Technical Reports

Examination of Cracks in Wabco and Knorr Disc Brakes

  • 01
  • Aug
  • 1979
AUTHOR: Paul Denney
SUBJECT: Braking Systems
ABSTRACT: The Knorr and Wabco disc brakes were examined for the cause of cracking and why there is a difference in the type of cracks found in the two designs. Microstructure, microhardness, hardness, composition, and crack surfaces were investigated. Little difference was noted between the two materials. The crack surfaces had been worn and corroded, and neither the origins of cracks nor directions of crack growth could be accurately determined. To further assess the performance of the Westinghouse Air Brake Co. disc brake, the tangs that join the disc to the hub in this design were examined for microstructure, micro-hardness, composition, dimensional, and visual evidence of wear. The data was compared to the design requirements furnished by the manufacturer. The connecting bolts were also examined for wear, debris, deformation, and/or cracks. The Wabco tangs and connecting bolts were found to meet the manufacturer's specifications. The tangs and connecting bolts showed no sign of wear, cracking, or deformation. The microstructure and microchardness of the tangs were found to be similar to the metal in the disc region.
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