548 橡膠履帶牽引車輛改進設計（高速行走機構(gòu)）（有cad圖）
548 橡膠履帶牽引車輛改進設計（高速行走機構(gòu)）（有cad圖）,548,橡膠履帶牽引車輛改進設計（高速行走機構(gòu)）（有cad圖）,橡膠,履帶,牽引,車輛,改進,改良,設計,高速,行走,機構(gòu),cad
外文資料譯文
3.1 Clutch
The engine produces the power to drive the vehicle. The drive line or drive train transfers the power of the engine to the wheels. The drive train consists of the parts from the back of the flywheel to the wheels. These parts include the clutch, the transmission, the drive shaft, and the final drive assembly.
The clutch which includes the flywheel, clutch disc, pressure plate, springs, pressure plate cover and the linkage necessary to operate the clutch is a rotating mechanism between the engine and the transmission. It operates through friction which comes from contact between the parts. That is the reason why the clutch is called a friction mechanism. After engagement, the clutch must continue to transmit all engine torque to transmission depending on the friction without slippage. The clutch is also used to disengage the engine from the drive train whenever the gears in the transmission are being shifted from gear ratio to another.
To start the engine or shift the gears, the driver has to depress the clutch pedal with the purpose of disengagement the transmission from the engine. At that time, the driven members connected to the transmission input shaft are either stationary or rotating at a speed that is slower of faster than the driving members connected to engine crankshaft. There is no spring pressure on the clutch assembly parts. So there is no friction between the driving members and driven members. As the driver let’s loose the clutch pedal, spring pressure increase on the clutch parts. Friction between the parts also increases. The pressure exerted by the springs on the driven members is controlled by the driver through the clutch pedal and linkage. The positive engagement of the driving and driven members is made possible the friction between the surfaces of the members. When full spring pressure is applied, the speed of the driving and driven members should be the same. At the moment, the clutch must act as a coupling device and transmit all engine power to the transmission, without slipping.
However, the transmission should be engaged to the engine gradually in order to operate the car smoothly and minimize tensional shock on the drive train because an engine at idle just develop little power. Otherwise, the driving members are connected with the driven members too quickly and the engine would be stalled.
The flywheel is a major part of the clutch. The flywheel mounts to the engine’s crankshaft and transmits engine torque to the clutch assembly. The flywheel, when coupled with the clutch disc and pressure plate makes and breaks the flow of power the engine to the transmission.
The flywheel provides a mounting location for the clutch assembly as well. When the clutch is applied, the flywheel transfers engine torque to the clutch disc. Because of its weight, the flywheel helps to smooth engine operation. The flywheel also has a large ring gear at its outer edge, which engages with a pinion gear on the starter motor during engine cranking.
The clutch disc fits between the flywheel and the pressure plate. The clutch disc has a splinted hub that fits over splints on the transmission input shaft. A splinted hub has grooves that match splints on the shaft. These splints fit in the grooves. Thus, the two parts held together. However, back – and – forth movement of the disc on the shaft is possible. Attached to the input shaft, the disc turns at the speed of the shaft.
The clutch pressure plate is generally made of cast iron. It is round and about the same diameter as the clutch disc. One side of the pressure plate is machined smooth. This side will press the clutch disc facing are against the flywheel. The outer side has shapes to facilitate attachment of spring and release mechanism. The two primary types of pressure plate assemblies are coil spring assembly and diaphragm spring.
In a coil spring clutch the pressure plate is backed by a number of coil springs and housed with them in a pressed – steed cover bolted to the flywheel. The spring pushes against the cover. Neither the driven plate nor the pressure plate is connected rigidly to the flywheel and both can move either towards it o away. When the clutch pedal is depressed a thrust pad riding on a carbon or ball thrust bearing is forced towards the flywheel. Levers pivoted so that they engage with the thrust pad at one end and the pressure plate tat the other end pull the pressure plate back against its springs. This releases pressure on the driven plate disconnecting the gearbox from the engine.
Diaphragm spring pressure plate assemblies are widely used in most modern cars. The diaphragm spring is a single thin sheet of metal which yields when pressure is applied to it. When pressure is removed the metal spring back to its original shape. The center portion of the diaphragm spring is slit into numerous fingers that act as release levers. When the clutch assembly rotates with the engine these weights are flung outwards by centrifugal plate and cause the levers to press against the pressure plate. During disengagement of the clutch the fingers are moved forward by the release bearing. The spring pivots over the fulcrum ring and its outer rim moves away from the flywheel. The retracting spring pulls the pressure plate away from the clutch plate thus disengaging the clutch.
When engaged the release bearing and the fingers of the diaphragm spring move towards the transmission. As the diaphragm pivots over the pivot ring its outer rim forces the pressure plate against the clutch disc so that the clutch plate is engaged to flywheel.
The advantages of a diaphragm type pressure plate assembly are its compactness, lower weight, fewer moving parts, less effort to engage, reduces rotational imbalance by providing a balanced force around the pressure plate and less chances of clutch slippage.
The clutch pedal is connected to the disengagement mechanism either by a cable or, more commonly, by a hydraulic system. Either way, pushing the pedal down operates the disengagement mechanism which puts pressure on the fingers of the clutch diaphragm via a release bearing and causes the diaphragm to release the clutch plate. With a hydraulic mechanism, the clutch pedal arm operates a piston in the clutch master cylinder. This forces hydraulic fluid through a pipe to the cutch release cylinder where another operates the clutch disengagement mechanism by a cable.
The other parts including the clutch fork, release bearing, bell – housing, bell housing cover, and pilot bushing are needed to couple and uncouple the transmission. The clutch fork, which connects to the linkage, actually operates the clutch. The release bearing fits between the clutch fork and the pressure plate assembly. The bell housing covers the clutch assembly. The bell housing cover fastens to the bottom of the bell housing. This removable cover allows a mechanic to inspect the clutch without removing the transmission and bell housing. A pilot bushing fits into the back of the crankshaft and holds the transmission input shaft.
3.2 Brake System
The breaking system is the most important system in cars. If the brakes fail, the result can be disastrous. Brakes are actually energy conversion devices, which convert the kinetic energy (momentum) of the vehicle into thermal (heat). When stepping on the brakes, the driver commands a stopping force ten times as powerful as the force that puts the car in motion. The braking system can exert thousands of pounds of pressure on each of the four brakes.
The brake system is composed of the following basic components: the “master cylinder” which is located under the hood, and is directly connected to the brake pedal, converts driver foot’s mechanical pressure into hydraulic pressure. Steel “brake lines” and flexible “brake hoses” connect the master cylinder to the “slave cylinders” located at each wheel. Brake fluid, specially designed to work in extreme condition, fills the system. “Shoes” and “Pads” are pushed by the salve cylinders to contact the “drum” and “rotors” thus causing drag, which (hopefully) slows the car.
The typical brake system consists of disk brakes in front and either disk or drum brakes in the rear connected by a system of tubes and hoses that link the brake at each wheel to the master cylinder.
Stepping on the brake pedal, a plunger is actually been pushing against in the master cylinder which forces hydraulic oil (brake fluid) through a series of tubes and hoses to the braking unit at each wheel. Since hydraulic fluid (or any fluid for that matter) cannot be compressed, pushing fluid through a pipe is just like pushing a steel bar through pipe. Unlike a steel bar, however, fluid can be directed through many twists and turns on its way to its destination, arriving with the exact same motion and pressure that it started with. It is very important that the fluid is pure liquid and that there is no air bubbles in it. Air can compress which causes sponginess to the pedal and severely reduced braking efficiency. If air is suspected, then the system must be bled to remove the air. There are “bleeder screws” at each wheel and caliper for this purpose.
On disk brakes, the fluid from the master cylinder is forced into a caliper where it pressure against a piston. The piton, in-turn, squeezes two brake pads against the disk (rotor) which is attached to the wheel, forcing it to slow down or stop. This process is similar to the wheel, causing the wheel to stop. In either case, the friction surface of the pads on a disk brake system, on the shoes on a drum brake convert the forward motion of the vehicle into heat. Heat is what causes the friction surfaces (lining) of the pads and shoes to eventually wear out and require replacement.
Brake fluid is special oil that has specifics properties. It is designed to withstand cold temperatures without thickening as well as very high temperatures without boiling. (If the brake fluid should boil, it will cause you to have a spongy pedal and the car will be hard to stop).
The brake fluid reservoir is on top of the master cylinder. Most cars today have a transparent reservoir so that you can see the level without opening the cover. The brake fluid lever will drop slightly as the brake pads wear. This is a normal condition and no cause for concern. If the lever drops noticeably over a short period of time or goes down to about two thirds full, have your brakes checked as soon as possible. Keep the reservoir covered expect for the amount of time you need to fill it and never leave a can of brake fluid uncovered. Brake fluid must maintain a very high boiling point. Exposure to air will cause the fluid to absorb moisture which will lower that boiling point.
The brake fluid travels from the master cylinder to the wheels through a series of steel tubes and reinforced rubber hoses. Rubber hoses are only used in places that require flexibility, such as at the front wheels, which move up and down as well as steer. The rest of the system uses non-corrosive seamless steel tubing with special fittings at attachment points. If a steel line requires a repair, the best procedure is to replace the complete line. If this is nit practical, a line can be repaired using special splice fittings that are made for brake system repair. You must never use brass “compression” fittings or copper tubing repair a brake system. They are dangerous and illegal.
3.2.1 Other Components in the Hydraulic System
Proportioning Valve or Equalizer Valve
These valves are mounted between the master cylinder and the rear wheels. They are designed to adjust the pressure between the front and the rear brakes depending on how hard you are stopping. The shorter you stop, the more of the vehicle’s weight is transferred to the front wheels, in some cases, causing the rear to lift and the front to dive. These valves are designed to direct more pressure to the front and less pressure to the harder you stop. This minimizes the chance of premature lockup at the rear wheels.
Pressure Differential Valve
This valve is usually mounted just below the master and is responsible for turning the brake warning light on when it detects a malfunction. It measures the pressure from the two sections of the master cylinder and compares them. Since it is mounted ahead of the proportioning or equalizer valve, the two pressures it detects should be equal. If it detects a difference, it means that there is probably a brake fluid leak somewhere in the system.
3．1 離合器
發(fā)動機產(chǎn)生動力來驅(qū)動汽車，它通過傳動系把動力傳遞到車輪上，傳動系包含從飛輪到車輪的所有零件。這些零件含離合器、變速箱，驅(qū)動橋和最后的駕駛總成。
離合器含飛輪、離合器壓盤、離合器從動盤、彈簧 、壓盤蓋和操作離合器所需的連桿組，連桿組是引擎和變速箱之間的一個旋轉(zhuǎn)機構(gòu)，它裝在離合器和變速器之間，離合器通過來自在兩零件之間的接觸的磨擦力來工作，這就是離合器為什么叫做一個磨擦機構(gòu)。在嚙合之后，離合器一定要依靠磨擦連續(xù)傳遞所有的引擎扭力到變速箱而中間不會有滑移。每當變速箱的齒輪由于換擋被移動時，離合器就用來斷開來自引擎的動力。
為了要啟動引擎或者移動齒輪，駕駛員必須踩下離合器踏板達到把變速器和引擎分離的目的。同時,對變速箱輸入軸的連接的被動的構(gòu)件是或不動或者對引擎曲軸被連接的構(gòu)件以一個比較慢的速度旋轉(zhuǎn)。沒有彈簧壓力在關鍵的總成零件上時，就沒有主動的構(gòu)件和被動的構(gòu)件之間的磨擦。駕駛員松開離合器踏板,離合器部件上的彈簧壓力增大，零件之間的磨擦也增加。駕駛員通過控制離合器踏板和連桿組來控制彈簧的壓力。主從動部件的結(jié)合使他們之間的摩擦成為可能。當整個彈簧壓力被應用的時候，主從動部件之間速度應該是相同的。此時，離合器成為一個聯(lián)結(jié)裝置，傳遞所有的引擎動力到變速箱，而不會有滑動。
然而，變速箱應該被逐漸地連接到引擎從而能平順地操作車而且在駕駛時能獲得較小的扭轉(zhuǎn)陡震因為此時引擎僅僅被使用了很少的動力。另外，主動構(gòu)件太快地與被動的構(gòu)件一起連接，引擎可能會被熄滅。
飛輪是離合器的一個主要部分。它連接在引擎曲軸上并把引擎動力傳遞到離合器總成上。飛輪通過連接從動盤和壓盤來傳遞從引擎到副箱的動力。
飛輪能很好的為離合器總成提供一個合適的位置。當離合器被應用的時候，飛輪把引擎扭力轉(zhuǎn)移到離合器。因為它的重量，飛輪能夠使引擎平順地運作。飛輪在它的外部邊緣有一個齒圈,在起動電動機上用一個驅(qū)動小齒輪來和它嚙合。
離合器從動盤裝在飛輪和壓盤之間。離合器從動盤上有一花鍵轂和變速箱輸入軸過盈配合。花鍵轂和軸上的花鍵聯(lián)接。這些花鍵裝在槽中。因此，這二個零件就連在了一起。然而,從動盤在軸上可能往前或后圓運動。從動盤和軸一起旋轉(zhuǎn)。
離合器壓盤通常是用鑄鐵做成的。它是圓的，與離合器從動盤有相同的直徑。壓盤的一個邊是光滑的。這一個邊將會壓著的離合器從動盤壓向飛輪。外部的邊有促進彈簧和分離機構(gòu)結(jié)合的輪磨配件。 這個壓盤總成的主要的兩個形式是螺旋彈簧總成和膜片彈簧。
彈簧推動對抗蓋。從動片和壓板都沒有被剛性地被連接到飛輪上，兩者可以向它移動也可以離開。當離合器踏板壓向止推軸承的推力軸瓦的時候飛輪被壓。壓向支點使他們在一端以推力軸瓦連接，而且壓板另一端把壓板拉回來壓向它的彈簧。這在將齒輪箱從引擎分離出來的從動片上釋放壓力。
膜片彈簧壓板總成廣泛地被用于現(xiàn)代的大多數(shù)汽車上。當壓力對它被應用的時候，膜片彈簧是一個單薄的形狀。當壓力被移動時它變成最初的形狀。膜片彈簧的中央部分進入擔任釋放桿的多數(shù)的手指之內(nèi)被縱切。當離合器總成和引擎輸出軸一起旋轉(zhuǎn)那些重力被離心板所投而且導致分離桿桿壓向壓板。在離合器的不工作期間，指端被分離軸承向前移動，彈簧支點在支撐環(huán)上和輸出軸移動遠離飛輪，伸縮彈簧拉著壓板遠離離合器片使離合器脫離工作。
分離軸承工作時膜片彈簧移向變速器。在樞上的隔膜樞嵌環(huán)它的外部輞強迫對抗離合器的壓板以便離合器片被連接到飛輪上。
隔膜型壓板總成的優(yōu)點是它的緊湊結(jié)構(gòu)，比較低的重量,比較少的移動零件,比較少的連接,在壓盤周圍提供一個平衡力來降低旋轉(zhuǎn)平衡和更少的離合器滑移幾率。
離合器踏板被連接到自由機構(gòu)或一個高壓線或,更普遍,或一個水力系統(tǒng)。任一方法,踩下踏板可推動分離軸承向前運動進而壓向壓盤使離合器與飛輪分離。由一個水力的機構(gòu)，離合器踏板臂在離合器主泵中操作一個活塞。
其他零件包括離合器叉,分離軸承,離合器殼，離合器殼蓋,分離軸襯連接和分離變速箱。離合器叉,和連桿組連接,實際上是操作離合器的。分離軸承裝在離合器叉和壓板總成之間。離合器蓋裝在離合器總成上。離合器蓋緊固到離合器殼的底部。這個可移動的蓋可以讓一個機匠不用去除變速箱和殼就可以檢驗離合器。導軸襯裝在曲軸的后部，并支撐變速箱輸入軸。
3.2 制動系統(tǒng)
制動系統(tǒng)是汽車中最重要的系統(tǒng)。如果煞車失敗，結(jié)果可能是損失慘重的。煞車實際上是能轉(zhuǎn)換裝置,把車輛的動能轉(zhuǎn)換成熱量。當煞車時，駕駛員在汽車上施加一個十倍于汽車運動的制動力。制動系統(tǒng)能在這四個煞車輪上對每一個輪施加數(shù)千磅的壓力。
制動系統(tǒng)由下列基本的組件組成:位于引擎蓋之下,而且直接地被連接到制動踏板的"主泵",進入液壓之內(nèi)變換駕駛腳的機械力。鋼“制動系統(tǒng)”和易曲的“煞車軟管”把主泵連結(jié)到位于每個輪的“被動泵”。煞車液,特別地設計在極端的工作情況下，加入系統(tǒng)?！疤恪焙汀巴邏K”是根據(jù)軟管汽缸推動連絡“鼓輪”和“轉(zhuǎn)子”如此引起動力,減慢車速。
典型的制動系統(tǒng)是前面的碟盤或后部的鼓式剎車，它們和一個筒的系統(tǒng)連接在每個輪的煞車和主泵的軟管。
腳踏在制動踏板上時,一個柱塞實際上推動一個主泵并作用在在每一個筒和軟管使液壓油的傳遞動力傳遞到各個輪上。因為流體不能夠被壓縮,推動流體管就像一個鋼條管不像一個鋼條然而，流體能被指示過許多扭轉(zhuǎn)而且在前往它的目的站的能中途轉(zhuǎn)向,以精確的相同動作和壓力到達目的地。非常重要的是，流體是純粹的液體而且沒有氣泡在它里面?？諝饽鼙粔嚎s，這對踏板而且嚴重地導致一個海棉狀減少剎效率。如果空氣被流入，那么系統(tǒng)一定要去除空氣。有“放氣螺栓”在每個輪和卡鉗可以達到這個目的。
在一個碟式殺車上，來自主泵的流體被迫壓向一個活塞的卡鉗?？ㄣQ在旋轉(zhuǎn),壓擠被附上到輪的碟盤的二個煞車瓦塊,使它減慢或者停止。這一個程序與輪類似,導致輪停止。在任一情況下，在一個碟式剎車系統(tǒng)方面的瓦塊的磨擦表面,在一個鼓式剎車上的表面上把車輛的前動動作轉(zhuǎn)換成熱。熱是引起瓦塊磨擦并穿透的原因，這就需要替換掉它了。
煞車液是一種特別的油。它被設計成既能耐低溫又能耐高溫，而不會被冷凍或達到沸點(如果萬一煞車液沸騰，它將會導致你使踏板成為海綿狀而且車將會很難停止)。
煞車液在主泵的頂部上。大多數(shù)的車今天都有一個透明的水庫，以便你沒有打開蓋能見到里面的情況。煞車液桿將會些微地降低隨著煞車瓦塊的磨耗。這是一個正常的狀態(tài)，沒必要擔心。如果桿在一段短時間內(nèi)明顯地降低或者變降到大約三分之二,盡快地檢查你的煞車系統(tǒng)。使水位保持你所期待的，直到需要填充它而不需要揭開一個煞車液的罐子。煞車液一定維持一個非常高的沸點。液體暴露在空氣中將會降低液體的沸點。
煞車液經(jīng)過一系列的鋼筒從主泵移動到輪。橡皮管只被用于需要可撓性的場所,像是在前面的輪,上下地移動，連同引導。系統(tǒng)的其它部分在輪磨配件點和特別的配件一起使用非腐蝕的鋼裝管。如果一個鋼管需要修補，最好的方法是換掉全部的。如果這不是實際的,要用一個特別的接合配件修理，它是專用于鋼管修理的。你一定不能使用黃銅的"壓縮"配件或銅裝管修補煞車系統(tǒng)。這是危險又違法的。
3.2.1 液體系統(tǒng)的其他的組件
比例氣門或平衡器氣門
這些氣門被裝在主泵和后車輪之間。他們被設計調(diào)整前面和后面的煞車之間的壓力，取決于你制動的難度。你停止的時間越短,車輛的重量更多地被轉(zhuǎn)移到前面的車輪,某些情況下導致齒輪移動和汽車前端點頭。
壓力差速器氣門
這一個氣門通常被裝在主泵下面而且負責它何時發(fā)現(xiàn)故障上轉(zhuǎn)煞車警告燈。它測量主泵來自這二個斷面的壓力而且比較它們的大小。它在那個比例或者平衡器氣門之前被安裝，它發(fā)現(xiàn)的二個壓力應該是相等。如果它發(fā)現(xiàn)一種不同，這意味著在系統(tǒng)某處有剎車液泄漏。
10
收藏