pitch surface: Meaning and Definition of

pitch' sur"face

Pronunciation: [key]
  1. (in a gear or rack) an imaginary surface forming a planea cylinderor a cone or frustrumthat moves tangentially to a similar surface in a meshing gear so that both surfaces travel at the same speed.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.