. Official proceedings . words, the metal is crowded togetlier from hub to treadAvith a tendenc\- to split or pull apart with the fracture alongradial lines. That the stresses are high is common knowledgebecause occasional wheels l)urst in the press, but very little orno attempt has been made to ascertain definitely just how greatthese stresses are. If the machine work in connection with turning the axleand boring the wheel is uniform, the stresses in the wheel willbe symmetrical and well within the factor of safety, but irregu-larity in Ixiring the wheels such as occurs vrhere the finished bo
. Official proceedings . words, the metal is crowded togetlier from hub to treadAvith a tendenc\- to split or pull apart with the fracture alongradial lines. That the stresses are high is common knowledgebecause occasional wheels l)urst in the press, but very little orno attempt has been made to ascertain definitely just how greatthese stresses are. If the machine work in connection with turning the axleand boring the wheel is uniform, the stresses in the wheel willbe symmetrical and well within the factor of safety, but irregu-larity in Ixiring the wheels such as occurs vrhere the finished boreis produced witli one cut, and the axle wheel seat is irregular,elliptical or tapered, the stresses in the wdieel may becomebunched and may destroy the wheel. The University of Illinois tests are expected t<i throw somelight on the result of irreernlar work as well as to establish the 273 best practice. The results fil)taine(l from a single pair of 725pouiul wheels pressed on at pounds is shown inFip^ure Fig. 38—Showing Location and Intensity of Compressive and Tensile Stresses Developed in the Outside Plate of a 725 Lb. M. C. B. Wheel From an Axle Pressure of 123,000 Lbs The stresses were fairly uniform, varyint;- from 15,500 to18,000 pounds in compression in the front plate, and consider-ably less in the back plate The tensile stresses ranp^e as highas pounds in the bcick hub and slightly less in the fronthub. As more tests are completed with varying- grades ofmachine work, information of real value will l)e obtained whichwill be helpful in eliminating rough and irregular machine workwliich is now sometimes the cause of broken wheels and brokenaxles as indicated by the government investigations. The relation of mounting pressure to diameter of axles anddistance through hub is shown in Figure 39. ()ur experiencewith the larger axles is very recent, but we know that the limitsgiven aie safe in practice. As far as design goes, the metal should be ])lac
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