. Proceedings of the annual convention . nished from a group of bars whichhad been reformed and reheat-treated by the Chicago, Milwaukee, St. Paul and PacificRailroad after grinding out the cracks on the top fishing surface at bars the grinding to ehminate cracks extended rather deeply into some of the bars, itwas thought desirable to make rolling-load tests on several joints in which the grindingon the bars was excessive; consequently, these bars were selected. The ground areas onthe bars ranged from 2 in to 2 13/16 in. in length and from fa in to 9/i2 in. in depth. Results o
. Proceedings of the annual convention . nished from a group of bars whichhad been reformed and reheat-treated by the Chicago, Milwaukee, St. Paul and PacificRailroad after grinding out the cracks on the top fishing surface at bars the grinding to ehminate cracks extended rather deeply into some of the bars, itwas thought desirable to make rolling-load tests on several joints in which the grindingon the bars was excessive; consequently, these bars were selected. The ground areas onthe bars ranged from 2 in to 2 13/16 in. in length and from fa in to 9/i2 in. in depth. Results of the 10 tests on the.«e bars are given in Tables 1 and 2. Three of thefractures are shown in Fig. S. Two of the joints ran to 2,000,000 cycles with no failure. Of the remaining 8 joints3 failed from the base at a gouge mark caused by a rail end, and 5 failed from the top,the crack originating on the under side of the head of the bar about 1 in below thefishing surface at the junction of an inner rib with the head of the bap. Rail 1231. Fig. 4—Micrographs from bars oil quenched below critical temperature. Magnification—about 60X; Etch—2 percent Bar 246N; b. Bar 247N; c. Bar 2S2N. The average cycles for failure was 852,660 cycles for the 10 joints, which comparesfavorably with the average of 748,500 cycles for 12 tests made last year on 115 K4headfree 36-in bars. No additional cracks were detected on the failed bars or companion bars, althoughthey were subjected to Magnaflux examination. The large ground areas on the top of thebars acted effectively as easements to eliminate gouging by the rail ends and apparently(lid not materially shorten the fatigue Hfe of the bars. Lateral deflection readings on the bars indicated that at 100,000 cycles the centersof the bars were bowed from in outward to in inward, with an average in inward for the upper flanges. Bending on the lower flanges ranged from outward to in inward, with an average
Size: 1762px × 1418px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthoramericanrailwayengine, bookcentury1900, bookdecade1900
