received by the International Bureau on 16 January 2018 (16.01.2018)

1. An axle beam (10), comprising:

a hollow middle portion (12) having a first comer-curved tapered arch cross- sectional shape; and

a pair of hollow end portions (.16) each having a substantially circular cross- sectional shape and extending at opposite ends of the middle portion (12);

wherein the hollow middle portion (12) has a first wall thickness: and wherein the hollow end portions (16) each have a second wall thickness that is larger than the first wall thickness.

2. The axle beam of claim 1 , further comprising a pair of angular portions (14) disposed at opposite ends of the axle beam (10) between the middle portion (12) and the pair of hollow end portions (16), respectively;

wherein the pair of angular portions (14) each have a second corner-curved tapered arch cross-sectional shape including the second wall thickness.

3. The axle beam of claim 2, wherein the angular portions (14) and the pair of end portions ( 16) are each oriented at an angle of about 30 degrees from the center (10b) of the hollow middle portion (12).

4. The axle beam of claim 1 , further comprising a pair of pivotable members ( 18) fixedly attached at the pair of end portions (16), respectively,

5. The axle beam of claim 4, wherein each of the end portions (16) has an inner diameter that is complementary to an outer diameter of each of the pivotable members (18) such that each pivotable member (18) is at least partially received within the end portion (16).

6. The axle beam of claim 1, wherein the hollow middle portion (12) tapers inwardly toward a center (16b) of each of the end portions (16) at each end of the axle beam (10).

7. The axle beam of claim 1 , wherein the second wall thickness is at least about 75% larger than the first wall thickness.

8. The axle beam of claim 1 , wherein the hollow middle portion (12) and the pair of hollow end portions (16) are formed from a single tubular blank (20).

9. An axle beam assembly (10), comprising:

an elongated middle portion (12) having a first hollow comer-curved tapered arch cross-sectional shape;

a pair of end portions (16) each having a hollow substantially circular cross- sectional shape and extending at opposite ends of the middle portion (12);

a pair of angular portions (14) disposed at opposite ends of the axle beam assembly (10) between the middle portion (12) and each of the end portions (16), respectively, wherein the pair of angular portions (14) each have a second hollow corner- curved tapered arch cross-sectional shape that is different from the first hollow corner- curved tapered arch cross-sectional shape; and

a pair of pivotable members (18) fixedly attached to the pair of end portions (16). respectively.

10. The axle beam assembly of claim 9, wherein the middle portion (12) has a first wall thickness, and wherein the pair of angular portions (14) and the pair of end portions (16) each have a second wall thickness that is larger than the first wall thickness,

1 1. The axle beam assembly of claim 10, wherein the second wall thickness is at least about 75% larger than the first wall thickness.

12. The axle beam assembly of claim 9, wherein the angular portions (14) and the pair of end portions (16) are each oriented at an angle of about 30 degrees from the center (10b) of the middl e portion (12).

13. The axle beam assembly of claim 9, wherein each of the end portions (16) has an inner diameter that is complementary to an outer diameter of each of the pivotable members (1 8) such that each pivotable member (18) is at least partially received within the end portion (16).

14. The axle beam assembly of claim 9, wherein the middle portion (12) tapers inwardly toward the center (16b) of each of the end portions (16) at each end of the axle beam (10).

15. A method of forming an axle beam, comprising:

forming a first wall thickness along a middle portion (22) of an elongated tubular member (20);

forming a second wall thickness along opposite end portions (26) of the tubular member (20), wherein the first wall thickness is less than the second wail thickness, and wherein the middle portion (22) is located between the two end portions (26);

reducing an inside diameter and an outside diameter of each of the end portions (26); and

forming a first comer-curved tapered arch cross-sectional shape along the middle portion (22) and a second comer-curved tapered arch cross-sectional shape at least partially along each of the end portions (26).

16. The method of claim 15, further comprising bending the tubular member (20) at opposite ends to fonn a pair of angular portions (24);

wherein the pair of angular portions (24) each have the second comer-curved tapered arch cross-sectional shape including the second wall thickness.

17. The method of claim 16, wherein the angular portions (24) are bent at an angle of about 30 degrees relative to the centerline of the middle portion (22).

18. The method of claim 16, further comprising:

at least partially inserting a pivotable member (28) into each of the end portions (26); and

fixedly attaching each of the pivotable members (28) to each of the end portions (26), respectively. 19, The method of claim 15, wherein forming the first wall thickness comprises reducing an outside diam eter of the tubular member (20),

20, The method of claim 15, wherein the second wall thickness is at least about 75% larger than the first wall thickness.