A suspension system for a commercial vehicle

Abstract

The suspension system for a commercial vehicle (300) in accordance with the disclosed invention comprises of, a front leaf spring suspension (100), and a rear leaf spring suspension (200). The auxiliary foam springs (20F and 20R) have been provided in the front and rear leaf spring suspension (100, 200) respectively. The suspension system for a commercial vehicle (300), so disclosed, improves ride comfort, increases the fatigue life of the leaf spring, has lower total component cost and is lighter in weight, it has better NVH behaviour and lower leaf spring peak loads.

Description

TITLE OF THE INVENTION“A SUSPENSION SYSTEM FORA COMMERCIAL VEHICLE”Field of Invention

[0001] The invention relates to suspension systems provided on commercial vehicles. It more particularly relates to suspension systems utilising leaf springs.Background of the Invention

[0002] Suspension is an essential component within the commercial vehicle industry. The most common and reliable type of suspension used in today's commercial vehicle industry is leaf spring suspension. In the Indian market, where customer abuse and overloading are day-to-day practices, these mechanical suspensions provide best- in-class robustness. However, ride and comfort have taken a steep interest in today’s market, specifically in the BUS segment.

[0003] When air suspension first appeared, it brought about another revolution because it offered the best ride comfort available. The basic idea behind how air suspension responds is that it dynamically adjusts pneumatic pressure to maintain a steady ride frequency by varying its internal stiffness. However, because mechanical springs work on the principle of constant stiffness, this is not possible.

[0004] In this work, a hybrid system with a mechanical leaf spring and an auxiliary spring with variable stiffness is proposed. This system offers a similar level of ride comfort as an air suspension. Progressive spring stiffness varies dynamically in response to varying input load conditions, as the system is meant to maintain a steady ride frequency throughout the load range. The touch load of an auxiliary spring is optimised to eliminate any jerk during an engagement. An improvement of 12-15% has been observed in vehicle roll and pitch (at higher speeds) since the auxiliary spring is engaged way before the laden load. This Innovation offers a reliable, cost-efficient solution with comfort parallel to an air suspension.

[0005] The constancy of frequency results in favourable ride comfort. The bump stopper exhibits a high degree of volume compressibility while minimising lateral expansion. Additionally, it effectively isolates noise at small amplitudes and high frequencies. This technology enhances the fatigue life of the leaf spring by 23% and offers amplitude-dependent damping. The objective of the present invention is to provide a suspension system for commercial vehicles that can provide variable stiffness.

[0006] It is another objective of the present invention to provide a suspension system for commercial vehicles that can provide improved rider comfort.

[0007] It is still another objective of the present invention to provide a suspension system for commercial vehicles with improved roll and pitch characteristics.Summary of the Invention

[0008] The invention achieving the stated objectives, i.e. the suspension system for a commercial vehicle comprises of a front leaf spring suspension, and a rear leaf spring suspension. The front leaf spring suspensions are mounted on either sides of the vehicle along the front of the vehicle chassis and, at their one end through their front suspension front hanger backet that is fixed on the vehicle’s chassis and at their other end through their front suspension rear backet that are fixed at position behind the mounting position of the front suspension front hanger backet on the vehicle’s chassis. A spacer and a front spacer bracket and mounting cup assembly of the front leaf spring suspension that is provided with a front mounting cup are together fixed in their position on the vehicle chassis using conventional fastening means. The spacer and the front spacer bracket and mounting cup assembly are so positioned on the vehicle chassis that the centre of an auxiliary foam spring front held within said front mounting cup is aligned with the centre of a front U bolt clamp of the front leaf spring suspension.

[0009] The rear leaf spring suspensions are mounted on either sides of the vehicle along the rear of the vehicle chassis and, at their one end through their rear suspension front hanger bracket that are fixed on the vehicle’s chassis, and at their other end through their rear hanger bracket that are fixed at position behind the mounting position of the rear suspension front hanger backet on the vehicle’s chassis. A rear auxiliary foam spring is held within a rear auxiliary foam spring bracket assembly of the rear leaf spring suspension. The rear auxiliary foam spring bracket assembly is itself attached to a rear frame support bracket through conventional fastening means. The rear frame support bracket is in turn fixed on the vehicle’s chassis in a position such that the centre of the rear auxiliary foam spring is aligned with the centre of a rear U bolt clamp of the rear leaf spring suspension, and an external rubber bump stopper that is also attached on lower surface of the rear auxiliary foam spring bracket assembly is aligned with the top surface of the rear U bolt clamp of the rear leaf spring suspension.Brief Description of Drawings

[0010] The present invention is illustrated in the accompanying drawings. The description of the present invention would, therefore, be better understood with reference to accompanying diagrams, wherein

[0011] Figure 1 discloses a suspension system for a commercial vehicle as fitted on the vehicle chassis.

[0012] Figure 2 discloses the exploded view of the front leaf spring suspension as fitted on the vehicle chassis in accordance with the present invention, as disclosed in Figure 1.

[0013] Figure 3 discloses the exploded view of the rear leaf spring suspension in accordance with the present invention, as disclosed in Figure 1.

[0014] Figure 4 discloses the isometric view of the unladen condition of the front leaf spring suspension, as disclosed in Figure 2.

[0015] Figure 5 discloses the isometric view of the laden condition of the front leaf spring suspension, as disclosed in Figure 2.

[0016] Figure 6 discloses the spacer bracket and mounting cup assembly as provided in the front leaf spring suspension disclosed in Figure 2.

[0017] Figure 7 discloses the rear auxiliary foam spring as provided in the rear leaf spring suspension disclosed in Figure 3.

[0018] Figure 8 discloses the rear auxiliary foam spring bracket assembly as provided in the rear leaf spring suspension disclosed in Figure 3.Brief Description of the Invention

[0019] Referring to the set of figures 1 and 2, a suspension system for a commercial vehicle (300), in accordance with the disclosed invention, comprises of, front leaf spring suspension (100), and rear leaf spring suspension (200).

[0020] The front leaf spring suspensions (100) (refer to Fig. 2) provided in the suspension system for a commercial vehicle (300) includes, the front suspension front hanger backet (10F), auxiliary foam spring front (20F), front spacer bracket and mounting cup assembly (23F), front mounting cup (25F), front U bolt clamp (28F), leaf spring assembly front (40F), front leaf spring clamp (45F), front U-bolt (50F), front shock absorber bottom mounting bracket (55F), front suspension rear backet (60F), front shackle plate (62F), front suspension pin (64F), and front suspension rear hanger bracket (66F).

[0021] The front leaf spring suspensions (100) (refer to Figs. 1 and 2) are mounted on either sides of the vehicle along the front of the vehicle chassis and, at their one endthrough their front suspension front hanger backet (10F) that is fixed on the vehicle’s chassis and at their other end through their front suspension rear backet (60F) that are fixed at position behind the mounting position of the front suspension front hanger backet (10F) on the vehicle’s chassis. A spacer (21F) and a front spacer bracket and mounting cup assembly (23F) of the front leaf spring suspension (100) that is provided with a front mounting cup (25F) are together fixed in their position on the vehicle chassis using conventional fastening means. The spacer (21F) and the front spacer bracket and mounting cup assembly (23F) are so positioned on the vehicle chassis that the centre of an auxiliary foam spring front (20F) held within said front mounting cup (25F) is aligned with the centre of a front U bolt clamp (28F) of the front leaf spring suspension (100).

[0022] The front U bolt clamp (28F) (refer to Fig. 2) is supported on top of the leaf spring assembly front (40F) which itself rests along its lower surface on the front shock absorber bottom mounting bracket (55F) and said front U bolt clamp (28F) and the leaf spring assembly front (40F) being attached to the vehicle’s axle by means of front U-bolts (50F) and conventional nuts. One end of the leaf spring assembly front (40F) is linked within the mounting point of the front suspension front hanger backet (10F) through a mounting bush, the other end of the leaf spring assembly front (40F) is linked with the front suspension rear backet (60F) through the front suspension rear hanger bracket (66F), the front shackle plate (62F), and the front suspension pin (64F), with the mounting bush being provided at the interface between the other end of the leaf spring assembly front (40F) and the front suspension rear hanger bracket (66F) and the front suspension pin (64F) being provided at the interface between the front shackle plate (62F) and the front suspension rear backet (60F).

[0023] The leaf springs together forming the leaf spring assembly front (40F) (refer to Fig. 2) are held together by a set of front leaf spring clamps (45F) that are provided at equal distance from the longitudinal centre, and on both halves of said leaf spring assembly front (40F). The front U-bolts (50F) fixed on the front shock absorber bottom mounting bracket (55F) through conventional nuts hold the front U bolt clamp (28F)at a position on the top surface and along the longitudinal centre of the leaf spring assembly front (40F). The front shock absorber bottom mounting bracket (55F) is itself fixed on the vehicle’s axle through conventional fastening means.

[0024] The front spacer bracket and mounting cup assembly (23F) (refer to Figs. 2 and 6) has a thick base that has an elongated shape made by combining two halves of a circle to two of the shorter sides of a rectangle. The front mounting cup (25F) is positioned at the centre of the base of the front spacer bracket and mounting cup assembly (23F) and joined with said base by conventional joining methods including welding. A circular opening is provided at the centre of the base within the front mounting cup (25F), this circular opening aligns with the central cylindrical shaped hole of the auxiliary foam spring front (20F). The front mounting cup (25F) has a circular cross section which at first decreases in area until the midpoint of the height is reached and then increases in area until the topmost edge of the front mounting cup (25F) is reached. The auxiliary foam spring front (20F) has the shape of a frustum that has been provided with multiple uniformly shaped depressions that form rings of reduced cross-sectional area along the height of said auxiliary foam spring front (20F). The auxiliary foam spring front (20F) held within the front mounting cup (25F) has an interference fit with said front mounting cup (25F).

[0025] The rear leaf spring suspension (200) (refer to Fig. 3) provided in the suspension system for a commercial vehicle (300) includes, the rear suspension front hanger bracket (10R), rear auxiliary foam spring (20R), rear frame support bracket (23R), rear auxiliary foam spring bracket assembly (25R), rear U bolt clamp (28R), rear leaf spring assembly (40R), rear leaf spring clamp (45R), rear U-bolt (50R), external rubber bump stopper (57R), rear hanger bracket (60R), rear mounting plate (62R), rear suspension mounting bush (64R), and rear suspension mounting bush (66R).

[0026] The rear leaf spring suspensions (200) (refer to Figs 1 and 3) are mounted on either sides of the vehicle along the rear of the vehicle chassis and, at their one endthrough their rear suspension front hanger bracket (10R) that are fixed on the vehicle’s chassis, and at their other end through their rear hanger bracket (60R) that are fixed at position behind the mounting position of the rear suspension front hanger backet (10R) on the vehicle’s chassis. A rear auxiliary foam spring (20R) is held within a rear auxiliary foam spring bracket assembly (25R) of the rear leaf spring suspension (200). The rear auxiliary foam spring bracket assembly (25R) is itself attached to a rear frame support bracket (23R) through conventional fastening means. The rear frame support bracket (23R) is in turn fixed on the vehicle’s chassis in a position such that the centre of the rear auxiliary foam spring (20R) is aligned with the centre of a rear U bolt clamp (28R) of the rear leaf spring suspension (200). An external rubber bump stopper (57R) that is also attached on lower surface of the rear auxiliary foam spring bracket assembly (25R) is aligned with the top surface of the rear U bolt clamp (28R) of the rear leaf spring suspension (200).

[0027] One end of the rear leaf spring assembly (40R) (refer to Fig. 3) is linked within the mounting point of the rear suspension front hanger backet (10R) through a mounting bush, the other end of the rear leaf spring assembly (40R) is linked with the rear hanger backet (60R) through the rear suspension mounting bush (66R), the front shackle plate (62F), and rear suspension mounting bush (64R), with the rear suspension mounting bush (66R) being provided at the interface between the other end of the rear leaf spring assembly (40R) and the rear mounting plate (62R) and the rear suspension mounting bush (64R) being provided at the interface between the rear mounting plate (62R) and the rear hanger backet (60R). The leaf springs together forming the rear leaf spring assembly (40R) are held together by a set of rear leaf spring clamp (45R) that are provided at equal distance from the longitudinal centre, and on both halves of said rear leaf spring assembly (40R). The rear U bolt clamp (28R) supported on top the rear leaf spring assembly (40R) along the longitudinal centre of said rear leaf spring assembly (40R), are together attached and held in their position on the vehicle’s rear axle by means of rear U-bolts (50R) and conventional fastening means.

[0028] The rear frame support bracket (23R) (refer to Fig. 3) is provided between the rear auxiliary foam spring bracket assembly (25R) and the vehicle chassis and fixed in their position on the vehicle chassis using conventional fastening means, the rear auxiliary foam spring bracket assembly (25R) is so positioned on the vehicle chassis that the centre of the rear auxiliary foam spring (20R) held within said rear auxiliary foam spring bracket assembly (25R) is aligned with the centre of the front U bolt clamp (28R).

[0029] The rear auxiliary foam spring bracket assembly (25R) (refer to Figs. 3, and 8) has a thick quadrilateral shaped base whose two adjacent comers have been given a curved profile. The rear auxiliary foam spring bracket assembly (25R) is provided with multiple openings in its base to allow it to be attached to lower surface of the rear frame support bracket (23R) using conventional fastening means. A cup (25RC) having a cylindrical external shape is joined to the base of the rear auxiliary foam spring bracket assembly (25R) by conventional joining means. This cup (25RC) has a central axis that passes through an off-centre location on the quadrilateral shaped base of said rear auxiliary foam spring bracket assembly (25R).

[0030] The rear auxiliary foam spring (20R) (refer to Fig. 7) has the shape of a frustum that has been provided with multiple uniformly shaped depressions that form rings of reduced cross-sectional area along the height of said auxiliary foam spring front (20R). The rear auxiliary foam spring (20R) is also provided with a metallic ring (20RR) that is accommodated in one of its the uniformly shaped depressions. A circular opening is provided in the base of the rear auxiliary foam spring bracket assembly (25R), this circular opening aligns with the central cylindrical shaped hole of the rear auxiliary foam spring (20R). The rear auxiliary foam spring (20R) has an interference fit with the cup of said rear auxiliary foam spring bracket assembly (25R) (refer to Fig. 8).

[0031] The construction and positioning of the front leaf spring suspension (100) and rear leaf spring suspension (200) on one side of the vehicle chassis is mirrored bythe front leaf spring suspension (100) and rear leaf spring suspension (200) respectively provided on other sides of the vehicle chassis. It must also be noted that the term conventional fastener used across this document represents all known fastening means that have characteristics similar to known nuts and bolts that can be used to hold features together.

[0032] In the unladen condition of the front leaf spring suspension (100) (refer to Fig. 4), there is a separation between the lower end of the auxiliary foam spring front (20F) and the top surface of the front U bolt clamp (28F). In this condition, therefore the vehicle’s load is being transmitted from the vehicle’s chassis to the front suspension hangar bracket (10F), and the front suspension rear bracket (60F) and their intervening joining components, to the leaf spring assembly front (40F) (that is constituted by multiple leaf springs held together by front leaf spring clamp (45F)) and then through said leaf spring assembly front (40F) to the front shock absorber bottom mounting bracket (55F) to the vehicle’s axle from where through the joining components it is transmitted to the wheels and then to the ground. In this condition, it only the leaf spring assembly front (40F) that absorb the load and give a matching suspension performance.

[0033] The laden condition of the front leaf spring suspension (100) (refer to Fig. 5) is achieved when either the vehicle is carrying a greater load or when, while moving it has passed over a road surface irregularity. In this condition, two load transmission paths exist. The first path is the same as that which has been described for the unladen condition. The second load transmission path goes from the vehicle’s chassis to the front spacer bracket and mounting cup assembly (23F), then the front cup (25F), then the auxiliary foam spring front (20F), then the front U bolt clamp (28F), then to the centre of the leaf spring assembly front (40F), and then through the front shock absorber bottom mounting bracket (55F) to the vehicle’s axle and then through their joining components to the wheels to the ground. In this condition, both the auxiliary foam spring front (20F) and the leaf spring assembly front (40F) get compressed tovarying degree and function to absorb the applied load and release it in accordance with their characteristics thereby giving a smoother suspension performance.

[0034] As the vehicle is moving, the vehicle can go back and forth between the laden to unladen condition (refer to Figs. 4 and 5) depending upon the loading and hence the deflection experienced by the leaf spring assembly front (40F). The components present between the leaf spring assembly front (40F) and the front suspension hangar bracket (10F), and the front suspension rear bracket (60F) allow limited relative motion to accommodate bending of said leaf spring assembly front (40F) as the vehicle moves between laden and unladen condition.

[0035] In case of the rear leaf spring suspension (200) provided in the suspension system for a commercial vehicle (300), in the unladen condition (similar to condition expressed through Figure 4 for the front leaf spring suspension (200)), the load is there is a separation between the lower end of the rear auxiliary foam spring (20R) and the external rubber bump stopper (57R), and the top surface of the rear U bolt clamp (28R). In this condition, therefore the vehicle’s load is being transmitted from the vehicle’s chassis to the rear suspension front hanger bracket (10R) and the rear hanger bracket (60R), and then to through their intermediate joining components to the rear leaf spring assembly (40R)(with the assembly being constituted by bringing together different leaf springs using the rear leaf spring clamp (45R)) and then through the rear leaf spring assembly (40R) to the vehicle’s axle and then to through the joining components to the wheels and then to the ground. In this condition, therefore the applied loads are absorbed by deflection of the rear leaf spring assembly (40R) alone. The suspension’s load absorption performance is therefore determined by the performance of the rear leaf spring assembly (40R) alone.

[0036] The laden condition of the rear leaf spring suspension (200) (similar to condition expressed through Figure 5 for the front leaf spring suspension (200)) is achieved when either the vehicle is carrying a greater load or when, while moving it has passed over a road surface irregularity. In this condition, ordinarily only two loadtransmission paths exist. The first path is the same as that which has been described for the unladen condition. In the second path for transmission of load, the vehicle chassis transfers some load to the rear frame support bracket (23R), from where it is transmitted to the rear auxiliary foam spring bracket assembly (25R), then through it to the rear auxiliary foam spring (20R), then through it to the rear U bolt clamp (28R), then through it to the centre of the rear leaf spring assembly (40R) and , and then to the vehicle’s axle and then through their joining components to the wheels and then to the ground. In this condition, therefore, the both the rear leaf spring assembly (40R) and the rear auxiliary foam spring (20R) get compressed to varying degree and function to absorb the applied load and release it in accordance with their characteristics thereby giving a smoother suspension performance.

[0037] In case of the rear leaf spring suspension (200) a third condition exists, which corresponds to the condition where extraordinary load is applied on the rear leaf spring suspension (200). In this condition, there are three load transmission paths, the first two paths correspond to the load transmission paths mentioned for the laden condition of the rear leaf spring suspension (200), as described above. But as an extraordinary load is applied (when vehicle is loaded beyond a capacity or when it has moved over a large road surface irregularity) both the rear leaf spring assembly (40R) and the rear auxiliary foam spring (20R) are compressed to their full possible extent. The lower surface of the external rubber bump stopper (57R) then comes into contact with the upper surface of the rear U bolt clamp (28R) and transmits the balance load directly to the centre of the rear leaf spring assembly (40R) and then through it to the vehicle’s axle and then through the joining components to the rear wheels. The rubber bump stopper (57R) is very hard in comparison to the rear leaf spring assembly (40R) and the rear auxiliary foam spring (20R) and does not compress a lot. This rubber bump stopper (57R) therefore functions to prevent overloading and hence breaking of the rear leaf spring assembly (40R) and the rear auxiliary foam spring (20R).

[0038] As the vehicle is moving, the vehicle can go back and forth between the laden to unladen condition and also the extra ordinarily loading condition dependingupon the loading and hence the deflection experienced by the rear leaf spring assembly (40R), and the rear auxiliary foam spring (20R). Given that a metallic ring has been provided on the rear auxiliary foam spring (20R), the integrity of said rear auxiliary foam spring (20R) is maintained in extraordinary loading condition, thereby enhancing its overall life. The components present between the rear leaf spring assembly (40R) and the rear suspension front hanger bracket (10R) and the rear hanger bracket (60R) allow limited relative motion to accommodate bending of said rear leaf spring assembly (40R) as the vehicle moves between laden, unladen condition and extreme loading condition.

[0039] The suspension system for a commercial vehicle (300) so described allows the vehicle designers to reduce the leaves provided in the front and rear leaf spring suspension (100, and 200) as the foam springs (20F and 20R) are also functioning to safely transmit load along the defined path to the wheels. Given that the described construction allows use of distinct combinations of springs, the suspension performance and hence the rider comfort is greatly improved.

[0040] The suspension system for a commercial vehicle (300) overcomes the deficiency of the conventional leaf spring suspension system that usually compromise on customer comfort in unladen and heavily laden conditions. In technical terms, the same can be noted as an observable improvement in ride frequency when the suspension system for a commercial vehicle (300) is utilised in commercial vehicles. As already stated, the suspension system for a commercial vehicle (300) is provided with fewer leaves in its leaf spring in the front and rear leaf spring suspension (100, and 200). The suspension system (300) with fewer leaf springs, which is hence softer, should ordinarily tend to deflect more, which in turn should cause the vehicle to tilt, experience more jerks on the vehicles chassis / frame, ands experience more instability.

[0041] The foam springs (20F and 20R), respectively provided in the front and rear leaf spring suspension (100, and 200) of the suspension system for commercial vehicle (300), counteracts all the stated negative effects thereby allowing the customer toexperience only the benefits of a softer suspension system. The foam springs (20F and 20R) share the load with the respective leaf springs provided in the front and rear leaf spring suspension (100, and 200) and enable suspension performance that is better than any conventional mechanical leaf spring suspension, while also reducing the suspension weight and its cost. The disclosed invention can be stated to be providing the best-in-class comfort in unladen condition of the commercial vehicles, a stable ride regardless of the vehicle load, and a lighter suspension system with about 23% reduction in its cost.

[0042] The suspension system for a commercial vehicle (300) so disclosed achieves all the stated objectives. Technical advantages offered by the invention, i.e., the suspension system for a commercial vehicle (300), are-It provides better ride comfortIt increases the fatigue life of the leaf springIt has lower total component cost and is lighter in weight.It reduces leaf spring peak loads with high energy absorption.It improves NVH behaviourIt provides damping of high-load impactsIt is abrasive resistant

[0043] 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 present invention has been herein described in terms of its preferred embodiment, those skilled in the art will recognise that the preferred embodiment herein disclosed can be practised with modifications within the scope of the invention herein described.

Claims

CLAIMS:We claim,1. A suspension system for a commercial vehicle (300) comprises of,• front leaf spring suspension (100),• rear leaf spring suspension (200),Wherein, front leaf spring suspensions (100) are mounted on either sides of the vehicle along the front of the vehicle chassis and, at their one end through their front suspension front hanger backet (10F) that is fixed on the vehicle’s chassis and at their other end through their front suspension rear backet (60F) that are fixed at position behind the mounting position of the front suspension front hanger backet (10F) on the vehicle’s chassis; a spacer (2 IF) and a front spacer bracket and mounting cup assembly (23F) of the front leaf spring suspension (100) that is provided with a front mounting cup (25F) are together fixed in their position on the vehicle chassis using conventional fastening means; the spacer (2 IF) and the front spacer bracket and mounting cup assembly (23F) are so positioned on the vehicle chassis that the centre of an auxiliary foam spring front (20F) held within said front mounting cup (25F) is aligned with the centre of a front U bolt clamp (28F) of the front leaf spring suspension (100); and rear leaf spring suspensions (200) are mounted on either sides of the vehicle along the rear of the vehicle chassis and, at their one end through their rear suspension front hanger bracket (10R) that are fixed on the vehicle’s chassis, and at their other end through their rear hanger bracket (60R) that are fixed at position behind the mounting position of the rear suspension front hanger backet (10R) on the vehicle’s chassis; a rear auxiliary foam spring (20R) is held within a rear auxiliary foam spring bracket assembly (25R) of the rear leaf spring suspension (200); the rear auxiliary foam spring bracket assembly (25R) is itself attachedto a rear frame support bracket (23R) through conventional fastening means; the rear frame support bracket (23R) is in turn fixed on the vehicle’s chassis in a position such that the centre of the rear auxiliary foam spring (20R) is aligned with the centre of a rear U bolt clamp (28R) of the rear leaf spring suspension (200), and an external rubber bump stopper (57R) that is also attached on lower surface of the rear auxiliary foam spring bracket assembly (25R) is aligned with the top surface of the rear U bolt clamp (28R) of the rear leaf spring suspension (200).

2. The suspension system for a commercial vehicle (300), as claimed in claim1, wherein- the front leaf spring suspension (100) includes the front suspension front hanger backet (10F), auxiliary foam spring front (20F), front spacer bracket and mounting cup assembly (23F), front mounting cup (25F), front U bolt clamp (28F), leaf spring assembly front (40F), front leaf spring clamp (45F), front U-bolt (50F), front shock absorber bottom mounting bracket (55F), front suspension rear backet (60F), front shackle plate (62F), front suspension pin (64F), and front suspension rear hanger bracket (66F); and- the rear leaf spring suspension (200) includes the rear suspension front hanger bracket (10R), rear auxiliary foam spring (20R), rear frame support bracket (23R), rear auxiliary foam spring bracket assembly (25R), rear U bolt clamp (28R), rear leaf spring assembly (40R), rear leaf spring clamp (45R), rear U-bolt (50R), external rubber bump stopper (57R), rear hanger bracket (60R), rear mounting plate (62R), rear suspension mounting bush (64R), and rear suspension mounting bush (66R).

3. The suspension system for a commercial vehicle (300), as claimed in claim2, wherein said front U bolt clamp (28F) is supported on top of the leaf spring assembly front (40F) which itself rests along its lower surface on thefront shock absorber bottom mounting bracket (55F), and said front U bolt clamp (28F) and the leaf spring assembly front (40F) being attached to the vehicle’s axle by means of front U-bolts (50F) and conventional nuts; one end of the leaf spring assembly front (40F) is linked within the mounting point of the front suspension front hanger backet (10F) through a mounting bush, the other end of the leaf spring assembly front (40F) is linked with the front suspension rear backet (60F) through the front suspension rear hanger bracket (66F), the front shackle plate (62F), and the front suspension pin (64F), with the mounting bush being provided at the interface between the other end of the leaf spring assembly front (40F) and the front suspension rear hanger bracket (66F) and the front suspension pin (64F) being provided at the interface between the front shackle plate (62F) and the front suspension rear backet (60F);- the leaf springs together forming the leaf spring assembly front (40F) are held together by a set of front leaf spring clamps (45F) that are provided at equal distance from the longitudinal centre, and on both halves of said leaf spring assembly front (40F); and- the front U-bolts (50F) fixed on the front shock absorber bottom mounting bracket (55F) through conventional nuts hold the front U bolt clamp (28F) at a position on the top surface and along the longitudinal centre of the leaf spring assembly front (40F); the front shock absorber bottom mounting bracket (55F) is itself fixed on the vehicle’s axle through conventional fastening means.

4. The suspension system for a commercial vehicle (300), as claimed in claim 2, wherein one end of the rear leaf spring assembly (40R) is linked within the mounting point of the rear suspension front hanger backet (10R) through a mounting bush, the other end of the rear leaf spring assembly (40R) is linked with the rear hanger backet (60R) through the rearsuspension mounting bush (66R), the front shackle plate (62F), and rear suspension mounting bush (64R), with the rear suspension mounting bush (66R) being provided at the interface between the other end of the rear leaf spring assembly (40R) and the rear mounting plate (62R) and the rear suspension mounting bush (64R) being provided at the interface between the rear mounting plate (62R) and the rear hanger backet (60R);- the leaf springs together forming the rear leaf spring assembly (40R) are held together by a set of rear leaf spring clamp (45R) that are provided at equal distance from the longitudinal centre, and on both halves of said rear leaf spring assembly (40R);- the rear U bolt clamp (28R) supported on top the rear leaf spring assembly (40R) along the longitudinal centre of said rear leaf spring assembly (40R), are together attached and held in their position on the vehicle’s rear axle by means of rear U-bolts (50R) and conventional fastening means; and- the rear frame support bracket (23R) is provided between the rear auxiliary foam spring bracket assembly (25R) and the vehicle chassis and fixed in their position on the vehicle chassis using conventional fastening means, the rear auxiliary foam spring bracket assembly (25R) is so positioned on the vehicle chassis that the centre of the rear auxiliary foam spring (20R) held within said rear auxiliary foam spring bracket assembly (25R) is aligned with the centre of the front U bolt clamp (28R).

5. The suspension system for a commercial vehicle (300), as claimed in claim 3, wherein- the front spacer bracket and mounting cup assembly (23F) has a thick base that has an elongated shape made by combining two halves of a circle to two of the shorter sides of a rectangle;- the front mounting cup (25F) is positioned at the centre of the base of the front spacer bracket and mounting cup assembly (23F) and joined with said base by conventional joining methods including welding; and a circular opening is provided at the centre of the base within the front mounting cup (25F), this circular opening aligns with the central cylindrical shaped hole of the auxiliary foam spring front (20F);- the front mounting cup (25F) has a circular cross section which at first decreases in area until the midpoint of the height is reached and then increases in area until the topmost edge of the front mounting cup (25F) is reached;- the auxiliary foam spring front (20F) has the shape of a frustum that has been provided with multiple uniformly shaped depressions that form rings of reduced cross-sectional area along the height of said auxiliary foam spring front (20F); and the auxiliary foam spring front (20F) held within the front mounting cup (25F) has an interference fit with said front mounting cup (25F).

6. The suspension system for a commercial vehicle (300), as claimed in claim 4, wherein- the rear auxiliary foam spring bracket assembly (25R) has a thick quadrilateral shaped base whose two adjacent corners have been given a curved profile;- the rear auxiliary foam spring bracket assembly (25R) is provided with multiple openings in its base to allow it to be attached to lower surface of the rear frame support bracket (23R) using conventional fastening means; a cup (25RC) having a cylindrical external shape is joined to the base of the rear auxiliary foam spring bracket assembly (25R) by conventional joining means; said cup (25RC) has a central axis that passes through an off-centre location on the quadrilateral shaped base of said rear auxiliary foam spring bracket assembly (25R);- the rear auxiliary foam spring (20R) has the shape of a frustum that has been provided with multiple uniformly shaped depressions that form rings of reduced cross-sectional area along the height of said auxiliary foam spring front (20R); said rear auxiliary variable spring (20R) is also provided with a metallic ring (20RR) that is accommodated in one of its the uniformly shaped depressions; and a circular opening is provided in the base of the rear auxiliary foam spring bracket assembly (25R), this circular opening aligns with the central cylindrical shaped hole of the rear auxiliary variable spring (20R); and- the rear auxiliary foam spring (20R) has an interference fit with the cup of said rear auxiliary foam spring bracket assembly (25R).

7. The suspension system for a commercial vehicle (300), as claimed in preceding claims, wherein the construction and positioning of the front leaf spring suspension (100) and rear leaf spring suspension (200) on one side of the vehicle chassis is mirrored by the front leaf spring suspension (100) and rear leaf spring suspension (200) respectively provided on other sides of the vehicle chassis.Dated: 19thJuly 2024

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