It was popular in the early twentieth century for its simplicity of use when compared to completely handbook gearboxes of that time.  Therefore the output spins the moment For each and every two-thirds of the rotation in the engine. In case the engine is turning at 2000 rotations per minute https://gearboxauto54207.blue-blogs.com/41076680/gearbox-auto-can-be-fun-for-anyone