French Patent # 792,639 - Lionaxe

French Patent 792,639 - Westminster Route main image

Although there are several designs shown on this patent, the key mechanism is the one shown in the picture above - featuring a cable, rigidly clamped to the derailleur body, but running over a moving roller in domed cover. This was the signature Westminster derailleur, and they were popular enough to ensure that, even today, you still come across them fairly frequently.

Browse associated derailleurs.

Lionaxe Westminster Route thumbnail