外文翻譯--四輪定位簡介

1、<p><b>　　1 英文翻譯原文</b></p><p>　　A Short Course onWheel Alignment</p><p>　　by Charles Ofria</p><p>　　In its most basic form, a wheel alignment consists of adjusting

2、 the angles of the wheels so that they are perpendicular to the ground and parallel to each other. The purpose of these adjustments is maximum tire life and a vehicle that tracks straight and true when driving along a st

3、raight and level road.</p><p>　　This article begins with information that any motorist should know; however, if you are interested in learning more about this topic, click on the underlined words for more de

4、tailed explanations of each term. We will cover various levels of detail with the deepest levels containing information that even a wheel alignment technician will find informative.</p><p>　　Wheel Alignment

5、is often confused with Wheel Balancing.  The two really have nothing to do with each other except for the fact that they affect ride and handling.  If a wheel is out of balance, it will cause a vibration at hig

6、hway speeds that can be felt in the steering wheel and/or the seat.  If the alignment is out, it can cause excessive tire wear and steering or tracking problems.</p><p>　　If you know anything about whee

7、l alignment, you've probably heard the terms Camber, Caster and Toe-in. </p><p><b>　　Camber</b></p><p>　　Camber is the angle of the wheel, measured in degrees, when viewed from t

8、he front of the vehicle. If the top of the wheel is leaning out from the center of the car, then the camber is positive, if it's leaning in, then the camber is negative. If the camber is out of adjustment, it will ca

9、use tire wear on one side of the tire's tread. If the camber is too far negative, for instance, then the tire will wear on the inside of the tread.</p><p>　　Camber wear pattern</p><p>　　If t

10、he camber is different from side to side it can cause a pulling problem. The vehicle will pull to the side with the more positive camber. On many front-wheel-drive vehicles, camber is not adjustable. If the camber is out

11、 on these cars, it indicates that something is worn or bent, possibly from an accident and must be repaired or replaced.</p><p><b>　　Caster</b></p><p>　　When you turn the steering wh

12、eel, the front wheels respond by turning on a pivot attached to the suspension system. Caster is the angle of this steering pivot, measured in degrees, when viewed from the side of the vehicle. If the top of the pivot is

13、 leaning toward the rear of the car, then the caster is positive, if it is leaning toward the front, it is negative. If the caster is out of adjustment, it can cause problems in straight line tracking. If the caster is d

14、ifferent from side to side, the</p><p>　　The best way to visualize caster is to picture a shopping cart caster. The pivot of this type of caster, while not at an angle, intersects the ground ahead of the whe

15、el contact patch. When the wheel is behind the pivot at the point where it contacts the ground, it is in positive caster. Picture yourself trying to push the cart and keep the wheel ahead of the pivot. The wheel will con

16、tinually try to turn from straight ahead. That is what happens when a car has the caster set too far negative. Lik</p><p><b>　　Toe-in </b></p><p>　　The toe measurement is the di

17、fference in the distance between the front of the tires and the back of the tires. It is measured in fractions of an inch in the US and is usually set close to zero which means that the wheels are parallel with each othe

18、r. Toe-in means that the fronts of the tires are closer to each other than the rears. Toe-out is just the opposite. An incorrect toe-in will cause rapid tire wear to both tires equally. This type of tire wear is called a

19、 saw-tooth wear pattern as show</p><p>　　If the sharp edges of the tread sections are pointing to the center of the car, then there is too much toe-in. If they are pointed to the outside of the car then ther

20、e is too much toe-out. Toe is always adjustable on the front wheels and on some cars, is also adjustable for the rear wheels.</p><p>　　Four Wheel Alignments</p><p>　　There are two main types of

21、4-wheel alignments. In each case, the technician will place an instrument on all four wheels. In the first type the rear toe and tracking is checked, but all adjustments are made at the front wheels. This is done on vehi

22、cles that do not have adjustments on the rear. The second type is a full 4-wheel alignment where the adjustments are first made to true up the rear alignment, then the front is adjusted. A full 4-wheel alignment will cos

23、t more than the other type becau</p><p>　　Other facts every driver should know about wheel alignments.</p><p>　　A proper wheel alignment should always start and end with a test drive. </p>

24、<p>　　The front end and steering linkage should be checked for wear before performing an alignment. </p><p>　　The tires should all be in good shape with even wear patterns.  If you have a tire wi

25、th excessive camber wear, for instance, and you correct the alignment problem that caused that wear, the tire will now be making only partial contact with the road. (see illustration on right) </p><p>　　Pull

26、ing problems are not always related to wheel alignment.  Problems with tires (especially unequal air pressure), brakes and power steering can also be responsible. It is up to a good wheel alignment technician to det

27、ermine the cause. </p><p>　　Advanced Wheel Alignment Information.</p><p>　　While Camber, Caster & Toe-in are the settings that are always checked when doing a wheel alignment, they are not t

28、he only settings. Below is a list of the alignment settings that are important for a wheel alignment technician to know about in order to diagnose front end problems.</p><p><b>　　Camber </b></

29、p><p>　　When camber specifications are determined during the design stage, a number of factors are taken into account. The engineers account for the fact that wheel alignment specifications used by alignment te

30、chnicians are for a vehicle that is not moving. On many vehicles, camber changes with different road speeds. This is because aerodynamic forces cause a change in riding height from the height of a vehicle at rest. Becaus

31、e of this, riding height should be checked and problems corrected before setti</p><p>　　For many years the trend has been to set the camber from zero to slightly positive to offset vehicle loading, however t

32、he current trend is to slightly negative settings to increase vehicle stability and improve handling.</p><p><b>　　Caster </b></p><p>　　Positive caster improves straight line tracking

33、 because the caster line (the line drawn through the steering pivot when viewed from the side) intersects the ground ahead of the contact patch of the tire. Just like a shopping cart caster, the wheel is forced behind th

34、e pivot allowing the vehicle to track in a straight line.</p><p>　　If this is the case, then why did most cars have negative caster specs prior to 1975 ? There are a couple of reasons for this. In those days

35、, people were looking for cars that steered as light as a feather, and cars back then were not equipped with radial tires. Non-radial tires had a tendency to distort at highway speed so that the contact patch moved back

36、past the centerline of the tire (Picture a cartoon car speeding along, the tires are generally drawn as egg-shaped). The contact patch gener</p><p><b>　　Toe</b></p><p>　　Like camber,

37、 toe will change depending on vehicle speed. As aerodynamic forces change the riding height, the toe setting may change due to the geometry of the steering linkage in relation to the geometry of the suspension. Because o

38、f this, specifications are determined for a vehicle that is not moving based on the toe being at zero when the vehicle is at highway speed. In the early days prior to radial tires, extra toe-in was added to compensate fo

39、r tire drag at highway speed.</p><p>　　On some older alignment machines, toe-in was measured at each wheel by referencing the opposite wheel. This method caused problems with getting the steering wheel strai

40、ght the first time and necessitated corrective adjustments before the wheel was straight. Newer machines reference the vehicle's centerline by putting instruments on all four wheels.</p><p>　　Steering Ax

41、is Inclination (SAI)</p><p>　　SAI is the measurement in degrees of the steering pivot line when viewed from the front of the vehicle. This angle, when added to the camber to form the included angle causes th

42、e vehicle to lift slightly when you turn the wheel away from a straight ahead position. This action uses the weight of the vehicle to cause the steering wheel to return to the center when you let go of it after making a

43、turn. Because of this, if the SAI is different from side to side, it will cause a pull at very slow spe</p><p>　　Included Angle</p><p>　　Included angle is the angle formed between the SAI and th

44、e camber. Included angle is not directly measurable. To determine the included angle, you add the SAI to the camber. If the camber is negative, then the included angle will be less than the SAI, if the camber is positive

45、, it will be greater. The included angle must be the same from side to side even if the camber is different. If it is not the same, then something is bent, most likely the steering knuckle.</p><p>　　Scrub Ra

46、dius</p><p>　　Scrub radius is the distance between where the SAI intersects the ground and the center of the tire. This distance must be exactly the same from side to side or the vehicle will pull strongly a

47、t all speeds. While included angle problems will affect the scrub radius, it is not the only thing that will affect it. Different wheels or tires from side to side will cause differences in scrub radius as well as a tire

48、 that is low on air. Positive scrub radius is when the tire contact patch is outside of</p><p>　　If the brake on one front wheel is not working, with positive scrub radius, stepping on the brake will cause t

49、he steering wheel to try to rip out of your hand. Negative scrub radius will minimize that effect.</p><p>　　Scrub radius is designed at the factory and is not adjustable. If you have a vehicle that is pullin

50、g even though the alignment is correct, look for something that will affect scrub radius</p><p>　　Riding Height</p><p>　　Riding height is measured, usually in inches, from the rocker panel to th

51、e ground. Good wheel alignment charts provide specs, but the main thing is that the measurements should be within one inch from side to side and front to rear. Riding height is not adjustable except on vehicles with tors

52、ion bar type springs.  The best way to fix this problem is to replace the springs (Note: springs should only be replaced in matched pairs). Changes in riding height will affect camber and toe so if springs a</p&g

53、t;<p><b>　　Set Back</b></p><p>　　Set back is when one front wheel is set further back than the other wheel. With alignment equipment that measures toe by using only the front instruments,

54、any setback will cause an uncentered steering wheel. Any good 4-wheel aligner will reference the rear wheels when setting toe in order to eliminate this problem.</p><p>　　Some good alignment equipment will m

55、easure set back and give you a reading in inches or millimeters. A set back of less than 1/4 inch is considered normal tolerance by some manufacturers. More than that and there is a good chance that something is bent.<

56、;/p><p>　　Thrust Angle</p><p>　　Thrust angle is the direction that the rear wheels are pointing in relation to the center line of the vehicle. If the thrust angle is not zero, then the vehicle will

57、 "dog track" and the steering wheel will not be centered. The best solution is to first adjust the rear toe to the center line and then adjust the front toe. This is normally done during a 4-wheel alignment as

58、long as the rear toe is adjustable. If the rear is not adjustable, then the front toe must be set to compensate for the thrus</p><p>　　Steering Center</p><p>　　Steering center is simply the fact

59、 that the steering wheel is centered when the vehicle is traveling down a straight and level road. A crooked steering wheel is usually the most common complaint that a customer has after a wheel alignment is performed. A

60、ssuming that the steering wheel stays in the same position when you let go of the wheel (in other words, the car is not pulling), then steering center is controlled by the front and rear toe settings. When setting steeri

61、ng center, the rear toe sh</p><p>　　Another problem with steering center has to do with the type of roads that are driven on. Most roads are crowned to allow for water drainage, and unless you drive in Engla

62、nd, Japan or another country where they drive on the wrong (sorry) left side of the road, you usually drive on the right side of the crown. This may cause the vehicle to drift to the right so that the steering wheel will

63、 appear to be off-center to the left on a straight road. The best way to compensate for this is as follows: </p><p>　　If there is a difference in caster, it should be that the left wheel is more negative tha

64、n the right wheel, but not more than 1/2 degree. Check the specs for any specific recommendations on side-to-side differences. </p><p>　　If there is a difference in camber, then the left wheel should be more

65、 positive than the right wheel. Check the specs to see what the allowable difference is.  </p><p>　　Toe Out on Turns</p><p>　　When you steer a car through a turn, the outside front wheel ha

66、s to navigate a wider arc then the inside wheel.  For this reason, the inside front wheel must steer at a sharper angle than the outside wheel.</p><p>　　Toe-out on turns is measured by the turning angle

67、 gauges (turn plates) that are a part of every wheel alignment machine. The readings are either directly on the turn plate or they are measured electronically and displayed on the screen.  Wheel alignment specificat

68、ions will usually provide the measurements for toe-out on turns. They will give an angle for the inside wheel and the outside wheel such as 20º for the inside wheel and 18º for the outside wheel. Make sure that

69、 the readings are at zero </p><p>　　The toe-out angles are accomplished by the angle of the steering arm. This arm allows the inside wheel to turn sharper than the outside wheel.  The steering arm is ei

70、ther part of the steering knuckle or part of the ball joint and is not adjustable. If there is a problem with the toe-out, it is due to a bent steering arm that must be replaced.</p><p><b>　　英文翻譯</b

71、></p><p><b>　　四輪定位簡介</b></p><p><b>　　——查爾斯</b></p><p>　　四輪定位的最基本工作功能是，調(diào)整四輪的個角度，保證車輪與地面垂直，且各輪之間相互平行。這些調(diào)整的目的是，最大化輪胎的壽命，讓車輛水平筆直道路上行駛時能夠保持直線穩(wěn)定的行駛狀態(tài)。</p>

72、<p>　　這篇文章介紹了所有駕駛員都必須知道的信息；如果你還想知道更多的詳細信息，請點擊帶有下劃線的單詞。我們能夠獲得眾多層次的詳細信息，而且這有些深層次的信息可能是四輪定位技術人員所不能提供的。</p><p>　　我們常常將四輪定位與車輪平衡混淆起來。除了都對駕駛員的駕駛和操作有影響之外，這兩者的概念是截然不同的。如果一個車輪失去平衡，那么在高速公路上行駛時，我們將明顯感覺到汽車前輪或者前部坐

73、椅有強烈的振蕩。而如果車輪沒有定位好時，輪胎將受嚴重的磨損，同時，汽車的駕駛和操縱都極為困難。</p><p>　　只要你對車輪定位概念稍有了解的話，那么你肯定對車輪外傾角、主銷后傾角和汽車前束這三個概念有所了解。</p><p><b>　　車輪外傾角</b></p><p>　　外傾角是從汽車的前部觀察時，車輪傾斜角度。如果車輪頂部偏離汽車

74、中心向外傾斜時，外傾角為正值；相反，如果其向內(nèi)傾斜時，則外傾角為負值。如果外傾角大小超出了標準，則所在的輪胎面將產(chǎn)生磨損。例如，當外傾角太小時（永遠超出了負的角度值范圍），輪胎內(nèi)側(cè)的胎面將磨損。</p><p>　　如果兩邊車輪的外傾角不一樣，汽車將產(chǎn)生一個跑偏的牽引力。若正的外傾角過大，汽車將向路邊跑偏。而若汽車的外傾角為零時，表明有某些零部件已經(jīng)損壞或變形了，這可能是有于意外的事故造成的，因此，必須及時修理或

75、替換。</p><p><b>　　主銷后傾角</b></p><p>　　當你轉(zhuǎn)向方向盤的時候，通過與懸架系統(tǒng)相聯(lián)的樞軸來調(diào)動前輪。主銷后傾角即是從側(cè)面觀察測得的這跟方向樞軸的偏角。如果樞軸的頂端向汽車后部傾斜時，測得的角度為正值。同理，當樞軸頂端向前端傾斜時，測得的角度為負值。如果，主銷后傾角沒有達到要求時，汽車將在直線方向不能正常行駛。如果左右兩個車輪的主銷后傾

76、角不同時，車輛將往較小正值車輪的那邊跑偏。如果左右輪的主銷后傾角相同，但是由于其過小，方向盤的操縱力將變得太輕，車輛行使將左右徘徊，很難讓其保持直線行使。而如果左右車輪的主銷后傾角相等，但是過大，方向盤操縱力將變得太沉重，那么一旦受到撞擊，轉(zhuǎn)動輪便會嚴重跳動。主銷后傾角對輪胎磨損的影響很小。</p><p>　　能夠觀察到主銷后傾角變動影響的最好方法是使用主銷后傾角調(diào)整儀器進行調(diào)整。如果此主銷后傾角的樞軸與地面垂

77、直時，其軸向延長線將與車輪與地面接觸點的前方地面交叉。當車輪與地面的接觸點在樞軸與地面的交叉點后面時，該主銷后傾角為正值。調(diào)整使得車輪與地面接觸點落在樞軸與地面交叉點前面。車輛將繼續(xù)在直線行使上走偏，這是由于所設置的主銷后傾角太小。與車輪外傾角一樣，許多前輪驅(qū)動汽車的主銷后傾角是不可調(diào)整的。如果這些車輛的主銷后傾角超出標準，則表明某個零部件由于以外事故已經(jīng)損壞或者變形了，因此必須對之進行修復或替換。</p><p&g

78、t;<b>　　汽車前束</b></p><p>　　車輪前束即左右兩車輪前端與后端距離的差值。在美國，通常將其調(diào)為幾分之幾的英寸，而且更經(jīng)常是將其調(diào)整到零，即表明左右兩個車輪相互平行。正前束表明左右輪胎前端之間的距離小于他們后端之間的距離。而負的前束正好相反。不合理的正前束將加速兩個輪胎胎面的同等磨損。如圖所虱，這種輪胎的磨損稱為鋸齒磨損形式。</p><p>　　

79、如果胎面斷面的銳利邊緣指向車的中心，這表明正的前束過大。而如果，它們指向車的外側(cè)，則表明，車輪的負的前束過大。前輪的前束一般都是能夠調(diào)整的，而且對于有些汽車，其后輪上的前束也可以調(diào)整。</p><p>　　有兩種形式的四輪定位方式。在每一種定位方式中，定位技術員都將在四個車輪上安裝車輪定位儀器。第一種方式是，后輪只進行前束和運行狀態(tài)的校樣，但是對前輪進行所有參數(shù)的檢測。這種定位方式是針對于那些后輪不能調(diào)整的車輛而

80、言的。第二種定位方式是對四個車輪全部定位，這種情況下，先對后輪進行檢測調(diào)整，再對前輪進行矯正。由于四輪全部定位涉及的工作內(nèi)容較多，所以，其花費也就變得較為昂貴了。</p><p>　　駕駛員還必須知道以下有關車輪定位的其他內(nèi)容。</p><p>　　1）要進行一個全面合理的車輪定位時，一般都得在檢測之前和之后都試車一遍。</p><p>　　2）在進行車輪定位檢測之

81、前，必須先檢查前輪以及轉(zhuǎn)向連桿是否磨損。</p><p>　　3）輪胎須保持良好的形狀，即要均衡磨損。例如，當你碰到由于外傾角過大而受磨損不均的輪胎時，你需找出產(chǎn)生該磨損的原因，并對之進行矯正，因為現(xiàn)在輪胎與地面的接觸不均勻。（詳細內(nèi)容請看右邊說明）</p><p>　　4）牽引力問題并不總是產(chǎn)生車輪不能正確定位的原因。輪胎的影響因素（尤其當空氣壓力分布不均時），制動系統(tǒng)以及轉(zhuǎn)向動力方面也

82、是必須考慮在內(nèi)的因素。這時，必須由車輪定位技術員來分析找出確切的不能定位原因。</p><p>　　更詳細的四輪定位信息</p><p>　　即使在四輪定位檢測時，車輪外傾角、主銷后傾角和前束都是必須涉及的，但是需要進行檢測的參數(shù)并不只是包括這三個。以下是一些作為個四輪校正技術人員需要知道并進行前輪診斷的重要問題。</p><p><b>　　車輪外傾角&

83、lt;/b></p><p>　　在設計期間，確定外傾角規(guī)格時須考慮許多因素。據(jù)設計者們透露，所設計的車輪定位參數(shù)是供車輪定位技術人員在汽車靜止情況下適用的。對大多數(shù)的車輛來說，車輪外傾角隨著汽車運行速度的改變而不同。這是因為在氣體動力學的作用下，車輛在靜止與運動兩個狀態(tài)下的高度不同。正由于如此，在設置外傾角之前，必須考慮運行高度和澄清各種問題。車輪外傾角的設置后，使得車輛在高速公路上行使時，該設定值為輪胎

84、達到最小磨損下的最優(yōu)值。</p><p>　　許多年趨勢是設定外傾從零到有些微正以彌補車輛荷載, 然而目前的趨勢是從零到有些微負設定，用以增加車輛穩(wěn)定度和改良操縱。</p><p><b>　　主銷后傾角</b></p><p>　　當主銷后傾角為正時，主銷軸軸線（即從側(cè)面看，通過樞軸中心的直線）在輪胎與地面接觸點的前方處與地面交叉，此時，可以

85、增強直線行使的能力。正如一個購物車的大王銷后傾角，輪與地面的接觸點在樞軸與地面的交叉點后面，這樣便可保證了購物車的直線行使能力。</p><p>　　既然這個問題這么重要，那么為什么在1975年之前，大多數(shù)的車都使用負的主銷后傾角？這個原因有很多。在那個年代，人們總是想能夠讓車的方向盤轉(zhuǎn)向力相當輕，以至于跟羽毛一般，而且當時的輪胎還不是輻射狀的。非輻射狀輪胎很可能在高速情況下變形，以至于輪胎與地面的接觸點向輪胎中

86、心線的后邊移動（拿個玩具車試驗，可以看到輪胎變形成雞蛋形狀了）。這種情況下，將產(chǎn)生正的主銷后傾角。這就是當你將次非非輻射狀輪胎安裝在正的主銷后傾角車輛上時，汽車便會行使不穩(wěn)定，不能再保持穩(wěn)定的直線行使能力。試圖糾正這個問題，可重新調(diào)整，將主銷后傾角設置為正值，這樣操縱時將感覺完全不一樣了。</p><p><b>　　前束角</b></p><p>　　跟車輪的外傾角

87、一樣，汽車的前束角值將隨著汽車速度的改變而改變。由于空氣動力改變了汽車的行使高度，前束值大小的設定可能隨著取決于汽車懸架的橫拉桿形狀的改變而變動。正由于如此，定出了靜止狀態(tài)下汽車的具體規(guī)格，這是基于高速時前束為零的情況下。在放射狀的輪胎產(chǎn)生之前，使用增加額外的正前束辦法來補償輪胎在高速行使下的變形。</p><p>　　在一些較老的汽車定位儀上，每個輪的前束都通過用對面的輪來測量的。這種方法引出了第一次糾正轉(zhuǎn)向輪

88、的許多問題，而且在使輪做直線形式之前必須進行正確的調(diào)整。新的四輪定位儀跟車輛的中心線有關，因為它必須在所有四個車輪上都安裝檢測儀器。</p><p><b>　　主銷內(nèi)傾角</b></p><p>　　主銷內(nèi)傾角是從汽車的正前方觀察時測得的主銷的傾斜角度。這個角和車輪外傾角組合起來組成包容角，此時，你打偏正在直線行使的方向盤時，車輛將稍微被提升。這時，利用車輛自身的重

89、量，當你轉(zhuǎn)向之后松開手，它將使方向盤自動回正。正由于如此，當兩邊的主銷內(nèi)傾角不同時，速度很小情況下會產(chǎn)生一個牽引力。大部分的車輪定位儀都可以測量出這個角，但是該角不能完全地校正。主銷內(nèi)傾角不合格產(chǎn)生的主要原因是存在彎曲變形的零部件，所以，必需對這些零部件進行更換才能糾正主銷內(nèi)傾角。在臺車和舊的車上 SAI 被也稱為KPI(轉(zhuǎn)向主銷磁傾角)，是用有轉(zhuǎn)向主銷代替球型萬向接合器。</p><p><b>　　

90、包容角</b></p><p>　　包容角是基于主銷內(nèi)傾角和車輪外傾角之間而形成的。包容角不能直接地被測得。包容角的大小是主銷內(nèi)傾角和車輪外傾角二者的相加。如果，車輪外傾角為負值，那么，包容角小于主銷內(nèi)傾角。而如果車輪外傾角為正值，得到的包容角將更大。即使兩邊車輪的主銷內(nèi)傾角可以不同，也必須保證兩端的包容角相等。如果不相等時，將使某個部件彎曲變形，而這個不見很可能就是轉(zhuǎn)向關節(jié)。</p>

91、<p><b>　　轉(zhuǎn)向主銷內(nèi)傾內(nèi)置量</b></p><p>　　轉(zhuǎn)向主銷內(nèi)傾內(nèi)置量是主銷和地面的交點與輪胎中心之間的距離。在車輪的兩邊這個距離必須相等，否則在所有速度下，車輛都會產(chǎn)生牽引力。雖然包容角能夠影響轉(zhuǎn)向主銷內(nèi)傾內(nèi)置量，但不是影響該量的唯一原因。不同的車輛與不同的輪胎在左右兩邊將產(chǎn)生不同的主銷內(nèi)傾內(nèi)置量，其中，胎內(nèi)的空氣不足也是一個原因。當輪胎與路面的接觸點在主銷與地面

92、交叉點的外部時，主銷內(nèi)傾內(nèi)置量是正的。同理，當輪胎與路面的接觸點在主銷與地面交叉點的內(nèi)部時，該值為負（前輪驅(qū)動的車輛通常該值為負）。</p><p>　　如果前輪上的制動器失靈時，且轉(zhuǎn)向主銷內(nèi)傾內(nèi)置量為正值，這時制動的話，轉(zhuǎn)向輪將試著擺脫你的控制。而當轉(zhuǎn)向主銷內(nèi)傾內(nèi)置量為負值時，這種不良效果會得到最大的抑制。</p><p>　　轉(zhuǎn)向主銷內(nèi)傾內(nèi)置量是由廠商制造時制定的，所以不能進行調(diào)整。如

93、果你發(fā)現(xiàn)即使個定位參數(shù)都符合要求，卻依然存在牽引阻力，這時可以考慮檢查一下看轉(zhuǎn)向主銷內(nèi)傾內(nèi)置量是否符合標準要求。</p><p><b>　　行使高度</b></p><p>　　行使高度表明從搖桿儀表板到地面間的高度，通常用英寸單位來測量的。良好的四輪校正圖表提供詳細說明書，但是主要的要求是所有的測量量，不管是左邊還是右邊，是前輪部分還是后輪部分，都必須在一英寸之內(nèi)

94、。除了帶有扭力桿的車輛上鍵入彈簧之外，行使高度一般是不能調(diào)整的。因而要解決這個問題的最好辦法是代替這些彈簧（注意：該彈簧只能被對稱地替代）。行使高度的變動將影響到主銷內(nèi)傾角和車輪外傾角，所以，一旦把彈簧替換了，或是調(diào)整扭力桿，那么必須檢查車輪的定位狀況以避免輪胎的磨損。值得注意的是，弱螺旋彈簧的唯一癥狀是行使的高度將下垂。如果行使高度良好，那么彈簧也良好。</p><p><b>　　向后地設定<

95、/b></p><p>　　向后地設定即使得一個前輪較大程度上比另一前輪滯后。利用只通過前輪儀器設備進行測量的四輪定位儀時，任何大小的向后設定都將使得方向盤偏離中心。任何一個好的四輪定位儀為了解決這個問題而試著調(diào)整前束都會參考后輪的狀況。</p><p>　　有些好的車輪定位儀可以測量這個向后的設定值，然后用英寸或微米單位給出尺寸值。1/4英寸被大多數(shù)的廠商公認的向后設定允許范圍。一

96、旦超出了這個值，則很可能某些部件會彎曲變形。</p><p><b>　　推力角</b></p><p>　　推力角即后輪相對于車輛中心線的指向。若推力角不為零，車輛將會 “牽轉(zhuǎn)具追蹤” ，而且方向盤將不被置中。最好的解決辦法是，先調(diào)整后輪前束到中心線，然后再調(diào)整前輪。只要后輪調(diào)整允許的話，這種辦法是一個四輪定位儀經(jīng)常使用的。若后輪不可調(diào)整，則必須調(diào)整前束使其補償推力

97、角，來使方向盤置中。</p><p><b>　　方向盤中心平衡</b></p><p>　　當方向盤中心可達到平衡時，轉(zhuǎn)動輪在直線水平道路上行使時，可保持中心平衡。進行車輪定位之后，顧客依然最經(jīng)常抱怨的是轉(zhuǎn)向輪老是歪曲。假想當你釋放方向盤時（即汽車不受約束），轉(zhuǎn)向輪能夠保持在原來位置，則可通過設置前后輪的前束值來實現(xiàn)控制。</p><p>　

98、　當設定方向盤中心的時候，先設定后輪的前束，盡量使得推力角與汽車中心線靠近。然后，將轉(zhuǎn)向前輪固定在正前方位置，對前輪前束進行設定。在固定轉(zhuǎn)向輪之前，必須開動引擎，并將前輪左右轉(zhuǎn)動數(shù)次，以消除轉(zhuǎn)向閥帶來的貼合壓力。設定了前束值之后，需要重新開動引擎，保證方轉(zhuǎn)向閥在進行拉桿調(diào)整時再一次載入。當然，高質(zhì)量檢測時，需要在每一個參數(shù)調(diào)整之后都進行一次測試。</p><p>　　方向盤中心平衡的另外一個問題與所行使路面的狀況

99、有關。大多數(shù)的道路都被強調(diào)要考慮到排水設施，所以除非在左手行使習慣的英國、日本或其他類似國家，你通常在隆起的右邊上驅(qū)動。這可能導致車輛漂流到右邊，這樣在筆直道路上行使時，轉(zhuǎn)向輪很可能會離開中心并偏向左邊。最好的補償方法如下：</p><p>　　1）如果主銷后傾角不同，很可能是左邊車輪比右邊車輪負的更小，但是不會超過1/2度。查看說明書來獲得較為詳盡的左右輪不同設定值信息。</p><p>

100、;　　2）如果是車輪外傾角不同，那么左邊車輪將比右邊車輪正的更大。核對說明書，確定最大允許的差值是多少。</p><p><b>　　在旋轉(zhuǎn)上的前展</b></p><p>　　當你對車進行轉(zhuǎn)向操作時，車前部的外側(cè)輪所走的弧度要比內(nèi)側(cè)輪的大。因此，內(nèi)部的前輪走過的角度要比外部的大。</p><p>　　每個四輪校正機器都有的部分規(guī)折轉(zhuǎn)角屏幕 (

101、 旋轉(zhuǎn)屏)，其可對旋轉(zhuǎn)上的前展進行測量。讀數(shù)結果直接在旋轉(zhuǎn)盤上表示出來，或可以用電顯示屏實現(xiàn)。四輪校正規(guī)格通常會提供測量給在旋轉(zhuǎn)上的前展 。他們將會為內(nèi)部和外部兩個輪各給出一個角度值，比如分別為20度和18度。在確保車輪朝向正前方并兩邊讀數(shù)都為零的條件下，轉(zhuǎn)動轉(zhuǎn)動輪使得內(nèi)側(cè)輪符合要求，然后檢查外側(cè)車輪。</p><p>　　旋轉(zhuǎn)的前展角是通過轉(zhuǎn)向臂的測角完成的。 這一個臂允許內(nèi)部的輪轉(zhuǎn)過的角度大于外部輪。 轉(zhuǎn)向臂