4WD 和AWD扫盲(ZT)

qwyes

What is the difference between
; z: D, M4 D5 }2 w+ dFull time Four Wheel Drive (4WD),
3 M3 G6 V% E* Q6 S: I! XAll Wheel Drive (AWD),
and automatic All Wheel Drive (auto AWD)?
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# y: @% X& O5 F  rFull time four wheel drive (not to be confused with: part time 4WD ) is a system that powers all four wheels at all times. Each tire creates about 25% of the available torque when the ground is level with a consistant surface. Driver has a choice of a "4-high" (that's your every day setting) and "4-low".

When "4-low" is selected the wheels create substantially more torque (on a Grand Cherokee its 2.72 times more) than in "4-high" - at the same time the vehicle moves at substantially slower speeds (2.72 times slower on J GC).

Important: "4-low" does not create more traction - it creates more torque and that can be detrimental when traction is marginal. Slipping tires are more likely in "low" than in "high"!

+ {( X' B% ^+ KThe low setting is an advantage for drivers who need to tow and maneuver a heavy trailer etc. and for drivers who at one point or another may want to negotiate difficult off-road terrain, when more torque and/or slower speed is needed.


$ t' W8 \7 k8 {/ cAll wheel drive is a system that powers all four wheels of a vehicle at all times as well. Full time symmetric AWD would be the best term to be used. Difference to full time 4WD is that a "4-low" setting is not available in AWD cars. Due to the lack of "low range" AWD vehicles are much less capable in off-road settings than full time 4WD vehicles, but work perfectly well on-road.


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  _1 R" B' O% ]) x8 K3 E: A3 lRecently some new "automatic" AWD systems have emerged. Fancy names like "Real Time 4WD" or "active AWD" are hiding the fact that they are essentially sophisticated 2WD systems. Automatic asymmetric AWD would be the best term for them. Unfortunately, since they offer AWD only part of the time, some magazines have now called it "part time 4WD" - but that term has been used since WW II for cars like the Willys and Wrangler and their part time 4WD. Automatic asymmetric AWD is much less capable in off-road settings than full time AWD systems and inferior to full time 4WD. However, automatic asymmetrical AWD is becoming more and more sophisticated and offers pretty much everything consumers expect for everyday (pavement) driving.

Here is how they work: During traction loss on the driven axle (could be front or rear) a fully automatic system (hydraulic, mechanical or electronic) routes torque to the axle with traction. This means you have to completely lose traction in 2WD on your driven axle first and then the other axle will take over and try to keep the car moving. So, for a moment you have 4WD (AWD). Doesn't mean much because only two wheels have traction. Once the primary driven axle regains traction and both axles rotate at the same speed again, the system reverts back to 2WD.

yj151

Who can translate it in Chinese?

yj151

Great!
Thank you very much!

加肥猫

GOOOOOOOOOOOOOOOD
! W9 \2 V: P3 r% i. Q: E" w7 s STUUUUUUUUUUUUUUUUUUUUUUUUUUUF!!!!!

放风儿

我个人认为：
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) e- B4 N' U# ^5 m& c- C0 o/ n, l4WD和AWD之间最大的区别是，4WD(4x4)有special low range 模式，也就是低传动比模式，车轮将得到更多的扭矩或牵引力。AWD没有这个功能。所以４x4也就是4WD有更强的拖载能力和off-Road能力。但一般在公路上行驶AWD足以应付绝大多数情况。
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" x* U6 ^( D/ q$ P' k7 P; y: R4WD(4x4),在路况良好时可以锁住前轮驱动，只有后轮驱动，更加经济。在需要是可以转到４轮驱动模式，这是有两个选择：４high或4low。4H与AWD模式没有区别，4L是在发动机低传动比模式下运行，也就是车速有限制，在３０－６０km/h左右。
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一般说来基本可以认为AWD=4x4 High，这时车辆有更好的牵引力，相当于一直在4H模式下行驶，油耗高。

4WD(４x4)有４x2 ，4x4H ，4x4L的选择。

$ z  `" i/ \# E% w' o5 y% v9 s[ 本帖最后由 放风儿 于 2007-1-14 09:30 编辑 ]