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View Full Version : How a differential gear works



Canoeyawl
08-11-2009, 11:48 AM
http://www.youtube.com/watch?v=K4JhruinbWc&feature=related

David W Pratt
08-11-2009, 02:43 PM
Thank you, for about half a century I have wondered how a differential works.
If Chevy were still making films like that, I'd feel better about their bailout.

Dan McCosh
08-11-2009, 02:49 PM
Thank you, for about half a century I have wondered how a differential works.
If Chevy were still making films like that, I'd feel better about their bailout.

That is the work of the old Jam Handy industrial film group--at one time one of the largest film production houses in the country, with studios on West Grand Blvd. in Detroit. Not sure, but I think Marilyn Monroe may have started there.

Paul Pless
08-11-2009, 02:52 PM
Wonder if they did a motorcycle demonstration of how a planetary gearbox works. :D

Dan McCosh
08-11-2009, 02:58 PM
Marilyn started in a film sponsored by General Motors, but it didn't involve Jam Handy.

Canoeyawl
08-11-2009, 05:10 PM
Bump -
I thought it was a pretty darn good job.
It reminded me of the corespondence courses taught during the war my father fought in.
I grew up with those books and courses and probably learned more than I ever did in public school.

Phillip Allen
08-11-2009, 05:28 PM
now that we have bailed them out...it costs me $100 for a spare key for my truck...must be plannin on payin us back quicker

MiddleAgesMan
08-11-2009, 05:29 PM
Marilyn started in a film sponsored by General Motors, but it didn't involve Jam Handy.

Marilyn Chambers? :)

I, too, have always wondered how a differential works. This video made it very clear. Thanks, Canoe!

Phillip Allen
08-11-2009, 05:56 PM
"Works fine, lasts a long time, fails safe and drains to the bilge"

paladin
08-11-2009, 06:09 PM
Spartan Aviation used some of the old films like that to show the workings of turbochargers, propeller feathering gearboxes etc.

Peter Malcolm Jardine
08-11-2009, 06:23 PM
What a great old video..

Can I have one of the motorcycles?:cool:

PeterSibley
08-11-2009, 06:27 PM
Thanks , a great explanation .

John of Phoenix
08-11-2009, 06:37 PM
Thanks, that was fascinating. Very well done.

I'd swear the narrator was in some Army training films in the 60's thru the 80's.

Peter Malcolm Jardine
08-11-2009, 07:55 PM
I have no need to check my health care... It's there when I need it, in a timely fashion, with no personal cost. Thanks for asking.

Bob (oh, THAT Bob)
08-11-2009, 11:15 PM
Standard 'diffs are relatively simple for the mechanically inclined. Now, pull apart a Detroit Locker or a Torsen and it gets a little weird. Yeah, differential action is great around turns when both tires have traction. The video didn't cover when one wheel loses traction and the drawbacks of an "open" differential.

And for those of you wondering, all of the above has nothing to do with differential equations. "You have a water tank of X liters capacity. Fresh water is entering the tank at a rate of Y liters per second at 20 degrees celsius. Salt is entering the tank at rate Z grams per second and dissolving at the rate of R grams per second. The salination limit of the water is H grams of salt per liter of water at 20 degrees celsius. Salinated water is leaving the tank at the rate of L liters per second. At time T seconds, how much salt is left undisolved in the tank? Show your work." :D

S B
08-11-2009, 11:35 PM
Standard 'diffs are relatively simple for the mechanically inclined. Now, pull apart a Detroit Locker or a Torsen and it gets a little weird. Yeah, differential action is great around turns when both tires have traction. The video didn't cover when one wheel loses traction and the drawbacks of an "open" differential.

And for those of you wondering, all of the above has nothing to do with differential equations. "You have a water tank of X liters capacity. Fresh water is entering the tank at a rate of Y liters per second at 20 degrees celsius. Salt is entering the tank at rate Z grams per second and dissolving at the rate of R grams per second. The salination limit of the water is H grams of salt per liter of water at 20 degrees celsius. Salinated water is leaving the tank at the rate of L liters per second. At time T seconds, how much salt is left undisolved in the tank? Show your work." :D
How much undisolved salt is leaving the tank due to turbulance?

Bob (oh, THAT Bob)
08-11-2009, 11:39 PM
How much undisolved salt is leaving the tank due to turbulance?

LOL. A good ficticious example by memory, but these days I can't even remember the problem complete, much less the solution. :D

The most long-winded problems of any class I ever took. I've had much harder problems that could be described in one sentence.

boylesboats
08-11-2009, 11:41 PM
ever notice train's (railroad) wheels?

S B
08-11-2009, 11:44 PM
LOL. A good ficticious example by memory, but these days I can't even remember the problem complete, much less the solution. :D

The most long-winded problems of any class I ever took. I've had much harder problems that could be described in one sentence.
Had a lot of classes, way back when, where expanding the problem was the game, I still enjoy it.:D

Bob (oh, THAT Bob)
08-11-2009, 11:49 PM
Had a lot of classes, way back when, where expanding the problem was the game, I still enjoy it.:D

"Assume ideal conditions. Instantaneous mixing. Standard temperature and pressure. No friction. No aerodynamic drag. Neglect entropy. All flow is laminar.":D

Oh for the days.

boylesboats
08-12-2009, 12:06 AM
Standard 'diffs are relatively simple for the mechanically inclined. Now, pull apart a Detroit Locker or a Torsen and it gets a little weird. Yeah, differential action is great around turns when both tires have traction. The video didn't cover when one wheel loses traction and the drawbacks of an "open" differential.

Those Detroit Locker are noisy at time.. I had one before going bad... At every corners "BANG"...:eek: Got rid of it and installed limited slip... It much quieter, tires and driveline last a little longer

S B
08-12-2009, 12:21 AM
"Assume ideal conditions. Instantaneous mixing. Standard temperature and pressure. No friction. No aerodynamic drag. Neglect entropy. All flow is laminar.":D

Oh for the days.
All the salt that didn't disolve, The application of abstract quantities makes the assumption that an excess of salt had been added, because a negative amount of salt left, voids the equasion.

Andrew Craig-Bennett
08-12-2009, 12:59 AM
Nice film. As a schoolboy I watched a lot of films like that made by ICI and the Cental Electricity Generating Board and I am still pretty sound on how plastics, detergents and nuclear power stations are made.

However, like most English boys of my generation, I found out how a differential gearbox works by making one with my Meccano set!

paladin
08-12-2009, 01:45 AM
Is Meccano anything like Tinker Toys?

PeterSibley
08-12-2009, 01:52 AM
This is Meccano ,
http://cgi.ebay.com.au/QUANTITY-OF-OLD-MECCANO-x-5-Kgs_W0QQitemZ320408553835QQcmdZViewItemQQptZAU_Toy s_Hobbies_Building_Toys?hash=item4a99d6896b&_trksid=p3286.c0.m14

I can't believe American kids were deprived of it .... the best toy ever !

boylesboats
08-12-2009, 02:35 AM
This is Meccano ,
http://cgi.ebay.com.au/QUANTITY-OF-OLD-MECCANO-x-5-Kgs_W0QQitemZ320408553835QQcmdZViewItemQQptZAU_Toy s_Hobbies_Building_Toys?hash=item4a99d6896b&_trksid=p3286.c0.m14

I can't believe American kids were deprived of it .... the best toy ever !

Ya know... I use to have a "Erector Set" when I was a kid... I don't know if they are discontinued in USA.. Probably because of choking hazard and Tetanus risks..

Man, I spend hours building and playing with it.. Makes parent happy, it kept me busy..

P.I. Stazzer-Newt
08-12-2009, 02:38 AM
....
I can't believe American kids were deprived of it .... the best toy ever !

You'd not believe what people do with it....
http://www.aburkitt.net/meccano/mmc2008/

http://www.aburkitt.net/meccano/mmc2008/100_3177.jpg

The strange thing is that the threads appear to be a unique setup.... but replicated in toolrooms in Starrett and Rolls Royce.

boylesboats
08-12-2009, 02:47 AM
You'd not believe what people do with it....
http://www.aburkitt.net/meccano/mmc2008/

http://www.aburkitt.net/meccano/mmc2008/100_3177.jpg

The strange thing is that the threads appear to be a unique setup.... but replicated in toolrooms in Starrett and Rolls Royce.

wow.... that's some work.. not only models, but a functional piece of work...

PeterSibley
08-12-2009, 02:58 AM
When I was a kid the most popular boy was the one whose Dad had bought a tea chest full of Meccano at an auction ! Bliss .

It wasn't me but he lived close by .

P.L.Lenihan
08-12-2009, 03:41 AM
Ah..... Meccano.....what sweet memories of a perfectly wonderful childhood that brought up! Many were the Christmasses when that large flat box,feeling rather heavy, was a sure sign another Meccano set had arrived no matter how well wrapped up! The best part was that it had my name on it and not my brothers' :)


Thanks Andrew!

Cheers!


Peter

Dan McCosh
08-12-2009, 04:14 AM
This is Meccano ,
http://cgi.ebay.com.au/QUANTITY-OF-OLD-MECCANO-x-5-Kgs_W0QQitemZ320408553835QQcmdZViewItemQQptZAU_Toy s_Hobbies_Building_Toys?hash=item4a99d6896b&_trksid=p3286.c0.m14

I can't believe American kids were deprived of it .... the best toy ever !

The American equivalent was the Erector Set, which came out about 10 years later. The two more or less merged later on. Erector sets were what forced vacuum makers to design the rug beater to pick up nuts and bolts.

Ron Williamson
08-12-2009, 05:26 AM
Meccano is great,but from the responses here, "Erector" is the more appropriate name.
R

Phillip Allen
08-12-2009, 06:34 AM
MMike posts a pic of an erector set from time to time

phiil
08-12-2009, 09:26 AM
ever notice train's (railroad) wheels?

Train wheels are fixed to a solid axle. There is a slight taper to the wheel surface. When rounding a curve, centrifugal force moves the wheels to the outside of the rails, so that the outer wheel is riding on a larger diameter than the inner one, hence covering a longer distance with each revolution. Pretty slick, but only practical for huge curve radii.

Dan McCosh
08-12-2009, 09:37 AM
Train wheels are fixed to a solid axle. There is a slight taper to the wheel surface. When rounding a curve, centrifugal force moves the wheels to the outside of the rails, so that the outer wheel is riding on a larger diameter than the inner one, hence covering a longer distance with each revolution. Pretty slick, but only practical for huge curve radii.

interesting.I thought the taper was there mainly to keep the wheels centered on the rails without scrubbing the wheel flanges.

Peter Malcolm Jardine
08-12-2009, 09:56 AM
I still have my dad's meccano set, complete with the electric motor for the crane and stuff. I loved that toy, it was awesome... all brass nuts and bolts... My dad's set would be late 30's I guess..

Beowolf
08-12-2009, 10:43 AM
When I was a kid, I had the Lego Auto Chassis (http://ericalbrecht.com/technic/8860.html). Taught me how rack and pinion steering, pistons and crankshaft, and universal joints work. The drivetrain also featured a three-speed transmission and a rear differential, and though I could assemble them and make the needed adjustments to make them work smoothly, I wouldn't go so far as to say that I understood them...

Lego Auto Chassis (http://www.youtube.com/watch?v=dTH9OT660Qg) In the video, it appears that the car is kept in high gear for all the demos.

BTW: The motorcycles in the opening sequence of that Chevy video are better than the Ohio State marching band! Very cool.

boylesboats
08-18-2009, 04:08 PM
Train wheels are fixed to a solid axle. There is a slight taper to the wheel surface. When rounding a curve, centrifugal force moves the wheels to the outside of the rails, so that the outer wheel is riding on a larger diameter than the inner one, hence covering a longer distance with each revolution. Pretty slick, but only practical for huge curve radii.

very true.... if it wasn't for the flange, train would've flew off the track 'round the bend...

Captain Blight
08-18-2009, 04:27 PM
"You have a water tank of X liters capacity. Fresh water is entering the tank at a rate of Y liters per second at 20 degrees celsius. Salt is entering the tank at rate Z grams per second and dissolving at the rate of R grams per second. The salination limit of the water is H grams of salt per liter of water at 20 degrees celsius. Salinated water is leaving the tank at the rate of L liters per second. At time T seconds, how much salt is left undisolved in the tank? Show your work." :DEnglish major's answer: "some."


Optimist: "The glass is half full."

Pessimist: "The glass is half empty."

Engineer: "The glass is twice as big as necessary."