How a differential gear works (1937) [video] (opens in new tab)

(youtube.com)

391 pointsedferda11y ago55 comments

55 comments

Wow, that was a fantastic video. I could understand it easily only because they iteratively added complexity to the models. It's amazing how well they have made the tutorial for the layman.

Thanks a lot for sharing.

wickawic11y ago

If you liked that, you might like this similar video about how a mechanical watch works:

http://www.youtube.com/watch?feature=player_detailpage&v=508...

journeeman11y ago

Enjoyed watching it. Thanks. :-)

mutagen11y ago

Nice to follow that with this short video illustrating how one type of locking differential works to eliminate some of the disadvantages of an open differential.

https://www.youtube.com/watch?v=MCxqUJCZGNU

pkulak11y ago

So, one wheel starts spinning, and then, at a certain speed, it gets immediately locked into the other wheel which isn't moving at all? How does that not blow up the entire differential?

draker11y ago

For manually operated lockers the axle shafts have to be moving at the same speed or with very little difference in speed to be engaged.

>Only engage the Eaton ELocker™ differential while the vehicle is stationary or operating at speeds of 3 mph or less with minimal wheel slippage.

This specific locker (Eaton G80) is self-engaging up to a set speed which is intended to prevent this from happening, though it has been known to occur.

>The G80 can be very effective when used within its limitations. However its very design can lead it to failure. It requires a certain amount of speed difference between both rear wheels to operate. Basically more slip than you would ever encounter going around a turn, but it will not lock at speeds above roughly 20-30mph. This it where it earned the name "gov-lock". It has a speed governor that operates off centrifugal force inside to govern locking.

When it locks, it locks hard. Imagine one tire sitting still, and suddenly being launched to a speed of 20-25mph. That takes a great deal of force and puts a lot of strain on internals. They have a tendency to break with no warning.

Page also has photos of one that has failed.

http://www.ar15.com/forums/t_1_134/1250761_g80_differential_...

bri3d11y ago

With a hard-locking differential ("lockers", generally used off-road), engagement while one wheel is spinning is ill-advised. They're generally toggled on at low/zero speed by the operator in anticipation of a traction-loss situation.

The variety of differential which does not immediately lock one wheel into another is http://en.wikipedia.org/wiki/Limited-slip_differential .

1 more reply

bithush11y ago

I use this video quite often to show an example of one of the best educational videos I have ever seen. The language, presentation, use of graphics (impressive for the time) and demonstrations is just superb.

Yahivin11y ago

I like how they start ghost riding the whip at 8:45 https://www.youtube.com/watch?v=K4JhruinbWc#t=519

mxfh11y ago

Around the Corner (1937)

Producer: Handy (Jam) Organization ☞

Sponsor: Chevrolet Division, General Motors Corporation

Probably the source of this re-encode, with significantly less artifacts, on archive.org: https://archive.org/details/Aroundth1937

☞ Named after Jam Handy: https://en.wikipedia.org/wiki/Jam_Handy

spiritplumber11y ago

If you like videos like this, check out Retrotechtacular on Hackaday. They have a series on mechanical firing computers on navy ship that is nothing short of mech-eng porn, and I mean the classy kind.

k2enemy11y ago

That was amazing, thanks. I found the integrator and multiplier especially simple and clever.

Here is a link to a youtube playlist: https://www.youtube.com/user/navyreviewer/videos?query=mecha...

rootbear11y ago

I watched that whole series a year ago and was fascinated. I believe it has been posted here before but it's worth repeating.

reckoner1311y ago

My favorite: Wave Behavior from Bell Labs: https://www.youtube.com/watch?v=DovunOxlY1k

analog3111y ago

Excellent use of graphics, created in the age before computer graphics.

hughlomas11y ago

A World War 2 training video for evading flak cannon fire is one of the best examples of graphical information presentation that I've seen. https://www.youtube.com/watch?v=qP_-WUMi-nw

It features smoothly animated and highly functional designs as well as overlaying graphics on real footage to achieve a fashion of "augmented reality". The production quality is astounding and it is amazing to think that it was produced in the 40s. The entire video is an inspiring example of conveying information.

joshontheweb11y ago

That was really interesting. I never knew there was this kind of strategy behind flak evasion. Man, must have taken some stones to do a bomber mission. I knew an old timer that flew bombers in WW2 and he said towards the end of the war the germans were running out of metal and all sorts of things were used as flak. He said nuts and bolts were pretty common. He'd find them embedded inside the cabin after close flak fire. Pretty scary to think that your end might come from a washer.

1 more reply

jonesdc11y ago

Thank you for posting this.

rahulmax11y ago

Wow! Amazing.

There's another video from 1949 about 'How a Watch Works' — http://www.youtube.com/watch?v=508-rmdY4jQ

draker11y ago

I had not seen this particular video but have seen the "How a manual transmission works" from the same series.

https://www.youtube.com/watch?v=aAWxZRuBXtw

JasuM11y ago

An interesting mechanism using differential gears, doubling the speed while only using gears of the same size:

http://507movements.com/mm_226.html

nopar811y ago

The way the teaching was sequential really made it an understandable to a layman like myself.

petercooper11y ago

There's a chap who collects tons of videos like this on YouTube. He was mentioned on MetaFilter the other day: http://www.metafilter.com/143903/Do-you-like-vintage-trainin...

Or you can find his channel direct on https://www.youtube.com/user/webdev17/videos

blt11y ago

This is the best technical education video I've ever seen. If all information were available in such an easy to understand form, the world would be full of geniuses.

The level of effort is astounding. The "support" part holding the spokes looks cast. They couldn't have possibly cast that part specifically for this video... could they?

niels_olson11y ago

casting one-offs with a disposable form (wax, styrofoam) isn't particularly difficult or expensive. They use big basins full of super-fine sand: a great insulator and the grains are too tightly packed for the liquid metal to flow into the tiny spaces between them. We used to do it in high school shop class.

haphazardeous11y ago

Brilliant video. It's definitely a lot better to see the basic principles and evolution of those principles in action.

charlieok11y ago

I remember reading through David Macaulay's “The Way Things Work” as a kid, soaking up the illustrations until I understood each one. It was life-changing. However, I remember having trouble with one page in particular -- the one describing differential gears. Of course, video would probably have helped a lot :)

hsshah11y ago

I remember seeing this a while back and realizing I learned more from this video than I learned in class during my college course. Amazing production value. We should properly catalog such gems so that students and even professors can use these to teach (instead of attempting to reinvent the wheel)

VLM11y ago

I'd like to see a Torsen gearcase. Strange little things, they look like pepper grinders.

amenghra11y ago

I remember building lego cars which had a differential: http://groups.csail.mit.edu/drl/courses/cs54-2001s/images/le...

clebio11y ago

The actual explanation doesn't start until about 2 minutes in: https://www.youtube.com/watch?v=K4JhruinbWc#t=110

charlysisto11y ago

I was generally not bad at physics but I remember not getting my head around this one...

What a great lesson for decoupling systems. I wonder what's the software equivalent in design pattern land. The facade maybe ?

noblethrasher11y ago

Not sure about a corresponding design pattern, but the content neatly maps (no pun intended) to function composition.

tapatio11y ago

I never really got my head around electricity and magnetism. That stuff is very abstract.

leeoniya11y ago

some may also enjoy a 3d-printed triple gear

https://www.youtube.com/watch?v=I9IBQVHFeQs

wmeredith11y ago

Does this have any possible practical applications? Or is it just cool?

jonmrodriguez11y ago

Is it possible to create a "negative differential gear" that puts more torque into the wheel that is stuck? (in the hopes of forcing it unstuck)

birdmanjeremy11y ago

Yes. You are referring to a locking differential, of which there are several types. Some use clutch plates, and will work even if one wheel has no traction at all, others use more complex gearing and can transfer torque from one to another at some multiple (called a Torsen Differential) and cannot drive when one wheel is completely unloaded.

jonmrodriguez11y ago

Awesome, thank you!

franciscop11y ago

It is just too awkward that I learned how they work with the same video last year, still better than my University's current presentations

joeblau11y ago

Differential -- the most misused word in sports. The video is a great explanation about the automobile version.

sreejithr11y ago

I'd have loved it if these guys had made a video on fly wheels. Dying to know more about those.

gradstudent11y ago

@edferda: props for posting this; the pedagogy here is just terrific!

1 more reply

sisar11y ago

Any idea for what purpose was this video originally made?

smilefreak11y ago

I guessed some of the next steps, and considering I have the automobilic knowledge of the ancient greeks, that was pretty impressive.

An education in how to present to a lay audience.

mickcartwright11y ago

love the clarity, simplicity and enunciation

nikant11y ago

Great Video:)

spacefight11y ago

Best spent 8minutes today, thanks!

thebladerunner11y ago

Interesting

__database__11y ago

Amazing!

Animats11y ago

We know. I put a link to that video (to the Internet Archive, not YouTube) on Wikipedia years ago.

There's a whole series of Chevrolet films from the Jam Handy organization at the Internet Archive. "Take it Easy", "Spring Harmony" and "Shockproof" cover how auto suspensions work. "Facts on Friction", "Hydraulics" and "What stops them" explain brakes. "Head on" and "No Ghosts" - auto frames. "Water Boy" - cooling. "Free Air" - carburetor. There's more.

cipherzero11y ago

I had never seen this, so i appreciate the link. Is there any similar video for a limited slip differential?

function_seven11y ago

Here's a good start. Alter search query to taste.

https://archive.org/search.php?query=creator%3A%22Handy%20%2...

j / k navigate · click thread line to collapse

55 comments

journeeman11y ago

Wow, that was a fantastic video. I could understand it easily only because they iteratively added complexity to the models. It's amazing how well they have made the tutorial for the layman.

Thanks a lot for sharing.

wickawic11y ago

If you liked that, you might like this similar video about how a mechanical watch works:

http://www.youtube.com/watch?feature=player_detailpage&v=508...

journeeman11y ago

Enjoyed watching it. Thanks. :-)

mutagen11y ago

Nice to follow that with this short video illustrating how one type of locking differential works to eliminate some of the disadvantages of an open differential.

https://www.youtube.com/watch?v=MCxqUJCZGNU

pkulak11y ago

So, one wheel starts spinning, and then, at a certain speed, it gets immediately locked into the other wheel which isn't moving at all? How does that not blow up the entire differential?

draker11y ago

For manually operated lockers the axle shafts have to be moving at the same speed or with very little difference in speed to be engaged.

>Only engage the Eaton ELocker™ differential while the vehicle is stationary or operating at speeds of 3 mph or less with minimal wheel slippage.

This specific locker (Eaton G80) is self-engaging up to a set speed which is intended to prevent this from happening, though it has been known to occur.

Page also has photos of one that has failed.

http://www.ar15.com/forums/t_1_134/1250761_g80_differential_...

bri3d11y ago

The variety of differential which does not immediately lock one wheel into another is http://en.wikipedia.org/wiki/Limited-slip_differential .

1 more reply

bithush11y ago

Yahivin11y ago

I like how they start ghost riding the whip at 8:45 https://www.youtube.com/watch?v=K4JhruinbWc#t=519

mxfh11y ago

Around the Corner (1937)

Producer: Handy (Jam) Organization ☞

Sponsor: Chevrolet Division, General Motors Corporation

Probably the source of this re-encode, with significantly less artifacts, on archive.org: https://archive.org/details/Aroundth1937

☞ Named after Jam Handy: https://en.wikipedia.org/wiki/Jam_Handy

spiritplumber11y ago

k2enemy11y ago

That was amazing, thanks. I found the integrator and multiplier especially simple and clever.

Here is a link to a youtube playlist: https://www.youtube.com/user/navyreviewer/videos?query=mecha...

rootbear11y ago

I watched that whole series a year ago and was fascinated. I believe it has been posted here before but it's worth repeating.

reckoner1311y ago

My favorite: Wave Behavior from Bell Labs: https://www.youtube.com/watch?v=DovunOxlY1k

analog3111y ago

Excellent use of graphics, created in the age before computer graphics.

hughlomas11y ago

A World War 2 training video for evading flak cannon fire is one of the best examples of graphical information presentation that I've seen. https://www.youtube.com/watch?v=qP_-WUMi-nw

joshontheweb11y ago

1 more reply

jonesdc11y ago

Thank you for posting this.

rahulmax11y ago

Wow! Amazing.

There's another video from 1949 about 'How a Watch Works' — http://www.youtube.com/watch?v=508-rmdY4jQ

draker11y ago

I had not seen this particular video but have seen the "How a manual transmission works" from the same series.

https://www.youtube.com/watch?v=aAWxZRuBXtw

JasuM11y ago

An interesting mechanism using differential gears, doubling the speed while only using gears of the same size:

http://507movements.com/mm_226.html

nopar811y ago

The way the teaching was sequential really made it an understandable to a layman like myself.

petercooper11y ago

There's a chap who collects tons of videos like this on YouTube. He was mentioned on MetaFilter the other day: http://www.metafilter.com/143903/Do-you-like-vintage-trainin...

Or you can find his channel direct on https://www.youtube.com/user/webdev17/videos

blt11y ago

This is the best technical education video I've ever seen. If all information were available in such an easy to understand form, the world would be full of geniuses.

The level of effort is astounding. The "support" part holding the spokes looks cast. They couldn't have possibly cast that part specifically for this video... could they?

niels_olson11y ago

haphazardeous11y ago

Brilliant video. It's definitely a lot better to see the basic principles and evolution of those principles in action.

charlieok11y ago

hsshah11y ago

VLM11y ago

I'd like to see a Torsen gearcase. Strange little things, they look like pepper grinders.

amenghra11y ago

I remember building lego cars which had a differential: http://groups.csail.mit.edu/drl/courses/cs54-2001s/images/le...

clebio11y ago

The actual explanation doesn't start until about 2 minutes in: https://www.youtube.com/watch?v=K4JhruinbWc#t=110

charlysisto11y ago

I was generally not bad at physics but I remember not getting my head around this one...

What a great lesson for decoupling systems. I wonder what's the software equivalent in design pattern land. The facade maybe ?

noblethrasher11y ago

Not sure about a corresponding design pattern, but the content neatly maps (no pun intended) to function composition.

tapatio11y ago

I never really got my head around electricity and magnetism. That stuff is very abstract.

leeoniya11y ago

some may also enjoy a 3d-printed triple gear

https://www.youtube.com/watch?v=I9IBQVHFeQs

wmeredith11y ago

Does this have any possible practical applications? Or is it just cool?

jonmrodriguez11y ago

Is it possible to create a "negative differential gear" that puts more torque into the wheel that is stuck? (in the hopes of forcing it unstuck)

birdmanjeremy11y ago

jonmrodriguez11y ago

Awesome, thank you!

franciscop11y ago

It is just too awkward that I learned how they work with the same video last year, still better than my University's current presentations

joeblau11y ago

Differential -- the most misused word in sports. The video is a great explanation about the automobile version.

sreejithr11y ago

I'd have loved it if these guys had made a video on fly wheels. Dying to know more about those.

gradstudent11y ago

@edferda: props for posting this; the pedagogy here is just terrific!

1 more reply

sisar11y ago

Any idea for what purpose was this video originally made?

smilefreak11y ago

I guessed some of the next steps, and considering I have the automobilic knowledge of the ancient greeks, that was pretty impressive.

An education in how to present to a lay audience.

mickcartwright11y ago

love the clarity, simplicity and enunciation

nikant11y ago

Great Video:)

spacefight11y ago

Best spent 8minutes today, thanks!

thebladerunner11y ago

Interesting

__database__11y ago

Amazing!

Animats11y ago

We know. I put a link to that video (to the Internet Archive, not YouTube) on Wikipedia years ago.

cipherzero11y ago

I had never seen this, so i appreciate the link. Is there any similar video for a limited slip differential?

function_seven11y ago

Here's a good start. Alter search query to taste.

https://archive.org/search.php?query=creator%3A%22Handy%20%2...

j / k navigate · click thread line to collapse