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Constrictor 'Conloy' derailleur gear

Author Keith Hellon

Constrictor gear KH
The Constrictor "Conloy" derailleur was made between 1947 and 1952 or 3.

It is made from stamped aluminium plates and it is a 4-bar link design (Parallelogram)with a single pulley. It is designed as a 3 speed but by filing away some aluminium on the lower rectangular plate top, the travel is increased.  Other factors prevent it from travelling more.

Today, at last, I managed to make it work consistently. 

Constrictor box

When changing gear, it wants to go onto the large sprocket, rather than the one just smaller on the downshift but the upshift will engage the next smaller one.

It seems to be very sensitive to spring tension. Actually, I am surprised how well it works for its crudity.

Left is an image of the original box for the gear.