Cruising my email this morning led to a trip down the rabbit hole.

I started with an article on a one-off Nissan Fairlady Z prototype, which led to another article about a Fairlady Z432R, which led to another on how a car differential works. The article is fairly short, but it includes a video from 1937 illustrating the concepts used in developing the modern diff, from the most basic representation (three sticks of wood) to the modern low-mount gear setup.

As a car guy/engineer/nerd, I found it fascinating. Enjoy:



Direct YouTube link

That was a great video, thanks for posting.

Great effort put into creating simple visualizations and progressing to the complete gear systems.

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That’s pretty cool. Now if they could just figure out how to get cars to make right angle turns.

Back in the day, these shorts would be run nonstop before, between, and after double features. After seeing the same film a few dozen times, a few of the kids would think of mechanical problems to solve. And become great engineers.

My first two trucks were 2WD but with no locking differential. So they were 1WD. In particular, I know the little one never once got stuck. Curb weight of about 3,050 pounds, 116HP, maximum capacity 1600 lbs. Although picking up shredded root mulch, the yard Jamaican got a kick out of dumping a ton into the truck, hoping he'd get to see the tires blow out. The second, a little heavier, might have wanted a little rocking back and forth, but also never got stuck.

I use this video in my training of associates at my company.

The differential gearset in the rear axle hasn't changed much in many decades. I point this out with a cutaway drawing from the 30s next to a cutaway drawing from the 2010s. The class members see both the ingenuity of the axle and the nearly static design.

With e-vehicles, fast approaching, the lubricant for axles may become obsolete, along with these hypoid gear "ring and pinion" axles. But, the differential gearset found in-between the left and right tires will likely live for a long time.

I remember building a differential out of Legos.

Took forever. That was one of a few things that was never taken apart.