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Old 25th January 2009, 22:29   #1
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Default Query on front wheel drive

I have wondered how the front wheel drive cars run.

dont think am silly. But few question arises about front wheel drive. (when in geared running mode)

1. If one wheel is lifted, and other touches ground, the lifted wheel only rotates, other wheel which is in contact with ground doesnt. How? I have searched net, but could not find information.

2. If both wheel is in contact, it moves. (its normal )

3. Also once the both axles are removed from gearbox and if we rotate inside one side of the gearbox with hand, the other side rotates in opposite direction. ( I have seen and felt in toyota 1N gearbox while ovehauling it).

Then how come both wheels rotate in same direction while in motion in normal condition?
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Old 25th January 2009, 22:32   #2
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look up "differential" somewhere..

http://en.wikipedia.org/wiki/Differe...hanical_device)

Last edited by Jomz : 25th January 2009 at 22:34.
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Old 25th January 2009, 23:37   #3
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http://en.wikipedia.org/wiki/Differential_(automotive)

By the way, excellent observation.
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Old 26th January 2009, 10:55   #4
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As already answered, it is differential. If you think of it, 1 and 2 holds true for RWDs too.

Re. 3 - the need to reverse the rotation arises mostly because most front wheel drive vehicles have a transversely mounted engines. The crank shaft will be at right angles to an imaginary line going from front to back at the center of the vehicle.

In most rear wheel drives, the crankshaft will be paralled to that line. (gurus will have more accurate terminology here).

I guess that transverse mounting of engines in FWDs makes it easier for the drive train design and maintenance.
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Old 26th January 2009, 11:32   #5
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Quote from Wiki:

"A vehicle's wheels rotate at different speeds, especially when turning corners. The differential is designed to drive a pair of wheels with equal force, while allowing them to rotate at different speeds. In vehicles without a differential, such as [COLOR=#0066cc]karts[/COLOR], both driving wheels are forced to rotate at the same speed, usually on a common [COLOR=#0066cc]axle[/COLOR] driven by a simple chain-drive mechanism. When cornering, the inner wheel travels a shorter distance than the outer wheel, resulting in the inner wheel spinning and/or the outer wheel dragging. This results in difficult and unpredictable handling, damage to tires and roads, and strain on (or possible failure of) the entire drive train."

Last edited by mura : 26th January 2009 at 11:35.
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Old 26th January 2009, 12:53   #6
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Is that same too in RWD too?

I think gearbox is more complicated than engine.

Is there any video on youtube or any pictorical diagram available to know it better.? If this 2 wheel drive is this much complex, then 4wd should me much complex. Have to get experience the working of it.
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Old 26th January 2009, 13:11   #7
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Quote:
Originally Posted by rajivanoj View Post
Is that same too in RWD too?

I think gearbox is more complicated than engine.

Is there any video on youtube or any pictorical diagram available to know it better.? If this 2 wheel drive is this much complex, then 4wd should me much complex. Have to get experience the working of it.
See this link.

HowStuffWorks "Torque, Traction, and Wheel Slip"

It explains 4 wheel drive with videos (3 pages total). This will solve your queries on front wheel drive.
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Old 26th January 2009, 13:19   #8
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Quote:
Originally Posted by rajivanoj View Post
Is that same too in RWD too?
If you meant the difference in speeds between the inner and outer wheels, yes. That is why we have something called a "differential" between the gear box and the driven wheels.

Quote:
I think gearbox is more complicated than engine.
Umm.... yes and no. I have not seen innards of a syncromesh gearbox; but of the GBs I have seen, they certainly require some care and precision in design. But in an engine, far more moving components need to work in tandem than in a GB.

Quote:
Is there any video on youtube or any pictorical diagram available to know it better.? If this 2 wheel drive is this much complex, then 4wd should me much complex. Have to get experience the working of it.
Look around in the 4x4 section here. Cant remember the exact title of the thread right now.
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