Gnome 100 hp Engine - Stationary Gear Motion

The exhaust timing is based on the 9 Cam gears, one cam per cylinder, mounted onto the Cam Shaft in the Valve Gear Case (Cam box). The cam shaft gear is driven by two planet gears which are mounted onto the front cover of the Valve Gear case (the Cam box is removed for better visibility).

These planet gears drive the cam shaft, causing it to rotate at half the engine speed, thus providing the correct timing for a 4 stroke 9 cylinder engine.