Resource Dictionary

Angle of draw

In coal mine subsidence, this angle is assumed to bisect the angle between the vertical and the angle of repose of the material and is 20¡ for flat seams. For dipping seams, the angle of break increases, being 35.8¡ from the vertical for a 40¡ dip. The main break occurs over the seam at an angle from the vertical equal to half the dip.