FIELD OF INVENTION
The present invention relates to agricultural tractor brakes. In particularly, the present invention relates to a brake equalizer mechanism for agricultural tractors. More particularly, the present invention relates to a brake equalizer linkage system for agricultural tractors.
BACKGROUND OF THE INVENTION
Presently, many automotive applications, such as agriculture tractor and track vehicles are available for the utilization of two separate brake units, which are selectively operated to facilitate in steering the vehicle or which are simultaneously actuated to only to transfer full engine torque one wheel for providing braking action to the vehicle.
An agricultural tractor requires a shorter turning radius during farming operations. This requires an independent braking system to make sharp steering by independently applying the right brake or the left brake.
Off-highway tractors are conventionally provided with brakes, which may be independently applied to steer the tractor by braking in addition to steering by the customary steerable front wheels. Frequently, a separate pedal is provided for each tractor wheel.
However, at times, it is desirable to apply both the brakes simultaneously. In certain models of the agricultural tractors, it is also desired to provide only for an equalized simultaneous operation of the brakes of both the rear wheels from a single brake pedal.
Usually, the tractor brakes are mechanically actuated and normally operate on the rear wheels only. The brake housing incorporates brake pressure plates mounted on bull pinion shaft are operated or actuated by rotating a brake shaft link. During combine braking, the operator engages both the LH and RH brake pedals with the help of a lock plate.

Thus, once the brake pedals are pressed, the brake pedal force moves the brake LH and RH links, which in turn presses the brake pressure plates against each other through the brake mechanism incorporated in the brake housing. This in turn stops the rotation of bull pinion shaft. This shaft transfers the drive to rear wheels via a bull gear and rear axle shaft. Due to stopping of the bull pinion shaft, the drive to rear wheel is stopped.
Similarly, when the lock plate is disengaged from the brake pedal, the operation can press each pedal independently. Thus each wheel drive gets independently stopped and accordingly, the tractor takes turn in either left or right direction.
DISADVANTAGES WITH THE EXISTING TRACTOR BRAKING SYSTEM
When the tractor is operated and both brakes are operated simultaneously with equal pressure, it is expected to have perfect a inline braking operation without the tendency to steer the vehicle in one direction or the other.
However, due to difference in linkage efficiencies of both LH and RH brakes and also because of the pressure plates’ wear, there are situation, in which the braking force is not transferred to the wheels equally, which therefore leads to the tractor turning either towards left or right during the braking operation.
DESCRIPTION OF THE PRESENT INVENTION
In order to avoid the occurrence of such a situation, a new brake equalizer linkage system is configured in accordance with the present invention, which transfers equal load to both the brakes, irrespective of the linkage inefficiency or any probable pressure plate wear. Accordingly, the present invention relates to a brake linkage for equalizing the braking effort applied to the tractor rear wheels.
OBJECTS OF THE INVENTION
Some of the objects of the present invention - satisfied by at least one embodiment of the present invention - are as follows:

An object of the present invention is to provide a linkage system for operating the brakes on both rear wheels of a tractor by using a single brake pedal.
Another object of the present invention is to provide a linkage system for operating the brakes on both rear wheels of a tractor to apply equal braking effort on both the rear wheels.
A further object of the present invention is to provide a linkage system for operating the brakes on both rear wheels of a tractor to operate the brakes independently by separate pedals.
A still further object of the present invention is to provide a linkage system for operating the brakes on both rear wheels of a tractor to independently apply equal braking effort on both the rear wheels using separate brake pedals.
Yet further object of the present invention is to provide a linkage system having a single brake pedal connected by a series of links for operating each brake shaft with equal force.
Still further object of the present invention is to provide a linkage system having a cam operated mechanism for operating the brake pedals independently whenever required.
Yet further object of the present invention is to provide a braking system for agriculture tractor, which is also safe on road and does not turn-on by itself on applying brakes.
One more object of the present invention is to provide a braking system for agriculture tractor, providing advantages of independent braking of rear wheels.
These and other objects and advantages of the present invention will become more apparent from the following description when read with the accompanying figures of drawing, which are, however, not intended to limit the scope of the present invention in any way.

SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a brake equalizer mechanism for agricultural tractors which generates equal braking effort to the rear wheels thereof.
The linkage mechanism comprises:
• a set of the first, second and third links provided both for left and right brakes on the rear-wheels of the tractor;
• a sliding joint each provided with the second link of the left and right brake pedals;
• a hinge joint each provided with the third link of the left and right brake pedals;
• each third link of the left and right brake pedals connected via a sliding joint to a fourth link;
• a fifth link connecting the latch plate to the second hinge joint; and
• a sixth link connecting the brake pedals to the fifth links via a cam mechanism.
Typically, the first latch joint and second latch joint can be locked or unlocked.
Typically, the first latch joint and second latch joint are locked for simultaneously applying the brakes on the left and right rear-wheels.
Typically, the first latch joint and second latch joint are unlocked respectively for separately applying brakes on the left or right rear-wheel.
Typically, the first latch joint and second latch joint are locked for simultaneously applying brakes on the left and right rear-wheels.
Typically, the first, second, third link, fourth and sixth links are configured similar for the left and right hand brakes.

Typically, the first and second sliding joints are configured similar for the left and right hand brakes.
Typically, the first hinge joints are configured similar for the left and right hand brakes.
Typically, the first and second latch joints are configured similar for the left and right hand brakes.
Typically, the fifth links are configured similar for the left and right hand brakes.
Typically, the second hinge joint is configured common for the left and right hand brakes.
The invention also provides a method for transferring equal force on the left and right brakes of the rear wheels of an agricultural tractor by means of the linkage mechanism as claimed in claims 1 to 9, wherein the method comprises the step of:
(a) the first latch joint and second latch joint are locked for simultaneously applying brakes on the left and right rear-wheels; or
(b) the first latch joint and second latch joint are respectively unlocked for separately applying brake on the left or right rear-wheel.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The present invention will be briefly described with reference to the accompanying drawings, which include:
Figure 1 shows a conventional rear wheel axle assembly having a left hand (LH) differential housing and a right hand (RH) differential housing and brake system encircled therein.
Figure 2 shows an enlarged view of the encircled brake system of Figure 1.

Figure 3 shows a perspective view of the conventional assembly of the brake pedal and the linkages thereof.
Figure 4 shows a schematic representation of the brake equalizer mechanism configured in accordance with the present invention, when both (LH and RH) brakes are applied together.
Figure 5a shows a detailed view of the engagement of the latch plate with the RH brake pedal depicted in Figure 4.
Figure 5b shows a detailed view of the brake pedal sliding in T slot of Figure 4.
Figure 5c shows a detailed view of the brake pedal locked in the T slot depicted in Figure 4.
Figure 6 shows a schematic representation of the brake equalizer mechanism configured in accordance with the present invention, when the (LH and RH) brakes are applied separately.
Figure 7 shows a schematic representation of the brake equalizer mechanism configured in accordance with the present invention, when brakes are to be applied independently.
DETAIL DESCRIPTION OF THE ACCOMPANYING DRAWINGS
In the following, different embodiments of the present invention will be described in more details with reference to the accompanying drawings without limiting the scope and ambit of the present invention in any way.
Figure 1 shows a conventional rear wheel axle assembly 8 having a left hand (LH) differential housing 2 and a right hand (RH) differential housing 4 and brake system 6 encircled therein. The two wheel ends are also depicted in the figure.

Figure 2 shows an enlarged view of the encircled brake system 6 of Figure 1 depicted along with the right hand (RH) differential housing 4. The brake system 6 is accommodated in a brake housing 7, which also houses a bull pinion shaft 5 and the brake pressure plates 9.
Figure 3 shows a perspective view of the conventional assembly of the brake pedals and the linkages thereof. The assembly consists of a clutch pedal CP, a left hand brake pedal LHBP and a right hand brake pedal RHBP connected via a cross shaft CS to the left hand brake link LHBL and the right hand brake link RHBL respectively. The brake pedals LHBP and RHBP are preloaded by means of a respective left brake spring LS and right brake RS, one end of which are fixed on the respective brake pedal lever and the other ends of which are fixed on the BIW. A brake lock plate BLP is also disposed between the two brake pedals LHBP and RHBP.
Figure 4 shows a schematic representation of the brake equalizer mechanism configured in accordance with the present invention in a situation when both (LH and RH) brakes are applied together. Here, the mechanism includes a left hand brake pedal 10 and a right hand brake pedal 20, a latch plate 30 connected via the respective latch joints 32, 34 and first links 41, 42 to the left hand brake pedal 10 and the right hand brake pedal 20 respectively. The left hand brake pedal 10 and the right hand brake pedal 20 are also connected via the respective first hinge joints 61, 62 to the respective sliding joints 51, 52 via the respective second links 43, 44 to the left hand brake 12 and right hand brake 22 of the tractor (not shown). The first hinge joints 61, 62 are also connected via the respective links 45, 46 and the respective sliding joints 53, 54 (connected to each other via a fourth link 48) to the second hinge joint 64 connected to the latch plate via another link 50. So, the latch link 50 has a hinge joint 64 with the link 48. It is to be noted that the hinge joints 61, 62 and the sliding joints 51, 52 and 53, 54 as well as links 41, 42; 43, 44 and 45, 46 are configured similar like mirror images for the LH and RH brake pedal-brake combinations.
Figure 5a shows a detailed view of the engagement of the latch plate with the RH brake pedal depicted in Figure 4. For example, a cam mechanism is

provided on the link 70 for latching the RHBP to the link 50. This applies to the LHBP as well.
Figure 5b shows a detailed view of the brake pedal sliding in T slot of Figure 4. Here, brake pedal is turned to activate sliding joint from fixed joint.
Figure 5c shows a detailed view of the brake pedal locked in the T slot depicted in Figure 4.
Figure 6 shows a schematic representation of the brake equalizer mechanism configured in accordance with the present invention in a situation when the (LH and RH) brakes are applied separately. The mechanism includes a left hand brake pedal 10 and a right hand brake pedal 20 with the configuration described in respect of Figure 4. Here, the latch joints 32, 34 are unlocked respectively, i.e. the latch plate 30 is unlocked from the respective latch joints 32, 34 and the respective sliding joints 53 and 54 are locked (marked X).
Figure 7 shows a schematic representation of the brake equalizer mechanism configured in accordance with the present invention in a situation when brakes are to be applied simultaneously. Here as well, the mechanism includes a left hand brake pedal 10 and a right hand brake pedal 20 with the configuration described in respect of Figure 4. The latch joints 32, 34 are both locked and the respective sliding joints 51, 52 are unlocked.
TESTS CARRIED OUT: SIMULATION
To simulate the new designed Brake Equalizer system, ADAMS software was used. A Rigid Body Model was built in ADAMS replicating 2D concept shown in Figure 4. Accordingly, the joints were given in virtual validation model. Brakes were modeled using bushings with very high stiffness and damping. A brake pedal force of 25 kgf was applied on both the brake pedals as per the conditions A and B described in Figure 6 and 7 respectively. The reaction forces and the corresponding displacements were monitored at the bushings of the LH and RH brakes respectively.

OBSERVATIONS
Condition A: When LH brake 12 or RH brake 22 is required to be applied separately, the latch joint 32 and latch joint 34 is unlocked respectively.
Based on the simulation of this condition, it is observed that when on pressing the brake pedals 10, 20 independently, the corresponding force and displacement is transferred to the respective LH or RH brake only. The other brake does not share any load.
Condition B: When LH brake 12 and RH brake 22 is to be applied simultaneously, the respective latch joint 32 or 34 is locked.
Based on the simulation of this condition, it is observed that on pressing the brake pedals 10, 20 simultaneously, the brake pedal force is equally distributed on both the brakes 12, 22 and a variation in displacement is observed, which is compensated by the brake equalizer mechanism configured in accordance with the present invention.
Therefore, based on the above described simulation, the new design of the Brake Equalizer Mechanism satisfies the requirement of transferring equal force to both the wheels, even when there is a difference in the efficiencies of the linkages of the LH 12 and RH brake 22.
TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE
The brake equalizer linkage system for agricultural tractors configured in accordance with the present invention has the following advantages:
• Equally transfers the braking force applied by brake pedals to the tractor wheels irrespective of any difference in inefficiencies in the LH and RH brake linkages.
• Allows the braking operation of the LH and RH brakes independently as well as simultaneously.

• Makes tractor braking operation more accurate.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, shall be understood to implies including a described element, integer or method step, or group of elements, integers or method steps, however, does not imply excluding any other element, integer or step, or group of elements, integers or method steps. In the claims and the description, the terms “containing” and “having” are used as linguistically neutral terminologies for the corresponding terms “comprising”.
The use of the expression “a”, “at least” or “at least one” shall imply using one or more elements or ingredients or quantities, as used in the embodiment of the disclosure in order to achieve one or more of the intended objects or results of the present invention. Furthermore, the use of the term “one” shall not exclude the plurality of such features and components described.
The description provided herein is purely by way of example and illustration. The various features and advantageous details are explained with reference to this non-limiting embodiment in the above description in accordance with the present invention. The descriptions of well-known components and manufacturing and processing techniques are consciously omitted in this specification, so as not to unnecessarily obscure the specification.
In the previously detailed description, different features have been summarized for improving the conclusiveness of the representation in one or more examples. However, it should be understood that the above description is merely illustrative, but not limiting under any circumstances. It helps in covering all alternatives, modifications and equivalents of the different features and exemplary embodiments.
Therefore, innumerable changes, variations, modifications, alterations may be made and/or integrations in terms of materials and method used may be devised to configure, manufacture and assemble various constituents, components, subassemblies and assemblies according to their size, shapes, orientations and interrelationships.

While considerable emphasis has been placed on the specific features of the preferred embodiment described here, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiments without departing from the principles of the invention. These and other changes in the preferred embodiment of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.
The exemplary embodiments were selected and described in order to be able to best represent the principles and their possible practical application underlying the invention. Many other examples are directly and immediately clear to the skilled person because of his/her professional knowledge in view of the above description. Thereby, the skilled persons can optimally modify and use the invention and its different exemplary embodiments with reference to the intended use.

We claim:
1. A linkage mechanism for transferring equal force on brakes of the rear
wheel of an agricultural tractor, wherein the linkage mechanism comprises:
• a set of the first, second and third links provided both for left and right brakes on the rear-wheels of the tractor;
• a sliding joint each provided with the second link of the left and right brake pedals;
• a hinge joint each provided with the third link of the left and right brake pedals;
• each third link of the left and right brake pedals connected via a sliding joint to a fourth link;
• a fifth link connecting the latch plate to the second hinge joint; and
• a sixth link connecting the brake pedals to the fifth links via a cam mechanism.

2. Brake equalizer linkage mechanism as claimed in claim 1, wherein the first latch joint and second latch joint can be locked or unlocked.
3. Brake equalizer linkage mechanism as claimed in claim 1, wherein the first latch joint and second latch joint are locked for simultaneously applying the brakes on the left and right rear-wheels.
4. Brake equalizer linkage mechanism as claimed in claim 1, wherein the first latch joint and second latch joint are unlocked respectively for separately applying brakes on the left or right rear-wheel.
5. Brake equalizer linkage mechanism as claimed in claim 1, wherein the first latch joint and second latch joint are locked for simultaneously applying brakes on the left and right rear-wheels.
6. Brake equalizer linkage mechanism as claimed in claims 1 to 3, wherein the first, second, third link, fourth and sixth links are configured similar for the left and right hand brakes.

7. Brake equalizer linkage mechanism as claimed in claims 1 to 4, wherein the first and second sliding joints are configured similar for the left and right hand brakes.
8. Brake equalizer linkage mechanism as claimed in claims 1 to 5, wherein the first hinge joints are configured similar for the left and right hand brakes.
9. Brake equalizer linkage mechanism as claimed in claims 1 to 6, wherein the first and second latch joints are configured similar for the left and right hand brakes.
10. Brake equalizer linkage mechanism as claimed in claims 1 to 7, wherein the fifth links are configured similar for the left and right hand brakes.
11. Brake equalizer linkage mechanism as claimed in claims 1 to 8, wherein the second hinge joint is configured common for the left and right hand brakes.
12. A method for transferring equal force on the left and right brakes of the rear wheels of an agricultural tractor by means of the linkage mechanism as claimed in claims 1 to 9, wherein the method comprises the step of:

(c) the first latch joint and second latch joint are locked for simultaneously applying brakes on the left and right rear-wheels; or
(d) the first latch joint and second latch joint are respectively unlocked for separately applying brake on the left or right rear-wheel.