The photo shows the internal mechanism: the L-shaped handle has a gear rack, which spins the white step-up gear, which in turn spins the flywheel on which is mounted both a centrifugal clutch (to allow freewheeling after the lever stops its travel and then returns) and a dark grey magnet, seen on the lower left. The magnet induces an electric current as it spins around the red copper winding, seen on the lower right. The current from the copper winding flows through the filament of an incandescent light bulb (not shown), giving off light. An L-shaped spring returns the handle to its original position after each engagement.