電動(dòng)汽車變速器設(shè)計(jì),電動(dòng)汽車,變速器,設(shè)計(jì) 畢業(yè)設(shè)計(jì)（論文）任務(wù)書 課題名稱 電動(dòng)汽車兩檔變速器結(jié)構(gòu)設(shè)計(jì) 副 標(biāo) 題 系 名 稱 機(jī)械與電氣信息工程系 專 業(yè) 機(jī)械設(shè)計(jì)制造及其自動(dòng)化 學(xué)生姓名 陳 晨 學(xué) 號(hào) 080190 畢業(yè)設(shè)計(jì)（論文）起訖時(shí)間： 自__2012__年_2__月_20日至__2012__年_6_月____日 共_____周 指導(dǎo)教師 簽名 年　　月　　　日 系主任 簽名 年 月 日 一、畢業(yè)設(shè)計(jì)（論文）的課題背景 隨著石油資源的日益減少和環(huán)境保護(hù)要求的提高，電動(dòng)汽車的發(fā)展越來(lái)越受到人們的重視，然而，對(duì)動(dòng)力傳動(dòng)系統(tǒng)部件的設(shè)計(jì)參數(shù)進(jìn)行研究是提高電動(dòng)汽車性能的重要手段之一。變速器是汽車重要的傳動(dòng)系組成，在較大范圍內(nèi)改變汽車行駛速度的大小和汽車驅(qū)動(dòng)輪上 扭矩的大小。 電動(dòng)汽車的變速器與普通變速器相比，其結(jié)構(gòu)有所不同。因?yàn)轵?qū)動(dòng)電機(jī)的旋向可以通過(guò)電路控制實(shí)現(xiàn)變換，所以電動(dòng)汽車無(wú)需內(nèi)燃機(jī)汽車變速器中的倒檔而設(shè)置倒檔軸，只需應(yīng)用電機(jī)反轉(zhuǎn)來(lái)實(shí)現(xiàn)倒車行駛。設(shè)計(jì)中利用已知參數(shù)確定變速器各參數(shù)，對(duì)軸和各擋齒輪進(jìn)行校核，繪制出裝配圖及零件圖。 同時(shí)本設(shè)計(jì)對(duì)電動(dòng)汽車的動(dòng)力傳動(dòng)系統(tǒng)進(jìn)行了匹配設(shè)計(jì)計(jì)算，計(jì)算結(jié)果表明達(dá)到性能要求。 二、畢業(yè)設(shè)計(jì)（論文）的技術(shù)參數(shù)（研究?jī)?nèi)容） 根據(jù)指導(dǎo)老師所給的基本參數(shù)。 發(fā)動(dòng)機(jī)輸出功率：， 發(fā)動(dòng)機(jī)最大扭矩： 汽車最高時(shí)速： 三、畢業(yè)設(shè)計(jì)（論文）應(yīng)完成的具體工作 1、撰寫開題報(bào)告一份； 2、撰寫計(jì)算說(shuō)明書一份，字?jǐn)?shù)不少于15000或正文不少于20頁(yè)； 3、繪制總布置圖，若干零件圖，總工作量不少于2張零號(hào)圖，其中要求手畫1份； 4、外文翻譯不少于20000個(gè)字符或5000個(gè)漢字，標(biāo)明原文出處； 5、將上述電子文件打包，刻成光盤一張，并打印電子文件。 四、畢業(yè)設(shè)計(jì)（論文）進(jìn)度安排 序號(hào) 設(shè)計(jì)（論文）各階段名稱 時(shí)間安排（教學(xué)周） 1 下達(dá)畢業(yè)設(shè)計(jì)任務(wù)書，布置具體任務(wù) 第1周 2 查閱相關(guān)資料，撰寫開題報(bào)告，構(gòu)建框架 第2～3周 3 查閱相關(guān)資料，參數(shù)選定，初步計(jì)算 第4～5周 4 查閱相關(guān)資料，初步設(shè)計(jì)，繪制草圖 第6～7周 5 校核，計(jì)算，中期檢查 第8周 6 繪制并修改總布置圖 第9～10周 7 繪制并修改零件圖， 第11～12周 8 撰寫并修改計(jì)算說(shuō)明書 第13-15周 9 論文裝訂、準(zhǔn)備畢業(yè)答辯 第16周 10 畢業(yè)論文答辯 第17周 同組學(xué)生姓名：胡立洋 葉守航 梁世概 五、應(yīng)收集的資料及主要參考文獻(xiàn) [1] 林學(xué)東，汽車工程手冊(cè)[M]，北京：人民教育出版社，2001 [2] 林學(xué)東，汽車動(dòng)力匹配技術(shù) [M]，北京:人民教育出版社，2001 [3] 黃曉榮，機(jī)械設(shè)計(jì)基礎(chǔ) [M]，北京：中國(guó)電力出版社2009 [4] 黃曉榮，機(jī)械設(shè)計(jì)基礎(chǔ)課程設(shè)計(jì)指導(dǎo)書 [M] 北京：中國(guó)電力出版社2009 [5] 陳于萍，互換性與測(cè)量技術(shù)[M],北京：機(jī)械工業(yè)出版社,2008 [6] 趙先仲 ，機(jī)電一體化系統(tǒng)設(shè)計(jì)手冊(cè)[M]，北京：機(jī)械工業(yè)出版社2001 [7] 李富波 張海萍，工程制圖與計(jì)算機(jī)繪圖 [M]，北京：中國(guó)電，力出版社，2005 [8] 李華 ，機(jī)械制造技術(shù) [M]， 北京：機(jī)械工業(yè)出版社2003 [9] 謝剛 沈冰，工程力學(xué) [M]，北京：機(jī)械工業(yè)出版社2001 [10] 朱孝錄，齒輪傳動(dòng)設(shè)計(jì)手冊(cè)[M]， 北京：機(jī)械工業(yè)出版社，2010 TONGJI ZHEJIANG COLLEGE 畢業(yè)設(shè)計(jì)（論文） 課題名稱 副 標(biāo) 題 系名稱： 專 業(yè)： 姓 名： 學(xué) 號(hào)： 指導(dǎo)教師： 日 期： 畢業(yè)設(shè)計(jì)（論文）開題報(bào)告 課題名稱　 電動(dòng)汽車兩檔變速結(jié)構(gòu)設(shè)計(jì) 副 標(biāo) 題 系 名 稱 機(jī)械與電氣信息工程系 專 業(yè) 機(jī)械設(shè)計(jì)制造及其自動(dòng)化 學(xué)生姓名 陳 晨 學(xué) 號(hào) 080190 2012 年 3 月 1 日 一、畢業(yè)設(shè)計(jì)（論文）課題背景（含文獻(xiàn)綜述） 隨著石油資源的日益減少和環(huán)境保護(hù)要求的提高，電動(dòng)汽車的發(fā)展越來(lái)越受到人們的重視，然而，對(duì)動(dòng)力傳動(dòng)系統(tǒng)部件的設(shè)計(jì)參數(shù)進(jìn)行研究是提高電動(dòng)汽車性能的重要手段之一。變速器是汽車重要的傳動(dòng)系組成，在較大范圍內(nèi)改變汽車行駛速度的大小和汽車驅(qū)動(dòng)輪上 扭矩的大小。 電動(dòng)汽車的變速器與普通變速器相比，其結(jié)構(gòu)有所不同。因?yàn)轵?qū)動(dòng)電機(jī)的旋向可以通過(guò)電路控制實(shí)現(xiàn)變換，所以電動(dòng)汽車無(wú)需內(nèi)燃機(jī)汽車變速器中的倒檔而設(shè)置倒檔軸，只需應(yīng)用電機(jī)反轉(zhuǎn)來(lái)實(shí)現(xiàn)倒車行駛。設(shè)計(jì)中利用已知參數(shù)確定變速器各參數(shù)，對(duì)軸和各擋齒輪進(jìn)行校核，繪制出裝配圖及零件圖。 同時(shí)本設(shè)計(jì)對(duì)電動(dòng)汽車的動(dòng)力傳動(dòng)系統(tǒng)進(jìn)行了匹配設(shè)計(jì)計(jì)算，計(jì)算結(jié)果表明達(dá)到性能要求。 2、 畢業(yè)設(shè)計(jì)（論文）方案介紹（主要內(nèi)容） 變速器設(shè)計(jì)方案論證 1）傳動(dòng)機(jī)構(gòu)布置方案分析 變速器傳動(dòng)機(jī)構(gòu)有兩種分類方法。根據(jù)軸的形式不同，分為固定軸式和旋轉(zhuǎn)軸式（常配合行星齒輪傳動(dòng)）兩類。固定軸式又分為兩軸式，中間軸式．雙中間軸式變速器。固定軸式應(yīng)用廣泛，。其中兩軸式變速器多用于發(fā)動(dòng)機(jī)前置前輪驅(qū)動(dòng)的汽車上。中間軸式變速器多用于發(fā)動(dòng)機(jī)前置后輪驅(qū)動(dòng)的汽車上。旋轉(zhuǎn)軸式主要用于液壓機(jī)械式變速囂。與中間軸式變速囂比較，兩軸式具有結(jié)構(gòu)簡(jiǎn)單，輪廓尺寸小，布置方便。此外，因?yàn)槠浣?jīng)過(guò)一對(duì)齒輪嚙合傳動(dòng)動(dòng)力，故傳動(dòng)效率高同時(shí)噪音低。三軸式變速囂與兩軸式相比各檔多了一對(duì)齒輪傳動(dòng)因而傳遞效率低噪音大。所以選擇本設(shè)計(jì)兩軸式雙擋變速器。 2）變速其主要參數(shù)選擇 （l）擋數(shù) 增加變速器的檔數(shù)能改善汽車的動(dòng)力性和經(jīng)濟(jì)性，擋數(shù)越多，變速器的結(jié)構(gòu)越復(fù)雜，并且是尺寸輪廓和質(zhì)量加大．同時(shí)操縱機(jī)構(gòu)復(fù)雜，而且在使用時(shí)換擋頻率也增高．由于電動(dòng)汽車的發(fā)展起步晚，受技術(shù)限制所以選用兩擋變速箱，倒擋由電機(jī)反轉(zhuǎn)來(lái)實(shí)現(xiàn)。 (2)傳動(dòng)比范圍 變速器的傳動(dòng)比范圍是指變速器最低檔傳動(dòng)比與最高檔轉(zhuǎn)動(dòng)比的比值．傳動(dòng)比范圍的確定與選定的發(fā)動(dòng)機(jī)參數(shù)，汽車的最高車速和使用條件等因素有關(guān)。 (3)中心距A 對(duì)兩軸式變速器，輸入軸與第二軸之間的距離稱為變速器中心距，其大小不僅對(duì)變速器的外形尺寸，體積和質(zhì)量大小，而日對(duì)輪齒的接觸強(qiáng)度有影響。中心距越小，齒輪的接觸應(yīng)力大，齒輪壽命短。最小允許中心距當(dāng)有保證齒輪有必要的接觸強(qiáng)度來(lái)確定。 （4）各檔齒輪齒數(shù)的分配 在初選中心距，齒輪模數(shù)和螺旋角以后．可更據(jù)變速器的擋數(shù)，傳動(dòng)比和傳動(dòng)方案來(lái)分配各檔齒輪的齒數(shù)。兩檔變速器為例，說(shuō)明分配齒數(shù)的方法．盡可能使各檔齒輪的齒數(shù)比應(yīng)該不是整數(shù)。 3)變速器的設(shè)計(jì)與計(jì)算 (1)齒輪的損環(huán)形式 輪齒折斷，齒面疲勞剝落，移動(dòng)換擋齒輪端部破壞， 輪齒折斷分兩種：輪齒受足夠大的沖擊載荷作用，造成輪齒彎曲折斷；輪齒再重復(fù)載荷作用下齒根產(chǎn)生疲勞裂紋，裂紋擴(kuò)展深度逐漸加大，然后出現(xiàn)彎曲折斷。前者在變速器中出現(xiàn)的很少，后看出現(xiàn)的多。 （2)齒輪強(qiáng)度計(jì)算 與其他機(jī)械行業(yè)相比，不同用途汽車的變速器齒輪使用田間仍是相似的。此外，機(jī)車變速器齒輪用的材抖，熱處理方法，加工方法，精度級(jí)別，支承方式也基本一致。如汽車變速器齒輪用低碳鋼制作，采用剃齒與磨齒精加工，齒輪表面采用溶碳淬火熱處理工藝，齒輪精度為JBI79-83，6級(jí)和7級(jí)。 4）軸承的選擇 變速器軸承常采用圓柱滾子軸承，球軸承，滾針軸承，圓錐滾子軸承，滑動(dòng)軸套等。至于何處應(yīng)當(dāng)采用何種軸承，是受結(jié)構(gòu)限制并隨所承受的載荷特點(diǎn)不同而不同。 汽車變速器結(jié)構(gòu)緊湊，尺寸小，采用尺寸大些的軸承結(jié)構(gòu)受限制，常在布置上有困難。如變速器的第二軸前端支承在第一軸常嚙合齒輪的內(nèi)腔中，內(nèi)腔尺寸足夠時(shí)可布置圓柱滾子軸承，若空間不足則采用滾針軸承．變速器笫一軸前端支承在飛輪的內(nèi)腔里，因有足夠大的空間常采用球軸承來(lái)承受向力。 5)變速器操縱機(jī)構(gòu) 根據(jù)汽車使用條件的需要駕駛員利用變速器的操縱機(jī)構(gòu)完成選擋和實(shí)現(xiàn)換擋或退到空擋的工作。 變速器操縱機(jī)構(gòu)應(yīng)當(dāng)滿足如下主要要求：換擋時(shí)只能掛入一個(gè)擋位，換擋后應(yīng)使齒輪在全齒長(zhǎng)上嚙合，防止自動(dòng)脫擋或自動(dòng)掛擋，防止誤掛倒擋，換擋輕便。 用于機(jī)械式變速器的操縱機(jī)構(gòu)，常見的是由變速軒，撥塊，撥叉、變速叉軸及互鎖、自鎖和倒擋鎖裝置等主要件組成，并依靠駕駛員手力完成換擋或退到空擋工作，稱為手動(dòng)換擋變速器。 三、畢業(yè)設(shè)計(jì)（論文）的主要參考文獻(xiàn) [1] 林學(xué)東，汽車工程手冊(cè)[M]，北京：人民教育出版社，2001 [2] 林學(xué)東，汽車動(dòng)力匹配技術(shù) [M]，北京:人民教育出版社，2001 [3] 黃曉榮，機(jī)械設(shè)計(jì)基礎(chǔ) [M]，北京：中國(guó)電力出版社2009 [4] 黃曉榮，機(jī)械設(shè)計(jì)基礎(chǔ)課程設(shè)計(jì)指導(dǎo)書 [M] 北京：中國(guó)電力出版社2009 [5] 陳于萍，互換性與測(cè)量技術(shù)[M],北京：機(jī)械工業(yè)出版社,2008 [6] 趙先仲 ，機(jī)電一體化系統(tǒng)設(shè)計(jì)手冊(cè)[M]，北京：機(jī)械工業(yè)出版社2001 [7] 李富波 張海萍，工程制圖與計(jì)算機(jī)繪圖 [M]，北京：中國(guó)電，力出版社，2005 [8] 李華 ，機(jī)械制造技術(shù) [M]， 北京：機(jī)械工業(yè)出版社2003 [9] 謝剛 沈冰，工程力學(xué) [M]，北京：機(jī)械工業(yè)出版社2001 [10] 朱孝錄，齒輪傳動(dòng)設(shè)計(jì)手冊(cè)[M]， 北京：機(jī)械工業(yè)出版社，2010 四、審核意見 指導(dǎo)教師審核意見：（針對(duì)選題的價(jià)值及可行性作出具體評(píng)價(jià)） 指導(dǎo)教師簽名 年 月 日 專業(yè)審核意見： 負(fù)責(zé)人簽名 年 月 日 ┊ ┊ ┊ ┊ ┊ ┊ ┊ ┊ ┊ ┊ ┊ ┊ ┊ 裝 ┊ ┊ ┊ ┊ ┊ 訂 ┊ ┊ ┊ ┊ ┊ 線 ┊ ┊ ┊ ┊ ┊ ┊ ┊ ┊ ┊ ┊ ┊ ┊ ┊ 畢業(yè)設(shè)計(jì)（論文）報(bào)告紙 發(fā)動(dòng)機(jī)輸出功率：， 發(fā)動(dòng)機(jī)最大扭矩： 汽車最高時(shí)速： 第 1 頁(yè) 共 1 頁(yè) AUTOMATIC TRANSMISSION The modern automatic transmission is by far , the most complicated mechanical component in today’s automobile . It is a type of transmission that sifts itself . A fluid coupling or torque converter is used instead of a manually operated clutch to connect the transmission to the engine . There are two basic types of automatic transmission based on whether the vehicle is rear wheel drive or front wheel drive . On a rear wheel drive car , the transmission is usually mounted to the back of the engine and is located under the hump in the center of the floorboard alongside the gas pedal position . A drive shaft connects the transmission to the final drive which is located in the rear axle and is used to send power to the rear wheels . Power flow on this system is simple and straight forward going from the engine , through the torque converter , then trough the transmission and drive shaft until it reaches the final drive where it is split and sent to the two rear transmission . On a front wheel drive car , the transmission is usually combined with the final drive to form what is called a transaxle . The engine on a front wheel drive car is usually mounted sideways in the car with the transaxle tucked under it on the side of the engine facing the rear of the car . Front axles are connected directly to the transaxle and provide power to front wheels . In this example , power floes from the engine , through the torque converter to a larger chain that sends the power through a 180 degree turn to the transmission that is along side the engine . From there , the power is routed through the transmission to the final drive where it is split and sent to the two front wheels through the drive axles . There are a number of other arrangements including front drive vehicles where the engine is mounted front to back instead of sideways and there are other systems that drive all four wheels but the two systems described here are by far the most popular . A much less popular rear and is connected by a drive shaft to the torque converter which is still mounted on the engine . This system is found on the new Corvette and is used in order to balance the weight evenly between the front and rear wheels for improved performance and handling . Another rear drive system mounts everything , the engine , transmission and final drive in the rear . This rear engine arrangement is popular on the Porsche. Automobile available more than a century, especially from the mass production of motor vehicles and the automotive industry since the development of large, Car has been the economic development of the world for mankind to enter the modern life and have had a tremendous impact on the immeasurable, The progress of human society has made indelible contributions to the great, epoch-making set off arevolution. From From the vehicle as a power plant using internal combustion engine to start, auto transmission has become an important component. Is Generation is widely used in automotive reciprocating piston internal combustion engine with a small size, light weight, reliable operation and the use of The advantages of convenience, but its torque and speed range of smaller changes, and complex condition requires the use of motor vehicles Traction and the speed can be considerable changes in the scope. Therefore, its performance and vehicle dynamics and economy of There are large inter-contradictions, which contradictions of modern automotive internal combustion engine by itself is insoluble. Because Here, in the automotive power train set up the transmission and main reducer in order to achieve the purpose of deceleration by moment. Speed The main function of performance: ⑴ change gear ratio of motor vehicles, and expand the wheel drive torque and rotational speed of the Fan Wai, in order to adapt to constantly changing driving cycle, while the engine in the most favorable conditions within the scope of work; ⑵ no change in the direction of engine rotation, under the premise of the realization of cars driving back; ⑶ the realization of the free, temporary Interruption of power transmission, in order to be able to start the engine, idling, etc.. Variable-speed drive transmission by the manipulation of institutions and agencies. Change the transmission ratio by way of transmission is divided into There are class-type, non-stage and multi-purpose three. Have class most widely used transmission. It uses gear drive, with a number of transmission ratio setting. Stepless transmission Continuously Variable Transmission (CVT) transmission ratio of a certain The framework of multi-level changes may be unlimited, there is a common type of power and torque (dynamic fluid-type) and so on. Continuously Variable Transmission Transmission development is the ultimate goal, because only it can make the most economical engine in working condition Can provide the best vehicle fuel economy and optimal power in order to provide the most comfortable By the feeling. Today's CVT is a typical representative of the CVT and IVT, however as a result of the reliability of Poor, non-durable materials and high cost issues, development is not very good. Comprehensive refers to transmission torque converter and the mechanical components have the level of transmission variable hydraulic mechanical Speed, the transmission ratio can be between the maximum and minimum range of a few discontinuous change for no class, but its Significantly lower transmission efficiency than the efficiency of gear drives. 2 By manipulation, transmission control type can be divided into mandatory, automatic and semi-automatic control to manipulate three - Species . Mandatory on the driver to manipulate the direct transmission gear shift control for the majority of motor vehicles used Also known as Manual Transmission Manual Transmission (MT). Automatic transmission control selection of the transmission ratio (transmission) is carried out automatically. Just add the driver to manipulate Speed pedal, you can control the speed, also known as Automatic Transmission Automatic Transmission (AT). It is According to the speed and load (throttle pedal travel) for two-parameter control, stall in accordance with the above two Parameters to automatically take-off and landing. AT and MT in common is that they are level transmission, but AT According to the speed of the speed shift automatically, you can eliminate the manual transmission "setback" of the shift feel. However, AT also have many drawbacks, such as body complex, mechanical efficiency is not high, high cost, reliability and control Sensitivity remains to be increasing . AMT (Automated Mechanical Transmission) is in the traditional dry clutch and manual transmission gear based on the transformation of form, mainly to change the part of the manual gearshift control. That is, the overall structure of the MT cases the same switch to electronically controlled automatic transmission to achieve. Semi-automatic control, there are two forms of transmission. A number of stalls is a common automatic control, and the remaining stalls manipulated by the driver; the other is pre-style, that is, pre-selected pilot stalls, the clutch pedal in the down or release the accelerator pedal, the for retirement or an electromagnetic device to shift the hydraulic device. In recent years, with advances in vehicle technology and road traffic density increased, the performance requirements of the transmission is also getting higher and higher. A large number of automotive engineers in improving the performance of automobile transmission study a great deal of effort devoted to the rapid transmission of technology development, such as AT, AMT, DCT, CVT and the emergence of IVT. The modern automatic transmission consists of many components and systems that designed to work together in a symphony of planetary gear sets , the hydraulic system, seals and gaskets , the torque converter , the governor and the modulator or throttle cable and computer controls that has evolved over the years into what many mechanical inclined individuals consider to be an art from . Here try to used simple , generic explanation where possible to describe these systems . 1）Planetary gear sets Automatic transmission contain many gears in various combinations . In a manual transmission , gears slide along shafts as you move the shift lever from one position to another , engaging various sizes gears as required in order to provide the correct gear ratio . In an automatic transmission , how ever , the gears are never physically moved and are always engaged to the same gears . This is accomplished through the use of planetary gear sets . The basic planetary gear set consists of a sun gear , a ring and two or more planet gears , all remaining in constant mesh . The planet gears are connected to each other through a common carrier which allows the gears to spin on shafts called “pinions” which are attached to the carrier . One example of a way that this system can be used is by connecting the ring gear to the input shaft coming from the engine , connecting the planet carrier to the output shaft , and locking the sun gear so that it can’t move . In this scenario , when we turn the ring gear , the planets will “walk” along the sun gear ( which is held stationary ) causing the planet carrier to turn the output shaft in the same direction as the input shaft but at a slower speed causing gear reduction ( similar to a car in first gear ) . If we unlock the sun gear and lock any two elements together , this will cause all three elements to turn at the same speed so that to output shaft will turn at the same rate of speed as the input shaft . This is like a car that is third or high gear . Another way we can use a planetary gear set is by locking the planet carrier from moving , then applying power to the ring gear which will cause the sun gear to turn in opposite direction giving us reverse gear . The illustration in Figure shows how the simple system described above would look in an actual transmission . The input shaft is connected to the ring gear , the output shaft is connected to the planet carrier which is also connected to a “Multi-disk” clutch pack . The sun gear is connected to drum which is also connected to the other half of the clutch pack . Surrounding the outside of the drum is a band that can be tightened around the drum when required to prevent the drum with the attached sun gear from turning . The clutch pack is used , in this instance , to lock the planet carrier with the sun gear forcing both to turn at the same speed . If both the clutch pack and the band were released , the system would be in neutral . Turning the input shaft would turn the planet gears against the sun gear , but since noting is holding the sun gear , it will just spin free and have no effect on the output shaft . To place the unit in first gear , the band is applied to hold the sun gear from moving . To shift from first to high gear , the band is released and the clutch is applied causing the output shaft to turn at the same speed as the input shaft . Many more combinations are possible using two or more planetary sets connected in various way to provide the different forward speeds and reverse that are found in modern automatic transmission . 2）Clutch pack A clutch pack consists of alternating disks that fit inside a clutch drum . Half of the disks are steel and have splines that fit into groves on the inside of the drum . The other half have a friction material bonded to their surface and have splines on the inside edge that fit groves on the outer surface of the adjoining hub . There is a piston inside the drum that is activated by oil pressure at the appropriate time to squeeze the clutch pack together so that the two components become locked and turn as one . 3）One-way Clutch A one-way clutch ( also known as a “sprag” clutch ) is a device that will allow a component such as ring gear to turn freely in one direction but not in the other . This effect is just like that bicycle , where the pedals will turn the wheel when pedaling forward , but will spin free when pedaling backward . A common place where a one-way clutch is used is in first gear when the shifter is in the drive position . When you begin to accelerate from a stop , the transmission starts out in first gear . But have you ever noticed what happens if you release the gas while it is still in first gear ? The vehicle continues to coast as if you were in neutral . Now , shift into Low gear instead of Drive . When you let go of the gas in this case , you will feel the engine slow you down just like a standard shift car . The reason for this is that in Drive , one-way clutch is used whereas in Low , a clutch pack or a band is used . 4）Torque Converter On automatic transmission , the torque converter takes the place of the clutch found on standard shift vehicles . It is there to allow the engine to continue running when the vehicle comes to a stop . The principle behind a torque converter is like taking a fan that is plugged into the wall and blowing air into another fan which is unplugged . If you grab the blade on the unplugged fan , you are able to hold it from turning but as soon as you let go , it will begin to speed up until it comes close to speed of the powered fan . The difference with a torque converter is that instead of using air it used oil or transmission fluid , to be more precise . A torque converter is a lager doughnut shaped device that is mounted between the engine and the transmission . It consists of three internal elements that work together to transmit power to the transmission . The three elements of the torque converter are the pump , the Turbine , and the Stator . The pump is mounted directly to the torque housing which in turn is bolted directly to the engine’s crankshaft and turns at engine speed . The turbine is inside the housing and is connected directly to the input shaft of the transmission providing power to move the vehicle . The stator is mounted to a one-way clutch so that it can spin freely in one direction but not in the other . Each of the three elements has fins mounted in them to precisely direct the flow of oil through the converter . With the engine running , transmission fluid is pulled into the pump section and is pushed outward by centrifugal force until it reaches the turbine section which stars it running . The fluid continues in a circular motion back towards the center of the turbine where it enters the stator . If the turbine is moving considerably slower than the pump , the fluid will make contact with the front of the stator fins which push the stator into the one way clutch and prevent it from turning . With the stator stopped , the fluid is directed by the stator fins to re-enter the pump at a “help” angle providing a torque increase . As the speed of the turbine catches up with the pump , the fluid starts hitting the stator blades on the back-side causing the stator to turn in the same direction as the pump and turbine . As the speed increase , all three elements begin to turn at approximately the same speed . Sine the ‘80s , in order to improve fuel economy , torque converters have been equipped with a lockup clutch which locks the turbine to the pump as the vehicle reaches approximately 40-50 mph . This lockup is controlled by computer and usually won’t engage unless the transmission is in 3rd or 4th gear . 5）Hydraulic System The hydraulic system is a complex maze of passage and tubes that sends that sends transmission fluid and under pressure to all parts of the transmission and torque converter and . Transmission fluid serves a number of purpose including : shift control ,general lubrication and transmission cooling . Unlike the engine ,which uses oil primary for lubrication ,every aspect of a transmission ‘s function is dependant on a constant supply of fluid is send pressure . In order to keep the transmission at normal operating temperature , a portion of the fluid is send to through one of two steel tubes to a special chamber that is submerged in anti-freeze in the radiator . Fluid passing through this chamber is cooled and then returned to the transmission through the other steel tube . A typical transmission has an avenge of ten quarts of fluid between the transmission , torque converter , and cooler tank , In fact , most of the components of a transmission are constantly submerged in fluid including the clutch packs and bands . The friction surfaces on these parts are designed to operate properly only when they are submerged in oil . 6）Oil Pump The transmission oil pump ( not to confused with the pump element inside the torque converter ) is responsible for producing all the oil pressure that is required in the transmission . The oil pump is mounted to front of the transmission case and is directly connected to a flange on the engine crankshaft , the pump will produce pressure whenever the engine is running as there is a sufficient amount of transmission fluid available . The oil enters the pump through a filter that is located at bottom of the transmission oil pan and travels up a pickup tube directly to the oil pump . The oil is then sent , under pressure to the pressure regulator , the valve body and the rest of the components , as required . 7）Valve Body The valve body is the control center of the automatic transmission . It contains a maze of channels and passages that direct hydraulic fluid to the numerous valves which when activate the appropriate clutch pack of band servo to smoothly shift to the appropriate gear for each driving situation . Each of the many valves in the valve body has a specific purpose and is named for that function . For example the 2-3 shift valve activates the 2nd gear up-shift or the 3-2 shift timing valve which determines when a downshift should occur . The most important valve and the one that you have direct control over is the manual valve. The manual valve is directly connected to the gear shift handle and covers and uncovers various passages depending on what position the gear shift is paced in . When you place the gear shift in Drive , for instance , the manual valve directs fluid to the clutch pack ( s ) that activates 1st gear . It also sets up to monitor vehicle speed and throttle position so that it can determine the optimal time and the force for the 1-2 shift . On computer controlled transmission , you will also have electrical solenoids that are mounted in the valve body to direct fluid to the appropriate clutch packs or bands under computer control to more precisely control shift points . 8）Seals and Gaskets An automatic transmission has many seals and gaskets to control the flow of hydraulic fluid and to keep it from leaking out . There are two main external seals : the front seal and the rear seal . The front seal seals the point where the torque converter mounts to the transmission case . This seal allows fluid to freely move from the converter to the transmission but keeps the fluid from leaking out . The rear seal keeps fluid from leaking past the output shaft . A seal is usually made of rubber ( similar to the rubber in a windshield wiper blade ) and is used to keep oil from leaking past a moving part such as a spinning shaft . In some cases , the rubber is assisted by a spring that holds he rubber in close contact with the spinning shaft . A gasket is a type of seal used to seal two stationary parts that are fasted together . Some common gasket materials are : paper , cork , rubber , silicone and soft metal . Aside