How do Center Differentials Work? - The Viscous Coupling Controlled Epicyclic Centre Diff
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- čas přidán 10. 07. 2024
- Today we look at how center differentials work, and in particular the Fergusson Viscous Coupling Controlled Epicyclic Center Differential. This is an important part of an AWD driveline, as it allows relative motion between the front and rear axles, as well as limitind slip to prevent traction loss. Such a differential can also provide torque splitting/biasing.
- Auta a dopravní prostředky
It's like watching Ryan Gosling explain center diffs.
Faith in humanity restored. Thanks Kyle
Bro explained it better than my UCSD aerospace professors could. Hats off my man
This is legit my favorite youtube channel. Kyle you da real mvp.
Dang, thanks for the video! You are a great teacher and know how to break down complex ideas into their basic ideas REALLY well. Thanks for posting!!
This guy is great. Knows how to convey the relationship between structure and function. refreshing.
Thanks for the explanation! Some of the best in all of CZcams. I had to draw a diagram and calculate the transfer of forces, moments and speeds from gear to gear in order to finally figure it out. And my little research has led me to the same conclusion that you are talking about. Thank you very much again.
This is so great keep up the good work
Now I got it I must install MLD in rear and centre and LSD in front, thanks your explanation helped me make a sure and clear decision.
Awesome video! Cheers mate!
Thnx it was a really good vid bout the center differential,and very helpful 👌
Thanks for the Info Harry!
Very well explained you explained many complex concepts in a very simple way, thanks and kudos 👍.
Lovely, articulate, and easy to follow explanation of an essentially simple mechanical device that many, many people have tried and miserably failed to explain
I thoroughly enjoy your videos and channel and you have truly and properly given me the ability to garner infinitely more enjoyment out of my passion for Motorsports of all kinds - and not only 1:1 scale vehicles, but my love for the workings of my small scale RC addiction
Thank you for sharing your knowledge and giving legitimate effort to your teachings - you truly succeed as a concise, precise educator where so, so many post 30-45 minute videos that thoroughly fail and confuse the people who suffer through them, coming out of the other end with a lesser understanding of the subject matter than when they started
Cheers mate!
You just tuned my rally car. The moment it clicked in my head I let out an audible "Ohhhhhhhhh" 🤣
That's awesome, man. You're a f.. genius. I've been wondering about this since I was a little boy. It has driven me mad sometimes.
Oh dear. You blew up my brain. I need the kindergarten version lol.
You lost me at “hello.” Not your fault, dude! You are excellent. I’m just dense like that! Great channel by the way!
Does fwd or rwd have no centre diff?
damn good video.
Next video series. Aerodynamics of concept cars. One car you should check out is the srt tomahawk X,that thing has crazy active aerodynamics. And look at all the other vision gran tourismo cars as well.all the new ones now have active aerodynamics
This is my favorite CZcams channel. Can you explain to me hood vents and which ones are actually functional? I hear around town how some hood vents are functional and some aren't.
ernesto perez a lot of the functionality isnt just aero but cooling and reducing pressure under the hood
ThaNks kyle great job. So its 3 "lsds"? Nice!!
I have a learning disability (ADD) and the way you explained that, I totally followed everything you said and it legit made me excited. Thanks mate
Mckauley Culkin?
Can a center diff allow you to have a bigger rear wheel while having 4wd?
I have a question. If say my sequoia with 4hi engaged and center diff unlocked is in a situation where 2 front tires are on the ice and 2 rear tires are on a pavement - am I benefiting from having it on 4hi or is it better to have it on 2hi? The reason I’m asking is as far as I understand if I’m on 4hi and the center diff is unlocked I’ll spin the 2 front tires on ice while rear 2 tires will not and if I just switch it back to 2hi at least 1 rear tire will spin. (I know I have a center diff lock button but assuming I don’t want to use it). I just want to know if I got the concept right:)
big up from Romania the central differential on scenic rx4 can be converted to rwd
Yeah it kind of explained it I was just wondering about an '03 4Runner with the center diff lock whenever it has four wheel low four wheel high is it the same concept
Is the fluid in the coupler like a non newtonian fluid
What i wanna know is what will happen when i press that button when im moving forward and when im still why do i feel that the car is heavy and wont move ??
Is this the system AMC eagles used?
Automotive engineer here. Thanks for explaining this especially with the viscous coupling uses to transfer torque to the shaft with most traction. Definitely was hard to find out how it works. Also want to point out clutch packs are also used in lieu of viscous coupling although I don't know what is the advantage between the two
Clutch pack in my Subaru dif' is just the locker - works like a limited slip - auto locks. It's an open 2 pin dif' most of the time and just locks if there's loss of traction. So the clutch pack could be removed and it'd still work as an AWD on the road but I don't have the opportunity to try it.
Fantastic video! Could you also give a few examples of vehicles that have:
1) THIS (the one you explained) type of center diff. Also, in such vehicles if, say, any of the front wheels lose traction, will all of the power be sent to the rear wheels due to the viscous coupling/locking mechanism?
2) An always open center diff
3) Other forms of auto-locking center diffs.
Hi there, thanks for the video. I´m trying to understand how to correlate that to a simulation game and in that particular game, AWD center differentials are simulated using the following 2 codes:
CENTRE_RAMP_TORQUE=56
CENTRE_MAX_TORQUE=800
Numbers are probably in NM and this code was created to be used by an Alfa 155 DTM car, which was in fact a further development, by Abarth, of the Lancia Delta Integrale rallying series, which means that these 2 lines of code are meant to simulate the Fergusson Viscous Coupling Controlled Epicyclic Center Differential.
Can you help me figuring it out?
Cheers
Yeah, me too... on Dirt Rally. Could Kyle or anyone else give any more subtle info regarding how strong vs loose centre diff affects driving characteristics?
I'd be willing to bet the game is simulating the center diff as a clutch pack style diff based on those 2 parameters. With Max Torque being the the maximum torque the differential will transfer from the slipping side to the non slipping side and ramp torque being the amount of torque needed to fully engage the clutch packs. Look up a video on clutch pack LSD's. you can see the "ramp" they are referring to.
thank you Ryan Gosling
Were did you get that Lego car
Is a transfer case always locked then? Because my understanding is a transfer case with front a rear diff lock is fully locked.
A transfer case is always locked. However, if you don't have front and rear lockers, even that would spin the wheels that no traction and you'll be just sitting there. However, it's certainly better than an "open centre diff" AWD. 😊
I can't tell the difference between my two and buggies, and one has a center diff and one doesn't. Are you sure having a center diff is better ?
Depends on what you want from your vehicle. My mk2 Shogun has a centre diff and I can drive around on dry, sound road surface in 4wd.
My friend's L200 pickup doesn't have the centre diff, so he can only 4wd when on wet or loose road surface.
sorry mate could you repeat the part about the thing?
Really nice. Can u help me on how to calculate torque split between front and rear by knowing number of teeth and carrier radius? Give some reference link or a book to do so. And my next doubts is,If torque is different for front and rear what happene to speed as all wheel to spin same speed in straight normal condition.
"It's been used on cars like the Lancia Delta"
Best example
so this is variable velocity
it seems like they may not have a long life span on something like a toyota matrix
There is a little error there, the output shafts of a geared asymmetric torque split center differential spin at different rotational speeds when the car is cruising at a constant speed on a straight road with all wheels spinning at the same rate.
For example if the bias is 60 rear 40 front, the speed of the front shaft will be slower than the speed of the rear shaft, and in order to spin both axle's halfshafts at the same final speed, the gearing of the front diff will be different than the rear one, that is how the wheels spin at the same speed but get different torque levels.
It is like 2 bicycles, one in front of the other, tied together with a rigid connection, but the front one using the large pedal pinion and the small wheel pinion, and the rear one using the small pedal pinion and the large wheel pinion.
Both bikes spin their wheels at the same speed, but delivered torque is different due to the difference in gear selections.
You cannot transmit a different torque to the axles with a differential with rigid static internals.
The planet carrier, sun and ring gear must all rotate at different speeds to produce the torque bias
Later edit, my explanation is not valid for all the differential types, some of them,like a quattro crown gear center diff split torque with static internals, the tooth count differs and so differentiated leverage is applied to the front and rear output shafts, while they spin at the same speed.
The moving internals would create too much heat and mechanical drag to be used across all types of geared planetary differentials
This is not correct even for planetary diffs. A planetary differential transfers a set percentage of the torque to each shaft regardless of the speed of each shaft. You absolutely can transmit different torques through a rigid system. We can prove this by imagining if there was no center diff at all, and instead just a solid connection between the front and rear wheels. If we give the front wheels no traction and the rear wheels unlimited traction and attempt to accelerate, it is clear that nearly all the torque must go to the rear. Just because there is no relative motion of the gears, it does not erase their interactions with each other. A linkage with a mechanical advantage still exists between the two outputs of the diff that will cause a difference in transmitted torque at any speed.
Still confused
Who’s here Bc dirt rally lol
Viscous center differentials are not real center differentials. Pkease give us a true center differential that locks.
explaining this complex subject................with Lego!..... are you kidding?
didn;t understand a bit.. my fault not the narrator's.
To fast talking especially with british english
Stop listening so slow then.