. Electric railway journal . ssion tests and transverse bending tests. In thefirst tests, the drill was used for a period of two min-utes, then resharpened, and the operation repeated fourtimes. It was found that all of the samples were prac-tically undrillable. The depth of the holes, after thecompletion of the tests, were measured to the in., and the average for the three was in. In the ball impression test a steel ball 7/16 in. indiameter was set on the faces of the three tongue-switchspecimens and subjected to a load of 35,000 lb. Uponremoval the diameter of the impress
. Electric railway journal . ssion tests and transverse bending tests. In thefirst tests, the drill was used for a period of two min-utes, then resharpened, and the operation repeated fourtimes. It was found that all of the samples were prac-tically undrillable. The depth of the holes, after thecompletion of the tests, were measured to the in., and the average for the three was in. In the ball impression test a steel ball 7/16 in. indiameter was set on the faces of the three tongue-switchspecimens and subjected to a load of 35,000 lb. Uponremoval the diameter of the impression in the surfaceof the manganese tongue was measured, and in eachcase it was found to be in. This indicated thatthe surface hardness averaged approximately the samein the three sample switch tongues tested. In the transverse bending tests of manganese tongueswitches, great care was exercised in applying the loadto the three samples so that the test conditions for eachmight be the same. Each tongue was laid on supports. Chicago Special Work—Fig. 3—Showing Cupping of Man-ganese Switch and Mate at Run-off from ChicagoRail, Installed January, 1911; Traffic, 221Wheels Per Hour 972 ELECTRIC RAILWAY JOURNAL [Vol. XLIII, No. 18.
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