

Video explaining how a differential gear works - soundsop
http://www.youtube.com/watch?v=K4JhruinbWc#t=1m50s

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gchpaco
The part about this that I find the most interesting is the way it explains
how a differential can be thought up, rather than presenting it as some bolt
from the blue.

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elblanco
What an amazingly excellent video.

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regularfry
About the only thing that could have improved it would have been a Feynman
voice-over.

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InclinedPlane
This prompted me to search for Feynman videos on youtube. Sure enough, there
are many. This will probably cut into my productive time the next several
days.

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elblanco
Feynman has a way of doing that. I'm about 6 years into a Tuvan Throat Singing
Obsession because of him.

<http://www.youtube.com/watch?v=DY1pcEtHI_w>

Wait till about 20seconds in before you hear the most amazing thing in the
history of music.

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pkulak
This kind of planetary gear is used for a lot of other things too, like
Toyota's hybrid system. It's really good for any system where you want to
split power, but not torque. I've never heard it explained like this though.
Really great video.

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InclinedPlane
You'll notice though that a differential doesn't solve the problem of one of
the drive wheels not having any traction (mentioned early in the video as a
problem of one wheel drive cars). In that case the differential will spin the
wheel with no traction while not sending any power to the wheel that does have
traction (in the same manner as it would if you happened to be taking a very
sharp turn that left one of the wheels nearly stationary). An excellent video
otherwise, but I thought that was an odd aspect.

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Deestan
> In that case the differential will spin the wheel with no traction while not
> sending any power to the wheel that does have traction

Boy do I ever get reminded of this every winter. It's a shame that cars that
have the option to lock the differential gear are a lot more expensive.

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mhb
And for more on limited slip differential:

<http://en.wikipedia.org/wiki/Limited_slip_differential>

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Deestan
Thanks! Now I know what to look for. It seems the "electronic limited slip
differential system" is what I want, as my main trouble is getting out of icy
parking spots.

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ajross
Bah, humbug. Lazy young'uns. When _I_ was growing up, we didn't have no
youtube. We had to learn differential gears by actually _assembling_ one in a
RC car model kit.

Obligatory irony: it was this one:
<http://www.youtube.com/watch?v=7OCeKMHzEbQ>

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Splines
Do modern cars no longer lower the drive shaft as in this video? I haven't
really seen a sedan with a flat floor in the rear for some time (ever, in my
lifetime anyway). Is it just that the floors have been lowered so much that
you can't really lower the drive shaft any further?

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jcoby
modern cars are much lower than cars from the 30s. the driveshaft pretty much
has to be recessed into the body to give any useful ground clearance and to
protect the drive shaft from speed bumps and road hazards.

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dmarble
Did they seriously use Tinkertoys for that model? Sure looks like it! Awesome
explanation.

Reminds me of what used to be my favorite website to kill time but still learn
something: <http://howstuffworks.com>

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glhaynes
Fake. Check out the obvious mouse pointer UI being used at 07:28!

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glhaynes
I guess I should've used a smiley. :)

