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Originally Posted by fazalaliadil I am learning. Thanks, |
Hope you enjoy more, Fazal-sahab!
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Originally Posted by sudev @SST: Thanks for starting this very interesting topic
The example....needs to understood... |
Thank YOU for explaining Ragul's question!
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Originally Posted by 4x4addict In a Full T ime 4WD vehicle like the Toyota Fortuner/Land Cruiser/Mitsubishi Pajero the Center differential needs to maintain a 50:50 torque split between the front and rear axles. This can be done manually by engaging the center differential lock. When the manual lock is not engaged the differential need some way to maintain the torque transfer between the front and rear differentials.
....If either off these systems are not used, then a center differential pretty much makes a vehicle 2WD (either front or rear only) unless it is manually locked. |
Very true. As I said,
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Originally Posted by SS-Traveller ...one wheel in the air leaves all the other wheels quite, quite useless in moving the vehicle. |
But locking & unlocking differentials manually was a cumbersome process at worst, and even in the best of times, it never was effortless for some - for people who will not drive a car with manual gearshift, you expect them to lock differentials manually??!
and oh, forgetting to unlock later on was even more trouble! So came the need to invent those limited slip differentials.
But then, LSDs were never as good in transferring rotational forces the other side (left to right, front to back, or vice versa), as locked differentials. Watch the video below of an Audi Quattro with both its left wheels off the ground (on rollers) - note the speed that has to be built up before LSD activates and pulls the car out.
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Originally Posted by valhallen.282 Would you'll kindly bless me with some gyaan! |
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Originally Posted by anujmishra I have newbiew question: |
You know what, guys? This thread was specifically started to explain & answer your questions about 4WD. There are so many folks who are utterly confused about 4WD, and here we have in India for the first time, an indigenous brand new vehicle called the Aria being rolled out - and folks imagining this is a car like the Gypsy/Thar, only its 7-star variant. Read what ex670c says about CR-Vs in sand above, or the comparo video between the Panda and a Rangie... Only problem here is, the Panda was far less expensive than the Rangie, but the Aria/CR-V are a whole lot more expensive than the Thar/Gypsy/Safari in this country.
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Originally Posted by valhallen.282 I want to know about the 4wd systems from the hallowed evo's and skylines. |
Mitsu Evos and Nissan Skylines are AWD vehicles, like the Audi Quattro, with every new generation incorporating more and more electronic wizardry to put down the phenomenal power their engines generate, on to the road. But in the end, they are best suited for smooth tarmac or at most, bad-road/snowy-road situations, not mud-plugging or rock-climbing. Watch this video and imagine a Thar there - where the Quattro struggles, the basic Thar would move like a Sunday walk in the park.
Remember, any car with all 4 wheels being driven, is not always an offroader. That's why the classification of different types of 4WD in vehicles, at the beginning of this thread.
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Originally Posted by anujmishra Wouldn't Torque on demand is killer for Tires?
Some tires would rotating more and some tires would be less and all tires engaged some how. If on 'not so good Tarmac' or on 'bad roads' if rear tire rotation is more and front tire rotation is less then rear tires would wear out faster than front due to excessive rotation. |
To an extent, you're right. To produce torque on demand in an LSD, wheelspin HAS to be created first. So one wheel /axle scrabbles for grip before transferring the torque to the other wheel / axle. In the process of wheelspin occurring on gravel, yes, there can be some wearing out or nicks & cuts on the spinning tyre. If you didn't want any damage to tyres at all, avoid driving on bad roads at all!
Finally, here's a video of how a Torsen LSD works - it's in French, but the animations are self-explanatory.