Bristol Hercules radial engine gear train - photos

[hemmjo]

It is indeed amazing. Designed in someones head, on a board, with pencils and instruments, no CAD or computer simulation for assistance. Then built by real machinists, with no CNC, who were under tremendous pressure. Assembled by hand with each gear messed properly with its bothers and sisters.

Having never seen one before, I was having trouble finding the valve train. All I could see were ports open into the side of the cylinders. It had me thinking surely it cannot be 2 cycle.

Discovered this explanation for that extensive gear train.