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1、 附 錄 How Manual Transmissions Work If you drive a stick-shift car, then you may have several questions floating in your head. How does the funny "H" pattern that I am moving this shift knob through have any relation to the gears inside the transmission? What is moving inside the transmission

2、 when I move the shifter? When I mess up and hear that horrible grinding sound, what is actually grinding? What would happen if I were to accidentally shift into reverse while I am speeding down the freeway? Would the entire transmission explode? In this article, we'll answer all of these qu

3、estions and more as we explore the interior of a manual transmission. Cars need transmissions because of the physics of the gasoline engine. First, any engine has a redline -- a maximum rpm value above which the engine cannot go without exploding. Second, if you have read How Horsepower Works, then

4、 you know that engines have narrow rpm ranges where horsepower and torque are at their maximum. For example, an engine might produce its maximum horsepower at 5,500 rpm. The transmission allows the gear ratio between the engine and the drive wheels to change as the car speeds up and slows down. You

5、shift gears so the engine can stay below the redline and near the rpm band of its best performance. Ideally, the transmission would be so flexible in its ratios that the engine could always run at its single, best-performance rpm value. That is the idea behind the continuously variable transmission

6、 (CVT). A CVT has a nearly infinite range of gear ratios. In the past, CVTs could not compete with four-speed and five-speed transmissions in terms of cost, size and reliability, so you didn't see them in production automobiles. These days, improvements in design have made CVTs more common. The Toy

7、ota Prius is a hybrid car that uses a CVT. The transmission is connected to the engine through the clutch. The input shaft of the transmission therefore turns at the same rpm as the engine. A five-speed transmission applies one of five different gear ratios to the input shaft to produce a differ

8、ent rpm value at the output shaft. A Very Simple Transmission To understand the basic idea behind a standard transmission, the diagram below shows a very simple two-speed transmission in neutral: Let's look at each of the parts in this diagram to understand how they fit together: The green shaf

9、t comes from the engine through the clutch. The green shaft and green gear are connected as a single unit. (The clutch is a device that lets you connect and disconnect the engine and the transmission. When you push in the clutch pedal, the engine and the transmission are disconnected so the engine c

10、an run even if the car is standing still. When you release the clutch pedal, the engine and the green shaft are directly connected to one another. The green shaft and gear turn at the same rpm as the engine.) The red shaft and gears are called the layshaft. These are also connected as a single pie

11、ce, so all of the gears on the layshaft and the layshaft itself spin as one unit. The green shaft and the red shaft are directly connected through their meshed gears so that if the green shaft is spinning, so is the red shaft. In this way, the layshaft receives its power directly from the engine whe

12、never the clutch is engaged. The yellow shaft is a splined shaft that connects directly to the drive shaft through the differential to the drive wheels of the car. If the wheels are spinning, the yellow shaft is spinning. The blue gears ride on bearings, so they spin on the yellow shaft. If the

13、engine is off but the car is coasting, the yellow shaft can turn inside the blue gears while the blue gears and the layshaft are motionless. Now, let's see what happens when you shift into first gear. First Gear In this picture, the green shaft from the engine turns the layshaft, which turns th

14、e blue gear on the right. This gear transmits its energy through the collar to drive the yellow drive shaft. Meanwhile, the blue gear on the left is turning, but it is freewheeling on its bearing so it has no effect on the yellow shaft. When the collar is between the two gears (as shown in the fir

15、st figure), the transmission is in neutral. Both of the blue gears freewheel on the yellow shaft at the different rates controlled by their ratios to the layshaft. From this discussion, you can answer several questions: When you make a mistake while shifting and hear a horrible grinding sound, y

16、ou are not hearing the sound of gear teeth mis-meshing. As you can see in these diagrams, all gear teeth are all fully meshed at all times. The grinding is the sound of the dog teeth trying unsuccessfully to engage the holes in the side of a blue gear. The transmission shown here does not have "sy

17、nchros" (discussed later in the article), so if you were using this transmission you would have to double-clutch it. Double-clutching was common in older cars and is still common in some modern race cars. In double-clutching, you first push the clutch pedal in once to disengage the engine from the t

18、ransmission. This takes the pressure off the dog teeth so you can move the collar into neutral. Then you release the clutch pedal and rev the engine to the "right speed." The right speed is the rpm value at which the engine should be running in the next gear. The idea is to get the blue gear of the

19、next gear and the collar rotating at the same speed so that the dog teeth can engage. Then you push the clutch pedal in again and lock the collar into the new gear. At every gear change you have to press and release the clutch twice, hence the name "double-clutching." You can also see how a small

20、linear motion in the gear shift knob allows you to change gears. The gear shift knob moves a rod connected to the fork. The fork slides the collar on the yellow shaft to engage one of two gears. In the next section, we'll take a look at a real transmission. A Real Transmission There are three fo

21、rks controlled by three rods that are engaged by the shift lever. Looking at the shift rods from the top, they look like this in reverse, first and second gear: Keep in mind that the shift lever has a rotation point in the middle. When you push the knob forward to engage first gear, you are actual

22、ly pulling the rod and fork for first gear back. You can see that as you move the shifter left and right you are engaging different forks (and therefore different collars). Moving the knob forward and backward moves the collar to engage one of the gears。 Reverse gear is handled by a small idler g

23、ear (purple). At all times, the blue reverse gear in this diagram is turning in a direction opposite to all of the other blue gears. Therefore, it would be impossible to throw the transmission into reverse while the car is moving forward -- the dog teeth would never engage. However, they will make a

24、 lot of noise! 手動變速器如何工作 如果你駕駛一臺手動小轎車，那么你可能會有幾個問題漂浮在腦海中。 當移動換擋操縱桿時，是怎樣通過變速器中齒輪的聯(lián)系實現(xiàn)有趣的“H”模式？當我移動操縱桿時，變速器里面是如何工作的呢？ 當我換錯擋并聽到可怕的摩擦聲時，實際是什么在磨削呢？如果我在高速公路上急行時，突然換倒檔會發(fā)生什么情況呢？變速器會爆炸嗎？ 在本篇文章中，我們將回答所有這些問題，更要探索手動變速器內(nèi)部。 由于物理學(xué)的汽油發(fā)動機，故汽車需要傳輸動力。首先，任何發(fā)動機都有一條紅界限——轉(zhuǎn)速超過最大值時，發(fā)動機不會運行也不會爆炸。第二，如果你知道馬力是如何工作

25、的，那么你一定知道當馬力和扭矩達到最大值時，發(fā)動機的轉(zhuǎn)速范圍縮小。例如，發(fā)動機可能產(chǎn)生的最大馬力為5500轉(zhuǎn)。變速器使發(fā)動機和驅(qū)動車輪之間的傳動比變小，以使汽車加速行駛。你變速行駛時，發(fā)動機能停留在紅界限或界限附近以達到最佳行駛狀態(tài)。 最理想的是，變速器以非常靈活的比率使發(fā)動機可以始終運行在單一的、最高性能的轉(zhuǎn)速。這種想法基于連續(xù)的變速傳動（無級變速器）。 無級變速器有近無窮的傳動比范圍。在過去，無級變速器在成本、大小和可靠性上不能與四檔和五檔變速器相比，所以沒有大量運用于汽車生產(chǎn)中。近年來，無級變速器的改進設(shè)計更為常見。豐田普銳斯是一輛使用無級變速器的混合動力型汽車。 變速器通過離合器

26、與發(fā)動機相連。因此，變速器輸入軸與發(fā)動機以同樣的轉(zhuǎn)速轉(zhuǎn)動。 五檔變速器適用于五個不同的傳動比的汽車，它把輸入軸產(chǎn)生的不同轉(zhuǎn)速值傳給輸出軸。 一個非常簡單的變速器 為了理解一臺標準變速器的原理，下面的圖表顯示了一個非常簡單的中間軸式雙速傳動變速器： 讓我們看一看圖表中的每一部分，理解他們是怎樣結(jié)合在一起的：發(fā)動機的動力通過離合器傳給輸入軸。輸入軸和輸入齒輪以一個單個單元連接。（離合器是一種裝置，它可以連接和斷開發(fā)動機和變速器。當你踏下離合器踏板時，發(fā)動機和離合器不連接，所以即使汽車停著不動，發(fā)動機也能運行。當你釋放離合器踏板時，發(fā)動機與輸入軸直接相連。輸入軸與輸出軸的轉(zhuǎn)速與發(fā)動機相同。）

27、 紅色軸和齒輪被稱為中間軸。這也是作為一個單一的連接件，所以所有的中間軸齒輪和其本身自旋為一個單元。輸入軸和中間軸通過嚙合齒輪直接相連，因此如果輸入軸旋轉(zhuǎn)，中間軸也旋轉(zhuǎn)。這樣，當離合器工作時，中間軸收到的動力直接來自發(fā)動機。 黃色軸是花鍵軸，它通過汽車上不同傳動齒輪與中間軸相連接。如果齒輪旋轉(zhuǎn)，輸出軸也跟著旋轉(zhuǎn)。 藍色齒輪套在軸承上，所以可以在輸出軸上旋轉(zhuǎn)。如果發(fā)動機停轉(zhuǎn)而汽車滑行時，當輸出軸齒輪與中間軸靜止不動時，輸出軸能在其齒輪中旋轉(zhuǎn)。 現(xiàn)在，讓我們看一看一擋工作過程。 一擋 圖中，輸入軸把來自發(fā)動機的動力傳給中間軸，通過向右推動藍色齒輪完成一擋傳動。齒輪通過嚙合套傳遞動力給輸

28、出軸，與此同時，輸出軸左側(cè)藍齒輪也旋轉(zhuǎn)，但是他是在軸承上空轉(zhuǎn)所以對輸出軸沒有影響。 當嚙合套在中間時，變速器處于空擋。兩個齒輪在輸出軸上被中間軸控制以不同的傳動速比。 從這次討論中，你可以回答幾個問題： 當你犯了一個錯誤掛錯擋并聽到可怕的磨削聲時，你聽到的只是齒輪錯誤嚙合的聲音。正如你看到的圖表一樣，所有的齒輪一直是嚙合的。磨削聲是齒輪在藍色齒輪內(nèi)部沒有正確使用造成的。 這里顯示的變速器沒有同步器，因此，如果你使用這樣的傳輸機構(gòu)，那么你應(yīng)該使用雙向離合器。雙向離合器在過去的轎車中常見，并且現(xiàn)代的賽車中也很常見。離合器雙向控制中，你首先踩下離合器踏板來分離變速器與發(fā)動機之間的動力。這樣脫

29、離了齒輪上的壓力，便可以把嚙合套移動到中間位置。然而，當你釋放離合器踏板，使發(fā)動機轉(zhuǎn)速為“合適的速度”。合適的速度是在發(fā)動機運行于齒輪下每分鐘適宜的轉(zhuǎn)速值。這樣是使藍色齒輪和嚙合齒輪以同一轉(zhuǎn)速旋轉(zhuǎn)，因此，嚙合齒可以工作。然后，再次踩下離合器踏板，并鎖止在新齒輪上。每一次齒輪傳動變化時，你將踩下并釋放離合器兩次，因此得名“雙向離合器”。 你還可以看到一個小型的直線運動的齒輪換擋操縱桿，可以讓你變更齒輪。操縱桿移動一支桿來連接撥叉，撥叉滑動嚙合套來控制輸出軸上的兩個齒輪。 在下一節(jié)，我們將看一下真正的變速器。 實時傳輸 三個撥叉軸控制換擋撥叉使操縱桿工作。看一下頂端的撥叉軸，它們像這樣旋轉(zhuǎn)，控制第一齒輪和第二齒輪： 記住換擋操縱桿的旋轉(zhuǎn)點在中間。當你向前推動撥塊換入一擋，實際上是拉動操縱桿撥叉使一擋齒輪旋轉(zhuǎn)。 你可以認為這是你向左和向右移動操縱桿來控制不同的撥叉（因此嚙合套不同）。向前和向后移動撥塊使其中一對齒輪工作。 倒檔齒輪是一個小惰性輪。在任何時候，圖中藍色倒檔齒輪是在一個方向轉(zhuǎn)向?qū)γ娴乃衅渌{色齒輪。因此，當汽車向前行駛時就不可能把傳輸逆轉(zhuǎn)。然而，它們將會制造很大的噪音！