Low Stress Conical Type Diaphragm

A multi-thickness diaphragm member including clamping sections that are sized for assembly of the diaphragm in standard air brake valve devices and a flexure portion intermediate the clamping sections that forms a convolution during assembly. The thickness of the flexure portion is less than that of the clamping sections to facilitate formation of the diaphragm convolution without wrinkling, in order to alleviate progressive fatigue failure. The thin flexure portion of the diaphragm is joined with the respective clamping sections through a tapered area, which lies entirely outside of the annular space in which the diaphragm convolution forms during assembly, to thereby maximize the radius of curvature of the convolution for optimum utilization of the flexure portion in forming the convolution.