FORM 2
THE PATENTS ACT 1970
[39 OF 1970]
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION [See section 10; rule 13]
TITLE OF THE INVENTION AXLE MOUNTING ON A VEHICLE CHASSIS
APPLICANT(S)
TATA MOTORS LIMITED
Bombay house, 24 Homi Mody Street,
Hutatma Chowk, Mumbai 400 001,
Maharashtra, India.
an Indian Company.
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
[001] The present invention relates to a vehicle, and more specifically related to mounting axles on a vehicle chassis.
BACKGROUND OF THE INVENTION
[002] A vehicle, such as a commercial vehicle (e.g., truck), may include a plurality of axles. Each axle may be supported on a chassis of the vehicle with the help of a suspension assembly. In some cases, a front side or a rear side of the vehicle may include a plurality of axles, such as a group of axles. For example, a rear side of the vehicle may include a rear forward axle and a rear rearward axle. The rear forward axle may be coupled to a forward spring assembly and the rear rearward axle may be coupled to a rearward spring assembly. In some cases, the spring assemblies of the axles on the same side, such as the rear forward axle and the rear rearward axle, may be supported on the chassis through a common part. For example, a rear end of the forward spring assembly and a fore end of the rearward spring assembly may be connected to a common mounting bracket that is mounted on the chassis, for being supported in the chassis.
SUMMARY OF THE INVENTION
[003] A vehicle includes a chassis, a forward spring assembly, and a rearward spring assembly. The forward spring assembly couples a forward axle with the chassis, and the rearward spring assembly couples a rearward axle with the chassis. A rear end of the forward spring assembly is coupled to the chassis at a first point of the chassis. The rearward spring assembly has a fore end that faces the rear end of the forward spring assembly. The fore end is coupled to the chassis at a second point of the chassis. The second point is longitudinally displaced from the first point on the chassis. A first shackle couples the rear end of the forward spring assembly with the first point and a second shackle couples a rear end of the rearward spring

assembly with the chassis. An orientation of the second shackle relative to the chassis is opposite an orientation of the first shackle relative to the chassis.
BRIEF DESCRIPTION OF DRAWINGS
[004] The features, aspects, and advantages of the subject matter will be better understood with regard to the following description, and accompanying figures. The use of the same reference number in different figures indicates similar or identical features and components.
[005] Fig. 1 illustrates a rear portion of a vehicle, according to an implementation of the present subject matter.
[006] Fig. 2 illustrates a rear portion of a vehicle, according to an implementation of the present subject matter.
[007] Fig. 3 illustrates a perspective view of a rear side of a vehicle, according to an implementation of the present subject matter.
[008] Fig. 4(a) illustrates side view of a three-axle vehicle, according to an implementation of the present subject matter.
[009] Fig. 4(b) illustrates top view of a three-axle vehicle, according to an implementation of the present subject matter.
[0010] Fig. 5(a) illustrates side view of a four-axle vehicle, according to an implementation of the present subject matter.
[0011] Fig. 5(b) illustrates top view of a four-axle vehicle, according to an implementation of the present subject matter.

[0012] Fig. 6(a) illustrates side view of a five-axle vehicle, according to an implementation of the present subject matter.
[0013] Fig. 6(b) illustrates top view of a five-axle vehicle, according to an implementation of the present subject matter.
[0014] Fig. 7(a) illustrates side view of a five-axle vehicle, according to an implementation of the present subject matter.
[0015] Fig. 7(b) illustrates top view of a five-axle vehicle, according to an implementation of the present subject matter.
DETAILED DESCRIPTION OF INVENTION
[0016] The present subject matter relates to mounting of axles on a vehicle chassis. The techniques of the present subject matter increase reliability and load-carrying capacity of a vehicle having multiple axles on the front and/or rear side.
[0017] Vehicles having multiple axles on the front side or on the rear side may have a common mounting bracket for supporting spring assemblies of the axles. The usage of the common mounting bracket aids in space optimization. Accordingly, common mounting brackets are widely used in current vehicles.
[0018] While the usage of the common mounting bracket provides multiple advantages, such an arrangement may cause various shortcomings. For example, since multiple spring assemblies are to be coupled to the common mounting bracket, the design of the common mounting bracket is adapted to allow such couplings. Such an adaptation complicates the design of the common mounting bracket. The complicated design is expensive to manufacture and may also be prone to failures. Further, in case of failure of the common mounting bracket, the working of all spring assemblies coupled to the common mounting bracket may get

impacted. Thus, the reliability of the vehicle reduces. Still further, the usage of the common mounting bracket limits the spacing between the axles, and consequently, limits the load-carrying capacity of the vehicle.
[0019] In accordance with an implementation of the present subject matter, a vehicle includes a forward spring assembly that couples a forward axle with the chassis and a rearward spring assembly that couples a rearward axle with the chassis. A rear end of the forward spring assembly is coupled to the chassis at a first point of the chassis and a fore end of the rearward spring assembly is coupled to the chassis at a second point of the chassis. The second point is longitudinally displaced from the first point on the chassis.
[0020] In an implementation, the first point of the chassis may have a first mounting bracket mounted thereon, and the rear end of the forward spring assembly may be coupled to the chassis through the first mounting bracket. Further, the second point of the chassis may have a second mounting bracket mounted thereon, and the fore end of the rearward spring assembly may be coupled to the chassis through the second mounting bracket.
[0021] The rear end of the forward spring assembly may be coupled to the first point by a first shackle. Further, a second shackle may couple a rear end of the rearward spring assembly with the chassis. An orientation of the second shackle relative to the chassis is opposite an orientation of the first shackle relative to the chassis. For example, when the vehicle is stationary, an end of the first shackle coupled to the forward spring assembly is rearward of an end of the first shackle coupled to the chassis, while an end of the second shackle coupled to the rearward spring assembly is forward of an end of the second shackle coupled to the chassis.
[0022] The longitudinal offset increases a clearance between a forward axle, mounted using the forward spring assembly, and a rearward axle, mounted using the rearward spring assembly, as compared to a case in which the rear end of the

forward spring assembly is longitudinally aligned with the fore end of the rearward spring assembly. The increased clearance increases stability of the vehicle.
[0023] Further, by offsetting the mounting point at which the rear end of the forward spring assembly is coupled to the chassis from the mounting point at which a fore end of the rearward spring assembly is coupled to the chassis, a degree of freedom for providing the two mounting points on the chassis is increased. For instance, a constraint that the two mounting points are to be vertically aligned to each other, as is present conventionally, is removed. In accordance with the present subject matter, the mounting points may be placed with more freedom to get best advantage in vehicle dynamics, such as roll, understeer, oversteer, tyre life, and the like.
[0024] The implementations herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting implementations that are illustrated in the accompanying drawings and detailed in the following description. It should be understood, however, that the following descriptions, while indicating preferred implementations and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the implementations herein without departing from the spirit thereof, and the implementations herein include all such modifications. The examples used herein are intended merely to facilitate an understanding of ways in which the implementations herein can be practiced and to further enable those skilled in the art to practice the implementations herein. Accordingly, the examples should not be construed as limiting the scope of the implementations herein.
[0025] Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the implementations herein. Also, the various implementations described herein are not necessarily mutually exclusive,

as some implementations can be combined with one or more other implementations to form new implementations.
[0026] In the below explanation, the techniques of the present subject matter are explained with reference to rear axles of a vehicle, i.e., axles in a rear half of the vehicle. However, techniques of the present subject matter can be utilized for forward axles of the vehicle as well.
[0027] Referring now to the drawings, where similar reference characters denote corresponding features consistently throughout the figures, there are shown preferred implementations. Further, for the sake of simplicity, and without limitation, the same numbers are used throughout the drawings to reference like features and components. The implementations herein will be better understood from the following description with reference to the drawings.
[0028] Fig. 1 illustrates a rear portion of a vehicle 100, according to an implementation of the present subject matter. The rear portion 100 refers to a rear portion in a longitudinal direction, i.e., in a travelling direction, of the vehicle 100. The vehicle 100 may be, for example, a Heavy commercial vehicle (HCV), such as a truck. The vehicle 100 may have multiple axles on the rear side. The axles on the rear side may be referred to as rear axles, and may be mounted on a chassis 102 of the vehicle. The rear axles include a forward rear axle 104, which supports a forward rear tyre 106, and a rearward rear axle 108, which supports a rearward rear tyre 110. The rearward rear axle 108 may be rearward of the forward rear axle 104 in the longitudinal direction of the vehicle 100. The forward rear axle 104 and the rearward rear axle 108 will be hereinafter referred to as forward axle 104 and rearward axle 108 respectively for the sake of simplicity.
[0029] The vehicle 100 may include a forward spring assembly 112 coupling the forward axle 104 with the chassis 102 and a rearward spring assembly 114 coupling

the rearward axle 108 with the chassis 102. In an example, each spring assembly may include a leaf spring, each of which may include a plurality of leaves.
[0030] A fore end 116 of the rearward spring assembly 114 may face a rear end 118 of the forward spring assembly 112. The rear end 118 may be coupled to a first point 120 on the chassis 102. Further, the fore end 116 may be coupled to a second point 122 on the chassis 102. The coupling of the ends of the spring assemblies with the chassis 102 may be achieved using mounting brackets. For instance, the rear end 118 may be coupled to the first point 120 using a first mounting bracket 124. Further, the fore end 116 may be coupled to the second point 122 using a second mounting bracket 126.
[0031] In an implementation, the coupling of the rear end 118 to the first point 120 may be achieved with the help of a first shackle 128. For instance, an end of the first shackle 128 may be coupled to the rear end 118, for example, by bolting. Another end of the first shackle 128 may be coupled to a first bellcrank lever 130. The first bellcrank lever 130 may also be coupled to the first mounting bracket 124. For example, the first bellcrank lever 130 may be pivotably coupled to the first mounting bracket 124, and may rotate about the first mounting bracket 124. Thus, the rear end 118 may be coupled to the second point 122 of the chassis 102 through the first shackle 128, the bellcrank lever 130, and the first mounting bracket 124.
[0032] By virtue of the connection between the rear end 118, the first shackle 128, the first bellcrank lever 130, and the first mounting bracket 124, the rear end 118 may undergo reciprocating motion when the forward rear tyre 106 travels on a bump. The reciprocating motion of the rear end 118 causes rotation of the first bellcrank lever 130 about the first mounting bracket 124.
[0033] As can be seen, the first point 120 and the second point 122 are displaced from each other in a longitudinal direction of the vehicle 100. For example, a clearance ‘C’ exists between the first point 120 and the second point 122. In an

example, the value of the clearance ‘C’ may be 370 mm. Accordingly, the rear end 118 and the fore end 116 are not aligned with each other in the longitudinal direction. The offset between the rear end 118 and the fore end 116 increases a displacement between the forward axle 104 and the rearward axle 108. In an example, the forward axle 104 may be displaced from the rearward axle 108 at least by 1800 mm. The increased displacement between the two axles increases stability of the vehicle 100.
[0034] By offsetting the mounting point at which the rear end 118 is coupled to the chassis 102 from the mounting point at which a fore end 116 is coupled to the chassis 102, a degree of freedom for providing the two mounting points on the chassis 102 is increased. For instance, a constraint that the two mounting points are to be vertically aligned to each other, as is present conventionally, is removed. In accordance with the present subject matter, the mounting points may be placed with more freedom to get best advantage in vehicle dynamics, such as roll, understeer, oversteer, tyre life, and the like. Although not shown, in an example, the first point 120 may be offset from the second point 122 on the chassis 102 in a vertical direction of the vehicle 100.
[0035] As can be seen, the rear end 118 is mounted on the chassis 102 using a mounting bracket different than the mounting bracket using which the fore end 116 is mounted on the chassis 102. The usage of the different mounting brackets ensures that mounting brackets of simpler construction can be used for the mounting, as compared to a case in which a common mounting bracket is used for mounting both the rear end 118 and the fore end 116. Since one mounting bracket is to couple a single spring assembly to the chassis 102, the mounting bracket may be provided with a mounting provision corresponding to a single suspension assembly. That is, the mounting bracket need not be provided with a plurality of mounting provisions. Therefore, the design of the mounting bracket used may be simplified. The simpler design may be easy to manufacture and may be less prone to failures. Further, since a mounting bracket is coupled to a single spring assembly, the failure of the

mounting bracket may impact only the corresponding spring assembly, while the other spring assembly may remain unaffected by the failure. Still further, the load on the vehicle is distributed between the multiple mounting brackets. Therefore, reliability of the vehicle may improve. Further, a sum of the loading limits of the individual mounting brackets may be more than the loading limit of a common mounting bracket. Thus, the loading limit of the vehicle is increased.
[0036] In an implementation, the first bellcrank lever 130 may be coupled to a second bellcrank lever 132 that is rearward of the first bellcrank lever 130 in the vehicle longitudinal direction. The coupling between the first bellcrank lever 130 and the second bellcrank lever 132 may be through a link rod 134. The second bellcrank lever 132 may be pivotably coupled to a third mounting bracket 136 mounted on the chassis 102, and may rotate about the third mounting bracket 136.
[0037] In an implementation, the link rod 134 may be disposed above the first bellcrank lever 130 and the second bellcrank lever 132. Further, a length of the link rod 134 is greater than a distance between the first mounting bracket 124 and the third mounting bracket 136.
[0038] A rear end 140 of the rearward spring assembly 114 may be coupled to the second bellcrank lever 132 through a second shackle 138. By virtue of such a connection, the rear end 140 may reciprocate when the rearward rear tyre 110 travels on a bump. The reciprocation causes the second bellcrank lever 132 to rotate about the third mounting bracket 136. Further, the connection between the first bellcrank lever 130 and the second bellcrank lever 132 causes the rearward spring assembly 114 to move when the forward rear tyre 106 travels on a bump and also causes the forward spring assembly 112 to move when the rearward rear tyre 110 travels on a bump. In other words, the forward axle 104 and the rearward axle 108 are tandem axles of the rear suspension assembly. The tandem connection of the axles enables a uniform load distribution between the forward and the rearward axles.

[0039] Fig. 2 illustrates a rear portion of the vehicle 100, according to an implementation of the present subject matter. Here, the axles and the tyres are not shown for the sake of clarity. The forward axle 104 may be supported on the chassis 102 with the help of a forward U-bolt 202. Similarly, a rearward axle 108 may be supported on the chassis 102 with the help of a rearward U-bolt 204. The rearward rear axle may be rearward of the forward rear axle in the vehicle driving direction.
[0040] As can be seen, an orientation of the second shackle 138 relative to the chassis 102 is opposite an orientation of the first shackle 128 relative to the chassis 102. For example, when the vehicle 100 is stationary, an end 206 of the first shackle 128 coupled to the forward spring assembly 112 is rearward of an end 208 of the first shackle 128 coupled to the chassis 102 (through the first bellcrank lever 130 and the first mounting bracket 124). In contrast, an end 210 of the second shackle 138 coupled to the rearward spring assembly 114 is forward of an end 212 of the second shackle 138 coupled to the chassis 102. Put another way, when the vehicle 100 is stationary, the first shackle 128 makes an acute angle with the forward spring assembly 112 and the second shackle 138 makes an obtuse angle with the rearward spring assembly 114. The orientation of the first shackle 128 is such that the first shackle 128 resists deflection of the forward spring assembly 112. In contrast, the orientation of the second shackle 138 is such that it aids the deflection of the rearward spring assembly 114. Accordingly, the opposite orientations of the shackles cause the forward spring assembly 112 to have a higher stiffness as compared to the rearward spring assembly 114. Therefore, a higher portion of the load is transferred to the forward axle 104, which is beneficial for traction and drivability of the vehicle 100.
[0041] Although the longitudinal offset is explained as being achieved by providing separate mounting brackets, in an implementation, the longitudinal offset may be achieved in a common mounting bracket as well. For example, a common mounting bracket may be provided with different mounting provisions for mounting the rear end of the forward spring assembly 112 and a fore end of the rearward spring

assembly 114, with the different mounting provisions being longitudinally offset from each other.
[0042] Fig. 3 illustrates a perspective view of the rear side of the vehicle 100, according to an implementation of the present subject matter. The vehicle 100 includes the forward axle 104 and the rearward rear axle 108 supported on the chassis 102. As illustrated, the rear end 118 of the forward spring assembly 112 is coupled to the first mounting bracket 124 and the fore end 116 of the rearward spring assembly 114 is coupled to the second mounting bracket 126, thereby avoiding the need to provide a common mounting bracket to couple the two ends.
[0043] The present subject matter can be utilized in commercial vehicles, such as heavy commercial vehicles (HCVs). For example, the present subject matter can be utilized in 6x2, 6x4, 8x2, 8x4, 10x2, and 10x4 trucks and tippers, as will be illustrated below.
[0044] Fig. 4(a) illustrates side view of a three-axle vehicle 400, according to an implementation of the present subject matter. The three-axle vehicle 400 may be a 6x2 vehicle or a 6x4 vehicle. The vehicle includes one front axle F1 and two rear axles R1 and R2. The two rear axles may be tandem axles, each having a spring assembly. A rear end of the spring assembly of the first rear axle R1 may be longitudinally offset from the fore end of the spring assembly of the second rear axle R2, in a manner similar to that explained with reference to Figs. 1-3. Accordingly, the first rear axle R1 and the second rear axle R2 may be displaced from each other by 1800 mm, or more.
[0045] Fig. 4(b) illustrates top view of the three-axle vehicle 400, according to an implementation of the present subject matter. As illustrated, the rear axles R1 and R2 may each have dual tyres at each of its ends. Further, the front axle F1 may have a single tyre at each end.

[0046] Fig. 5(a) illustrates side view of a four-axle vehicle 500, according to an implementation of the present subject matter. The four-axle vehicle 500 may be an 8x2 vehicle or an 8x4 vehicle. The vehicle 500 includes one front axle F1, one lift axle LA, and two rear axles R1 and R2. The two rear axles may be tandem axles, each having a spring assembly. A rear end of the spring assembly of the first rear axle R1 may be longitudinally offset from the fore end of the spring assembly of the second rear axle R2, in a manner similar to that explained with reference to Figs. 1-3. Accordingly, the first rear axle R1 and the second rear axle R2 may be displaced from each other by 1800 mm, or more.
[0047] Fig. 5(b) illustrates top view of the four-axle vehicle 500, according to an implementation of the present subject matter. As illustrated, the rear axles R1 and R2 may each have dual tires at each of its ends. Further, the front axle F1 and the lift axle LA may each have a single tyre at each end.
[0048] Fig. 6(a) illustrates side view of a five-axle vehicle 600, according to an implementation of the present subject matter. The five-axle vehicle 600 may be a 10x2 vehicle or a 10x4 vehicle. The vehicle 600 includes two front axles F1 and F2, one lift axle LA, and two rear axles R1 and R2. The two rear axles R1 and R2 may be tandem axles, each having a spring assembly. A rear end of the spring assembly of the first rear axle R1 may be longitudinally offset from the fore end of the spring assembly of the second rear axle R2, in a manner similar to that explained with reference to Figs. 1-3. Accordingly, the first rear axle R1 and the second rear axle R2 may be displaced from each other by 1800 mm, or more.
[0049] Fig. 6(b) illustrates top view of the five-axle vehicle 600, according to an implementation of the present subject matter. As illustrated, the rear axles R1 and R2 may each have dual tires at each of its ends. Further, the front axles F1 and F2 and the lift axle LA may each have a single tyre at each end.

[0050] Fig. 7(a) illustrates side view of a five-axle vehicle 700, according to an implementation of the present subject matter. The five-axle vehicle 700 may differ from the five-axle vehicle 600 by the number of tyres on the lift axle LA – while the lift axle LA of the five-axle vehicle 600 has one tyre at each end, the lift axle LA of the five-axle vehicle 700 has two tyres at each end. The five-axle vehicle 700 may be a 10x2 vehicle or a 10x4 vehicle. The vehicle 700 includes two front axles F1 and F2, one lift axle LA, and two rear axles R1 and R2. The two rear axles R1 and R2 may be tandem axles, each having a spring assembly. A rear end of the spring assembly of the first rear axle R1 may be longitudinally offset from the fore end of the spring assembly of the second rear axle R2, in a manner similar to that explained with reference to Figs. 1-3. Accordingly, the first rear axle R1 and the second rear axle R2 may be displaced from each other by 1800 mm, or more.
[0051] Fig. 7(b) illustrates top view of the five-axle vehicle 700, according to an implementation of the present subject matter. As illustrated, the rear axles R1 and R2 and the lift axle LA may each have dual tires at each of its ends. Further, the front axles F1 and F2 may each have a single tyre at each end.
[0052] The present subject matter can be utilized to increase the load-bearing capacity (e.g., higher GVW, i.e., gross vehicle weight) and stability of the trucks. Accordingly, total cost of ownership (TCO) for an owner of the vehicle can be reduced.
[0053] The foregoing description of the specific implementations will so fully reveal the general nature of the implementations herein that others can, by applying current knowledge, readily modify and/or adapt for various applications without departing from the generic concept, and, therefore, such modifications and adaptations should and are intended to be comprehended within the meaning and range of equivalents of the disclosed implementations. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the implementations herein have been

described in terms of preferred implementations, those skilled in the art will recognize that the implementations herein can be practiced with modification within the spirit and scope of the implementations as described herein.

We Claim:
1. A vehicle comprising:
a chassis;
a forward spring assembly coupling a forward axle with the chassis, wherein a rear end of the forward spring assembly is coupled to the chassis at a first point of the chassis;
a first shackle coupling the rear end of the forward spring assembly with the first point;
a rearward spring assembly coupling a rearward axle with the chassis, the rearward spring assembly having a fore end that faces the rear end of the forward spring assembly, wherein the fore end is coupled to the chassis at a second point of the chassis, and wherein the second point is longitudinally displaced from the first point on the chassis; and
a second shackle coupling a rear end of the rearward spring assembly with the chassis, wherein an orientation of the second shackle relative to the chassis is opposite an orientation of the first shackle relative to the chassis.
2. The vehicle as claimed in claim 1, wherein the forward axle is displaced from the rearward axle by at least 1800 mm.
3. The vehicle as claimed in claim 1, comprising:
a first mounting bracket mounted on the chassis at the first point, wherein the rear end of the forward spring assembly is coupled to the chassis through the first mounting bracket; and
a second mounting bracket mounted on the chassis at the second point, wherein the fore end of the rearward spring assembly is coupled to the chassis through the second mounting bracket.

4. The vehicle as claimed in claim 1, wherein the first point and the second point are displaced from each other by at least 370 mm.
5. The vehicle as claimed in claim 1, wherein the first point is vertically offset from the second point on the chassis.
6. The vehicle as claimed in claim 3, comprising:
a first bellcrank lever coupling the first shackle with the first mounting
bracket;
a third mounting bracket mounted on the chassis; and
a second bellcrank lever coupling the second shackle with the third
mounting bracket.
7. The vehicle as claimed in claim 6, comprising a link rod coupling the first bellcrank lever and the second bellcrank lever.
8. The vehicle as claimed in claim 7, wherein the link rod is disposed above the first bellcrank lever and the second bellcrank lever.
9. The vehicle as claimed in claim 5, wherein a length of the link rod is greater than a distance between the first mounting bracket and the second mounting bracket.
10. The vehicle as claimed in claim 1, wherein each of the forward spring assembly and the rearward spring assembly comprises a leaf spring.
11. The vehicle as claimed in claim 1, wherein when the vehicle is stationary, an end of the first shackle coupled to the forward spring assembly is rearward of an end of the first shackle coupled to the chassis and wherein an end of the second shackle coupled to the rearward spring assembly is forward of an end of the second shackle coupled to the chassis.

12. The vehicle as claimed in claim 1, wherein when the vehicle is stationary, the first shackle makes an acute angle with the forward spring assembly and the second shackle makes an obtuse angle with the rearward spring assembly.
13. The vehicle as claimed in claim 1, wherein the forward axle and rearward axle are tandem axles of rear suspension assembly.
14. The vehicle as claimed in claim 1, wherein the vehicle is one of: a 6x2 vehicle, a 6x4 vehicle, an 8x2 vehicle, an 8x4 vehicle, a 10x2 vehicle, and a 10x4 vehicle.