Safety assessment of railroad wheels through roll-by detection of tread cracks

Al V. Clark; Raymond E. Schramm; Stephen R. Schaps; B. J. Filla

doi:10.1117/12.212694

30 June 1995 Safety assessment of railroad wheels through roll-by detection of tread cracks

Al V. Clark, Raymond E. Schramm, Stephen R. Schaps, B. J. Filla

Proceedings Volume 2458, Nondestructive Evaluation of Aging Railroads; (1995) https://doi.org/10.1117/12.212694
Event: Nondestructive Evaluation of Aging Infrastructure, 1995, Oakland, CA, United States

Abstract

A prototype system has been developed for roll-by inspection of cracks in the treads of freight car wheels. The system uses noncontacting electromagnetic-acoustic transducers (EMATs) which generate and receive surface waves propagating along the tread surface. If a defect is present it reflects an echo back to the EMAT. The EMAT itself consists of a coil and permanent magnet which are embedded in a 'rocking shoe'. This device is a piece of impact- absorbing polymeric material having a curvature to match the radius of a 910 mm (36 in) diameter wheel. The rocking shoe is suspended by a spring system in a recess, machined into the outer surface of a rail plug. When the wheel is centered over the shoe, it activates a trigger circuit which energizes the EMAT and causes propagation of the surface wave. The detected echoes are analyzed by a microprocessor which characterizes the wheel as being safe or unsafe. The crack detector system has been subjected to field testing using actual locomotive and rolling stock. It has been able to detect both artificial and real defects at roll-by speeds of 25 km/h (15mph).

Citation Download Citation

Al V. Clark, Raymond E. Schramm, Stephen R. Schaps, and B. J. Filla "Safety assessment of railroad wheels through roll-by detection of tread cracks", Proc. SPIE 2458, Nondestructive Evaluation of Aging Railroads, (30 June 1995); https://doi.org/10.1117/12.212694

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