Here we find a ZF9HP automatic box. It's one of the most complicated mechanical things you can imagine and was designed by battalions of very clever engineers in Friedrichshafen. They were aided by electricity, which enabled them to use very clever computers and CAD programs. It's so complex that only about three people in the world understand it all and fortunately one of them has described it here
Here by way of contrast we find a Napier Nomad turbocompound diesel aero engine. It was designed nearly seventy years ago by some British chaps using drawing boards, paper, pencil and slide rules. They were aided by electricity, which powered the lights. For all that it makes the 9HP seem the model of simplicity.