the passageways 114 define a conical taper as illustrated in fig7 fig8 illustrates an axle stub 116 defining a central passageway 118 a pair of coaxial axially spaced apart bearing surfaces 120 and a threaded terminal portion 122 comparison of fig4 and 8 reveals that the stub axle 116 is identical in all respects with the termial portion of the axle 14 particularly that portion removed the diameter of the portion of the stub axle 116 opposite the threaded portion 122 is an interference fit with the inside diameter of the bored cavity 110 referring now to fig9 the stub axle 116 is now inserted into the bored cavity 110 due to the interference fit it has been found preferable to heat the portion of the axle 14 adjacent the bored cavity 110 in order to enlarge its inside diameter likewise the end of the stub axle 116 opposite the threaded portion 122 may be chilled in order to further facilitate insertion of the stub axle 116 into the bored cavity 110 of the axle 14 with reference to fig1 the final step of the rebuilding procedure comprehends the addition of material 126 by welding or other suitable means within the radial passageways 114 and generally within.