【機(jī)械類畢業(yè)論文中英文對(duì)照文獻(xiàn)翻譯】Fuller雙中間軸變速器結(jié)構(gòu)特點(diǎn)分析【word英文3671字10頁(yè)word中文翻譯5639字8頁(yè)】

【機(jī)械類畢業(yè)論文中英文對(duì)照文獻(xiàn)翻譯】Fuller雙中間軸變速器結(jié)構(gòu)特點(diǎn)分析【word英文3671字10頁(yè)word中文翻譯5639字8頁(yè)】,機(jī)械類畢業(yè)論文中英文對(duì)照文獻(xiàn)翻譯,word英文3671字10頁(yè),word中文翻譯5639字8頁(yè),機(jī)械類,畢業(yè)論文,中英文,對(duì)照,對(duì)比,比照,文獻(xiàn),翻譯,fuller,中間,變速器,結(jié)構(gòu),特點(diǎn),特色,特征 附 錄B Fuller雙中間軸變速器結(jié)構(gòu)特點(diǎn)分析 富勒（Fuller）雙中間軸變速器是美國(guó)伊頓Eaton 公司六十年代的獨(dú)創(chuàng)產(chǎn)品，于1965年申請(qǐng)專利，隨即投入生產(chǎn)、供應(yīng)市場(chǎng)。它是針對(duì)以下情況設(shè)計(jì)的：當(dāng)時(shí)美國(guó)已逐漸建成高速公路網(wǎng)，為了提高汽車貨運(yùn)經(jīng)濟(jì)效益，促使貨車向著大型 化、高速化、專用化的方向發(fā)展。在美國(guó)較為盛行的一種運(yùn)輸方式是由鞍式牽引車牽引的半掛車和汽車列車，此種牽引車是美國(guó)公路用重型汽車中的主要車型，其特征是軸距短，加之美國(guó)公路法規(guī)限定該類車的前懸不得大于800，因之使變速器軸向尺寸受到很大限制。面發(fā)展的需要卻一再要求提高汽車發(fā)動(dòng)機(jī)功率，并相應(yīng)加大變速器的承載能力，這對(duì)傳統(tǒng)的單中間軸變速器來(lái)說(shuō)，其軸向尺寸必然要加大因而產(chǎn)生了矛盾，雙中間軸變速器即是在此種情況下應(yīng)運(yùn)面生的。它大大提高了變速器的扭矩容量（Fuller產(chǎn)品最大已達(dá)到2240），并減小了軸向尺寸。它供應(yīng)市場(chǎng)以后，在美國(guó)的重型車上逐漸取代了傳統(tǒng)的單中間軸變速器。八十年代以來(lái)它幾乎獨(dú)占了美國(guó)重型車用變速器的市場(chǎng)（其中Eaton公司產(chǎn)品約占75%)。七十年代中期以后，伊頓公司產(chǎn)品在降低噪音、提高壽命和可靠性方面又有顯著提高。且在變速器基本結(jié)構(gòu)不變的情況下，又研制成功細(xì)齒系列新一代變速器。同時(shí)，調(diào)整了原產(chǎn)品，重新編制了產(chǎn)品系列并實(shí)現(xiàn)標(biāo)準(zhǔn)化。八十年代初已經(jīng)按新系列生產(chǎn)。本文是以原900系列（即新系列11600，二者基本結(jié)構(gòu)相同）的RT—915型組臺(tái)式變速器的結(jié)構(gòu)為例進(jìn)行分折。 附B1RT—915型變速器的基本結(jié)構(gòu) 圖B1所示為RT—915型變速器結(jié)構(gòu)簡(jiǎn)圖，它由一個(gè)五檔主箱與一個(gè)三檔位的后置倍檔副箱組合而成，它有15個(gè)前進(jìn)檔和三個(gè)倒檔。主箱和副箱齒輪中心距均為148.43它們各有兩套中間軸總成，全部齒輪為直齒圓柱齒輪，常嚙合式傳動(dòng)，二者輸出軸上齒輪均為浮動(dòng)，主箱輸出軸亦浮動(dòng)。主箱各檔無(wú)同步器，副箱高低檔裝有鎖銷式慣性同步器，超低檔采用外齒接合套式換檔裝置。主箱各檔為機(jī)械式手操縱，副箱各檔采用全氣動(dòng)式操縱換檔。當(dāng)副箱同步器接合套④與接合套⑤均左移至接合位置時(shí)，組合式變速器分別處于高速區(qū)、低速區(qū)、超低速區(qū)，備有五種速比供選用。 圖 B1 Fuller雙中間軸變速器 Ⅰ—主箱第一軸 Ⅱ—主箱第二軸 Ⅲ—主箱中間軸 R—主箱倒檔軸 Ⅳ—副箱中間軸 Ⅴ—副箱輸出軸 ①②③—換檔接合套 ④—副箱高低檔同步器接合套 ⑤—副箱超低檔同步器接合套 ZR2—主箱倒檔惰輪 附B2結(jié)構(gòu)特點(diǎn)分析 附B2.1雙中間軸功率分流 圖B1所示變速器主箱和副箱各有兩套中間軸總成，輸入的動(dòng)力分兩路傳給二中間軸總成，再由輸出軸總成將兩路動(dòng)力合流后輸出。輸入、輸出軸上的齒輪同時(shí)有兩個(gè)齒分別與二中間軸上的齒輪嚙合，工作時(shí)每齒所受載荷相對(duì)單中間軸結(jié)構(gòu)而言，理論上降低了1/2，實(shí)際上則由于齒形誤差、齒厚誤差、中心距誤差等， 使二中間軸上齒輪與相應(yīng)嚙合齒輪受載不均勻，使實(shí)際降低值少于1/2。此情況使雙中間軸變速器較之單中間軸變速器具有明顯的優(yōu)勢(shì)。 附B2.1.1雙中間軸變速器齒輪壽命 鑒于齒輪的疲勞壽命約與其負(fù)荷的3次方成反比，關(guān)系式如下: （常數(shù)） 式(B1) 式中： P—齒輪輪齒負(fù)荷； N—輪齒疲勞損壞的循環(huán)次數(shù)； 由式B1可知，設(shè)單齒傳力情況下，輪齒負(fù)荷，對(duì)應(yīng)的疲勞損壞循環(huán)次數(shù)為。當(dāng)雙齒傳力時(shí)，每一單齒負(fù)荷，較前者理論上降低了1/2，即，此時(shí)對(duì)應(yīng)的疲勞損壞循環(huán)次數(shù),即傳遞相同扭矩,雙齒傳力時(shí)，齒輪疲勞壽命可大幅度提高．如果保持齒輪疲勞壽命不變，即，，則，這說(shuō)明了在齒輪疲勞壽命相等的情況下，雙齒傳力時(shí)，每一單齒的負(fù)荷可由提高到，即可提高一倍．若按最差的實(shí)際情況，考慮，二齒載荷分布不均勻系數(shù)取為0.6，由計(jì)算知道此時(shí)扭矩容量仍可提高67％。這也就是雙中間軸變速器設(shè)計(jì)原理所根據(jù)的事實(shí)。 附B2.1.2雙中間軸變速器中心距 雙中間軸變速器的齒輪中心距按下列公式計(jì)算 式(B2) 式中： B—載荷分布不均勻系數(shù) ( 取0.52～0.60)； 由式B2可知，齒輪中心距可較單中間軸結(jié)構(gòu)減小15～20%，這對(duì)改善變速器的經(jīng)濟(jì)性和輕量化有著重要的意義，我們知道齒輪中心距稍許減小，質(zhì)量即可減輕許多。 因此，齒輪中心距是齒輪傳動(dòng)設(shè)計(jì)中最基本的參數(shù)，它影響到變速器的很多重要性能指標(biāo)，并直接和齒輪傳動(dòng)的結(jié)構(gòu)設(shè)計(jì)及承載能力有密切關(guān)系。長(zhǎng)期以來(lái)，國(guó)內(nèi)外對(duì)減小傳統(tǒng)變速器的齒輪中心距進(jìn)行了不懈的努力，終因受到軸承、材料 工藝水平及換檔同步器成的設(shè)計(jì)制造技術(shù)水平的制約而進(jìn)展不大。雙中間軸結(jié)構(gòu)的出現(xiàn)，由于功率分流大大改善了齒輪、軸、軸承和箱體的受載情況，并可降低加工精度要求，因而能做到既保證了變速器的使用性能，又減小了齒輪中心距。 由于齒輪輪齒應(yīng)力較傳統(tǒng)變速器減小近一半，故可減小齒寬約40%，既減小了變速器軸向尺寸，又保持了齒輪的承載能力，同對(duì)還改善了載荷沿齒面的分布狀況，有利于提高齒輪壽命。 附B2.2齒輪浮動(dòng) 主箱輸出軸上的齒輪同時(shí)與對(duì)稱布置的二中間軸上的齒輪嚙合，它在二齒輪之間可沿徑向浮動(dòng)，靠嚙合圓自動(dòng)定心，副箱也是如此。這是Fuller雙中間軸變速器結(jié)構(gòu)的顯著特點(diǎn)，其優(yōu)點(diǎn)是：（1）使輸出軸上齒輪和二中間軸上齒輪正確嚙合，并均勻分配載荷。（2）省去了傳統(tǒng)變速器中輸出軸上所有常嚙合齒輪處的滾針軸承。此滾針軸承是傳統(tǒng)變速器結(jié)構(gòu)中的弱點(diǎn)，取消它，對(duì)提高變速器壽命和工作可靠性有明顯作用。（3）對(duì)齒輪精度、軸的精度以及箱體軸承孔的位置精度可降低要求。（4）使齒形誤差引起的動(dòng)載荷影響減小。（5）試驗(yàn)表明，浮動(dòng)嚙合可減小強(qiáng)烈的諧振的噪音強(qiáng)度。 附B2.3軸的布置與受力 主箱第二軸為浮動(dòng)結(jié)構(gòu)，二軸后端與副箱驅(qū)動(dòng)齒輪花鍵聯(lián)接，通過(guò)軸承支承在箱體上；軸前端軸頸與含油軸承之徑向間隙較大（陜西汽車輪廠測(cè)量為0.9 )，全軸以后端為支點(diǎn)，前端浮動(dòng)。因此，第二軸上齒輪均是浮動(dòng)的，換檔時(shí)，在第二軸上的外齒接合套隨軸浮動(dòng)，便于換檔。 圖B1所示，二中間軸之中心連線與水平線之間夾角，F(xiàn)uller 為19°，此角若過(guò)小，將使箱體寬度尺寸加大，攪油損失增加，此損失是影響變速器效率的主要因素；如果過(guò)大，則箱體高度尺寸加大，且使上方軸承潤(rùn)滑條件變壞。 對(duì)稱布置的雙中間軸使第一軸、第二軸上齒輪所受徑向力相互平衡，使此二軸均不承受彎矩，而僅承受扭矩，放可使第一 軸、第二軸直徑減小。二中間軸亦因此所受彎矩減小1/2，可使軸保證足夠剛度（這是設(shè)計(jì)中間軸應(yīng)主要考慮的問(wèn)題 ），以改善齒輪和軸承的工作條件，這對(duì)提高齒輪和軸承的壽命和降低噪音甚為有利。 附B2.4解決了軸承使用壽命問(wèn)題 由上可知，輸入軸與輸出軸軸承所受徑向力的合力為零，傳動(dòng)齒輪為直齒，無(wú)軸向力，軸承僅承受重力；中間軸的軸承所受徑向力減小近1/2,無(wú)軸向力。所有軸承受載荷情況均獲極大改善，這是造成此種變速器軸承壽命長(zhǎng)的基本因素。 另外，主副箱中間軸的一端仍采用了承載能力較強(qiáng)的滾柱軸承，既獲容量大的好處，也是由于中間軸需采用游動(dòng)式支承，且分離型軸承使裝折方便。主箱其余軸承雖為常見類型，但與傳統(tǒng)變速器比較，其壽命系數(shù)卻高了許多。 副箱輸出軸是由兩個(gè)反裝的圓錐滾子軸承支承，按分析主要是為了增強(qiáng)懸臂式軸的支承剛度及穩(wěn)定性，和增大軸承容量。 在軸承負(fù)荷較小的情況下，盡可能增大軸承容量，既可提高軸承壽命，使之與變速器總壽命相適應(yīng)；又可提高支承剛度，加強(qiáng)軸的運(yùn)轉(zhuǎn)剛性，保證齒輪正確嚙合，提高齒輪壽命及降低噪音。新系列產(chǎn)品為降低噪音，又新設(shè)計(jì)了軸承，從而改進(jìn)了軸承品質(zhì)。實(shí)際使用結(jié)果：Fuller雙中軸變速器在48萬(wàn)公里內(nèi)無(wú)需更換軸承，此壽命值在同等級(jí)變速器中居世界最佳水平。 附B2.5主箱無(wú)同步器，采用拉型離合器配合換擋 Fuller雙中間軸變速器主箱沒有采用同步器，而是采用外齒接合套式換檔裝置。按理，對(duì)于扭矩容量大的變速器而言，由于齒輪大，轉(zhuǎn)動(dòng)慣量大，換檔時(shí)在將要進(jìn)入嚙合的轉(zhuǎn)速差較大的輪齒之間產(chǎn)生的沖擊力也大，造成換檔困難。因此，應(yīng)加裝同步器好。但采用同步器，當(dāng)前需解決其使用壽命問(wèn)題。大扭矩容量的西德ZF單中間軸變速器是享譽(yù)世界的產(chǎn)品,仍然存在同步器早期損壞的問(wèn)題,此問(wèn)題在世界各生產(chǎn)廠家也均未獲解決。Fuller雙中間軸變速器主箱沒有采用同步器，而是與拉型離臺(tái)器配合，實(shí)現(xiàn)同步換檔。它是在主箱第一軸上裝設(shè)一摩擦制動(dòng)盤，當(dāng)換檔分離離合器時(shí)，分離撥叉向后拉動(dòng)分離軸承，將摩擦制動(dòng)盤壓向第一軸端蓋，制動(dòng)第一軸，以加速齒輪的同步過(guò)程，按此，它只能使第一軸作減速運(yùn)動(dòng)，故只可在原地起步及向上換擋時(shí)使用，而不能在向下?lián)Q檔時(shí)使用。 在設(shè)計(jì)原理、結(jié)構(gòu)及計(jì)算方面進(jìn)行了探索性的實(shí)踐，從原理和結(jié)構(gòu)上可做到在向上和向下?lián)Q檔時(shí)均可使用。 根據(jù)分析，這種裝置在簡(jiǎn)化操作、縮短換檔時(shí)間、實(shí)現(xiàn)同步換檔上可起到與同步器相近的作用，但因這種結(jié)構(gòu)不具有同步器所具有的鎖止作用，要實(shí)現(xiàn)無(wú)沖擊換檔，還有賴于駕駛員操作的熟練程度。伊頓公司聲言在換檔機(jī)構(gòu)中，外齒接合套的花鍵齒兩端與相應(yīng)的齒輪花鍵孔之間均設(shè)計(jì)有大倒角，它在換檔過(guò)程中能起到一定的鎖止作用。這種獨(dú)特的換檔機(jī)構(gòu)，從美國(guó)重型汽車普遍使用的情況來(lái)看，是成功的，若經(jīng)改善?？赏耆〈狡鞯墓δ?，達(dá)到取消同步器的目的．這樣作的好處是明顯的，它避開了同步器這個(gè)難題，以及變速器壽命中的弱點(diǎn)，提高了變速器的工作可靠性，簡(jiǎn)化了變速器結(jié)構(gòu)，使其軸向尺寸減短，質(zhì)量減輕，減少了對(duì)工藝和材料要求較高的零件，使變速器造價(jià)降低。 附B2.6全直齒齒輪傳動(dòng) Fuller雙中間軸變速器主箱和副箱的全部齒輪采用直齒齒輪常嚙合傳動(dòng)，在國(guó)內(nèi)外大扭矩容量變速器中實(shí)為少見。除副箱驅(qū)動(dòng)齒輪副是采用單徑節(jié)制齒輪外，余均是采用雙徑節(jié)制短齒齒輪，主箱和副箱之各檔齒輪均各取一種經(jīng)節(jié)，分別為6/7 和5/7，換算成模數(shù)為4.32/3.63和5.08/ 3.63(新系列產(chǎn)品的細(xì)齒齒輪，其模數(shù)小于1.27其齒形細(xì)長(zhǎng)，易形成多齒嚙合)。主箱所有齒輪副的齒輪齒數(shù)為 22～23齒，全部齒輪采用小齒形角及正變位修正。為了達(dá)到新的交通法規(guī)對(duì)噪音的限制，伊頓公司對(duì)新系列產(chǎn)品采取了如下措施：（1）改進(jìn)齒形結(jié)構(gòu)；（2）提高齒輪副重合系數(shù)；（3）提高齒輪精度（細(xì)齒系列齒輪精度比粗齒系列高一級(jí)，是使齒間負(fù)荷分布均勻）；（4）改進(jìn)軸承品質(zhì)；（5）提高箱體剛性。取得了較好效果，新系列產(chǎn)品較老產(chǎn)品噪音強(qiáng)度降低了5～7。 分析以上結(jié)構(gòu)有如下特點(diǎn)（1）全部采用直齒齒輪，對(duì)整體式箱體的雙中間軸結(jié)構(gòu)，便于總成組裝與解體（2）采用短齒制齒輪可增強(qiáng)輪齒的抗彎強(qiáng)度，但同時(shí)也加重了直齒齒輪重合系數(shù)小的缺陷，采用小齒形角和多齒嚙合的辦法可彌補(bǔ)此缺陷，新系列產(chǎn)品的重合系數(shù)可達(dá)到2.2 （傳統(tǒng)設(shè)計(jì)重合系數(shù)僅1.5左右）。瑞典Scania公司生產(chǎn)的GR860主變速器采用全斜齒輪常嚙合傳動(dòng)，其重臺(tái)系數(shù)為，1.45～1.68。重合系數(shù)的提高可改善齒輪嚙合性能，試驗(yàn)表明：①降低了噪音；②使受表面疲勞影響的齒輪壽命有了明顯提高（因齒面壓力減?。?；③較大重合度系數(shù)齒輪的抗沖擊能力高于低重合系數(shù)齒輪（因前者負(fù)荷分配較均勻），此能力是重型汽車變速器所要求的。（3）因采用小齒形角會(huì)降低齒根強(qiáng)度，故采用正變位修正齒輪，以增強(qiáng)齒根強(qiáng)度。（4）為了保證主箱二中間軸上齒輪與第一軸、第二軸上齒輪能同時(shí)嚙合，也使第二軸上齒輪能將負(fù)荷均勻地分配給二中間軸，故需保證第一軸、第二軸上齒輪的齒數(shù)均為偶數(shù)，中間軸上各齒輪均有一齒位于同一縱平面內(nèi)，且所有齒輪的模數(shù)相同。（7）因齒輪外徑較小，齒寬較窄，便于采用拉齒、剃齒等高效加工方式生產(chǎn)。 道路試驗(yàn)結(jié)果表明：平均運(yùn)行64萬(wàn)公里的新系列產(chǎn)品，其可靠性系數(shù)為92%，80萬(wàn)公里時(shí)為90%。說(shuō)明此種變速器不僅結(jié)構(gòu)簡(jiǎn)單，工藝性好，而且工作可靠，壽命指標(biāo)居世界先進(jìn)水平，耐用容易制造，是一成功的實(shí)例。 附B2.7主箱、副箱和箱體結(jié)構(gòu)特點(diǎn) 整個(gè)Fuller雙中間軸變速器系列族是以兩種中心距（135.128 與148.43 ）的五檔主箱為基本型，采取主箱變型和按單元組合原理，與不同副箱組合后，實(shí)現(xiàn)產(chǎn)品的系列化標(biāo)準(zhǔn)化多品種生產(chǎn)，圖1所示主箱為此進(jìn)行的結(jié)構(gòu)設(shè)計(jì)是很有特色的，其變型是在保持齒輪中心距不變和除齒輪外的其余零件基本不變更的情況下，用18對(duì)齒輪進(jìn)行不同的組合，從而獲得8種不同速比組合的主箱。又如圖B1所示，在全套零件不變更的情況下，僅將齒輪與，齒輪與裝配位置互換后，又可獲得具有超速檔的主箱，從而使整個(gè)系列產(chǎn)品品種增加多種。對(duì)變型需要更換的零件采取花鍵聯(lián)接的組合結(jié)構(gòu)；第一軸、第二軸上所有齒輪的內(nèi)孔為同一規(guī)格的花鍵孔，使齒輪可按需要換位安裝；并因此采用外齒接合套式換檔機(jī)構(gòu)，且各檔通用。使主箱易于實(shí)現(xiàn)變型，也可實(shí)現(xiàn)等強(qiáng)度。因?yàn)檎麄€(gè)產(chǎn)品的零件通用化程度高達(dá)70%以上，極大地方便了生產(chǎn)，獲得很高的經(jīng)濟(jì)效益。 副箱的二中間軸軸線與主箱二倒擋軸軸線共線，副箱與主箱的箱體為一整體，副箱內(nèi)全部零體均安裝在箱蓋上，成為一個(gè)總成，二速和三速副箱均如此，二者箱蓋通用，當(dāng)變型時(shí)更換此總成即可，十分方便。 整體式箱體省去了主箱與副箱之間的殼體與軸承，使整個(gè)結(jié)構(gòu)緊湊、合理、縮短 了軸向尺寸，減輕了質(zhì)量，簡(jiǎn)化了加工。 Fuller產(chǎn)品箱體的通用化程度高，同一齒輪中心距的單獨(dú)主箱，它的各種變型產(chǎn)品可通用一種箱體；組合相同的整體式箱也可通用一種箱體；箱體齒輪中心距僅有兩種卻覆蓋了整個(gè)系列族產(chǎn)品，這對(duì)大批量生產(chǎn)的變速器專業(yè)廠而言，意義是很大的。在變速器的生產(chǎn)中，箱體生產(chǎn)線個(gè)性最強(qiáng)，耗資最大，保持箱體生產(chǎn)線不變，不僅經(jīng)濟(jì)上十分合算，而且可迅速方便地適應(yīng)市場(chǎng)競(jìng)爭(zhēng)的需要，使工廠具有很強(qiáng)的應(yīng)變能力。 附B3結(jié)論 由于Fuller變速器采取了一些獨(dú)特的結(jié)構(gòu)，極大地改善了內(nèi)部結(jié)構(gòu)的受力狀況，它不僅具有性能指標(biāo)先進(jìn)、工作可靠、壽命長(zhǎng)等突出優(yōu)點(diǎn)，而且結(jié)構(gòu)與加工工藝較簡(jiǎn)單，與國(guó)外目前較新的幾種同級(jí)別單中間軸變速器相比較，如西德的ZF變速器、瑞典Scania的GR860和VOLVO的SR61、法 國(guó)Berllet的BRL3 和NM9—150、蘇聯(lián)的RM3-201和日本尼桑的THM501等，它們性能指標(biāo)不及Fuller雙中間軸變速器，但精度要求、制造難度均超過(guò)后者。按我國(guó)當(dāng)前的工藝水平，借鑒后者的設(shè)計(jì)與制造技術(shù)在品質(zhì)上較易過(guò)關(guān)。此種變速器雖多一個(gè)中間軸總成，只不過(guò)增加了零件數(shù)量，質(zhì)量并未增加，高效生產(chǎn)可彌補(bǔ)所增成本，更因它工作可靠性好、壽命長(zhǎng)，在使用中可增效益、減損耗，使它所獲總的經(jīng)濟(jì)效益是可取的。我國(guó)現(xiàn)引進(jìn)了此種變速器的制造技術(shù)，對(duì)促進(jìn)我國(guó)汽車變速器的設(shè)計(jì)、制造技術(shù)迅速達(dá)到世界先進(jìn)水平將起到積極作用。此外，此種變速器設(shè)計(jì)構(gòu)思周密、新巧，設(shè)計(jì)、試驗(yàn)方法嚴(yán)謹(jǐn)，有助于開拓思路，這是具有長(zhǎng)遠(yuǎn)意義的。 附 錄A The Analysis of Fuller Twin Countershafts Transmission Structure Sharacteristics Fulham (Fuller) because American Eaton is twin countershafts transmission Eaton company of the 60's original products, in 1965 patent application, and then put into production, supply market. It is aimed at the condition of design: when the U.S. has gradually built highway system, in order to improve the economic benefit to freight cars, trucks, and fast pace to large, specialty direction. In the United States more prevalent mode of transportation is by the saddle type tractor trailer and car pulled the tractor is the train, the main road with heavy car models, its characteristic is short wheelbase, in addition to the U.S. highway law caps the car before hanging must not be more than 800, and consequently make twin countershafts transmission shaft to size is very limited. The needs of the development of surface but repeated requests to improve the car engine power, and corresponding enlarges the bearing capacity of the transmission, this to the traditional single axis twin countershafts transmission for, its axial dimensions must increase thus had a contradiction, double the axis is that the twin countershafts transmission in such a situation of The Times looks unfamiliar. It greatly improve the twin countershafts transmission torque capacity (Fuller products has reached 2240), largest and decreases the axial dimensions. It supply market in the United States, after the heavy car gradually replaced the traditional single axis transmission. Eighty s it almost exclusive American heavy vehicle twin countershafts transmission market (including Eaton company products accounted for about 75%). Since the mid seventy s, Eaton products in reducing noise and improve life and reliability have increased significantly. And in the twin countershafts transmission basic structure under the condition of invariable, and has successfully developed series presentation of a new generation transmission. At the same time, adjusted the original, redesign the product series and realize standardization. Eighty s has the new series production. This paper is based on the original 900 series (namely the new series 11600, both the same basic structure of RT-915) type group structure of the desktop twin countershafts transmission for an example cent fold. Figure A1 Fuller Twin Countershafts Transmission Ⅰ-The first shaft Ⅱ-Lord box box axial Ⅲ-The second Lord box in the axis R-Lord box in reverse Ⅳ Thaft axis Ⅴ-vice Box-vice box output shaft ①②③-Bhift joints set ④-Vice box high low synchronizer joints sets ⑤-Vice box super cheap synchronizer joints set of ZR2-Lord box in reverse presence wheel Attached A1 RT-915 type the basic structure of transmission Figure A1 shows is the RT-915 type twin countershafts transmission structure diagram, it consists of a main five gear box and a rear times of three gear shift combination to vice box, it has 15 forward gears and three in reverse. The Lord box and vice gearbox which is 148.43center distance they each have two sets of intermediate bearing assembly, all the gear for spur gear, often meshing type transmission , both on the output shaft gear are floating, Lord box output shaft also float. The box without the file synchronizer, vice box with high cheap locking pin type synchronizer, ultra low inertia by outer profile of mating type shift device. The box for each file mechanical hand manipulation, vice box every file adopted the pneumatic control shift. When vice box synchronizer joints set with mating set of ⑤(④) are moved to the mating position when the left ④and the twin countershafts transmission were at high speed area, low speed area, super-low speed area, equipped with five ratio for selection. Attached A2 Structure analysis Attached A2.1 Dual axis power diversion Figure A1 shows twin countershafts transmission box and vice box the Lord had two sets of the axis assembly, input power points to two road axis assembly, again by the output shaft assembly will be two road after mixing power output. Input and output shaft of the gear has at the same time two teeth on the axis of the two respectively with gear, work by load per tooth structure is concerned, because the relative single reduced 1/2, in fact, in theory, the tooth shape error, the tooth thickness error, the center distance, the error on the axis gear and corresponding mesh loading not even, make the actual reduce the value of less than 1/2. This situation than single axis transmission double the axis has obvious advantages. Attached A2.1.1 Dual axis gears life In view of the fatigue life of gear with its load of three times about square of inverse ratio, the formula is as follows: (constant) type (A1) Type: P-Gear load; N-Fatigue damage of gear tooth cycles. The type that a single tooth, A1 power twin countershafts transmission cases, gear load, the corresponding fatigue damage cycle times. When double teeth power transmission, every single tooth load, a former theory, that is, the lower half of the corresponding fatigue damage at this time, that same cyclic number transfer torque, double teeth power transmission , the fatigue life of gear can be increased greatly. If keep gear fatigue life, that is, the constant,, this shows that the fatigue life of gear equal, double teeth power transmission , every single tooth can be increased by the load to, can improve a times. If the worst of the actual situation, according to consider, two teeth load distribution non-uniform coefficient for 0.6, by calculating know that the torque capacity still can be increased by 67%. This is double the axis on the basis of which the design principle of the twin countershafts transmission facts. Attached A2.1.2 Double the axis center distance transmission The axis of gear twin countershafts transmission of center distance to the following formula Type (A2) Type: B-the load distribution non-uniform coefficient (for 0.52 ~ 0.60); By typeA2, it is known that the center distance gear is single axis structure reduce 15 to 20%, this to improve the twin countershafts transmission efficiency and lightweight has the important meaning, we know that gear center distance is reduced, quality can reduce a lot. Therefore, the center distance gear is gear twin countershafts transmission in the design the most basic parameters, it affects the twin countershafts transmission many of the important performance index, and direct and gear twin countershafts transmission and structure design of carrying capacity has close relationship. For a long time, to reduce the twin countershafts transmission of the domestic and foreign traditional gear from center made unremitting efforts, eventually because of bearing, material by technological level and shift the design and manufacture of synchronizer into the technical level of the check and little progress. The axis of the structure of the double appear, because power diversion has greatly improved the gears, bearings and the axis, the loading condition, and may reduce the processing accuracy requirement, and can therefore do not only ensure the twin countershafts transmission performance, and reduced the gear from the center. Due to the stress of gear twin countershafts transmission gear with a more traditional nearly half, it can be reduced to about 40% of the reduced width, already reduced the twin countershafts transmission shaft to size, and keep the bearing capacity of the gear, with improved load of the tooth, and to improve the distribution of gear life. Attached A2.2 Gear floating The box on the output shaft gear at the same time and the two symmetrically arranged on the axis of gear engagement, it in two gears can be along radial direction between floating, rely on meshing round self-centering, vice box also is such. This is because of the structure of the double Fuller twin countershafts transmission characteristics, its advantage is: (1) to make the output shaft gear and two on the axis gear meshing, and correct evenly distributed load. (2) tell the traditional twin countershafts transmission output shaft in all often mesh in the needle bearing. The needle bearing is the weaknesses in traditional twin countershafts transmission structure, cancel it, to improve the twin countershafts transmission of life and the working reliability have obvious function. (3) on gear precision, accuracy and the shaft bearing hole position precision can reduce requirements. (4) make tooth shape by the error of dynamic load less of an effect. (5) test shows that the meshing can reduce the floating strong resonance noise intensity. Attached A2.3The arrangement of the shaft and stress The second shaft for the box floating structure, two axis back end and vice box drive gear spline connection, and through the bearing can support on the enclosure; Shaft front shaft neck and oil bearing radial clearance of the big (shaanxi automobile wheel factory measurement for the 0.9), the shaft is the fulcrum, front after floating. Therefore, the second shaft gear are floating, shift, in the second shaft of the outer profile of engagement with floating, facilitate change gear shaft. Figure A1 shows, the axis of the centre of the attachment and the Angle between horizontal, Fuller 19° Angle, this is too small, if will make the width dimension increase, stir oil loss increases, the loss is the main factors of influence twin countershafts transmission efficiency; If too much, is the size, and increase the height above bearing bad lubrication condition. Symmetrical arrangement of the axis make first shaft, double the second shaft gear by radial force balance each other, make this second shaft under bending moment, and are not only bear torque, put can make the first axis, the second shaft diameter. 2 the axis also this by bending moment, can make the shaft decrease 1/2 ensure enough (this is intermediate bearing stiffness design should be the main consideration question), to improve the working conditions of the gear and bearing, this to raises gear and bearing life and reduce the noise is favorable. Attached A2.4 Solve the bearings use life problem By that, input shaft and the output shaft bearings by composition of radial force to zero, twin countershafts transmission gears for straight teeth, no axial force, bearing under gravity only; The axis of the bearing by radial force nearly 1/2, reduce without axial force. All bearing load conditions have been great improvement, this is caused such twin countershafts transmission bearing life long basic factors. In addition, the one end of the intermediate bearing vice box still used bearing capacity of strong roller bearing, already won the benefits of large capacity, but also because of the axis must be adopted to support, and separate swimming type type bearings with convenient fold to. The box is a common type though bearing the rest, but compared with the traditional twin countershafts transmission coefficient of its life, but many high. Deputy box output shaft is made up of two the outfit's circular cone roller bearings, according to the analysis of the main support is to enhance the cantilevered shaft stiffness and stability, and increase the bearing capacity. In bearing load is small, as far as possible increase bearing capacity, can rise already bearing life, to that of the twin countershafts transmission adapt to life always; And enhance the stiffness, strengthen the functioning of the shaft rigidity, ensure gear meshing, improve the correct life and reduce noise. The new series of products to reduce noise, and the new design, so as to improve the bearing the bearing quality. The actual application result: Fuller double central axis in the twin countershafts transmission within 480000 kilometers, the life without changing bearing the same level in the value of the world's best level in transmission. AttachedA2.5 The Lord without synchronizer and the box, type clutch cooperate with shifted gears Fuller double the axis twin countershafts transmission box has not adopted the synchronizer, but the outer profile of mating type shift device. Normally, for large capacity for the twin countershafts transmission torque, due to the large inertia gear, big, shift in entering when the speed of the difference of the larger meshing between gear from the impact is big also, cause shift difficult. Therefore, we should add synchronizer. But the synchronizer, to solve the current problem of its service life. Big torque capacity of the single axis twin countershafts transmission is west Germany government is world famous products, there are still a synchronizer early damage, the problem in the world each production manufacturer also have been solved. Fuller double the axis twin countershafts transmission box has not adopted the synchronizer, but from a device with pull model, with a simultaneous shift. It is in the box on the first shaft installed a friction brake disc, when shift separation clutch, separate fork pulled back bearings, will friction brake disc pressure to the first axis, brake first shaft cover, to speed up the process, according to the gear synchronous this, it can only make the first shaft for, so can only slow movement in place the start up and use, and can't shift in downward shift when used. In the design principle, structure and calculation on the practice of exploratory, from the principle and structure can be done on the up and down when shift all can use. According to the analysis, the device in the simplified operation, shorten the time shift, a simultaneous shift on can be as effective as synchronizer similar role, but for this structure does not have synchronizer is the lock function, to realize no impact shift, but also depends on the driver of the operation of proficiency. Eaton company claimed that the shift in institutions of the engagement of the set, the spline tooth ends and the corresponding spline gears between a big hole are design Angle pouring in shift, it can play a certain process lock up the role. This kind of unique shift agencies from the United States, heavy duty truck generally use the situation, is successful, if via improved. Expected to completely replace the synchronizer function, to cancel synchronizer purpose. So the benefits of the obvious, it avoided the synchronizer this difficult problem, and transmission , improve the life the weaknesses in the work of transmission , simplify the structure reliability transmission , make its axial dimensions cut short, quality, reduce the ease of technology and materials to demand higher parts, make the twin countershafts transmission cost reduced. Attached A2.6 The straight teeth gear transmission Fuller double the axis twin countershafts transmission box and Lord of all gear vice box USES the straight teeth gear meshing twin countershafts transmission at home and abroad, often torque capacity is rare in transmission. In addition to deputy box drive gear is the single diameter temperance gear outside, are more than double diameter temperance short gears, Lord box and vice box of each shift gears are one from each kind of the festival, 6/7 and 5/7 respectively, converted to 4.32/3.63 and 5.08/3.63 module (new series of the products, the modulus gear presentation is less than 1.27 the tooth shape, easy to form more slender gear meshing). The Lord all gear pair of gear box for 22 to 23 of gear teeth, all gear tooth shape by small Angle and deflection is fixed. In order to achieve the new traffic regulations for noise limit, Eaton for new products to take the following measures: (1) improve tooth shape structure; (2) improve the superposition coefficient; vice (3) improve the precision (presentation than thick tooth gear series precision high level, is make series load distribution among gear teeth uniform); (4) improve bearing quality; (5) improve the rigidity. Good results have been achieved, new series product is old products to reduce noise intensity by 5 ~ 7. Analysis the characteristics of structure above (1) all adopt the straight teeth gear, to the double integral of the intermediate bearing structure, easy to assembly assembly and collapse (2) using short teeth gear system can enhance the gear bending strength, but at the same time, they have also made the straight teeth gear coincidence, the defects of small coefficient by small teeth shape Angle and more to the teeth mesh areas, it can make up the defects, new series of products to the superposition coefficient reaches 2.2 (the traditional design superposition coefficient around 1.5) only. Sweden Scania company produces the GR860 main twin countershafts transmission adopts full inclined gear meshing transmission, its often heavy machine, coefficient of 1.45 to 1.68. The improvement of superposition coefficient can improve the gearing mesh performance, test shows that: (1) to reduce the noise; (2) make is the influence of surface fatigue life of gear was obviously improved (for tooth face pressure decrease); (3) the coincidence degree coefficient of large gear impact resistant ability than superposition coefficient low gear (by the former load distribution is more homogeneous), this ability is heavy auto twin countershafts transmission is required. (3) with small teeth shape Angle will reduce the strength, the root is adopted deflection is modified, in order to enhance strength of tooth root gear. (4) in order to guarantee the box on the axis with the first two gear shaft, the second shaft gear can at the same time, also make the second shaft meshing gears can will load on evenly distributed to two axis, so should guarantee the first axis, the second shaft gear the number of teeth are even on the gear axis all have a tooth is located in the same longitudinal plane inside, and all of the same modulus gear. (7) for gear teeth smaller diameter, wide is narrower, facilitate the pull teeth and shaving teeth and other high efficient processing method production. The road test results show that: the average operation 640000 kilometers of the new series products, the reliability coefficient was 92%, 90% at 800000 km. Not only that such twin countershafts transmission of simple structure, good technology, and reliable work, life index in the advanced world level, durable, easy to make a successful example. Attached A2.7 The Lord box, vice box and the structure characteristics The Fuller double the axis twin countershafts transmission series is two kinds of the center distance (135.128 and 148.43) of the five gear box for basic, take the Lord box and click unit variant combination principle, and different combination, realize after vice box serialization of products standardization many varieties, production figure 1 box in the structure design is very distinctive, the variant is to keep away from the same center in gear and the rest of the parts in addition to the gear basic don't change in the 18 to gear different combinations, to get eight different ratio of combination of Lord box. And as shown in figure A1 shows, in the full set of parts does not change, only change geargear, gearandassembly and position, and also can get after exchange with the overdrive Lord box, so that the entire series products DuoZhong increase. Variant need to replace parts to take the combination of the spline connection structure; The first axis, the second shaft all gear hole for the same specifications of the spline hole, make gear according to need conversion installation; And so the tooth of the engagement of shift institutions and each file, general. Main box easy to realize the form, also can realize for strength. Because the entire product parts generalization degree is as high as 70% above, great show, where production for high economic performance. The two vice box in the axis axis and the main box two reverse gear axis line, the deputy