brake pedal mechanism (200) further comprises an intermediate link (204) having an upper end (204a) and a lower end (204b) is pivotally connected to the lower end (203b) of the first link (203) through its upper end (204a) to form a rolling pair with the first link (203). A bell crank lever (205) having an upper end (205a), center area of pivot (205b) and a lower end (205c) is

pivotally connected between the intermediate link (203) and a pivotable rod (206a) of brake booster (206) to transfer rotation motion from the intermediate link (203) to the pivotable rod (206a) of brake booster (206) for operating the brake. The upper end (205a) of the bell crank lever (205) is pivotally connected to the lower end (204a) of the intermediate link (204) to form a rolling pair with the intermediate link (204). And the lower end (205c) of the bell crank lever (205) is pivotally connected to the pivotable rod (206a) of the brake booster (206) for forming the rolling pair with pivotable rod (206a) of the brake booster (206) to transfer rotation motion from intermediate link (204) to the brake booster for operating the brake. The bell crank lever (205) is pivotally mounted to the to the support bracket (201) at a second pivot point (B) through its centre area of pivot (205b). The variable pedal ratio is created by changing the angle of bell crank lever (205) and the intermediate link (204) and by changing the direction of input force on to the pedal arm (202). The angle of the bell crank lever (205) changes with the rotation of first link (203) and intermediate link (204) and the pedal ratio changes gradually. A preloaded torsion spring (208) with first tangential leg (208a) and a second tangential leg (208b) is mounted coaxially at the second pivot point (B) for retracting the bell crank lever (205) and the intermediate link (203) to their original position when the brake pad is released.
The variable ratio brake pedal mechanism (200) further comprises plurality of spring stoppers (209) in predetermined locations of support bracket (201) and first link (203) for supporting first tangential leg (208a) and a second tangential leg (208b) of the torsion spring (208) mounted coaxially at first pivot point (A) and plurality of spring stoppers (209) are provided in predetermined locations of bell crank lever (205) and support bracket (201) for supporting first tangential leg (208a) and a second tangential leg (208b) of the torsion springs (208) mounted coaxially at second pivot point (B). The spring stoppers (209) support the first and second tangential legs (208a and 208b) of the spring stoppers to maintain the preloaded torsion.
Further, a stopper (207) is mounted onto the support bracket (201) in such a way to prevent the movement of pedal arm (202) towards the driver of the vehicle due to torsion in preloaded spring when the pedal arm is disengaged. The stopper (207) is a U-shaped

bracket which restricts the movement of pedal arm (202) towards the driver of the vehicle and holds the pedal arm (202) in position.
The first link (203), the intermediate link (204), the bell crank lever (205), the pivotable rod (206b) of the brake booster (206) and the support bracket (201) are pivotably connected to each other using a member selected from group comprising but not limited to rivets, screws and nuts and bolts. The first link (203), the intermediate link (204), the bell crank lever (205), the pivotable rod (206b) of the brake booster (206) and the support bracket (201) are pivotably connected such that they form rotary pair with each other to transfer the oscillation motion from pedal arm (202) to the brake booster (206) for applying the brake on wheels to stop the vehicle.
In alternative embodiment of the present disclosure, the bell crank lever (205) can be replaced with two links to transfer the rotary motion from intermediate link (204) to the pivotable rod (206a) of the brake booster (206) for operating the brake. The first additional link having upper end and lower end can be connected to the lower end (204b) of the intermediate link (204) and the lower end can be hinged at second pivot point (B). The second additional link having upper end and lower end pivotally connected to the lower end of first additional link at second pivot point (B) and lower end of the second additional link is pivotally connected to the pivotable end (206a) of the brake booster (206) for applying the brake on wheels to stop the vehicle.
The variable pedal ratio is created by changing angle of the first link (203), intermediate link (204) and bell crank lever (205) and direction of input force. The angle of the links (203 and 204) and bell crank lever (205) changes with rotation of the links and results change in pedal ratio gradually. In the present variable ratio brake pedal mechanism (200) when the brake pad is engaged by the driver/user the first link (203) will transmit its rotary motion to intermediate link (204) with the help of hinge at first pivot point (A). The intermediate link (204) transmits its rotary motion to bell crank lever (205), then the bell crank lever (205) transmits its rotary motion to the pivotable rod (206a) of the brake booster (206) for applying the brake. Further, the brake booster (206) is operatively

connected to a master cylinder, and the master cylinder is operatively connected to a braking mechanism via brake lines for applying the brake to stop the wheels.
FIG. 4 illustrates graph showing a comparison between brake pedal mechanism with constant pedal ratio and brake pedal mechanism with variable pedal ratio. To improve the brake the pedal feel, the brake pedal ratio should be less initially and should be increased gradually. So that driver can feel good brake pedal feel with less pedal effort. Hence, the variable pedal ratio is helpful in providing good brake pedal feel.
As shown in the graph (FIG. 4), the conventional brake pedal mechanisms will have constant pedal ratio. In this case the brake pedal ratio remains same throughout the braking cycle and hence results in unsatisfactory brake pedal feel. Whereas, in the variable ratio brake pedal mechanism (200) as discussed in the disclosure the brake pedal ratio will be less initially and it increases gradually. The variable pedal ratio is created by changing angle of the first link (205), intermediate link (204) and bell crank lever (205) and direction of input force. The angle of the links change with rotation of the links and results change in pedal ratio gradually, which results in satisfactory brake pedal feel.
FIGS. 5a-5c are exemplary embodiments illustrating working principle of the variable ratio brake pedal mechanism (200).
The FIG. 5a shows initial position of the pedal arm (202) when the brake is in disengaged condition. During this stage the pedal arm stopper (207) prevents the movement of pedal arm (202) towards the driver of the vehicle due to torsion in preloaded spring.
When the pedal arm (202) is pressed by the driver as shown in FIG. 5b, the pedal arm (202) rotates the first link (203) in anti-clock wise direction, since the first link (203) and pedal arm (202) are roatatbly connected to each other at first pivot point (A). The first link (203) will transmit its rotary motion to intermediate link (204) with the help of hinge at first pivot point (A). The rotation movement of intermediate link (204) rotates the bell crank lever (205) in anti-clock wise direction, and then the bell crank lever (205) transmits its rotary motion to the pivotable rod (206a) of the brake booster (206) for

applying the brake. The pivotable rod (206a) moves to and fro for applying the brake. Hence, by above explained arrangement the variable brake pedal ratio is achieved.
The FIG. 5c shows final position pedal arm (202) when the brake is in fully engaged condition. In fully engaged condition the pivotable rod (206a) applies pressure on the brake booster (206) to operate the master cylinder to apply the brake for stopping the wheels of the vehicle. When, the driver release the pedal arm (202) the first link, intermediate link and bell crank lever moves anti-clock wise direction to their respective initial positions due to preloaded torque in the torsion springs. During this action the pivotable rod (206a) will be pulled by bell crank lever (205) to releases the brake.
Advantages:
The present disclosure provides a variable ratio brake pedal mechanism which improves the brake pedal feel.
The present disclosure provides a variable ratio brake pedal mechanism which meets meet customer satisfaction with less pedal travel and with moderate pedal effort.
The present disclosure provides a variable ratio brake pedal mechanism which is simple in construction and easy to assemble.
Equivalents
With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.
It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further

understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.
Referral Numerals;

Reference Number Description
200 Variable ratio brake pedal mechanism
201 Support bracket
201a Mounting face of support bracket
201b Side arms of the support bracket
202 Pedal arm
202a and 202b Upper and lower ends of the pedal arm
203 First link
203a and 203b Upper and lower ends of the first link
204 Intermediate link
204a and 204b Upper and lower ends of the intermediate link
205 Bell crank lever
205a and 205c Upper and lower ends of the bell crank lever
205b Centre area of pivot of bell crank lever
206 Brake booster
206a Pivotable rod of the brake booster
207 Stopper
208 Torsion spring

208a and 208b
First and second tangential legs of the torsion spring
209 Stoppers for supporting tangential legs of the torsion spring

We claim
1. A variable ratio brake pedal mechanism (200) of a vehicle comprises:
a support bracket (201);
a pedal arm (202), wherein an upper end (202a) of said pedal arm (202) is pivotally mounted to said support bracket (201) at a first pivot point (A) and a pedal pad (202b) is mounted to a lower end of said pedal arm (202);
a first link (203) having an upper end (203a) and a lower end (203b), movably connected to the pedal arm (202) at the first pivot point (A) through its upper end (203a);
an intermediate link (204) having an upper end (204a) and a lower end (204b), pivotally connected to the lower end (203b) of the first link (203) through its upper end (204a); and
a bell crank lever (205) having an upper end (205a), center area of pivot (205b) and a lower end (205c), wherein upper end (205a) of the bell crank lever
(205) is pivotally connected to the lower end (204a) of the intermediate link (204)
and lower end (205c) of the bell crank lever (205) is pivotally connected to a
pivotable rod (206a) of brake booster (206);
wherein, the bell crank lever (205) is pivotally mounted to the support bracket (201) at a second pivot point (B) through its centre area of pivot (205b) for transmitting rotation motion from intermediate link (204) to the brake booster
(206) for operating the brake in variable pedal ratio.
2. The mechanism as claimed in claim 1, wherein at least one preloaded torsion spring (208) is mounted coaxially at each of the first pivot point (A) and second pivot point (B) respectively for retracting the first link (203) and bell crank lever (205) to their original position when brake pedal arm (202) is released.
3. The mechanism as claimed in claim 2, wherein the springs (208) are coil springs.
4. The mechanism as claimed in claim 2, wherein plurality of spring stoppers (209) are provided in predetermined location of support bracket (201) and first link (203) for supporting first tangential leg (208a) and a second tangential leg (208b) of the torsion

spring (208) mounted coaxially at first pivot point (A) and plurality of spring stoppers (209) are provided in predetermined locations of bell crank lever (205) and support bracket (201) for supporting first tangential leg (208a) and a second tangential leg (208b) of the torsion springs (208) mounted coaxially at second pivot point (B).
5. The mechanism as claimed in claim 1, wherein a stopper (207) is mounted on the support bracket (201) to prevent the movement of the pedal arm (202) due to torsion in preloaded torsion springs (208).
6. The mechanism as claimed in claim 1, wherein the first link (203), the intermediate link (204), the bell crank lever (205) and the pivotable rod (206a) of the brake booster (206) forms rotary pair with each other.
7. The mechanism as claimed in claim 1, wherein the rotation motion of the intermediate link (204) and angular motion of the bell crank lever (205) creates variable brake pedal ratio.
8. The mechanism as claimed in claim 1, wherein the first link (203), the intermediate link (204), the bell crank lever (205), the pivotable rod (206b) of the brake booster (206) and the support bracket (201) are pivotably connected to each other using a member selected from atleast one of rivets, screws and nuts and bolts.
9. A method of assembling a variable ratio brake pedal mechanism (200) of a vehicle, said method comprising acts of;
mounting a support bracket (201) on firewall of the vehicle;
mounting a pedal arm (202) pivotally to the support bracket (201) at a first pivot point (A);
connecting a first link (203) having an upper end (203a) and a lower end (203b) movably to the pedal arm (202) at a first pivot point (A) through its upper end (203a);

connecting an intermediate link (204) having an upper end (204a) and a lower end (204b) pivotally to the lower end (203b) of the first link (203) through its upper end (204a); and
connecting a bell crank lever (205) having an upper end (205a), center area of pivot (205b) and a lower pivotally (205c) to the lower end (204b) of the intermediate link (204), the support bracket (201) and a pivotable rod (206a) of brake booster (206) respectively;
wherein, the upper end (205a) of the bell crank lever (205) is pivotally connected to the lower end (204b) of the intermediate link (204) and lower end (205c) of the bell crank lever (205) is pivotally connected to a pivotable rod (206a) of brake booster (206), and the bell crank lever (206) is pivotally mounted to the support bracket (201) at a second pivot point (B) through its centre area of pivot (205b) for transmitting rotation motion from intermediate link (204) to the pivotable rod (206a) of the brake booster (206) for operating the brake in variable pedal ratio.
10. The method as claimed in claim 9, wherein mounting at least one preloaded torsion spring (208) coaxially at each of the first pivot point (A) and second pivot point (B) retracting the first link (203), intermediate link (204) and bell crank lever (205) to their original position when brake pedal arm (202) is released.
11. The method as claimed in claim 9, wherein mounting plurality of plurality of spring stoppers (209) in predetermined location of support bracket (201) and first link (203) for supporting first tangential leg (208a) and a second tangential leg (208b) of the torsion spring (208) mounted coaxially at first pivot point (A), and mounting plurality of spring stoppers (209) in predetermined locations of bell crank lever (205) and support bracket (201) for supporting first tangential leg (208a) and a second tangential leg (208b) of the torsion springs (208) mounted coaxially at second pivot point (B).

12. A vehicle comprising a variable ratio brake pedal mechanism as claimed in claim 1.