Axle suspension system having a shear bolt

1. A shear bolt comprising:

a shank that extends along an axis;

a shear head that extends along the axis and is spaced apart from the shank, wherein the shear head is configured to sever from the shear bolt; and

an enlarged head that is axially positioned between the shank and the shear head, the enlarged bead including:

a first surface that faces toward the shear head;

a second surface that faces toward from the shank;

a first protrusion that extends from the first surface toward the second surface and that has a first tool engagement surface that extends from the first surface toward the second surface; and

a second protrusion that extends from the first surface toward the second surface and that has a second tool engagement surface that extends from the first surface toward the second surface, wherein the second protrusion has the same configuration as the first protrusion and the first protrusion and the second protrusion do not have mirror symmetry with respect to a first center plane that is disposed perpendicular to the axis.

2. The shear bolt of claim 1 wherein the second surface is disposed opposite the first surface, extends from the shank, and extends further from the axis than the first surface.

3. The shear bolt of claim 1 wherein the first surface is substantially planar and is disposed substantially parallel to the second surface.

4. The shear bolt of claim 1 wherein the first protrusion and the second protrusion are spaced apart from the second surface.

5. The shear bolt of claim 1 wherein the first tool engagement surface of the first protrusion is disposed substantially parallel to the second tool engagement surface of the second protrusion.

6. The shear bolt of claim 5 wherein the first tool engagement surface and the second tool engagement surface are disposed parallel to the first center plane and the axis.

7. The shear bolt of claim 1 further comprising a first outer surface that extends from the first surface toward the second surface.

8. The shear bolt of claim 7 wherein the first outer surface is concave.

9. The shear bolt of claim 7 wherein the first surface has a first arcuate edge that extends from the first protrusion to the second protrusion and a second arcuate edge that is spaced apart from the first arcuate edge and extends from the second protrusion to the first protrusion.

10. The shear bolt of claim 9 wherein the first arcuate edge and the second arcuate edge are disposed at a constant radial distance from the axis.

11. The shear bolt of claim 9 wherein the first outer surface extends from the first arcuate edge toward the second surface and a second outer surface extends from the second arcuate edge toward the second surface.

12. The shear bolt of claim 9 wherein the first protrusion has an end surface that extends from the first surface toward the second surface, wherein the end surface is disposed in a non-parallel and non-perpendicular relationship with the first tool engagement surface, the first center plane, and the axis.

13. The shear bolt of claim 12 wherein the end surface extends from an end of the first arcuate edge and the first outer surface.

14. The shear bolt of claim 13 further comprising a second center plane that is disposed perpendicular to the first center plane, wherein the first center plane and the second center plane intersect along the axis and the end surface of the first protrusion extends progressively further from the second center plane in a direction that extends from the first surface toward the second surface.

15. The shear bolt of claim 14 wherein the second protrusion has an end surface that extends from the first surface toward the second surface, wherein the end surface of the first protrusion is disposed in a non-parallel relationship with the end surface of the second protrusion.

16. The shear bolt of claim 15 wherein the end surface of the second protrusion extends progressively further from the second center plane in the direction that extends from the first surface toward the second surface.

17. The shear bolt of claim 12 wherein the first protrusion is continuously curved from the first tool engagement surface to the end surface of the first protrusion.

18. An axle suspension system comprising:

a trailing arm assembly;

a hanger bracket; and

a shear bolt that pivotally couples the hanger bracket to the trailing arm assembly, the shear bolt including:

a shank that extends along an axis;

a shear head that extends along the axis and is spaced apart from the shank, wherein the shear head is configured to sever from the shear bolt; and

an enlarged head that is axially positioned between the shank and the shear head, the enlarged head including:

a first surface that faces away from the hanger bracket;

a second surface that faces toward the hanger bracket, wherein the second surface extends further from the axis than the first surface;

a first protrusion that extends from the first surface toward the second surface and that has a first tool engagement surface that extends from the first surface toward the second surface; and

a second protrusion that extends from the first surface toward the second surface and that has a second tool engagement surface that extends from the first surface toward the second surface and is disposed parallel to the first tool engagement surface, wherein the first protrusion and the second protrusion have rotational symmetry about the axis and do not have mirror symmetry.

19. The axle suspension system of claim 18 wherein the enlarged head extends further from the axis than the shank and the shear head.

20. The axle suspension system of claim 18 wherein the trailing arm assembly has a sleeve, the shear bolt extends through the sleeve, the shank has a threaded portion that is at least partially disposed outside the hanger bracket, and a nut receives the threaded portion.