Flat Belt Drive
From DT Online
Flat Belts made of leather were the traditional means of transmitting power throughout factories using Line Shaft type arrangements. They could be twisted to reverse the direction of rotation and easily moved from a ‘live pulley’ across to a ‘loose pulley’ to remove power to an individual machine from a continuously rotating Line Shaft.
Note: The pulleys used in Flat Belt drives are not in fact ‘flat’ but rather they are slightly convex or barrel shaped. This ensures that the flat belt stays central because it always rides to the top of the curve - try it in a model by using round wooden beads as pulleys and connecting them with a wide elastic band.