Pages, some stolen, some original

Tuesday, April 18, 2023

1920 Zenith Gradua model C

1920 Zenith Model C Gradua

Fred ('Freddie') W. Barnes was hired as chief engineer in 1905, and patented the "Gradua" variable-ratio belt drive transmission that year. The Gradua system simultaneously changed the diameter of the crankshaft belt-drive pulley to alter the drive ratio, while moving the rear wheel forward or back to maintain belt tension. The Gradua system was among the first attempts to provide multiple drive ratios for a motorcycle, at a time when very simple, direct belt-drive transmission was the industry norm. - Car & Classic

If you look closely you can see the large diameter drive pulley on the far side of the rear wheel and a bit of the drive belt in the space between the engine and the rear fender. It looks to be a multi-piece belt. They are still in use:

Gates Quick-Link Belt

No comments:

Post a Comment