Metallurgy Of Cast Iron

DROP TESTS, ETC., FOR CAR WHEKI.S.
447
94). A wheel rarely fails in service in the hub, double plates, or at the intersection of the plates (see letters A, B, and C on Fig1. 94). If a crack does occur at these points it does not necessarily cause the wheel to become dangerous. If a crack occurs in the single plate (see letter A on Fig. 93), we then have a dangerous wheel, and. it will not run long before giving way entirely. It will also be noted that wheels tested under the M.
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(\ B. drop are placed flange downward on an anvil block, having three supports for the llunge of the wheel to rest upon. The hammer strikes the central part or hub and the whole of the wheel resists the concussion, while the wheels tested under the Burr drop are placed flange downward on a flat surface anvil block and the wheel receives the concussion ;it our point only, The Chicago, Burlington \* Ouincy speeilieiitiuns require wheels tested tinder the Barr drop to stand fifty blowsrcentage of wheels that fail in the brackets can be ascribed to a poorly designed pattern; too light brackets will crack because they cool more rapidly than the plate of the wlu'f-l, which would cause a strain on them; too heavy a bracket will throw the strain on the plates, causing tin- f'l.tfi's to crack. For those who are not familiar v, nil tin- drop u*st used in testing wheels, Pig. 93 •/i',« ^ ,tii inspiration of the 'Ban* drop, and Fig. 94 the M l II. »!/»p. It \vill be noted that, the hammer of !•)• P ni drop striki-s tin* single plait- of tin- wheel {*<•»• <»!!'! A ««n Fu'a, M..*K Tin* hammer of the M. I'. P». ilr*,p -trila-s tin.- hub of the wlii.-el (si-c letter A on i;ig. is claimed for it, 1 Kvan.se. the steel-tiredrcf. Ilirlinn* whrii thr pomm-»'r-r.r-,