The pistons, also of cast iron, used three rings between the wrist pin and top. They were essentially all compression rings since they wanted oil to move freely throughout the engine for adequate lubrication. The wrist pin was locked in place with a set screw. There is some controversy on whether the original 1903 engine used an oil pump or simply used a "slinger" lubrication system. The connecting rod ends had scuppers to fling the oil from the crankcase sump area throughout the engine.