> Once, I was out for a rural drive, and saw a dirt path that went up a very
> steep hill. I thought it would be interesting to see how far I could go from a
> dead start before my wheels would spin. I was bitterly dissapointed. Only one
> wheel would spin, and I was hardly tilted to an angle that was steep enough to
> make my beer spill over.
> Well, maybe I do need some $50 cup holders!

this quote from "4-wheel freedom" by Brad DeLong explains how 2wd works.

"2wd delivers maximum traction with both wheels turning with the same
power at the same speed. but yo can't drive like this for very long
because of the trade-ofs.  driving in locked-2wd all the time(not like
detroit locker which unlocks for turns), quickly wears out the tires,
since the inside wheel can't turn more slowly when turning a curve, or
corner.  Instead, it scuffs off a layer of rubber around every turn.
turning is difficult with the outside and inside wheels locked together,
adn it puts alot of wear on the drivetrain.  Strain and wear are avoided
using a differential to connect the inside and outside wheels so they can
rotate at different speeds. A standard differential(like synchro's diff
unlocked) sends more power to the faster-turning wheel.  Ths gives much
better control, and avoids wear and tear... but leads to different
problems.  If one of the two wheels is spinning on a slippery surface, the
differential will send all the power to that wheel becausse it's moving
faster.  The wheel that still has traction doesn't get any power and goes
nowhere fast. the rig just sits there with one wheel spinning. this
standard type of differential is called an open differential."

if you want to maintain traction, do these things plus more i failed to
mention:
1. do not accelerate/decellerate any more than necessary.
2. if one tire breaks loose, feather the brakes to slow down the spinning
        tire, and hopefully, send more power to the other wheel.

Sudhir H. Desai                         1984 VW Vanagon 3.4 liter Chevy V-6
cdes@welchlink.welch.jhu.edu            1996 Subaru Outback 2.2 liter flat-4
sudhir_desai@geocities.com              1997 Jeep Cherokee 4.0 liter I-6
ICQ# 8255956
http://www.geocities.com/MotorCity/Speedway/1889