I believe you're describing the Simplex Selection Standard derailleur. It is illustrated in the 1939 Fonteyn catalogue, which I posted awhile ago to my website.
See http://www.peterbrueggeman.com/
It is also illustrated with less information in the 1937-1938 Fonteyn
catalogue available from Chuck Schmidt's Velo Retro:
http://www.velo-retro.com/
Peter ...................................... Peter Brueggeman La Jolla, California USA 4peebee(AT)peterbrueggeman.com
In reference to:
WTB/WTT a Simplex change fork. I dont have a date of introduction but guess
it was probably pre WW 2, Simplex produced a derailleur system very similar
to the Super Champion, or Osgear as it was known in the UK. I have located a
complete tension arm. I also have 2 gear change quadrants. Does any one have
a Simplex change fork so that I can complete the gear? I have Osgear spares
to trade. Can anyone help with a fork or images or any history from
magazines etc?
Mark Stevens Evanton Scotland.