FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
PROVISIONAL SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION An improved brake pedal assembly for vehicles
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
Anshuman Gupta, Raman Chouda, Sushil Yadav & Datta S. Kad
all 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 the Invention:
The present invention relates to an improved brake pedal assembly for vehicles which can reduce the clearances at the booster and TMC assembly and give the driver better brake feel by tuning the brake system to a higher level.
Background of the Invention:
The brake pedal is used on all automobiles to actuate the braking function of the vehicle as per the requirements of the driver. The brake pedal mechanism consists of a brake pedal suitable connected to the brake booster pushrod through a pin. Whenever the pedal is pressed, the force gets transferred to the booster, thereby generating hydraulic pressure in the system, through the pin. The initial phase of pedal travel corresponding to the effort applied overcomes all the clearances in the brake system which includes tolerance at pedal bushes, clevis pin, ineffective stroke of booster and TMC assembly, clearance between pad and disc and clearance between drum and liner. Out of these clearances, the major portion is due to clearances in booster and TMC assembly. The initial phase of pedal travel does not generate any vehicle deceleration and hence the driver gets a feeling of an ineffective brake system. The aforementioned clearances can be reduced but cannot be reduced to zero due to machining and production constraints. Making clearances close to zero would also increase the probability of a jammed brake system. A conventional brake pedal assembly has been illustrated in figure 1 of the accompanying drawings.
Hence, it can be concluded that clearances mentioned earlier are a necessary evil for a properly functioning brake system. This problem is generally one of the most common issues in vehicle braking systems.

With a view therefore, to overcome the problems associated with conventional brake pedal system, the inventors felt the need to develop a novel brake pedal assembly that can be used with a conventional brake systems (with clearances) and that would reduce the clearances at the booster and TMC assembly and thus give a better 'brake feel" to the driver, by tuning the brake system to a higher level.
Advantageously, the construction of the invented brake pedal assembly is simple and at the same time production cost effective.
Summary of the Invention:
Accordingly, the present invention provides a brake pedal assembly having, a brake pedal having a force input end, a brake pedal pivoting end about which said brake pedal moves, said brake pedal pivoting end is pivotally connected to a bush, a linkage means having, a booster end and a linkage means pivoting end about which said linkage means moves, said booster end is disposed adjacent to said brake pedal pivoting end, while said linkage means pivoting end is disposed away from the said brake pedal pivoting end, and said linkage means pivoting end is pivotally connected to a second bush, a securing means for securing said brake pedal to said linkage means, said securing means being configured to transfer the movement of said brake pedal to said linkage means, a brake booster pushrod pivotally connected to said linkage means at the booster end by means of a pivotal attachment, wherein said linkage means is configured to allow movement of said securing means, and wherein the distance between said pivotal attachment and the second bush is always greater than the distance between the securing means and the second bush.
Advantageously, by maintaining the distance between the pivotal attachment and the second bush greater than the distance between securing means and the second bush, the displacement of the pivotal attachment and in turn the brake booster pushrod is always

higher than the displacement of the securing means from their respective initial positions when the brake pedal is pressed. In other words, in the invented brake pedal assembly, the arrangement of the pivotal attachment and the securing means in respect of the second bush is such that the angular velocity of the linkage means will always be equal to or greater than the angular velocity of the pedal and the securing means. This amplified motion of the linkage means is transferred to the booster pushrod through said pivotal attachment. Thus, a positive relative motion is achieved between the brake pedal and the booster pushrod through the linkage means. This arrangement enables quick actuation of the brake system as compared to a conventional brake system.
According to a particular embodiment of the invention said linkage means is a slotted link having an integral slot and said securing means is a mechanical fastener attached to said brake pedal and disposed with the integral slot of said linkage means, said mechanical fastener being configured to slide along the integral slot. The cross-sectional of the integral slot is suitably chosen to reduce the localised stresses over the securing means.
According to a further embodiment of invention said linkage means is provided with at least one pivoting hole for establishing a pivotal connection to said secondary bush.
A further embodiment of invention is such that said slotted link is provided with a plurality of said pivoting holes for adjusting the distance between the linkage means and the second bush.
Yet another embodiment of invention is such that said pivotal attachment for pivotally connecting said linkage means with said brake booster pushrod is a clevis pin.

According to a preferred embodiment of the embodiment of the invention, said slotted link has a rectangular profile and said integral slot extends longitudinally between said booster end and said linkage means pivoting end of said slotted link.
Preferably, said securing means is a rigidly mounted cylindrical protrusion extending from said brake pedal.
According to another preferred embodiment of invention, said cylindrical protrusion is a cylindrical pin.
A still further embodiment of invention is such that said cylindrical pin is configured to undergo an angular movement in sync with said brake pedal upon application of the brake.
A further embodiment of invention is such that said brake pedal assembly is fastened to the vehicle body.
In the invented brake pedal assembly, the linkage means and the securing means are hardened to withstand physical wear and tear .
Advantageously, in the invented brake pedal assembly the outer profile of the linkage means is such that it does not interfere with any of the neighbouring parts of the vehicle. Also, there are no sharp edges in the linkage means ensuring adequate safety while assembling and servicing of the assembly.
Although the invented brake pedal assembly has specific application in the field of vehicle braking mechanisms it can be easily adapted for any other mechanism in a vehicle where mechanical advantage is required.

Brief Description of the Drawings:
For better understanding various embodiments of the invention will now be described with reference to the accompanying drawings. It will ,however, be appreciated that the embodiments exemplified in the drawings are merely illustrative and not limitative to the scope of the invention, because it is quite possible, indeed often desirable, to introduce a number of variations in the particular embodiments that have been shown in the drawings. In the accompanying drawings:
Figure 1 schematically illustrates a conventional brake pedal system
Figure 2, schematically shows a perspective view of a preferred embodiment of the invented brake pedal assembly.
Detailed Description of the Drawings:
Referring to figure 2 of the accompanying drawings, the brake pedal assembly according to a particular embodiment, comprises of a brake pedal (1), having a pedal end (11) and a brake pedal pivoting end (12), and a slotted link (2), having a linkage means pivoting end (13) and a brake booster end (14), which are pivotally connected to each other by a cylindrical pin (5), wherein the said cylindrical pin (5) is integral to the brake pedal (1) but slides vertically within the slot (4) of said slotted link (2). Both brake pedal (1) and slotted link (2) are pivotally connected to primary and secondary bushes (3, 7) respectively. The brake booster pushrod (8) is connected to the slotted link (2) with a clevis pin (6).The secondary bush (2) is secured to a rigid support by means of an attachment (9).

The brake pedal (1) is the link receiving the input form the driver. During brake application an angular movement of the cylindrical pin (5) along with the brake pedal (1) is initiated. The cylinder pin (5) then generates the motion in the slotted link (2) by sliding in the slot (4). Due to the sliding of the cylinder pin (5) in the slot (4), the slotted link (2) generates motion with a varying angular velocity with regards to the constant angular velocity of the brake pedal (1) and cylindrical pin (5). During brake application, the said brake pedal (1) moves angularly with regards to the pivot at the primary bush (7). The motion of the brake pedal (1) transfers to the slotted link (2) through the cylindrical pin (5). The pivotal fastener can take the form of a cylindrical pin (5) integrally fixed to the brake pedal (1). This motion of the slotted link (2), pivotally connected to the secondary bush (3) is transferred to the brake booster pushrod (8) through the clevis pin (6) pivotally connected to the booster end (14) of the said slotted link (2). The vertical distance of the first pivotal fastener, in this case a clevis pin (6) and the second pivotal fastener, in this case a cylindrical pin (5) over the slotted link (2) with regards to the secondary bush (3) is such that the first pivotal fastener in this case, a clevis pin (6) is always farther than the second pivotal fastener, in this case a cylindrical pin (4). Due to this arrangement, for any given displacement or velocity of the second pivotal fastener, in this case a cylindrical pin (5), the displacement or velocity of the first pivotal fastener, in this case a clevis pin (6) and in turn the booster pushrod (8) will be more. This would essentially lead to a faster rate of pressure generation inside the vehicle braking system for the same given input conditions at the brake pedal (1). The amount of desired positive relative motion between the brake pedal (1) and the booster pushrod (8) can be adjusted by varying the said vertical distances.
Advantageously, due to the fitment of the booster pushrod (8) to the slot (4) of the slotted link (2), the articulation remains the same throughout the brake pedal stroke.

Due to the positive relative motion between the brake pedal (1) and the brake booster pushrod (8), the driver would feel an improved brake performance. The co-relation between the brake pedal (1) travel, effort and pressure generation would become even better with this mechanism and as a result of which the reaction time of the vehicle braking system would reduce. Since the brake booster is now working at a faster rate with regards to the brake pedal (1), the driver would apparently feel less ineffective brake pedal travel.
The orientation of the slotted link (2) is such that it would be held in a vertical condition when the brake pedal (1) is at its home position. This would ensure maximum efficiency and effectiveness of the said mechanism. Further, the design of the slotted link (2) is such that it can be formed with a plurality of pivoting holes (10) to suit varying vehicle designs.
In addition to the above working, the cylindrical pin (5) also slides inside the slot (4) of the slotted link (2). Due to this sliding action the vertical distance of the first pivotal fastener, in this case a clevis pin (6) and the second pivotal fastener, in this case a cylindrical pin (5) over the slotted link (2) with regards to the secondary bush (3) varies giving a variable ratio to the mechanism. This reduces the overall force requirement at the brake pedal (1) to achieve a particular vehicle deceleration level. As already mentioned, the foregoing description is illustrative of the invention and not limitative to its scope, because it will be apparent to persons skilled in the art to device other alternatives embodiments without departing from the broad ambit of the disclosures made herein.

We claim:
1. A brake pedal assembly comprising;
- a brake pedal having a force input end, a brake pedal pivoting end about which said brake pedal moves, said brake pedal pivoting end is pivotally connected to a bush,
- a linkage means having, a booster end and a linkage means pivoting end about which said linkage means moves, said booster end is disposed adjacent to said brake pedal pivoting end, while said linkage means pivoting end is disposed away from the said brake pedal pivoting end, and said linkage means pivoting end is pivotally connected to a second bush,
- a securing means for securing said brake pedal to said linkage means, said securing means being configured to transfer the movement of said brake pedal to said linkage means,
- a brake booster pushrod pivotally connected to said linkage means at the booster end by means of a pivotal attachment,
wherein said linkage means is configured to allow movement of said securing means, and wherein the distance between said pivotal attachment and the second bush is always greater than the distance between the securing means and the. second bush.
2. The brake pedal assembly as claimed in claim 1, wherein said linkage means is a
slotted link having an integral slot, and wherein said securing means is a

mechanical fastener attached to said brake pedal and disposed with the integral slot of said linkage means, said mechanical fastener being configured to slide along the integral slot.
3. The brake pedal assembly as claimed in any of the above claims, wherein said linkage means is provided with at least one pivoting hole for establishing pivotal connection to said secondary bush.
4. The brake pedal assembly as claimed in claim 4, wherein said slotted link is provided with a plurality of said pivoting holes for adjusting the distance between the linkage means and the second bush.
5. The brake pedal assembly as claimed in any of the above claims, wherein said pivotal attachment for pivotally connecting said linkage means with said brake booster pushrod is a clevis pin.
6. The brake pedal assembly as claimed in any of the above claims 2 to 5, wherein said slotted link has a rectangular profile and said integral slot extends longitudinally between said booster end and said linkage means pivoting end of said slotted link.
7. The brake pedal assembly as claimed in any of the above claims, wherein said securing means is a rigidly mounted cylindrical protrusion extending from said brake pedal.
8. The brake pedal assembly as claimed in any claim 7, wherein said cylindrical protrusion is a cylindrical pin.

9. The brake pedal assembly as claimed in any claim 8, wherein said cylindrical pin is configured to undergo an angular movement in sync with said brake pedal upon application of the brake.
10. The brake pedal assembly as claimed in any of the above claims, wherein said brake pedal assembly is fastened to the vehicle body.