发信人: mlracing()
整理人: formulaone(2001-02-12 14:47:55), 站内信件
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LIMITED-SLIP DIFFERENTIALS (LSD)
限制滑动差速器
节选、翻译自 http://www.drivingtechniques.co.uk
翻译者 Michael Liang [email protected]
What they actually do is limit the differnce in the speeds of the two
drive shafts (let't say wheels for simplicity).
限制滑动差速器所做的是限制差速器两边的驱动轴（为简单起见，说成“两
边驱动轮”好了）之间的速度差。
When you put your foot on the loud pedal, power is sent to the diff.
The diff then has to distribute the power to the wheels. In a normal
diff, the power is channeled to the path of least resistence (the whee
l with the least grip). What a LSD does is limit the amount of power
which can be sent to this path.
当你用脚踩油门时，动力首先被传到差速器。差速器就把动力分配给与之连
接的车轮。用一般的差速器，动力会被引导到受阻力最小的车轮，而 LSD 则会限
制这种动力分配方式。
The most extreme version of a LSD would be a fixed axle. i.e. there w
ould be no difference in the amount of power sent to either wheel. Th
e least extreme would be a completely open diff where ALL of the power
is sent to the path of least resistence.
最极端的 LSD 当然是固定不变的一条车轴了。也就是两个车轮分配到的动力
是相等的。最低程度的就是完全开放的差速器，用这种差速器，所有动力会向受
到最小阻力的途径分配。
Clear?
明解啦？（无聊！）
What this means in real life is that the car puts down a more even dis
tribution of power to the driven wheels. On a standing start drag rac
e, this is advantageous as when you put your foot down it will not all
ow one wheel to spin wildly whilst the other just rolls along. Both w
heels will be pulling / pushing the car forward.
在实际操作中这意味着车会比较均衡地分配驱动轮得到的动力。在 DRAG RA
CE （静止起跑、在一段直路上斗快的赛车形式）里，使用 LSD 有很大帮助。因
为当你踩下油门时，LSD 不允许其中一个驱动轮发狂地空转而另一个则只是沿着
地面滚动，两个驱动轮都起到 拉/推 车前进的作用。
On a bend however, it is not as straight forward. If you have an open
diff on a rear wheel drive car and put your foot down hard on a bend.
The inside rear wheel will be the one with the least grip so will re
ceive all of the power. This wheel will then spin causing it to have
even less traction than before. This probably won't cause a big deal
though because it is the outside rear which is doing all the work anyw
ay and it will probably continue to do its job merrily.
而在转弯中，和直路前进有所不同。如果你的后轮驱动赛车使用的是完全开
放的差速器，而你大力踩油门，内侧后轮因为与地面之间的摩擦力较小 ※1 而被
分配到所有的动力，那么这个轮就会开始打滑，这个轮打滑后会比打滑前产生更
小的牵引力 ※2 。不过，这个车轮的打滑可能并不重要，因为无论如何只是外侧
驱动轮在帮助赛车加速，它会继续安分地做好它的工作。（？？）
With a LSD though, as you put your foot down, torque is sent to both w
heels causing them both to spin and lose traction, almost certainly en
ducing oversteer.
然而使用了 LSD 之后，当你踩下油门，转动力被送到两个驱动轮，使它们都
开始打滑并减少牵引力，肯定可以增强“转向过度” ※3。
Now this means that LSDs are a judgement call. You may want lots of p
ower oversteer in your rear wheel drive car, in which case, get a LSD.
But in your front wheel drive car, you want lots of off the line tra
ction but don't want terminal understeer every time you put your foot
down round a bend.
要不要 LSD 在乎你自己的选择。你可能想你的后轮驱动车能做出“帅呆了”
的“甩尾动作”，那么应该使用 LSD。但如果你的是前轮驱动车，你当然想在转
弯时得到更多的驱动力而又不会每次踩油门都产生太多的“转向不足” ※3 。
In AWD cars (particularly in rallying) it is often beneficial to have
a tighter diff at the back than the front. This counteracts the under
steer characteristics caused by the front wheels being driven and allo
ws more control over the attitude of the car mid bend.
对四轮驱动车（尤其是越野赛中使用的四轮驱动车），后差速器比前差速器
紧一些通常会有好处。因为这可以减少由有驱动力的前轮引起的“转向不足”特
性，并让你更容易控制车身在转弯时的姿势。
The fact that this is such a judgement call has spurred the clever men
in white coats to come up with all sorts of solutions. Computer cont
rolled diffs are now commonplace in rallying allowing the computer to
alter the distribution of power on the fly to suit the driver input an
d road surface.
正因为这是模棱两可的，聪明的设计人员就想出了各种方法以让赛车表现得
更好。电脑控制的差速器在拉力赛车中已经普遍使用，让电脑以极快的速度改变
差速器对动力的分配，以配合车手的操作以及路面情况。
注释：
※1 为什么转弯时内侧车轮与地面之间摩擦力较小？简单说来是因为转弯时“重
量转移”到外侧。可以参看
http://go.163.com/~mlracing/article/weitrans/weitrans.htm （我
写的，错了不要怪）
※2 打滑的车轮会比不打滑的车轮有更小的牵引力？一般说来接触双方之间速度
差越大，摩擦力越小。（我说的，错了不要怪）
※3 关于“转向过度”和“转向不足”可以参看
http://go.163.com/~mlracing/teach/mid3.htm （我写的，错了不要怪
）
或 http://go.163.com/~mlracing/article/techs/science.htm （英文）
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