Permanent 4WD is similar to full-time 4WD, but it has no two-wheel-drive
mode. The vehicle is always in 4WD, so you don’t have to determine whether
conditions are right to engage it. We still have transmission, transfer gearbox,
and center differential coupling the front and rear wheels. The only difference is
that torque (or power) is constantly being applied to all the wheels, giving
maximum traction in all weather and road conditions. Current systems have high
and low modes for when the going gets tough. Most important, the system does
the thinking for you. It automatically applies as much lock up (to all the wheels)
as needed for maximum traction.
All-wheel drive is used on a lot of cars where a high-low range is not needed.
Think of the all-wheel-drive system as a permanent 4WD system without the
two-speed transfer gearbox. There is no high and low range and the system is
always in automatic four-wheel drive. If your idea of “off-road” is a smooth,
level dirt road, then all-wheel drive may be all you need. But for serious rock
climbing, towing in mud and snow, or even slopping through heavy, deep,
unplowed snow and forging new roads, a two-speed gearbox coupled with the
ruggedness of a heavy-duty 4WD system, whether it is part time or full time, is a
must.
singke
(singke)
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