FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
The Patent Rules, 2003
Complete Specification
(See section 10 and rule 13)
Pedal Linkage Mechanism
Mahindra and Mahindra Ltd.
An Indian company registered under the Indian Companies Act, 1956.
Gateway Building, Apollo Bunder, Mumbai - 400001, Maharashtra, India.
The following specification particularly describes the invention and the manner in which it is to be performed:

Pedal Linkage Mechanism
Field of invention
The present invention relates to a pedal linkage mechanism. These mechanisms are employable in any applications where a force needs to be applied by an operator using either their arms or legs, or by any other means, such that the force releases a device, such as a clutch or a break.
Background of invention
In many industrial applications release mechanisms are required which operate under a force that travels during the course of release operation. Typical applications are clutches and brakes used in the automotive industry.
Heavy vehicles or high torque vehicles typically require large clutch-operating force. A huge pressure is required on the clutch plate and pressure plate to transmit the engine torque to the transmission. There are several aspects of the clutch design. First, there are ergonomic limitations on the amount of travel of the clutch pedals so that operators are able to operate the pedal comfortably. A typical clutch operates with the help of mechanical linkage mechanisms which transfer the force applied by the operator of a vehicle at the clutch pedal to the clutch

itself. The clutch pedal travel and the clutch pedal operating force have an inverse relationship with conventional mechanical linkage. It is also known that the force required to operate the clutch pedals for heavy vehicles (or high-torque vehicles) is much larger compared to light vehicles, when provided with conventional linkage mechanism. Finally, as a clutch is a very frequently operated part, the high level of clutch-operating force frequently leads to operator fatigue; in particular, it makes it extremely difficult for an average female driver to operate vehicles such as tractors.
Figure 4 shows pedal effort v. pedal travel characteristic curves for various pedal systems. Curve 1 represents a typical existing pedal system. It is evident from it not only that a great amount of the pedal effort needs to be exerted to operate it, but that this force needs to be exerted over a significant amount of pedal travel. This leads to operator fatigue. There has existed for a long time a need to reduce the required clutch force.
There have been several attempts made in this directions as have been reported in the prior art.
US patent 2009/0071285A1 discloses a pedal arrangement for operating a clutch to provide a variable pedal force transmission ratio. It comprises an arrangement where the push rod is connected to the pedal such that it moves radially along the

slotted portion there by giving a variable linkage ratio. The radial movement of the actuating rod is achieved by guiding it through a slotted cam groove provided on the guide.
US patent US 7219576B2 discloses a variable ratio brake pedal actuating assembly. It comprises a cam guided structure, a guide slot and the link member to provide a variable pedal ratio.
US patent 4624152 discloses clutch actuating device for maintaining the actuating force of the clutch pedal. It comprises a drive mechanism with a control leaver which in turn gives a variable ratio by using an eccentric action of a linkage.
US patent 4846012 discloses an actuating linkage for a clutch. It uses a hydraulic cylinder and a compensating spring.
US patent 5165299 discloses a pedal depression assisting mechanism which reduces the clutch depressing source by placing the two assists springs in the clutch actuation linkage mechanism.

US pedant 4793456 discloses a variable ration clutch lever. It is an apparatus or method for varying the effective length of levers which actuates a collector ring in a clutch.
The study of related aforementioned prior art reveals various short coming such as:
• In the case of US 2009/ 0071285A1, the mechanism disclosed is complicated and uses a number of bearings, and two cam groove arrangements which requires high accuracy of part construction and operation, and resulting higher maintenance and other costs
• In the case of US patent 516529, the reduction in clutch force is inherently limited as it discloses use of assist springs
• Use of hydraulic cylinder and/or compensating springs increase costs
• Complicated lever mechanism with the eccentric action or cam guided structure disclosed in the prior art is costly and require high accuracy of part construction and operation
The need for developing a simple mechanism which is easy to manufacture and maintain while reducing significantly the clutch force is real. In particular, the

max operating force of the clutch pedal is reduced around 20-30% by providing a variable force transmission (linkage ratio) ratio, is highly desirable.
It is also desirable to provide reduced clutch force and its relationship with clutch pedal travel such that after the clutch disengagement the pedal force will be decline, as it will help and enable the driver to get out of the habit of riding a clutch.
Objectives and advantages of the invention
Accordingly, one of the objectives of the invention is to provide a clutch pedal operation linkage mechanism that is suitable for heavy/high torque vehicles.
Another objective of the invention is to reduce the max pedal operating force within the acceptable amount of clutch pedal travel.
Yet another objective of the invention is to reduce the clutch pedal operating force after the effective clutch disengagement travel.

A further objective of the invention is to reduce the brake force and increase the breaking force effectively by using this mechanism in brake linkage mechanism.
A yet further objective of the invention is to provide mechanism to provide the desired output force and travel characteristics for the clutch/brake pedal.
A still further objective of the invention is to provide a linkage mechanism which is stable during operation and giving a smooth operation.
Still another object of the invention is to provide a simple cost effective linkage mechanism to reduce the clutch/brake pedal force.
Thus in accordance with the invention the system comprises of a linkage mechanism which is used to provide a variable linkage ratio (force transmission ratio), and which can be used to operate a break or clutch mechanism in a vehicle.
Summary Of Invention:
In automotive industry, there are various applications where a force is used in 'release operations', where the applied force travels through a distance before the 'release' takes place. A typical example is that of a clutch where a force is applied

to release the clutch plates during the torque transmission process. The force is applied by an operator using a pedal, and which is transmitted to the gear box through a system of mechanical linkages. The present invention discloses a pedal linkage mechanism which works on a variable linkage ratio. The linkage ratio of a mechanical linkage system reduces the force required to be applied to the pedal and the distance over which the applied force has to travel to operate the intended application, i.e. a clutch or a brake. The invention provided several advantages over the currently available linkage system which operate on a fixed linkage ratio principle.
Brief Description of the Figures:
Figure 1a shows a schematic of the typical existing pedal mechanisms
Figure lb shows a schematic of a preferred embodiment of the present invention
Figures 2 and 3 provide further schematics of the pedal mechanism of the present invention
Figures 3 b and 3 c show perspective views of the present invention
Figure 4 shows schematic of pedal effort v. pedal travel characteristic
Figures 5 and 6 show plots of effect of variations of key parameters of the present invention

Figure 7 provides the pedal effort v. pedal travel characteristic curve for a specific case of a typical existing pedal system
Figure 8 provides the pedal effort v. pedal travel characteristic curve for a specific case of present invention
Figure 9 shows schematic of the another embodiment of the present invention
List of Parts
Clutch pedal - 1 First pin joint - 11
First fixed angle— la Second pin joint- 12
Support-2 Third pin joint- 13
First pivot shaft - 3 Release rod - 14
First bush - 4 Second driving link - 7a
Second pivot shaft - 5 Second connecting link - 15
Second bush - 6 Fourth pin joint - 16
First driving link - 7 Second driven link - 17
First driven link - 8 Third bush - 18
First Lever - 9 Second lever - 19
Second fixed angle - 9a Fifth pin joint - 20
First connecting link - 10
Detailed description of the invention

In the automotive industry, there are various applications where a force is used in 'release operations', where the applied force travels through a distance before the 'release' takes place. A typical example is that of a clutch where a force is applied to release the clutch plates during the torque transmission process. The force is applied by an operator using a pedal, and which is transmitted to the gear box through a system of mechanical linkages. These mechanical linkages typically work on a linkage ratio principle. The existing linkage systems have a fixed linkage ratio.
A schematic of the system of the present invention is shown in Figure 1 and Figure 2.
The present invention is now disclosed as applicable in a clutch. It discloses a linkage system with a variable linkage ratio used in clutch operation. It incorporates a clutch pedal arm 1 that is maintained at a fixed first angle la with a first driving link 7. This is achieved by rigidly connecting both the clutch pedal arm 1 and the first driving link 7 to a first bush 4 which is abie to rotate around its central axis. The first bush 4 is pivoted on a first pivot shaft 3 which is rigidly connected to a support 2. A connecting link 10 is rotatably connected at its one end to the first driving link 7 through a first pin joint 11. The other end of the first connecting link 10 is rotatably connected to a first driven link 8 through a second

pin joint 12. The first driven link 8 is rigidly connected to a second bush 6, to which is also rigidly connected a first lever 9. There is maintained a second fixed angle 9a between the first driven link 8 and the lever 9. The bush 6 is pivoted on a second pivot shaft 5. The second pivot shaft 5 is rigidly connected to a support, preferably the support 2. The first lever 9 is rotatably connected to the clutch release rod 14 through a third pin joint 13.
During clutch operation, the clutch pedal arm 1 is pushed under the force applied by the operator. This in turn rotates the first bush 4 about the first pivot shaft 3 and consequently rotates the first driving link 7 about the first pivot shaft 3. During this motion, the first angle remains constant. Next, the first driving link 7 pushes the first connecting link 10 through the first pin joint 11. The first connecting link 10, in turn, pushes the first driven link 8 through the second pin joint 12. The pushing action of first connecting link 10 causes the first driven link 8 to rotate about the second pivot shaft 5 through the second bush 6. The angles between the first driving link 7 and the first connecting link 10, and that between the first connecting link 10 and the first driven link 8 are adjusted according to the movement. Furthermore, as the first driven link 8 is rigidly connected to first lever 9, the latter also rotates about the same pivot shaft. The movement of the first lever 9 causes the movement (push or pull) of a clutch release rod 14, as it is rotatably connected with the driven link through the third pin joint 13.

The arrangement of the linkages for clutch operation, specifically that of the first driving link 7, the connecting link 10 and the first driven link 8 connected with respective parts through first and second pin joints (11 and 12), the first pivot shaft 3 and the second pivot shaft 5 rigidly, all connected through a rigid support 2 gives the required operating characteristics which are discussed below (ref. figure 2).
During the operation of the pedal linkage mechanism of the present invention, variation of the three key variable parameters—the length of the first driving link 7, the length of driven length 8 and their angular positions—causes variations in the effective length of the driving link and the effective length of the driven link. The effective lengths are the lengths projected on a perpendicular to the connecting link drawn from the pivot points (see figure 2). This in turn gives the variable linkage ratio (for transmission of the pedal force) during the operation of the clutch pedal. The linkage ratio obtained for the present invention is defined as (A/B) x (C/D), wherein (see Figure 2):
A = length of the pedal arm
B = projected (or effective) length of the driving link
C - projected (or effective) length of the driven link
D = length of the lever

The effect of variable linkage mechanism on the force/travel characteristics is shown in Figure 4. It schematically shows (indicated by solid line) the work involved in operation of a typical clutch, which is calculated as the area under the force-travel curve. It can be seen that the present invention effectively redistributes the work (shown by the curve represented by a dash-dot line) done during the clutch operation through the travel which the force undergoes.
A clutch is in an engaged position as the operator starts to apply force while changing gears. As the applied force increases, the clutch pedal travels and the clutch enters the disengagement zone, the applied force reduces. In the existing systems, the applied force increases up to the disengagement zone and then it plateaus. Thus the operator continues to apply a high magnitude of force even after the pedal has travelled considerably. Any force-travel curve has two characteristic aspects of interest in a clutch application - the peak force and the average force in the disengagement zone. The latter of the two is of greater importance as it is what contributes to operator fatigue. The force in the disengagement zone is applied by the operator with the leg in a stretched position. If the magnitude of this force is high, this combined with the stretched position of the leg leads to operator fatigue. This also makes it prone to losing control over the clutch operation. Reduction in the average force in the disengagement zone is

therefore highly desirable. This results in reduction in the amount of work done in the disengagement zone, which is compensated by greater amount of work done in the engagement zone. The system of the present invention thus helps reduce the overall peak force, and, more importantly, the average force required in the disengagement travel/zone. As we have seen earlier, the Curve 1 (represented by a solid line) of Figure 4 represents a typical existing pedal system. Curve 2 (represented by a dash-dot line) of Figure 4 represents the pedal system of the present invention. It is clear from it that the characteristic curve for the present system has a distinct peak, which occurs at a shorter magnitude of pedal travel and after which the pedal effort decreases.
At the same time it is recognized that different applications may have different force-travel characteristic requirements. The present invention makes this possible as it makes it feasible to design clutch systems with any linkage ratios. Curve 3 (represented by a dash line) of Figure 4 is indicative of the fact that any characteristic curve is possible to be achieved using the pedal system of the present invention. In other words, any desired output characteristics for the pedal travel v/s force are obtainable by selecting specific values for lengths of and angle between the first driven link 8 and the first driving link 7, and the distance between the first pivot shaft 3 and the second pivot shaft 5.

The clutch operation mechanism of the present invention to get the desired variable linkage (force transmission) ratio addresses all shortcomings of the prior art discussed earlier. Specifically, the system of the present invention provides a simple arrangement that easy and inexpensive to construct and operate. This is borne out of the fact that the system of the present invention does not involve any slider mechanism or grooved arrangement or cam arrangement to get the desired variability of the linkage ratio. Also it does not require any hydraulic cylinder to reduce the clutch effect. On the other hand, the assist springs can be used with this mechanism as usual.
It can be seen from the figures accompanying this application that the plane in which the linkage works is shown to be vertical. However, the linkage may be constructed in any one plane, and not necessarily a vertical one. It is also possible that it may operate in more than one plane depending on space requirement of a specific vehicle.
Further the said linkage arrangement can be modified to get the desired output results by simple changes in lengths and angles of the elements. The system is properly constrained and capable of giving longer life in the usage and trouble free service.

An additional advantage of the said system is virtually eliminates the scope of operator fatigue for the clutch operation by reducing the operating force in the area of its peak zone. Also more increasing the linkage ratio in the clutch disengagement zone offers better control over the vehicle.
In a manner similar to the adaptation of the invention to clutch systems, the said mechanism can be also adapted to operate the breaks to get the desired force-travel characteristics and smooth brake operation.
It can be seen from the plots shown in Figures 5 and 6 that the increase in lengths of driving link and the driven link have exactly the opposite effect on the pedal effort that needs to be applied and also on the corresponding travel. It can be seen that as the length of the driving link increases, the pedal effort increases and so does the pedal travel. This means that if we increase the length of the driving link, the operator not only has to apply greater force but also that the force has to be sustained over a greater travel. This could easily lead to the operator fatigue, which is undesirable.
On the other hand, in the case of the driven link, as its length increases, the required pedal effort reduces and so does the amount of pedal travel. While this is desirable to some extent, it means that the clutch becomes too sensitive to

movement and applied force and difficult to control. The third factor that has an effect on the working of the system of the invention is the second fixed angle 9a. However, it was seen from a number of trials that this factor has very little effect; this is evident from figures 4 and 5.
Mechanisms similar to the ones described above are also used for brakes of automotive vehicles.
One of the alternative embodiments of the invention is depicted in the figure 9. This illustrates how the force travel characteristic curves are adjusted using the inventive concepts disclosed herein. In this embodiment, two pivot shafts are connected together to transmit the applied force from the pedal to the release rod. Using the mechanism shown therein it is possible to obtain a variable linkage (transmission force) ratio in order to get the desired characteristics of the force and travel relationship of the clutch pedal.
The clutch pedal arm 3 is rigidly connected to the first driving link 7 through a first bush 4. The first bush 4 is pivoted on a first pivot shaft 3 which is rigidly connected to the support 2. A first connecting link 10 is operatively connected to a first driving link 7 through a first pin joint 11. The other end of the first connecting link 10 is operatively connected to a first driven link 8 through a

second pin joint 12. The first driven link 8 and the second driving link 7a are rigidly connected through a second bush 6, which is pivoted on a second pivot shaft 5. The second pivot shaft 5 is rigidly connected to the support 2. The second driving link 7a is connected to a second connecting link 15 through a third pin joint 13. The other end of the second connecting link 15 is connected to a second driven link 17 through a fourth pin joint 16. The second driven link 17 is rigidly connected to a second lever 19 through a third bush 18, which is pivoted on the first pivot 3. The second lever 19 is operatively connected to the clutch release rod 14 through a fifth pin joint 20.
In this case, the linkage ration has been calculated as follows: LR - (A/B) x (C/D) x (E/F), where
A = length of the pedal arm
B = projected (or effective) length of the first driving link
C = projected (or effective) length of the first driven link
D = length of the lever
E = projected (or effective) length of second driven link
F = projected (or effective) length of second driving link

Yet another representation of the effect of the variation of lengths of the driving link and the lever can be seen from Figure 6 (contour plot), which shows the effect of the variation of the lengths of these two links on the pedal effort for the value of the second fixed angle 9a held at 27°. A number of such plots are derived for various values of second fixed angle 9a. It is easily possible to arrive at required value of pedal effort by selecting a combination of these lengths and the second fixed angle 9a.
Thus it is evident that with a judicious combination of the lengths of the driving link 7, driven link 8 and pivot shafts 3 and 5 and the first connecting link 10, it is possible to provide a pedal system with desired pedal effort and travel characteristics. In the case of the second preferred embodiment, it is evident that with a judicious combination of the lengths of the driving links 7 and 7a, the driven links 8 and 17 and pivot arrangement 3 and 5 and the connecting links 10 and 15, it is possible to provide a pedal system with desired pedal effort and travel characteristics.
The present invention thus provides a variable linkage (force transmission) ratio to reduce the overall peak and average clutch operating force that needs to be exerted by the tractor operator in the clutch disengagement zone. It provides a desired force travel relationship of clutch pedal to reduce the operator fatigue and provide

effective control on the vehicle. This has been achieved by reducing the linkage ratio in the engagement zone/travel, which in turn increases the required force. In the disengagement zone the linkage ratio increases, which helps reduce the required force. The key here is to first reduce the linkage ratio followed by its reduction. If the linkage ratio were to be fixed at a higher level than existing systems, it will pose the issue of clutch not disengaging fully leading to undesirable clutch wear.
As a wider application of the present invention, the release rod is an actuation rod which connects to any other application that requires a force applied by an operator to travel over a distance and which requires to actuate another mechanism. An example of this is a brake.
The present invention is now illustrated through some examples.
Example 1 (see Figure 8):
A clutch pedal system of the present invention was installed on (give the tractor type). The following parameters were used:
Driving link - 62mm Connecting link - 95mm

Driven link - 86mm First fixed angle - 138° Second fixed angle -38°
A plot of pedal travel and pedal force was plotted as shown in Figure 8. It is seen from this plot that the peak pedal force was 22kg and was achieved at the pedal travel of 70mm. As the pedal travel increased further, the pedal force reduced significantly down to 14kg at the pedal travel of 150mm. The average operating force in the clutch disengagement travel was found to be 18kg.
For the optimal rider comfort, it is expected that:
At start of clutch travel, linkage ratio should be close to 7.5 and at the end of the clutch travel it should be greater than 12 (larger is good).
- Pedal force should be near 17kg at the end of the pedal travel
- Total Travel of clutch fork should be at least 12 mm at 27 degree pedal travel
Similar experiments carried out on a tractor with existing pedal systems showed the following results (see Figure 7):
Linkage ratio at the start: 7.5

- Peak force - 25kg
- Average Force applied through the clutch disengagement travel - 23 kg
It is clear that the pedal system of the present invention provides a number of advantages over the existing pedal system. These are summarized below:
- It provides greater rider comfort and control by reducing the peak pedal effort and the amount of pedal travel over which the peak pedal travel has to be exerted
- The pedal effort decreases after the peak pedal travel is attained, unlike the existing systems where the pedal travel plateaus but does not reduce
- There is an effective redistribution of the overall work done by the operator thereby considerably reducing the operator fatigue. This has been achieved by applying a greater force (than required for the existing pedal systems) in the early stages of pedal travel and reducing the magnitude of pedal force in the clutch disengagement travel.
The present system helps the operator to overcome the clutch riding habit and reduces the undesired clutch wear
It is therefore evident that the present invention has several embodiments as disclosed below:

1. A pedal linkage mechanism comprising at least one pedal arm, at least two pivot shafts and at least two bushes, each bush being rotatably situated around a push, at least one lever and a release rod, at least one of each of a driving link, a driven link, and a connecting link, wherein:
said pedal arm transfers an applied force to a first bush, said first bush being pivotally and rotatably positioned around a first pivot shaft, a first driving link being rigidly connected at its first end to said first bush such that there is maintained a first fixed angle between said pedal arm and said first driving link, said driving link at its other end is rotatably connected through a first pin joint to a first connecting link; said connecting link being rotatably connected to a first driven link through a second pin joint, and further where said first driven link is rigidly connected to a second bush which is pivotally and rotatably situated around a second pivot shaft, to which said second pivot shaft is connected a first lever of which the second end is connected rotatably to an actuation rod through a third pin joint, wherein both pivot shafts are rigidly connected with a support. 2. A pedal linkage mechanism as disclosed in embodiment 1 such that said first fixed angle varies between 60° to 120°, preferably between 90° to 100°.

3. A pedal linkage mechanism as disclosed in embodiments I to 2 such that said second fixed angle varies between 20° to 50°, preferably between 25° to 40°.
4. A pedal linkage mechanism as disclosed in embodiments 1 to 3 wherein the said actuation rod is connected to a clutch.
5. A pedal linkage mechanism as disclosed in embodiments 1 to 4 wherein said actuation rod is connected to a brake.
6. A pedal linkage mechanism as disclosed in embodiments 1 to 5 such that said first fixed angle varies between 60° to 120°, preferably between 90° to 100°.
7. A pedal linkage mechanism as disclosed in embodiments 1 to 6 such that said second fixed angle varies between 20° to 50°, preferably between 25° to 40°.
8. A pedal linkage mechanism as disclosed in embodiments 1 to 6 such that said first fixed angle varies between 60° to 120°, preferably between 90° to 100°.
9. A pedal linkage mechanism as disclosed in embodiments 1 to 7 such that said second fixed angle varies between 20° to 50°, preferably between 25° to 40°.
10. A method of providing a variable linkage ratio pedal linkage mechanism, said method comprises the steps of:
providing a pedal linkage mechanism as described in claim 1

operating said mechanism by pushing said pedal such that when said pedal is pushed, said first bush rotates about said first pivot shaft, which in turn rotates said first driving link about said first pivot shaft, during which motion, said first fixed angle remains constant; furthermore, said first driving link pushes said first connecting link through said first pin joint, which causes said first connecting link to push said first driven link through the second pin joint, wherein the pushing action of said first connecting link causes said first driven link to rotate about said second pivot shaft through said second bush such that the angle between said first driving link and said first connecting link, and the angle between said first connecting link and said first driven link are adjusted according to the movement, and as the first driven link is rigidly connected to said lever, the latter also rotates about the same pivot shaft so that the movement of said lever causes the movement (push or pull) of a clutch release rod, as it is rotatably connected with the driven link through the third pin joint.
11. A pedal linkage mechanism as disclosed in embodiment 1 further comprising a second connecting link, a fourth and a fifth pin joint, a second driven link and a second lever, and a third bush such that:
said second connecting link at its one end is rotatably connected to said first lever through said third pin joint, said second connecting link

being rotatably connected to said second driven link through a fourth
pin joint,
said second driven link being rigidly connected to a third bush which
is rotatably and pivotally positioned around a pivot shaft, preferably
said first pivot shaft;
said second lever is rigidly connected to said third bush and said
release rod being rotatably connected to said second lever through a
fifth pin joint.
While the above description contains much specificity, these should not be construed as limitation in the scope of the invention, but rather as an exemplification of the preferred embodiments thereof. It must be realized that modifications and variations are possible based on the disclosure given above without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their legal equivalents.

We claim:
1. A pedal linkage mechanism comprising at least one pedal arm, at least two pivot shafts and at least two bushes, each bush being rotatably situated around a push, at least one lever and a release rod, at least one of each of a driving link, a driven link, and a connecting link, wherein:
said pedal arm transfers an applied force to a first bush, said first bush being pivotally and rotatably positioned around a first pivot shaft, a first driving link being rigidly connected at its first end to said first bush such that there is maintained a first fixed angle between said pedal arm and said first driving link, said driving link at its other end is rotatably connected through a first pin joint to a first connecting link; said connecting link being rotatably connected to a first driven link through a second pin joint, and further where said first driven link is rigidly connected to a second bush which is pivotally and rotatably situated around a second pivot shaft, to which said second pivot shaft is connected a first lever of which the second end is connected rotatably to an actuation rod through a third pin joint, wherein both pivot shafts are rigidly connected with a support.

2. A pedal linkage mechanism as claimed in claim I such that said first fixed angle varies between 60° to 120°.
3. A pedal linkage mechanism as claimed in claim 1 such that said first fixed angle varies between 90° to 100°.
4. A pedal linkage mechanism as claimed in claim 1 such that said second fixed angle varies between 20° to 50°.
5. A pedal linkage mechanism as claimed in claim 1 such that said second fixed angle varies between 25° to 40°.
6. A pedal linkage mechanism as claimed in claim 1 wherein the said actuation"rod is connected to a clutch.
7. A pedal linkage mechanism as claimed in claim 1 wherein said actuation rod is connected to a brake.
8. A pedal linkage mechanism as claimed in claims 6 and 7 such that said first fixed angle varies between 60° to 120°.
9. A pedal linkage mechanism as claimed in claim 6 and 7such that said first fixed angle varies between 90° to 100°.

10. A pedal linkage mechanism as claimed in claims 6 and 7 such that said second fixed angle varies between 20° to 50°.
11. A pedal linkage mechanism as claimed in claims 6 and 7 such that said second fixed angle varies between 25° to 40°.
12. A method of providing a variable linkage ratio pedal linkage mechanism,, said method comprises the steps of:
providing a pedal linkage mechanism as described in claim 1 operating said mechanism by pushing said pedal such that when said pedal is pushed, said first bush rotates about said first pivot shaft, which in turn rotates said first driving link about said first pivot shaft, during which motion, said first fixed angle remains constant; furthermore, said first driving Jink pushes said first connecting Jink through said first pin joint, which causes said first connecting link to push said first driven link through the second pin joint, wherein the pushing action of said first connecting link causes said first driven link to rotate about said second pivot shaft through said second bush such that the angle between said first driving link and said first connecting link, and the angle between said first connecting link and said first driven link are adjusted according to the movement, and as the first driven link is rigidly connected to said lever, the latter also rotates

about the same pivot shaft so that the movement of said lever causes the movement (push or pull) of a clutch release rod, as it is rotatably connected with the driven link through the third pin joint.
13. A pedal linkage mechanism as claimed in claim 1 further comprising a
second connecting link, a fourth and a fifth pin joint, a second driven link and a second lever, and a third bush such that:
- said second connecting link at its one end is rotatably connected to said first lever through said third pin joint, said second connecting link being rotatably connected to said second driven link through a fourth pin joint,
- said second driven link being rigidly connected to a third bush which is rotatably and pivotally positioned around a pivot shaft, preferably said first pivot shaft;
- said second lever is rigidly connected to said third bush and said release rod being rotatably connected to said second lever through a fifth pin joint.