Newsham Engine circa 1730
Fig #3: Detail of "Double" Bow-tie Gears in Back of Engine.
This illustration shows an expanded view of the two magenta bow-tie gears in the back of the engine inside the Pump Housing. The magenta gear in front is connected to the treadles and translates the up down motion of the treadles to rotate the center metal shaft.
The magenta gear in back translates the rotating motion of the shaft to an up and down motion of the piston rods. The compressed air vessel sits inside the housing next to the gears and pistons.