外文翻譯--鼓式制動器

1、<p><b>　　中文4800字</b></p><p>　　Drum brake</p><p>　　A drum brake with the drum removed as used on the rear wheel of a car or truck. Note that in this installation, a cable-operate

2、d parking brake uses the service shoes.</p><p>　　A drum brake is a brake in which the friction is caused by a set of shoes or pads that press against a rotating drum-shaped part called a brake drum.</p>

3、;<p>　　The term "drum brake" usually means a brake in which shoes press on the inner surface of the drum. When shoes press on the outside of the drum, it is usually called a clasp brake. Where the drum i

4、s pinched between two shoes, similar to a conventional disk brake, it is sometimes called a "pinch drum brake", although such brakes are relatively rare. A related type of brake uses a flexible belt or "ba

5、nd" wrapping around the outside of a drum, called a band brake.</p><p><b>　　History</b></p><p>　　A drum brake at the rear wheel of a motorbike</p><p>　　Kawasaki W80

6、0</p><p>　　The modern automobile drum brake was invented in 1902 by Louis Renault, though a less-sophisticated drum brake had been used by Maybach a year earlier. In the first drum brakes, the shoes were mec

7、hanically operated with levers and rods or cables. From the mid-1930s the shoes were operated with oil pressure in a small wheel cylinder and pistons (as in the picture), though some vehicles continued with purely-mechan

8、ical systems for decades. Some designs have two wheel cylinders.</p><p>　　The shoes in drum brakes are subject to wear and the brakes needed to be adjusted regularly until the introduction of self-adjusting

9、drum brakes in the 1950s. In the 1960s and 1970s brake drums on the front wheels of cars were gradually replaced with disc brakes and now practically all cars use disc brakes on the front wheels, with many offering disc

10、brakes on all wheels. However, drum brakes are still often used for handbrakes as it has proven very difficult to design a disc brake suitable for </p><p>　　Early type brake shoes contained asbestos. When wo

11、rking on brake systems of older cars, care must be taken not to inhale any dust present in the brake assembly. The United States Federal Government began to regulate asbestos production, and brake manufacturers had to sw

12、itch to non-asbestos linings. Owners initially complained of poor braking with the replacements; however, technology eventually advanced to compensate. A majority of daily-driven older vehicles have been fitted with asbe

13、stos-free </p><p>　　Self-applying characteristic</p><p>　　Drum brakes have a natural "self-applying" characteristic.[1] The rotation of the drum can drag either or both of the shoes in

14、to the friction surface, causing the brakes to bite harder, which increases the force holding them together. This increases the stopping power without any additional effort being expended by the driver, but it does make

15、it harder for the driver to modulate the brake's sensitivity. It also makes the brake more sensitive to brake fade, as a decrease in brake friction also r</p><p>　　Disc brakes exhibit no self-applying ef

16、fect because the hydraulic pressure acting on the pads is perpendicular to the direction of rotation of the disc. Disc brake systems usually have servo assistance ("Brake Booster") to lessen the driver's pe

17、dal effort, but some disc braked cars (notably race cars) and smaller brakes for motorcycles, etc., do not need to use servos.</p><p>　　Note: In most designs, the "self applying" effect only occurs

18、 on one shoe. While this shoe is further forced into the drum surface by a moment due to friction, the opposite effect is happening on the other shoe. The friction force is trying to rotate it away from the drum. The for

19、ces are different on each brake shoe resulting in one shoe wearing faster. It is possible to design a two-shoe drum brake where both shoes are self-applying (having separate actuators and pivoted at opposite ends), but &

20、lt;/p><p>　　Drum brake designs</p><p>　　Rendering of a drum brake</p><p>　　Drum brakes are typically described as either leading/trailing or twin leading.[1]</p><p>　　Rear

21、 drum brakes are typically of a leading/trailing design(For Non Servo Systems), or [Primary/Secondary] (For Duo Servo Systems) the shoes being moved by a single double-acting hydraulic cylinder and hinged at the same poi

22、nt.[1] In this design, one of the brake shoes will always experience the self-applying effect, irrespective of whether the vehicle is moving forwards or backwards.[1] This is particularly useful on the rear brakes, where

23、 the footbrake (handbrake or parking brake) must exert e</p><p>　　Front drum brakes may be of either design in practice, but the twin leading design is more effective.[1] This design uses two actuating cylin

24、ders arranged so that both shoes will utilize the self-applying characteristic when the vehicle is moving forwards.[1] The brake shoes pivot at opposite points to each other.[1] This gives the maximum possible braking wh

25、en moving forwards, but is not so effective when the vehicle is traveling in reverse.[1]</p><p>　　The optimum arrangement of twin leading front brakes with leading/trailing brakes on the rear allows for more

26、 braking force to be deployed at the front of the vehicle when it is moving forwards, with less at the rear. This helps to prevent the rear wheels locking up, but still provides adequate braking at the rear when it is ne

27、eded.[1]</p><p>　　The brake drum itself is frequently made of cast iron, although some vehicles have used aluminum drums, particularly for front-wheel applications. Aluminum conducts heat better than cast ir

28、on, which improves heat dissipation and reduces fade. Aluminum drums are also lighter than iron drums, which reduces unsprung weight. Because aluminum wears more easily than iron, aluminum drums will frequently have an i

29、ron or steel liner on the inner surface of the drum, bonded or riveted to the aluminum oute</p><p>　　Advantages</p><p>　　Drum brakes are used in most heavy duty trucks, some medium and light dut

30、y trucks, and few cars, dirt bikes, and ATV's. Drum brakes are often applied to the rear wheels since most of the stopping force is generated by the front brakes of the vehicle and therefore the heat generated in the

31、 rear is significantly less. Drum brakes allow simple incorporation of a parking brake. Drum brakes are also occasionally fitted as the parking (and emergency) brake even when the rear wheels use disk brakes as </p>

32、;<p>　　In hybrid vehicle applications, wear on braking systems is greatly reduced by energy recovering motor-generators (see regenerative braking), so some hybrid vehicles such as the GMC Yukon hybrid and Toyota P

33、rius (except the third generation) use drum brakes.</p><p>　　Disc brakes rely on pliability of caliper seals and slight runout to release pads, leading to drag, fuel mileage loss, and disc scoring. Drum brak

34、e return springs give more positive action and, adjusted correctly, often have less drag when released.</p><p>　　Certain heavier duty drum brake systems compensate for load when determining wheel cylinder pr

35、essure; a feature unavailable when disks are employed. One such vehicle is the Jeep Comanche. The Comanche can automatically send more pressure to the rear drums depending on the size of the load, whereas this would not

36、be possible with disks.</p><p>　　Due to the fact that a drum brakes friction contact area is at the circumference of the brake, a drum brake can provide more braking force than an equal diameter disc brake.

37、The increased friction contact area of drum brake shoes on the drum allows drum brake shoes to last longer than disc brake pads used in a brake system of similar dimensions and braking force. Drum brakes retain heat and

38、are more complex than disc brakes but are often times the more economical and powerful brake type to use i</p><p>　　Brake technology, just like suspension technology and fuel-system technology, has come a lo

39、ng way in recent years. What began in the '60s as a serious attempt to provide adequate braking for performance cars has ended in an industry where brakes range from supremely adequate to downright phenomenal. The in

40、troduction of components like carbon fiber, sintered metal and lightweight steel, along with the adoption of ABS, have all contributed to reduced stopping distances and generally safer vehicles</p><p>　　Alth

41、ough drum brakes are often the better choice for rear brake applications in all but the highest performance applications, vehicle manufactures are increasingly installing disc brake system at the rear wheels. This is due

42、 to the popularity rise of disc brakes after the introduction front ventilated disc brakes. Front ventilated disc brakes performed much better than the front drum brakes they replaced. The difference in front drum and di

43、sc brake performance caused car buyers to purchase cars </p><p>　　Disadvantages</p><p>　　Drum brakes, like most other types, are designed to convert kinetic energy into heat by friction.[1] This

44、 heat is intended to be further transferred to atmosphere, but can just as easily transfer into other components of the braking system.</p><p>　　Brake drums have to be large to cope with the massive forces t

45、hat are involved, and they must be able to absorb and dissipate a lot of heat. Heat transfer to atmosphere can be aided by incorporating cooling fins onto the drum. However, excessive heating can occur due to heavy or re

46、peated braking, which can cause the drum to distort, leading to vibration under braking.</p><p>　　The other consequence of overheating is brake fade.[1] This is due to one of several processes or more usuall

47、y an accumulation of all of them.</p><p>　　1. When the drums are heated by hard braking, the diameter of the drum increases slightly due to thermal expansion, this means the brakes shoes have to move farther

48、 and the brake pedal has to be depressed further.</p><p>　　2. The properties of the friction material can change if heated, resulting in less friction. This is usually only temporary and the material regains

49、 its efficiency when cooled,[1] but if the surface overheats to the point where it becomes glazed the reduction in braking efficiency is more permanent. Surface glazing can be worn away with further use of the brakes, bu

50、t that takes time.</p><p>　　3. Excessive heating of the brake drums can cause the brake fluid to vapourise, which reduces the hydraulic pressure being applied to the brake shoes.[1] Therefore less retardatio

51、n is achieved for a given amount of pressure on the pedal. The effect is worsened by poor maintenance. If the brake fluid is old and has absorbed moisture it thus has a lower boiling point and brake fade occurs sooner.[1

52、]</p><p>　　Brake fade is not always due to the effects of overheating. If water gets between the friction surfaces and the drum, it acts as a lubricant and reduces braking efficiency.[1] The water tends to s

53、tay there until it is heated sufficiently to vapourise, at which point braking efficiency is fully restored. All friction braking systems have a maximum theoretical rate of energy conversion. Once that rate has been reac

54、hed, applying greater pedal pressure will not result in a change of this rate, and i</p><p>　　Disc brakes are not immune to any of these processes, but they deal with heat and water more effectively than dru

55、ms.</p><p>　　Drum brakes can be grabby if the drum surface gets light rust or if the brake is cold and damp, giving the pad material greater friction. Grabbing can be so severe that the tires skid and contin

56、ue to skid even when the pedal is released. Grabbiness is the opposite of fade: when the pad friction goes up, the self-assisting nature of the brakes causes application force to go up. If the pad friction and self-ampli

57、fication are high enough, the brake will stay on due to self-application even when the</p><p>　　Another disadvantage of drum brakes is their complexity. A person must have a general understanding of how drum

58、 brakes work and take simple steps to ensure the brakes are reassembled correctly when doing work on drum brakes. Incompetent mechanics should not attempt working on drum brakes.</p><p><b>　　Re-arcing&

59、lt;/b></p><p>　　Before 1984, it was common to re-arc brake shoes to match the arc within brake drums. This practice, however, was controversial as it removed friction material from the brakes and caused a

60、 reduction in the life of the shoes as well as created hazardous asbestos dust. Current design theory is to use shoes for the proper diameter drum, and to simply replace the brake drum when necessary, rather than perform

61、 the re-arcing procedure. Before you can appreciate the difference between drum and disc bra</p><p>　　Adjustment</p><p>　　Early drum brakes (before about 1955) required periodic adjustment to co

62、mpensate for drum and shoe wear. If not done sufficiently often long brake pedal travel ("low pedal") resulted. Low pedal can be a severe hazard when combined with brake fade as the brakes can become ineffectiv

63、e when the pedal bottoms out.</p><p>　　Self adjusting brakes may use a mechanism that engages only when the vehicle is being stopped from reverse motion. This is a traditional method suitable for use where a

64、ll wheels use drum brakes (most vehicles now use disc brakes on the front wheels). By operating only in reverse it is less likely that the brakes will be adjusted while hot (when the drums are expanded), which could caus

65、e dragging brakes that would accelerate wear and increase fuel consumption.</p><p>　　Self adjusting brakes may also operate by a ratchet mechanism engaged as the hand brake is applied, a means suitable for u

66、se where only rear drum brakes are used. If the travel of the parking brake actuator lever exceeds a certain amount, the ratchet turns an adjuster screw that moves the brake shoes toward the drum.</p><p>　　T

67、here are different Self Adjusting Brake Systems. Basically can be divided in to RAI and RAD. RAI systems are much more efficient than RAD systems and have built in systems that avoids the systems to recover when the brak

68、e is over heating. The most famous RAI are developed by Lucas, Bendix, Bosch, AP. For RAD systems the most famous are Bendix, AP, VAG ( Volkswagen ) and FORD recovery systems.</p><p>　　The manual adjustment

69、knob is usually at the bottom of the drum and is adjusted via a hole on the opposite side of the wheel. This requires getting underneath the car and moving the clickwheel with a flathead screwdriver. It is important and

70、tedious to adjust each wheel evenly so as to not have the car pull to one side during heavy braking, especially if on the front wheels. Either give each one the same amount of clicks and then perform a road test, or rais

71、e each wheel off the ground and spin i</p><p>　　Use in music</p><p>　　A brake drum can be very effective in modern concert and film music to provide a non-pitched metal sound similar to an anvil

72、. Some have more resonance than others, and the best method of producing the clearest sound is to hang the drum with nylon cord or to place it on foam. Other methods include mounting the brake drum on a snare drum stand.

73、 Either way, the brake drum is struck with hammers or sticks of various weight.</p><p>　　It is also commonly used in steelpan ensembles, where it is called "the iron."</p><p><b>

74、　　鼓式制動器</b></p><p>　　鼓式制動器是由一組摩擦蹄片擠壓一個叫做制動鼓的旋轉(zhuǎn)鼓狀部分實現(xiàn)摩擦動。</p><p>　　術(shù)語“鼓式制動器”意味著制動蹄片壓緊在制動鼓的內(nèi)表面。當制動蹄片壓在制動的外表面時通常叫做一扣剎。制動鼓夾在兩制動蹄片間，類似盤式制動器時，通常叫做捏鼓式制動器，這樣的剎車很少見。還有一中類似形式的制動器，它采用一個活動的或者固定的帶披在鼓的外

75、表面，叫做帶式制動器。</p><p><b>　　歷史</b></p><p>　　在摩托車的后輪鼓式制動器川崎W800</p><p>　　現(xiàn)代汽車鼓式制動器由路易斯雷諾發(fā)明于1902年,盡管一年前邁巴赫已經(jīng)使用了，一種有欠成熟的鼓式制動器。在早期的鼓式制動器里，那些蹄片由桿和電纜機械的組合在一起。從30年代中期開始，蹄片以一個小輪缸與活塞

76、的油壓運作，盡管車輛仍然以純粹的機械系統(tǒng)持續(xù)了幾十年，有些設(shè)計有兩個輪缸。</p><p>　　在鼓式制動器里蹄片很容易磨損同時剎車還需要定時調(diào)節(jié)，知道20世紀50年代才引進鼓式制動器自動調(diào)節(jié)系統(tǒng)。在60和70年代前輪逐漸以盤式制動器取代了鼓式制動器，現(xiàn)在幾乎所有的前輪都是盤式制動器，同時提供所有輪子的盤式制動器。然而，鼓式制動器仍然經(jīng)常用于手剎，因為事實證明很難設(shè)計一個盤式制動器去保持一輛不在使用時的汽車。此外

77、，它很容易適合一個盤式制動器里面的鼓內(nèi)手剎，這樣一個部件就既能實現(xiàn)剎車跟手剎。</p><p>　　早期型制動蹄含有石棉。當舊汽車制動系統(tǒng)工作時，必須注意不要吸入任何灰塵在制動器總成存在。美國聯(lián)邦政府開始管制石棉生產(chǎn)，剎車制造商不得不轉(zhuǎn)向非石棉墊??。業(yè)主最初的抱怨更換剎車，但最終由于先進的技術(shù)得以補償。大量的日常使用的舊車輛大部分無石棉襯片。許多其他國家也限制使用石棉剎車。早期的汽車制動系統(tǒng)，在經(jīng)過了手拉式杠桿

78、制動的時代后，在所有的4個輪子上設(shè)計一個鼓用來制動。它之所以被稱作鼓式制動器是因為它的工作組件被裝在一個隨著車輪轉(zhuǎn)動的鼓里。里面有一雙制動蹄片，當剎車踏板踩下時，蹄片被迫使摩擦鼓以減慢輪子的速度。液壓用于傳遞制動踏板的運動到制動蹄片的運動，而制動蹄片本身由類似做離合器的耐熱摩擦材料制成。</p><p>　　這樣設(shè)計的鼓式制動器被證明在大多數(shù)情況是可實現(xiàn)制動的，但是同時它也有一個重大缺陷。在高難度制動條件下，像在

79、一個陡峭的山坡上高負荷，或者反復(fù)高速制動，鼓式制動器就會制動力就會衰退而失去效力。通常產(chǎn)生這種衰退的原因是制動過熱。我們要知道鼓式制動器的原理是將車輪的動能轉(zhuǎn)換為熱能。出于這個原因，鼓式制動器只有在能吸收減慢汽車車輪速度產(chǎn)生的熱量時才能實現(xiàn)制動。一旦制動器的制動元件本身以熱飽和，他們就會失去停止車輛的能力，這可能會寧一些車輛的運營商感到不安。</p><p><b>　　自應(yīng)用特點</b>&

80、lt;/p><p>　　鼓式制動有個天然的“自應(yīng)用”特性。旋轉(zhuǎn)的鼓可以拖動一片的一邊或兩邊進入摩擦表面，引起剎車咬負荷加重，這樣增加了壓力把它們壓在一起。這增加停止阻力，不需要司機額外的動作，但這卻又使得司機調(diào)整剎車的靈敏性更加困難。這也使得剎車衰退更加敏感，由于制動摩擦的減少同時也降低了制動輔助系統(tǒng)的效果。</p><p>　　盤式制動器沒有展現(xiàn)自應(yīng)用效果，是因為液壓壓力作用在垂直制動盤的旋

81、轉(zhuǎn)方向，盤式制動器通常帶有伺服援助（“制動助力器”）來減輕駕駛員對踏板的努力，但是一些裝了盤式制動器的汽車（特別是三車）和小型盤式剎車的摩托車，等等，并不需要伺服援助系統(tǒng)。</p><p>　　注：在大多數(shù)設(shè)計中，“自應(yīng)用”效果只發(fā)生在一只蹄片上。當一只蹄片壓入制動鼓產(chǎn)生摩擦的一刻，作用效果卻是發(fā)生在相對的另一只蹄片上。摩擦力試圖遠離旋轉(zhuǎn)鼓。產(chǎn)生的效果在兩只蹄片上不同，導致一只蹄片磨損的更快。雖然可能設(shè)計一個雙蹄

82、鼓式制動器，且兩只蹄片都能自應(yīng)用效果（具有獨立的執(zhí)行器和兩端），但這在實踐中是非常罕見的。</p><p><b>　　鼓式制動器設(shè)計</b></p><p>　　鼓式制動器通常稱為領(lǐng)從蹄式尾從蹄式或雙領(lǐng)蹄式。</p><p>　　后鼓式制動器通常設(shè)計為領(lǐng)從蹄式（非伺服系統(tǒng)），（對于雙伺服系統(tǒng)）（主/副）制動蹄片通過一個單一的雙液壓缸和鉸鏈連接

83、在同一點而運動。這種設(shè)計中，一個制動蹄會一直產(chǎn)生自應(yīng)用效果，不管車輛是在前進或后退。當制動器（手剎或者駐車制動）需要施加足夠大的力量阻止汽車后退或者使汽車停在斜坡上時，這個特點對后制動器是非常有用的。提供制動器足夠大的接觸面積不是自應(yīng)用效應(yīng)能安全的停穩(wěn)汽車的唯一的原因，還因為當汽車后退或者斜坡上時車輛的重量轉(zhuǎn)移到后制動器上。用一個獨立的液壓缸在后的另一個優(yōu)點是，相對的支撐點在一個雙瓣形式的凸輪上，由駐車制動系統(tǒng)的運動帶動其旋轉(zhuǎn)。<

84、/p><p>　　前鼓式制動器在實踐和設(shè)計中都是存在的，但是雙領(lǐng)蹄式的設(shè)計更有效。本設(shè)計采用兩個驅(qū)動汽缸排列，以便兩個蹄片在車輛前進中都能利用其自應(yīng)用特點。兩制動蹄片相對，這在前進時給出了最大的制動可能，但當車輛后退時就不那么有效。前輪采用雙領(lǐng)蹄式制動器配合后輪采用領(lǐng)從蹄式制動器，這樣最佳的安排能在汽車前進是提供更大的制動力。這有助于防止后輪鎖死，卻仍然能在需要時提供后輪足夠的制動力。</p><

85、p>　　制動鼓本身通常由鑄鐵制成，雖然一些在使用車輛，特別是前輪應(yīng)用鋁鼓。鋁合金比鑄鐵導熱，提高散熱性能更好，減少褪色。鋁桶，也輕于鐵桶，從而降低了簧下重量。因為鋁比鐵更容易磨損，鋁鼓會經(jīng)常對的內(nèi)表面襯鐵或鋼鼓，保稅或鉚接到鋁外殼。</p><p><b>　　優(yōu)點</b></p><p>　　鼓式制動器用于多數(shù)重型卡車，部分中、輕型卡車，還有一些汽車、輕型摩托

86、車和沙灘車。由于車輛的制動力大部分由前輪產(chǎn)生，因此鼓式剎車常用于后輪，使其產(chǎn)生的熱量顯著減少。鼓式制動器可以簡單結(jié)合手停車制動。即使后輪主要使用的是蝶式剎車器，鼓式制動器也偶爾適用于制動和緊急停車。通常被安裝在剎車盤內(nèi)部或作為其一部分的小鼓，在這種情況下被稱為班克西亞剎車。</p><p>　　在混合驅(qū)動汽車的應(yīng)用中，能源再生馬達發(fā)電機（見再生制動）使制動系統(tǒng)的磨損大大減少，因此，一些諸如GMC育空和豐田普瑞斯（

87、除第三代）的混合制動汽車使用鼓式制動器。</p><p>　　蝶式剎車器依靠卡鉗密封的柔韌性和輕微的跳動來釋放襯墊，導致阻力、燃油的里程損失和閥瓣而得分。而復(fù)位彈簧鼓式制動器則有更積極的舉動來進行恰當?shù)恼{(diào)整，使其在釋放時往往產(chǎn)生更小的阻力。</p><p>　　當限定了輪缸壓力時，某些負荷更重的鼓式制動系統(tǒng)就會補償負荷，而用盤式制動器則無這一特點。吉普科曼奇就是一輛這樣的車。科曼奇可以根據(jù)

88、負荷的大小來自動給后方鼓更大的壓力，然而這對盤式制動器來說是不可能的。</p><p>　　基于摩擦接觸面積在于剎車的周長這一事實，鼓式制動器可以提供比同等直徑的盤式制動器更多的制動力。鼓式制動器剎車片增加的摩擦接觸面積使其在相似規(guī)格和制動力的制動系統(tǒng)中比盤式剎車片在鼓上持續(xù)更長的時間。鼓式制動器保持熱量且比盤式制動器復(fù)雜，但很多時候，由于后輪剎車產(chǎn)生的低熱量，自適應(yīng)性，大的摩擦接觸面積，磨損壽命長等特點使其在后

89、軸制動器的應(yīng)用中顯得更經(jīng)濟，更強大。</p><p>　　雖然在幾乎所有的高性能的剎車裝置中，對于后剎車裝置，鼓式制動器是一個很好的選擇，但是還是越來越多的人在汽車后輪上安裝盤式剎車系統(tǒng)。這是由于前面通風盤式制動器引進后，盤式制動器的大量流行。前面通風盤式制動器比他們?nèi)〈墓氖街苿悠髡宫F(xiàn)出更好的性能。前面通風盤式制動器與鼓式制動器性能的區(qū)別將會影響汽車買主對車的購買，同時也會影響后輪盤式制動器。另外，后輪盤式制動

90、器通常與那些能夠在馬路上增加他們的知名度的賽車是相關(guān)的。后輪盤式制動器在大多數(shù)的裝置中是不通風的，與鼓式制動器相比通常是沒有性能優(yōu)勢的。即使后輪盤式制動器能夠通風，后輪制動可能還是從這個通風設(shè)備中得不到任何益處，除非在高性能要求的賽車過程中。</p><p><b>　　缺點</b></p><p>　　鼓式制動器像大多數(shù)其他類型，旨在通過摩擦轉(zhuǎn)化為熱能的動能。[1]

91、這種熱是為了進一步轉(zhuǎn)移到大氣中，但也可以很容易地轉(zhuǎn)移到制動系統(tǒng)的其他組件中去。</p><p>　　制動鼓要大，以應(yīng)付所涉及的巨大力量，他們必須能夠吸收和浪費的大量熱量。傳遞到大氣中的熱量可以被納入到制動鼓的散熱片中。然而，過度的熱會發(fā)生頻繁反復(fù)制動，這會導致鼓變形，制動時振動。</p><p>　　過熱的其它后果是導致剎車衰退。這是由于幾個進程中的一個過于頻繁運動積累導致的。</p

92、><p>　　當制動鼓經(jīng)過強制動時，制動鼓的直徑由于熱膨脹略微增加，這意味著制動蹄片必須運動更遠同時剎車踏板的行程也增大。</p><p>　　如果過熱摩擦材料的特性也會改變，造成摩擦不夠。只通常是短暫的，當冷卻后材料就會回復(fù)其效率，但如果材料表面過熱到極點而變得光滑制動效率就會大大的降低。光滑的表面經(jīng)過長久的使用會磨掉，但需要太多時間。</p><p>　　剎車鼓的過

93、熱會導致制動液的蒸發(fā)，從而降低了應(yīng)用到制動蹄上的液壓。因此給定一個一定的制動踏板的額定值。如果保養(yǎng)不善其結(jié)果會更加惡化。如果制動液過舊，吸收了水分，就會具有較低的沸點導致制動遲早會衰退。</p><p>　　制動衰退也不總是由于過熱引起的。如果有水在制動鼓和摩擦表面之間，水起到潤滑的作用也會降低制動效能。水會一直待在那里，知道被加熱到蒸發(fā)，此時制動效能才會恢復(fù)。所有的摩擦制動系統(tǒng)都有一個最大能量轉(zhuǎn)換理論率。一旦這

94、比率達到，在制動踏板加更大的力也不會產(chǎn)生變化，而事實上，上述提到的不良影響可以大大的減少。不論其他機制，這才是剎車衰退的根本原因。</p><p>　　盤式制動器也不能幸免于這些過程中的任何一個，但是它們能比鼓式制動器更好的處理水跟熱的影響。</p><p>　　鼓式制動器會產(chǎn)生多余的制動當制動鼓的表面有輕微的銹跡或者制動鼓潮濕和過冷，這時會給予摩擦襯片更大的摩擦。使得輪胎打滑，有時甚至在

95、制動踏板松開時，輪胎還會打滑。這是一種相對的剎車衰退：當摩擦墊上升，剎車的自我協(xié)調(diào)性能迫使制動效能因素也上升。如果摩擦墊和自我放大足夠高，制動會由于自我申請始終停留，即使外部應(yīng)用程序力量被釋放。</p><p>　　鼓式制動器的另一缺點是其復(fù)雜性。一個從事鼓式制動器工作的人，必須具備對鼓式制動器如何工作有一定的了解以確保鼓式制動器正確的組裝。不稱職的技工不適合從事鼓式制動器的工作。</p><

96、p><b>　　再弧制</b></p><p>　　在1984年之前，為了與鼓式制動器內(nèi)的弧度相匹配，對剎車片進行二次彎曲是很常見的。然而這種做法備受爭議，因為這樣就會使剎車的摩擦材料脫落從而減少剎車片的壽命，同時也會產(chǎn)生有危害的石棉灰。當今的設(shè)計理論認為剎車片應(yīng)該使用在適當直徑的鼓上從而能在必要的時候代替剎車鼓，而不應(yīng)該對剎車片進行二次彎曲。</p><p>

97、<b>　　校準</b></p><p>　　早期的鼓式制動器（1995年）需要進行定期的調(diào)整來對鼓和摩擦板進行補償。如果沒有進行這樣的定期補償那么會造成制動器踏板行程變長（低踏板）。而低踏板有時是十分危險的，特別是在剎車踩到底而失靈的時候。制動系統(tǒng)只可能在汽車的反向運動停止時使用自我調(diào)節(jié)的機制，這是一種傳統(tǒng)方的應(yīng)用（現(xiàn)在大部分車輛都是用的是前輪盤式制動器）。只有當反向操作時，它才不太可能在

98、制動器發(fā)熱的時候被調(diào)整（當鼓擴大），這可能造成剎車剎車拖拉，加速摩擦板以及燃油的消耗。如果進行手剎的話，自我調(diào)節(jié)的制動系統(tǒng)還可能作為棘輪機制使用，這也只有在后輪鼓剎使用時才適合。如果車載制動桿超過了一定的行程，棘輪就會變成一個調(diào)節(jié)螺釘來使剎車板向鼓移動。存在著不同的自我調(diào)節(jié)制動系統(tǒng)，基本上可以劃分為RAI和RAD.RAI系統(tǒng)比RAD系統(tǒng)更加有效，并且已經(jīng)設(shè)立了避免剎車過熱而能自動停止運行的機制。最著名的RAI系統(tǒng)是由LUCAS，BEND

99、IX，BOSCH,AP研發(fā)。而RAD系統(tǒng)最著名的是為BENDIX，AP,VAG以及FORD公司研制的恢復(fù)系統(tǒng)。</p><p>　　手動調(diào)節(jié)旋鈕通常是在鼓的底部并且是通過一個在輪子里面的小孔來行調(diào)節(jié)。這需要到車輛的底部并且要用平頭螺絲刀來把輪子取下。最重要也是最繁瑣的是為了不至于在進行急剎時車會傾斜，我們必須等量的調(diào)節(jié)每個輪子，特別是在裝置處于前輪的時候。要么給每個相同的旋量，然后進行道路試驗，或?qū)⒚總€車輪提升使