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All wheel drive mechanism

  1. May 5, 2013 #1
    i was studying about four wheel drive/ all wheel drive and while studying about it i was just wondering how does your vehicle decide, to which wheel power should be transmitted more and to which one the power should be reduced, while cornering or while whee skidds.
     
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  3. May 5, 2013 #2

    Simon Bridge

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    Welcome to PF;
    The technology that differentiates the wheels on cornering etc is called the "differential" - there are different kinds - look it up.
     
  4. May 6, 2013 #3
    yeah i read about the differentials and got the idea of power distribution while cornering and i also read about the transfer case which distributes the power b/w front and rear wheel. but i was considering the case of automated system where driver does not have to sit and think that if he is climbing a hill or going through ice or slippery road he have to choose between high or low setting, cause he knows that his car is smart enough to detect the moment when to distribute power and where to distribute the car can switch automatically.
     
  5. May 6, 2013 #4

    Simon Bridge

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    I don't get you - are you thinking of automatic transmission?
     
  6. May 6, 2013 #5
    yeah i am thinking of automatic transmission for 4 wheel drive
     
  7. May 6, 2013 #6

    Simon Bridge

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    Do you not know how automatic transmission works, or is it that there is something about all-wheel drive that puzzles you concerning automatic transmission?
     
  8. May 6, 2013 #7
    actually its both, first of all i wanted to know exactly about how each component of automatic transmission work,and then how exactly does it then works with the 4 wheel drive. i have read many articles on it but none have been satisfactory till now. thats why i put up my question over here.
     
  9. May 6, 2013 #8

    Simon Bridge

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    What you have asked for is beyond what we do here.
    For this, you should consult an auto-engineering manual.

    If you have specific questions about something you found unsatisfactory somewhere, then we can help.
     
  10. May 17, 2013 #9
    Hello,

    While I'm not very knowledgeable about Physics, I do know a few things about cars, so I hope the following is helpful.

    First, there are many different configurations of AWD and 4WD systems. Each one has its own inherent characteristics, which also can create flaws or weakness that can be exploited under specific conditions.

    Now, more modern AWD systems have an increasing amount of electronic monitoring and computer control, which can offset or sometimes completely overcome such flaws. At the least, a modern system will have individual wheel speed sensors feeding data to the computer, which will interpret other data (such as throttle position, and gear selection among other things) to make a "decision" on how and where to distribute torque.

    Let's take a step back. Are you familiar with how a differential works? At a basic level, there are "open" differentials (generally the most common), "limited slip", and "Lockers" as I would describe it. I know the basics, but would recommend you read up and understand differentials. I wouldn't want to steer you wrong by trying to describe them here.

    Also, up until recently, the transmission (whether automatic or manual) didn't have a whole lot to do with the actual distribution of torque throughout the AWD system. It functioned more independently at its role. Now with more modern vehicles, the transmission is again a more integral part of the whole system. Particularly with a trans axle, the differential is usually integrated, and thus becomes part of the torque distributing process.

    I'll wait for more direct questions before I keep rambling on.

    I hope that helps somewhat.
     
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