Joe Bender-Zanoni said: "...I think these brakes go back further. CR sites says 1930's and I have a set stamped "Type 730" that I suppose are from around 1950 based on the bikes other components. ..."
Rick's original inquiry was when the short-reach Weinmann 500 brakeset first appeared, and Weinmann 730 brakes are longer-reach than 500s.
The 1952 Brown Brothers catalogue illustrates a longer reach looking brake without a model number; the omission of mention of a short-stirrup model brake (model 500) is probably significant since these are listed just a few years later. The 1955 Ron Kitching Everything Cycling catalogue lists a Weinmann brakeset with 730 rear brake and 500 front brake. The 1956 Brown Brothers catalogue lists a shallow stirrup model brakeset with the 500 on the front and the 730 on the rear. As I mentioned previously, the 1956 Holdsworth catalogue first mentions the 500 shallow stirrup brake. So 1955 is the earliest I can document the short reach Weinmann 500 brake.
.......... Peter Brueggeman La Jolla California USA 4peebee(at)peterbrueggeman.com
Peter Brueggeman said: "...The 1957 Holdsworth Aids to Happy Cycling catalogue lists Weinmann Standard (730) and Shallow (500) brakes. The 1956 catalogue lists Weinmann "...standard or shallow front stirrup..." which would be the 500. The 1955 catalogue lists "Weinmann. Quick Release... " with no mention on standard or shallow or model number.
Rick Olson asked: "... the approximate intro date of the Weinmann 500 brakeset? ..."