
How Differential Steering Works (1937) [video] - Phithagoras
https://www.youtube.com/watch?v=yYAw79386WI&feature=youtu.be
======
dclowd9901
I wish, in school, teachers would have taught us things like this, how gears
are just concurrent levers, how cams introduce asynchronicity to an operation.
This is stuff I only started learning from working on and learning about cars.

I remember even when I was in school (a good time ago now), they were already
killing off shop classes and the like. How sad that schools couldn't see what
values classes like that have in critical problem solving.

~~~
rdtsc
I was in a Soviet school system (it was towards the end). And somehow we had a
really fun shop class. We did stuff with electricity. Had a lathe, wood and
metal. Remember making our own hammers. Learned to use a coping saw, a wood
plane. School was remodeling so they let do demo work. Totally unsafe but
loads of fun. Didn't learn about cars much though.

We had so many things there that would be considered unsafe and dangerous
these days for US kids here I'd imagine. Same thing with chemistry
experiments. Though interestingly there more encouragement here to play
contact sports like football which leads to concussions and injuries.

~~~
eternalban
> Though interestingly there more encouragement here to play contact sports
> like football which leads to concussions and injuries.

Better brain dead than Red ;)

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Animats
It's part of a series for Chevrolet by Jam Handy. The Internet Archive has
many more of them. A few:

"Streamlines":
[https://archive.org/details/0142_Streamlines_M7960_09_08_44_...](https://archive.org/details/0142_Streamlines_M7960_09_08_44_00)

"Down the Gasoline Trail":
[https://archive.org/details/0542_Down_the_Gasoline_Trail_06_...](https://archive.org/details/0542_Down_the_Gasoline_Trail_06_12_55_14)

"What Stops Them":
[https://archive.org/details/0797_What_Stops_Them_M6850_06_27...](https://archive.org/details/0797_What_Stops_Them_M6850_06_27_31_00)

"No Ghosts":
[https://archive.org/details/0797_No_Ghosts_M7860_06_16_49_00](https://archive.org/details/0797_No_Ghosts_M7860_06_16_49_00)

They were really trying to get across how a car works.

~~~
Stratoscope
Jam Handy was a national treasure. Another of my favorites from them is "Back
of the Mike", a look at how radio dramas and their sound effects were
produced:

[https://archive.org/details/Backofth1938](https://archive.org/details/Backofth1938)

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eosrei
The differential stops sliding of the rear wheels, Ackermann Steering Geometry
stops sliding of the front turn wheels:
[https://en.wikipedia.org/wiki/Ackermann_steering_geometry](https://en.wikipedia.org/wiki/Ackermann_steering_geometry)
Tires slide during sharp low speed turns on some vehicles due to lowering,
lifts, tire changes and even production defects.

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amenghra
You can buy a Lego differential gear to keep as a desk toy:
[https://www.amazon.com/LEGO-Technic-Differential-
connectors-...](https://www.amazon.com/LEGO-Technic-Differential-connectors-
pieces/dp/B01DC74EA4)

~~~
llsf
Omg, great! I did it with lego technic back in early 90's (without those new
fancy gears) when the simplicity and power of the differential struck me :)
The simplicity of the differential is just beautiful !

~~~
glandium
FWIW, there was a differential in the lego technic 8865 Test Car from 1988:
[http://www.technicopedia.com/8865.html](http://www.technicopedia.com/8865.html)
I think this was the first model with a differential. At least, that's what
introduced me to it.

~~~
amenghra
The 8865 was the first model with a differential. I wrote about being an adult
fan of lego[1]. Over time, I purchased all 7 "super cars" that Lego
manufactured. One of each car was sold every ~5 years and each one improved
the previous generation's already amazing gears, steering, etc.

Fun fact: who is the largest manufacturer of tires in the world?

[1] [https://www.facebook.com/notes/alok-menghrajani/afol-
adult-f...](https://www.facebook.com/notes/alok-menghrajani/afol-adult-fan-of-
lego/10153486258678947)

~~~
glandium
You typoed, you meant the 8860 :) I actually saw it in a catalogue back in the
day, but I hadn't realized it had a differential. It was also already old when
I was into Lego technic in my teens, at which time the 8865 was new and shiny.

Edit: It also seems both the 8860 and the 8865 were using the same parts for
the differential.

~~~
amenghra
Yes, 8860. A few years before the 8865.

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Analemma_
The training video for old Navy mechanical fire control computers is a similar
classic:
[https://www.youtube.com/watch?v=lr1uK24SND8](https://www.youtube.com/watch?v=lr1uK24SND8)

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epx
The nice thing is, a planetary gearset can do basically the same, and is the
building block of automatic gearboxes and Prius power distribution between
ICE, electric motogenerator and wheels.

~~~
THE_PUN_STOPS
Relevant and amazing link:
[http://eahart.com/prius/psd/](http://eahart.com/prius/psd/)

Did a project based around the Prius PSD in my Mechanical Dynamics and
Vibrations class. Very cool, really opened my mind to the power of gears.

~~~
derekp7
Also, a youtube demonstration:
[https://www.youtube.com/watch?v=dLNDGUISTYM](https://www.youtube.com/watch?v=dLNDGUISTYM)
(this is the Toyota eCVT), and a teardown of the Ford version:
[https://www.youtube.com/watch?v=hHU5xFOBcsU](https://www.youtube.com/watch?v=hHU5xFOBcsU)

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polote
Same video over and over again
[https://hn.algolia.com/?query=differential%20gear&sort=byPop...](https://hn.algolia.com/?query=differential%20gear&sort=byPopularity&prefix=false&page=0&dateRange=all&type=story)

~~~
crispyambulance
Hey, its the first time I saw it. Nice stuff. Should be recycled.

~~~
thatswrong0
Wait you didn't see this when it was posted the first time 8 years ago? Then
you clearly shouldn't get the chance to see it again.

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leoc
There's a flood of these mid-century instructional videos appearing the Web
just over the past couple of years, right up to the present week. (I quite
like the Jeff Quitney account on YT [https://www.youtube.com/channel/UCM-
kjdrQge9AACfB3MSRyrg](https://www.youtube.com/channel/UCM-
kjdrQge9AACfB3MSRyrg) , a fairly nice firehose of videos in good quality,
which even seems to have some that aren't on the IA.) One thing I've taken
from watching them is that US accents seem to have changed a lot in the past
few decades: you hear presenters with accents that afaict don't seem to exist
anymore. Jam Handy's is one, but there are more dramatic examples.

~~~
michaelbuckbee
The TransAtlantic Accent! ->
[https://www.youtube.com/watch?v=Gpv_IkO_ZBU](https://www.youtube.com/watch?v=Gpv_IkO_ZBU)

~~~
leoc
But listen to how he pronounces the 'o's (in particular) in "and it couldn't
get a good enough grip on the road" and "both rear wheels to the engine"
[https://youtu.be/yYAw79386WI?t=164](https://youtu.be/yYAw79386WI?t=164) :
Handy surely didn't learn that from an elocution class teaching RP-lite. Is it
a trace of an Irish accent? a Scandinavian-American "Lutheran" accent?

~~~
janzer
To be clear, I'm pretty sure the narrator in these films is not Jam Handy.
There is an interview with Mr. Handy himself here
[https://www.youtube.com/watch?v=AlDdE3Q5BWM](https://www.youtube.com/watch?v=AlDdE3Q5BWM)

Possibly interesting sidenote, to this day a large number of the audio/visual
and staging companies in the Detroit area can trace their lineage back to the
Jam Handy Organization. Although I have a feeling we may now be a generation
far enough removed that many of them may no longer know it.

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csours
Jam Handy is under-appreciated in my opinion [0]. I wonder how videos like
this would be received today.

0\.
[https://en.wikipedia.org/wiki/Jam_Handy](https://en.wikipedia.org/wiki/Jam_Handy)

~~~
jerf
Ten years ago I also would have wondered. Now I know; there are a lot of fine
YouTube channels of a similar nature. It is certainly true that one must
filter through a lot of garbage to find them, but they are there. Different
topic, but here's just an example to get you started:
[https://www.youtube.com/watch?v=KfuARMCyTvg](https://www.youtube.com/watch?v=KfuARMCyTvg)

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gkya
I like how informative these videos are. Some more of these and I'd feel I
could make working toyish automobile. I wonder why we dont get this kind of
videos for our time's tech. Maybe computers and especially software are too
complex to represent like this?

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chb
I like how they ghost ride the whip at the end of the video.

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dsfyu404ed
Hopefully coming soon "Show HN: I wrote a bot to re-post highly up-voted
videos if they haven't been re-posted for a certain time period."

