Title of Invention

"SUSPENSION SYSTEM FOR A RAILWAY WAGON"

Abstract

The present application discloses a suspension system for a railway wagon for use with freight bogies. The suspension system comprises two distinct elastomeric pad components installed between a roller bearing adaptor and a side frame of a bogie. The suspension system has a first elastomeric pad component comprising pair of shear pads configured to have an upper surface and a base surface with an upper side wall portion and a lower side wall portion, the said base surface being adapted for fixed positioning with respect to an upper face of the roller bearing adaptor. The shear pads are disposed between the upper side wall portion and the lower side wall portion of the upper surface and base surface of the first elastomeric pad component. The suspension system has a second elastomeric pad component comprising base pad, a top plate and a bottom plate. The second elastomeric pad component is disposed between the upper surface and the base surface of the first elastomeric pad component. The second elastomeric pad component is screwed to the base surface of the first elastomeric pad component.

Full Text

BACKGROUND OF THE INVENTION [0001] Suspension systems are used to provide support to railway vehicles during transportation. Shock and vibrations may be substantial in railway, commercial truck and ihe like transportation. The bouncing or vibrations during railway and truck travel disrupts passenger comfort, may damage cargo and may also reduce the operational life of the vehicles themselves. Thus, trains and trucks require adequate support or cushioning during transportation to reduce the disruptive shock and vibrations caused to the vehicle, cargo, passengers and the like. [00021 The adequate support or cushioning is generally achieved by a suspension system disposed between an axle box and a side frame of a bogie. Elastomeric pads are generally used as primary suspension systems in railway wagons and particularly for certain kind of bogies. The elastomeric pads transmit forces between the axle box and the side frame of the bogie. It is situated above a roller bearing housing on an adaptor plate and sandwiched by the side frame of the bogie. The elastomeric pads are generally attached to an upper steel plate and a lower steel plate. The role of the elastomeric pad is to withstand the compressive, longitudinal and shear forces on the bogie and provide anti vibration or cushioning and damping effect to the whole wagon. [0003 ] The elastomeric pads used currently in railway wagons have an approximate life of 18 months. Premature failure of these pads is often reported. One reason for this premature failure was the rubber loosing its shock absorbing property rendering the pad useless as a suspension. A second reason for this failure was the separation of the steel plates from the elastomeric pads. This failure is called the bond line failure. A third reason for this failure was the failure of the metal due to fatigue or creep. The fourth reason for this failure was peeling, breaking or cracking of the rubber component of the pad. [0004] The loss to the operator is due to the fact that the wagons generally have an 18 month maintenance cycle and any premature failure goes unnoticed till the next maintenance cycle. The premature failure means that the wagons are travelling without appropriate suspension system resulting in unmanageable compressive, longitudinal and shear forces between the wheel and the body of the railway wagon. This leads to damage of track, wagon wheels, bearing, axle box, axle and other components. These are very costly items and have high replacement costs associated with them. [0005] The railway industry is constantly on the alert and receptive to suspension structures capable of overcoming these problems. There remains a need in the art for an effective suspension system for a railway wagon, which ameliorates the problems hitherto encountered. SUMMARY OF THE INVENTION [0006] The aforementioned application discloses a suspension system for a railway wagon comprising two distinct elastomeric pad components installed between a roller hearing adaptor and a side frame of a bogie. The suspension system has a first elastomeric pad component comprising pair of shear pads configured to have an upper surface and a base surface with an upper side wall portion and a lower side wall portion, the said base surface being adapted for fixed positioning with respect to an upper face of the roller bearing adaptor. The shear pads are disposed between the upper side wall portion and the lower side wall portion of the upper surface and base surface of the first elastomeric pad component. The suspension system has a second elastomeric pad component comprising base pad, a top plate and a bottom plate. The second elastomeric pad component is disposed between the upper surface and the base surface of the first elastomeric pad component. The second elastomeric pad component is screwed to the base surface of the first elastomeric pad component. BRIEF DESCRIPTION OF DRAWINGS [0007] FIG.l is a side elevation view of portion of a railway wagon showing the sideframe of the bogie, suspension system, roller bearing adaptor and the axle box. [00081 FIG. 2 is a side view of the suspension system with two distinct elastomeric pad components. i 0009) FIG. 3 is a top view of the suspension system. [0010] FIG.4 representatively shows a load applied in a vertical direction under static condition to the suspension system for carrying out a compressive load deflection test. [00111 FIG.5 representatively shows a load applied in a vertical direction and another load applied in a lateral direction to the suspension system for carrying out a shear load deflection test. (0012] FIG. 6 is a graph showing the relationship between the forces in kilo Newton and the displacement in millimetre when a compressive load of [00 kilo Newton is applied in the vertical direction to the suspension system. [00131 FIG. 7 is a graph showing the relationship between the forces in kilo Newton and the displacement in millimetre when the suspension system is subjected to a shear force with a compressive load of [00 kilo Newton applied in the vertical direction. DETAILED DESCRIPTION [ 0014 ] As used in the present disclosure, the term longitudinal, lateral and vertical refer to three different axes oriented at right angles to each other. The longitudinal axis lies in the plane of the suspension system and is parallel to the direction in which the railway wagon runs and is denoted as y-axis. The lateral axis is at right angles to the longitudinal axis and lies in the plane of the suspension system and is denoted as x-axis. The vertical axis lies in a plane perpendicular to the plane of the suspension system and is denoted as the /-axis. [0015] The present disclosure relates to a suspension system for a railway wagon for use with freight bogies to withstand the compressive, longitudinal and shear forces on the bogie and provide anti vibration or cushioning and damping effect to the whole wagon. I he life of the suspension system of the present disclosure is greater than or equal to ! about 3 years and less than or equal to about 8 years or 1.5 million kilometres of actual I railway wagon usage, whichever is earlier. [0016] A suspension system 10 for a railway wagon for use with freight bogies and installed between a roller bearing adaptor 12 and a side frame of a bogie 14 as illustrated in FIG. I. The bogie side frame is formed at each end of the bogie with a recess into which upwardly fits an axle bearing with an axle box 16 surmounted by the roller bearing adaptor 12, and the suspension system 10 seated within a space envelope on the upper face of the roller bearing adaptor 12. The suspension system 10 is sized to fit snugly into the space envelope on the upper face of the roller bearing adaptor 12. >0()17j FIG. 2 illustrates the suspension system 10 comprising two distinct elastomeric pad components. It has a first elastomeric pad component comprising pair of shear pads 22. an upper surface 24 and a base surface 26 with an upper side wall portion 28 and a lower side wall portion 30. The base surface 26 is adapted for fixed positioning on the upper face of the roller bearing adaptor 12. The shear pads 22 are disposed between the upper side wall portion 28 and the lower side wall portion 30 of the upper surface 24 and the base surface 26 of the first elastomeric pad component. [00181 In an exemplary embodiment, the shear pads 22 are bonded to the upper side wall portion 28 and lower side wall portion 30 of the upper surface 24 and the base surface 26 of the first elastomeric pad component. The shear pads are disposed at an angle of 45 degrees to the vertical axis. Also, the shear pads are sized to fit snugly into the space envelope between the upper side wall portion 28 and the lower side wall portion 30. In another exemplary embodiment, the shear pads have a trapezoidal cross section. The surface area of each shear pad bonded with the upper surface 24 of the first elastomeric pad component is greater than or equal to about 6[00 square millimetre and less than or equal to about 6350 square millimetre and the surface area of each shear pad bonded with the base surface 26 of the first elastomeric pad component is greater than or equal to about 5500 square millimetre and less than or equal to about 5720 square millimetre. The thickness of each shear pad is greater than or equal to about 8 millimetres and less than or equal to about 12 millimetres. [0019] In another exemplary embodiment, the upper surface 24 of the first elastomeric pad component is a steel plate. The steel plate is a high strength material suited for the present purpose with regard to its formability, its strength characteristics, process ability, hardenability and costs. The steel plate has a tensile strength of about 900 Newton per square millimetre to about 14-00" Newton per square millimetre, a yield stress of greater than or equal to about/700 Newton, per square millimetre, an elongation after fracture of greater than or equal to about 12 percent and an impact resilience value of about 45 Joule. [00201 Also, the base surface 26 of the first elastomeric pad component is a steel plate. The steel plate is a high strength material suited for the present purpose with regard to its lormability, its strength characteristics, process ability, hardenability and costs. The steel / ' C L: 1plate has a tensile strength of about [000 Newton per square millimetre to about 1206" Newton per square millimetre, a yield stress of greater than or equal to about r750 Newton per square millimetre, an elongation after fracture of greater than or equal to about 11 percent and an impact resilience value of about 35 Joule. [00211 The suspension system as illustrated in Figure 2 has a second elastomeric pad component comprising base pad 32, a top plate 34 and a bottom plate 36. The second elastomeric pad component is disposed between the upper surface and the base surface of the first elastomeric pad component. The second elastomeric pad component is screwed to the base surface 26 of the first elastomeric pad component. In an exemplary embodiment the second elastomeric pad component is screwed to the base surface 26 of the first elastomeric pad component by 8 screws as shown in FIG. 3. [00221 In an exemplary embodiment, the base pad 32 is bonded to the top plate 34 and bottom plate 36. The base pad 32 has a rectangular cross section and the surface area of the base pad is greater than or equal to about 21180 square millimetre and less than or equal to about 21800. The thickness of the base pad is greater than or equal to about 13.6 millimetre and less than or equal to about 14 millimetre. [0023] In another exemplary embodiment, the top plate 34 of the second elastomeric pad component comprises a polyamide resin. The polyamide resin may be a generic family of reisns known nylons, characterized by the presence of amide groups(-CONH-) in the backbone chain, for example, nylon-6, nylon-6,6 and nylon-12 or maybe a filled polyamide containing, for example, glass fibres and/or mineral fillers. The polyamide resin used for the top plate 34 is characterized by good rigidity, hardness, abrasion resistance and thermal stability. It may be used at continuous service temperatures of up to [00 degree centigrade and is particularly suitable for parts, which are subjected to high mechanical and thermal loads. In an exemplary embodiment, the polyamide resin has a hardness of about [00 mega Pascal to about 170 mega Pascal, a sliding friction of about 0.35 to about 0.42, an ultimate elongation of about 40 percent to about 150 percent and an elasticity modulus of about 2000 rnega Pascal to about 3300 mega Pascal. [00241 In another exemplary embodiment, the bottom plate 36 of the second elastomeric pad component is a steel plate. The steel plate is a high strength material suited for the present purpose with regard to its formability, its strength characteristics, process ability, hardenability and costs. The steel plate has a tensile strength of about 490 Newton per square millimetre to about 630 Newton per square millimetre, a yield stress of greater than or equal to about 335 Newton per square millimetre, and an elongation after fracture of greater than or equal to about 20 percent. [002 5 j The shear pads 22 of the first elastomeric component and the base pad 32 of the second elastomeric component comprise resilient material. In an exemplary embodiment, the resilient material is a rubber mixture. Such a rubber material is economical and easy to process as well possesses a considerable mechanical strength. Such a rubber material shows an excellent vibration damping property among polymers, however, if a rubber material is used singly, its damping ability may be limited. Thus, a metal plate is generally incorporated in a rubber-type vibration damping material. Such a rubber material composite form may be used as a laminate with steel plates as the shear pads 22 of the present disclosure installed between the steel plates, which plastically deform to absorb the forces. The rubber mixture composition has high rate of heat dissipation. Bonding to the steel plates effectively increases the stiffness of the natural rubber mixture. The bonding between the rubber and the metal is such that the rubber does not bulge out under compression at any of the pad side walls. [0026] The hardness of the rubber mixture is determined by using a method known as Shore hardness by means of durometers. The method permits measurement of the initial indentation of the rubber, the indentation after a specified period of time, or both. The indentation hardness is inversely related to the penetration and is dependent on the modulus of elasticity and the viscoelastic properties of the material. The shape of the mdenter. the force applied, and the test duration influence the results obtained. [0027] The shear pads 22 comprise a rubber mixture characterized by a Shore hardness of greater than or equal to about 70 and less than or equal to about 76, a tensile strength of greater than or equal to about 15 Newton per square millimetre, a rebound resilience of greater than or equal to about 40 percent, an ultimate elongation of greater than or equal to about 250 percent, and a compression set of less than or equal to about 25. The base pad 22 comprises a rubber mixture characterized by a Shore hardness greater than or equal to about 54 and less than or equal to about 60, a tensile strength of greater than or equal to about 15 Newton per square millimetre, a rebound resilience of greater than or equal to about 55 percent, an ultimate elongation of about 400 percent, and a compression set of less than or equal to about 20 percent. [ 00281 Rust formation takes place anywhere on the exposed metal and then has a tendency to spread. The rust spreads and gets to the bond line and slowly works itself onto the bond line till the entire bond is weakened or broken. The metallic parts of the elastomeric pad components may be surface treated to ensure that there is no rust formation at the bond line of the bond between the rubber and the metallic parts and thus no separation of the rubber from the metallic parts. The steel plates of the elastomeric pad components that are not involved in bonding with the resilient material of the pads may he xinc coated and bichromated. The surface treated steel plates exhibit good anti-corrosive properties. [0029] The suspension system of the present disclosure may be used with a railway wagon for isolating compressive, longitudinal and shear forces developed between the body of the bogie and the wheel of the bogie. The second elastomeric pad component is to serve to the compressive forces in the vertical direction The forces in the vertical direction are greater then or equal to about 80 kilo Newton and less than or equal to about i 20 kilo Newton. Also, the second elastomeric pad component isolates small shear forces in the lateral direction and small forces in the longitudinal direction by means of a sliding force. The sliding force is generated when the lower portion of the upper surface 24 of i he first elastomeric pad component slides over the top plate 34 of the second elastomeric pad component. [0030] The first elastomeric pad component is to serve to the shear forces in the lateral direction. The maximum shear force in the lateral direction is about 40 kilo Newton. Also. the first elastomeric pad component absorbs a small component of the compressive forces in the vertical direction and a small component of the forces in the longitudinal direction. [0031 ] The other benefits of the suspension system are listed below. The suspension system weighs less than the conventional suspension systems. The suspension system reduces cargo damage in transit, and reduces the wheel and rail wear. Also, it reduces or eliminates resonance and their associated derailments, which will reduce noise. [0032] Various tests were conducted on the suspension system of the present disclosure at the Gummi-Metal Technik (GMT) Test Lab in Germany. One objective of this test was to ascertain the mechanical strength of the elastomeric pad components of the suspension system. A second objective is to find out the various mechanical properties of the elastomeric pad components. Another objective of these tests is to find out the approximate life of the suspension system. [0033] The present disclosure will be explained in more detail by the test examples below. However, the present disclosure is not limited to these test examples. TEST EXAMPLES Compressive load deflection test or 1-Axle test [0034] A pre load of 500 Newton is applied at the beginning of the test to press the test specimen firmly to a metallic floor bed. The test may be carried out at a machine speed of about 5 millimetre per minute to about 15 millimetre per minute. The suspension system is subjected to two successive loadings of [00 kilo Newton for the two pre-setting cycles and the suspension system is locked in a static position. Now a compressive load of [00 kilo Newton is applied in a vertical direction as representatively illustrated in FIG. 4. The load is applied starting from 0 kilo Newton and going up to [00 kilo Newton in ascending and regular intervals. The deflection may be digitally recorded on the attached computer. FIG. 6 is a graph showing the relationship between the forces in kilo Newton and the displacement in millimetre when a compressive load of [00 kilo Newton is applied in the vertical direction. The resultant stiffness in the vertical direction is 60 kilo Newton per millimetre. The stiffness value is in line with the desired value required by the railway industry. The loads used in the compressive deflection test are as per the limits of the equipment and as per the actual loading conditions on the suspension system in the working conditions. Shear load deflection test or 2-Axle test [003 5] The specimen is tested for deflection both in the vertical and lateral directions. A pre load of 500 Newton is applied at the beginning of the test to press the test specimen firmly to the metallic floor bed. The test may be carried out at a machine speed of about 5 millimetres per minute to about 15 millimetres per minute. The suspension system is subjected to a compressive load of [00 kilo Newton in the vertical direction The suspension system is then subjected to shear force of 90 kilo Newton in a lateral direction as representatively illustrated in FIG. 5. The load is applied starting from 0 kilo Newton and going up to 90 kilo Newton in ascending and regular intervals. The deflection may be digitally recorded on the attached computer. FIG. 7 is a graph showing the relationship between the forces in kilo Newton and the displacement in millimetre when the suspension system is subjected to a shear force with a compressive load of [00 kilo Newton applied in the vertical direction. The resultant stiffness in the vertical direction is 60 kilo Newton per millimetre and the resultant stiffness in the lateral direction is 22 kilo Newton per millimetre. The stiffness value is in line with the desired value required by the railway industry. The loads used in the compressive deflection test are as per the limits of the equipment and as per the actual loading conditions on the suspension system m the working conditions. Fatigue test [0036] The Fatigue test is performed to assess the approximate life of the suspension system. The suspension system is to be fatigue tested for a minimum of 1.5 million cycles to determine the fatigue life of the suspension system. The Fatigue test equipment as available with the GMT has the capability of pulling and pushing the specimen from the mean position. One cycle defined by the GMT Fatigue test is the actuator pushing the product from mean position to its maximum position and then pulling it back to mean position and further pulling it to its minimum position in the opposite direction and pushing it back to the mean position. [003 7] The maximum position was at a distance of 2 millimetres from the mean position and the minimum position was at a distance of 2 millimetres from the mean position in a direction opposite to the direction in which the maximum position lies. The mean load is 0 kilo Newton. The maximum load applied for this purpose was 80 kilo Newton in a push direction and the maximum force in a pull direction(i.e., a direction opposite to the push direction ) was also 80 kilo Newton. The load was applied at a frequency ranging from about 1 hertz to about 1.5 hertz. The Fatigue test was carried on for 1.64 million cycles at which the elastomeric pad components of the suspension system lost only 25 percent of its stiffness value and thus have a residual life to work more cycles. The above loss in the stiffness value shows that the elastomeric pad components still have shock absorbing capability within the operational limit for the wagon to operate even after being subjected to prolonged endurance. [0038] The suspension system did not show signs of any failure after it was subjected to the Fatigue test. There was no visual crack at any surface of the natural rubber mixture. There was no bond failure between the natural rubber mixture and the metal plates of the elastomeric pad components of the suspension system. The field conditions have comparable loadings as the ones used, in the test. There was no metal failure detected and tlie dynamic stiffness value fell only by 25 percent, which is well above the minimum 30 percent drop in dynamic stiffness before reaching a state of permanent set. Hysterisis Loss test [0039] In dynamic applications, the viscoelastomeric properties of elastomers are very important. Lost energy, in the form of heat, arises from molecular friction as a result of an applied load. The percentage energy loss per cycle of operation with the applied load is known as hysterisis loss. The hysterisis loss as calculated from the data obtained from tests is approximately 10 percent. This is a very desirable value since for effective working of the suspension system, the pads must not loose more than 30 percent of the desired stiffness. [0040] While the disclosure has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the essential scope thereof. Therefore, it is intended that the disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this disclosure, but that the disclosure will include all embodiments falling within the scope of the appended claims. We claim: 1. A suspension system (10) for a railway wagon, comprising: two distinct elastomeric pad components installed between a roller bearing adaptor(12) and a side frame of a bogie(14); a first elastomeric pad component comprising a pair of shear pads(22) configured to have an upper surface(24) and a base surface(26) with an upper side wall portion(28) and a 10wer side wall portion(30); wherein the base surface(26) being adapted for fixed positioning with respect to an upper face of the roller bearing adaptor(12); and wherein the shear pads(22) are disposed between the upper side wall portion(28) and the 10wer side wall portion(30) of the upper surface(24) and the base surface(26) of the first elastomeric pad component; a second elastomeric pad component comprising a base pad(32), a top plate(34) and a bottom plate(36); wherein the second elastomeric pad component is disposed between the upper surface(24) and the base surface(26) of the first elastomeric pad component; and wherein the second elastomeric pad component is screwed to the base surface! 26) of the first elastomeric pad component. 2. Hie suspension system(10) of claim 1, wherein the shear pads(22) of the first elastomeric pad component are bonded to the upper side wall portion(28) and the 10wer side wall portion(30) of the upper surface(24) and the base surface(26) of the first elastomeric pad component. 3. The suspension system(10) of claim 2, wherein the shear pads(22) of the first elastomeric pad component are disposed at an angle of 45 degrees to a vertical axis. 4. The suspension system(10) of claim 2, wherein the shear pads(22) of the first elastomeric pad component comprise a rubber mixture having a Shore hardness of greater than or equal to about 70 and less than or equal to about 76. 5 Fhe suspension system (10) of claim 2, wherein the shear pads(22) of the first elastomeric pad component have a trapezoidal cross section. 6. The suspension system(10) of claim 5, wherein the surface area of each shear pad(22) of the first elastomeric pad component bonded with the upper surface(24) of the first elastomeric pad component is greater than or equal to about 6100 square millimetre and less than or equal to about 6350 square millimetre. 7 The suspension system(10) of claim 5, wherein the surface area of each shear pad(22) of the first elastomeric pad component bonded with the base surface(26) of the first elastomeric pad component is greater than or equal to about 5500 square millimetre and less than or equal to about 5720 millimetre. K. The suspension system(10) of claim 5, wherein the thickness of each shear pad(22) of the first elastorneric pad component is greater than or equal to about 8 millimetre and less than or equal to about 12 millimetre. 9. The suspension system (10) of claim 1, wherein the upper surface(24) of the first elastorneric pad component is a steel plate. 10. The suspension system(10) of claim 5, wherein the steel plate has a tensile strength of about 900 Newton per square millimetre to about 1000 Newton per square millimetre. 11. The suspension system(10) of claim 9, wherein the steel plate has a yield stress of about 650 Newton per square millimetre to about 700 Newton per square millimetre. 1 2. The suspension system(10) of claim 9, wherein the steel plate has an e10ngation after fracture of greater than or equal to about 12 percent of an initial size of the steel plate. 1 3. The suspension system (10) of claim 9, wherein the steel plate has an impact resilience value of about 45 Joule. 14, The suspension system of claim 1, wherein the base surface(26) of the first elastorneric pad component is a steel plate. ! 5, The suspension system(10) of claim 14, wherein the steel plate has a tensile strength of about 1000 Newton per square millimetre to about 1100 Newton per square millimetre. 16. The suspension system(10) of claim 14, wherein the steel plate has a yield stress of greater than or equal to about 700 Newton per square millimeter to 750 Newton per square millimetre. 17. The suspension system(10) of claim 14, wherein the steel plate has an e10ngation after fracture of greater than or equal to about 11 percent of an initial size of the steel plate. 18. The suspension system (10) of claim 14, wherein the steel plate has an impact resilience value of about 35 Joule. 19. The suspension system(10) of claim 1, wherein the base pad(32) of the second elastomeric pad component is bonded to the top plate(34) and the bottom plate(36) of the second elastomeric pad component. 20. The suspension system(10) of claim 19, wherein the base pad(32) of the second elastomeric pad component comprises a rubber mixture having a Shore hardness of greater than or equal to about 54 and less than or equal to about 60. 21. The suspension system (10) of claim 19, wherein the base pad(32) of the second elastomeric pad component has a rectangular cross section. 22. The suspension system(10) of claim 21, wherein the surface area of the base pad (32) of the second elastomeric pad component is greater than or equal to about 21180 square millimetre and less than or equal to about 21800 square millimetre. 23. The suspension system(10) of claim 21, wherein the thickness of the base pad(32) of the second elastomeric pad component is greater than or equal to about 13.6 millimetre and less than or equal to about 14 millimetre. 24. The suspension system(10) of claim 1, wherein the top plate(34) of the second elastomeric pad component comprises a polyamide resin. 25. The suspension system(10) of claim 24, wherein the polyamide resin has a hardness of about 100 mega Pascal to about 170 mega Pascal. 26. The suspension system (10) of claim 24, wherein the polyamide resin has a sliding friction of about 0.35 to about 0.42. 27. The suspension system(10) of claim 24, wherein the polyamide resin has an ultimate e10ngation of about 40 percent to about 150 percent. 28. The suspension system(10) of claim 24, wherein the polyamide has en elasticity modulus of about 2000 mega Pascal to about 3300 mega Pascal. 29. The suspension system (10) of claim 1, wherein the bottom plate(36) of the second elastomeric pad component is a steel plate. 30. The suspension system(10) of claim 29, wherein the steel plate has a tensile strength of about 490 Newton per square millimetre to about 630 Newton per square millimetre. 3 1. The suspension system(10) of claim 29, wherein the steel plate has a yield stress of greater than or equal to about 335 Newton per square millimetre. 32, The suspension system(l 0) of claim 29, wherein the steel plate has an e10ngation after fracture of greater than or equal to about 20 percent of an initial size of the steel plate. 33. The suspension system (10) of claim 1, wherein the second elastomenc pad component is screwed to the base surface (26) of the first elastomeric pad component by 8 screws.

Documents:

1511-del-2003-abstract.pdf

1511-del-2003-claims.pdf

1511-del-2003-complete specification (granted).pdf

1511-DEL-2003-Correspondence-Others-(03-02-2009).pdf

1511-del-2003-correspondence-others.pdf

1511-del-2003-correspondence-po.pdf

1511-del-2003-description (complete).pdf

1511-del-2003-drawings.pdf

1511-del-2003-form-1.pdf

1511-del-2003-form-13-(03-02-2009).pdf

1511-del-2003-form-18.pdf

1511-del-2003-form-2.pdf

1511-del-2003-form-3.pdf

1511-del-2003-form-5.pdf

1511-del-2003-pa.pdf