大運(yùn)輕卡驅(qū)動(dòng)橋的設(shè)計(jì)含開題及CAD圖,大運(yùn)輕卡,驅(qū)動(dòng),設(shè)計(jì),開題,CAD XX XX XXXX XX設(shè)計(jì)中期報(bào)告 學(xué) 生 姓 名： 學(xué) 號(hào)： 學(xué) 院： 專 業(yè)： 設(shè)計(jì)題目： 大運(yùn)輕卡驅(qū)動(dòng)橋的設(shè)計(jì) 指 導(dǎo) 教 師: 20XX年 5 月 12 日 設(shè) 計(jì) 中 期 報(bào) 告 姓名 班級(jí) 學(xué)號(hào) 設(shè)計(jì)題目： 大運(yùn)輕卡驅(qū)動(dòng)橋的設(shè)計(jì) 本人在該設(shè)計(jì)中具體 應(yīng)完成的工作： a. 畢業(yè)設(shè)計(jì)開題報(bào)告一份； b. 英文翻譯一份； c. 完成驅(qū)動(dòng)橋結(jié)構(gòu)圖； d、按學(xué)校要求的論文格式提交畢業(yè)設(shè)計(jì)論文一篇，字?jǐn)?shù)不少于15000字； 1. 簡(jiǎn)述畢業(yè)設(shè)計(jì)（論文）開始以來所做的具體工作和取得的進(jìn)展（要詳細(xì)內(nèi)容） 1). 通過查閱《汽車構(gòu)造》等書籍和利用網(wǎng)絡(luò)搜集相關(guān)資料來掌握汽車驅(qū)動(dòng)橋的組成和結(jié)構(gòu)與設(shè)計(jì)要求。 2). 完成開題報(bào)告，確定研究?jī)?nèi)容和研究方法并完成答辯。 3).根據(jù)給定的參數(shù)結(jié)合市面相應(yīng)的大運(yùn)輕卡驅(qū)動(dòng)橋的結(jié)構(gòu)初步選定驅(qū)動(dòng)橋的結(jié)構(gòu)方案、主減速器的結(jié)構(gòu)形式、差速器的結(jié)構(gòu)形式和傳動(dòng)裝置的方案；根據(jù)課題的設(shè)計(jì)要求和給定的參數(shù)計(jì)算主減速器的基本參數(shù)和計(jì)算載荷、錐齒輪強(qiáng)度計(jì)算、軸承載荷計(jì)算，其中要選擇適當(dāng)?shù)闹鳒p速比，以保證汽車在給定的條件下具有最佳的動(dòng)力性和燃油經(jīng)濟(jì)性；設(shè)計(jì)計(jì)算差速器各參數(shù)，齒輪及其他傳動(dòng)件工作平穩(wěn)，噪聲小，傳動(dòng)效率要高且具有足夠的強(qiáng)度和剛度；然后進(jìn)行車輪傳動(dòng)裝置和驅(qū)動(dòng)橋殼的設(shè)計(jì)與計(jì)算，體積盡量要小的 保證汽車具有足夠的離地間隙，滿足汽車通過性要求。且簧下質(zhì)量較小，滿足汽車平順性的要求。 4).通過驅(qū)動(dòng)橋設(shè)計(jì)相應(yīng)書籍的經(jīng)驗(yàn)總結(jié)和公式來進(jìn)行初步的校核，滿足了設(shè)計(jì)的基本要求。 5).根據(jù)計(jì)算的主要零件的結(jié)構(gòu)參數(shù)在CATIA中完成驅(qū)動(dòng)橋的建模工作并完成裝配，并開始繪制二維CAD工程圖。 設(shè) 計(jì) 中 期 報(bào) 告 2.目前存在的問題，下一步的主要研究任務(wù)，具體設(shè)想與安排（要詳細(xì)內(nèi)容） 1. 目前存在的問題 1).在論文書寫過程中相關(guān)數(shù)據(jù)沒有辦法完全確定，因此對(duì)校核產(chǎn)生了影響。 2).在繪圖過程中相關(guān)模塊較為復(fù)雜，只能近似的繪圖。 3).論文書寫過程中前后文銜接不夠緊密，內(nèi)容不夠全面。 2.后期的任務(wù)安排 下一步的研究任務(wù)主要是認(rèn)真的進(jìn)行論文的書寫和完善，并進(jìn)行三維模型的的建立和二維圖紙的的繪制。通過廣泛查閱研究相關(guān)論文和權(quán)威書籍來完善 論論文的書寫。對(duì)已完成的內(nèi)容進(jìn)行多次審閱，從內(nèi)容、結(jié)構(gòu)及用語等方面進(jìn)行行調(diào)整。 設(shè) 計(jì) 中 期 報(bào) 告 3.指導(dǎo)教師對(duì)該學(xué)生前期研究工作的評(píng)價(jià)（是否同意繼續(xù)研究工作） 指導(dǎo)教師簽字： 年 月 日 備注：1、本表由學(xué)生填寫，指導(dǎo)教師親筆簽署意見。 2、以上各項(xiàng)句間距可以根據(jù)實(shí)際內(nèi)容需要調(diào)整。 - 5 - 驅(qū)動(dòng)橋總成的結(jié)構(gòu)和操作 引言 后橋總成用于后輪驅(qū)動(dòng)車輛。這個(gè)組件是傳動(dòng)系的最后的部件。它通常被稱為最終驅(qū)動(dòng)器或后端。后橋總成常被誤稱為差速器。但差速器僅是后橋總成的一部分。 后橋總成的基本設(shè)計(jì)已被所有廠家多年采用。有幾個(gè)變化，但都按照相同的基本原則操作。后橋總成的主要區(qū)別取決于車輛是否有實(shí)心軸后懸架或獨(dú)立后懸架。實(shí)心軸懸架采用剛性驅(qū)動(dòng)軸和軸管；兩輪移動(dòng)取決一固體結(jié)構(gòu)。獨(dú)立后懸架采用萬向節(jié)驅(qū)動(dòng)車軸（無軸管），允許靈活性和獨(dú)立性的車軸運(yùn)動(dòng)。 本章的目的是識(shí)別和解釋的各種后軸組件的結(jié)構(gòu)和操作。本章的材料為了解如何妥善排查和修理后橋組件提供了一個(gè)基礎(chǔ)。 結(jié)構(gòu)和發(fā)展前景 后橋總成包括差速器總成、后驅(qū)動(dòng)橋和后橋殼。后軸組件承受發(fā)動(dòng)機(jī)和道路的重載。他們構(gòu)造堅(jiān)固，很少損壞。最常見的后橋故障是車軸軸承故障。一個(gè)典型的后橋總成如圖16.1所示。 圖16.1 在后橋總成中，發(fā)動(dòng)機(jī)動(dòng)力從主減速器小齒輪與聯(lián)軸器結(jié)合處傳入驅(qū)動(dòng)橋。與環(huán)齒輪嚙合的主動(dòng)小齒輪使環(huán)齒輪轉(zhuǎn)動(dòng)。從動(dòng)和主動(dòng)小齒輪之間的相互作用使功率流以90°角轉(zhuǎn)動(dòng)。環(huán)齒輪和主動(dòng)小齒輪的齒數(shù)的差異導(dǎo)致減速比。這降低了轉(zhuǎn)彎速度，同時(shí)增加扭矩。從環(huán)齒輪的功率流經(jīng)差速器殼，行星齒輪，和半軸齒輪的驅(qū)動(dòng)橋。驅(qū)動(dòng)軸從差速器總成將動(dòng)力傳遞給后輪。 軸承和后橋殼體的后橋裝配關(guān)鍵組件。它們的目的是支持和調(diào)整差分總成和驅(qū)動(dòng)橋。注意軸承和橋殼是大型重型部件。這是為了確保他們?cè)趷毫訔l件下的使用。 密封件和墊圈對(duì)于后橋總成的操作也非常重要。密封件用于差速器小齒輪和外驅(qū)動(dòng)軸之間。墊圈用于外殼接口，例如差速器蓋和外殼之間，以提供從外部密封的密封件。 圖16-2是鑒于后橋總成的常見類型的爆炸圖。注意內(nèi)部部件與橋殼的相互關(guān)系。注意當(dāng)車輛有獨(dú)立的后懸架時(shí)，后橋殼和驅(qū)動(dòng)橋的設(shè)計(jì)將有所不同。此外，當(dāng)后橋總成配備了有限滑差，它將包含更多的部分。這些特性將在本章后面討論。 減速器總成 后輪驅(qū)動(dòng)車輛中的差速器總成有三個(gè)功能。第一，也是最明顯的，是重定向的改變轉(zhuǎn)矩的方向驅(qū)動(dòng)后輪。動(dòng)力流必須在驅(qū)動(dòng)軸總成和后輪之間作90°轉(zhuǎn)向。這是通過差分裝配由驅(qū)動(dòng)小齒輪和環(huán)形從動(dòng)齒輪來實(shí)現(xiàn)的。 差速器總成的第二個(gè)功能是增加發(fā)動(dòng)機(jī)功率，降低輸出過程中的轉(zhuǎn)速。如果沒有齒輪減速（1:1齒輪比），車輛將加速非常緩慢。在某些情況下，發(fā)動(dòng)機(jī)將無法驅(qū)動(dòng)車輛。至少，油耗會(huì)受到影響，因?yàn)榘l(fā)動(dòng)機(jī)將無法達(dá)到其最有效的轉(zhuǎn)速范圍。出于這個(gè)原因，環(huán)形齒輪和驅(qū)動(dòng)小齒輪總成，通過設(shè)計(jì)，提供了一個(gè)在其輸出速度降低。根據(jù)發(fā)動(dòng)機(jī)的大小，重量，和車輛的用途，主減速比減少到2:1和5:1之間。 差速器總成的第三個(gè)功能是使車輛轉(zhuǎn)彎。如果裝配不允許在轉(zhuǎn)彎時(shí)后輪的不同速度，當(dāng)車輛轉(zhuǎn)彎時(shí)，一個(gè)輪胎會(huì)將會(huì)失去與地面的牽引力。差速器總成允許車輛作平滑轉(zhuǎn)彎。 差速器總成由許多部件組成，包括差速器驅(qū)動(dòng)齒輪（環(huán)形齒輪和驅(qū)動(dòng)小齒輪）、小齒輪軸承、差速器殼、星形齒輪和半軸齒輪和側(cè)軸承如圖16-3。這些部分及其功能在下面的章節(jié)中詳細(xì)描述。 圖16-4。驅(qū)動(dòng)小齒輪和環(huán)齒輪的位置總是相同的。兩個(gè)小齒輪軸承和兩個(gè)側(cè)軸承總是圓錐滾子軸承，必須仔細(xì)調(diào)整。一些驅(qū)動(dòng)小齒輪有三分之一支持齒輪導(dǎo)軸承。軸承和調(diào)節(jié)裝置（墊片或調(diào)整螺母）通常位于如圖所16-4所示。 主減速器齒輪 差動(dòng)齒輪傳動(dòng)又稱環(huán)和小齒輪齒輪組，由環(huán)和驅(qū)動(dòng)小齒輪，圖16-4。這些準(zhǔn)雙曲面齒輪重定向功率流90°。在環(huán)齒輪中的齒數(shù)與傳動(dòng)銷中的齒數(shù)相比，設(shè)置后橋比。例如，如果環(huán)齒輪40齒，小齒輪有10個(gè)齒，比40:10，或4:1。環(huán)齒輪總是比驅(qū)動(dòng)小齒輪有更多的齒。后橋比可以通過在傳動(dòng)齒輪上的齒數(shù)除以環(huán)齒輪上的齒數(shù)來確定。 主動(dòng)小齒輪 驅(qū)動(dòng)小齒輪淬火鋼齒輪與軸，圖16-5。它是加工嚙合和旋轉(zhuǎn)的環(huán)齒輪。軸的外花鍵齒輪有相對(duì)適合的微分齒輪軛/法蘭的內(nèi)花鍵端。齒輪是由兩個(gè)圓錐滾子軸承，稱為小齒輪軸承。 通過設(shè)計(jì)，驅(qū)動(dòng)小齒輪的軸向中心線低于環(huán)齒輪的軸向中心線。通過這種設(shè)計(jì)，小齒輪被放在后橋殼中。這樣做是為了降低驅(qū)動(dòng)軸，因此，在車輛乘員室的驅(qū)動(dòng)軸駝峰。齒輪的螺旋設(shè)計(jì)允許齒輪嚙合的滑動(dòng)運(yùn)動(dòng)，創(chuàng)建一個(gè)平滑的功率傳遞。由于滑動(dòng)作用，齒輪必須有適當(dāng)?shù)臐櫥瑒┕?yīng)。這種齒輪稱為準(zhǔn)雙曲面齒輪。 后齒輪軸承壓到齒輪端的驅(qū)動(dòng)小齒輪軸上。前齒輪軸承通常是軸的小端滑動(dòng)配合。兩軸承的外圈或軸承杯壓入后軸殼中。、 無論是固體間隔或可折疊墊片（壓碎墊圈）是用來設(shè)置小齒輪軸承預(yù)緊力。當(dāng)驅(qū)動(dòng)小齒輪安裝在后橋殼時(shí)，可折疊的間隔件被設(shè)計(jì)成輕微壓縮。墊片保持前和后齒輪軸承之間的溫和的壓力，使得能夠準(zhǔn)確地調(diào)整軸承預(yù)緊力。 差速器小齒輪軛/凸緣具有適合驅(qū)動(dòng)小齒輪軸上的外花鍵的內(nèi)花鍵。圖16-6。后面的軛/法蘭，它適合后橋殼，加工順利。這是小齒輪密封的密封面。軛架/法蘭由一個(gè)大螺母和墊圈連接到驅(qū)動(dòng)小齒輪軸上。這種螺母是一種稱為鎖死螺母。螺母的頂部螺紋變形，緊緊抓住主動(dòng)齒輪軸上的螺紋。這是一個(gè)干擾配合。擰緊螺母還調(diào)整小齒輪軸承預(yù)緊力。 小齒輪軛架被加工成接受后萬向節(jié)的軸承杯。杯子是壓在舉行與卡環(huán)，或連接到U型螺栓軛或螺栓上的帶子。 小法蘭只是兩個(gè)軛的配對(duì)法蘭連接。外部分有軛，內(nèi)部分有小齒輪軸的外花鍵。這些配對(duì)法蘭，他們也被稱為，將分離出來的法蘭部分拆下傳動(dòng)軸總成。 傳動(dòng)齒輪相對(duì)于環(huán)齒輪的位置必須精確設(shè)置。否則，齒輪會(huì)噪音，并會(huì)很快磨損。傳動(dòng)小齒輪在殼體中的位置必須小心調(diào)整，以使齒輪與齒圈的齒面完全接觸。為了使此調(diào)整到環(huán)和驅(qū)動(dòng)小齒輪間隙，一個(gè)小齒輪墊片安裝在住房，后面的軸承杯后面。墊片的厚度決定殼體中驅(qū)動(dòng)小齒輪的深度。該墊片安裝在后端組裝時(shí)。當(dāng)驅(qū)動(dòng)小齒輪被移除時(shí)，必須檢查適當(dāng)?shù)暮穸取? 圖16-8顯示在最后橋齒輪墊片的位置。該圖還顯示了可折疊墊片的相對(duì)位置。 環(huán)形齒輪 環(huán)形齒輪，圖16-9，從驅(qū)動(dòng)小齒輪差速器傳遞動(dòng)力。環(huán)齒輪和殼體都是緊密結(jié)合在一起的。螺栓被用來保持環(huán)齒輪的情況下。螺栓穿過殼體中的孔，并在環(huán)齒輪的后面插入螺紋孔。 由于環(huán)和驅(qū)動(dòng)小齒輪齒必須嚙合準(zhǔn)確地傳遞運(yùn)動(dòng)沒有噪聲或損壞，環(huán)齒輪的位置是重要的。汽車技術(shù)人員應(yīng)熟悉齒輪術(shù)語將會(huì)同時(shí)調(diào)整差速器總成獲得正確的齒輪位置遇到。凸側(cè)，或驅(qū)動(dòng)側(cè)，與凹側(cè)，或海岸邊，在環(huán)形齒輪指出圖16-9a。這些條款時(shí)將使用差動(dòng)齒輪調(diào)整。必須仔細(xì)調(diào)整圖16-9b確定齒部分。腳跟和腳趾的條款將廣泛用于環(huán)和小齒輪齒輪的調(diào)整。 差速器殼總成 當(dāng)車輛轉(zhuǎn)彎時(shí)，外車輪的行駛距離比內(nèi)輪大，外側(cè)的圓弧（或半徑）大于外車輪。如果后驅(qū)動(dòng)橋只連接在一起，那么兩個(gè)輪子在轉(zhuǎn)彎時(shí)都必須走同樣長(zhǎng)度的圓弧。由于這是不可能的，其中一個(gè)輪胎將失去牽引，或滑移，在轉(zhuǎn)彎。如果輪胎沒有打滑，它就會(huì)跳過路面。這種情況叫做輪跳。 差速器殼體總成的目的是使車輛轉(zhuǎn)彎時(shí)不打滑或車輪跳動(dòng)。它這樣做的齒輪的安排，使兩后輪轉(zhuǎn)向以不同的速度前行。兩種基本類型的情況下，用于完成這項(xiàng)任務(wù)的標(biāo)準(zhǔn)差分和鎖差。 對(duì)稱錐齒輪式的差速器 對(duì)稱式的差速器，也稱為單差分差速器，由差速器和差速器殼組成。參見圖16-10。 對(duì)稱式差速器通常是單件式的。環(huán)齒輪是螺栓的情況下。這個(gè)箱子通常是鑄鐵或鋁做的。側(cè)軸承通常壓在殼體上。 行星齒輪由淬硬鋼制成，并由一個(gè)稱為小齒輪軸的鋼軸固定。小齒輪軸穿過差速器殼體和星形齒輪的中心。它附有一個(gè)螺栓的情況下。行星齒輪也稱為小齒輪。 與行星齒輪嚙合的半軸齒輪，也由淬硬鋼制成。當(dāng)齒圈和微分的情況下，行星和側(cè)齒輪轉(zhuǎn)動(dòng)。功率流是通過的情況下，進(jìn)入行星齒輪，并進(jìn)入半軸齒輪。半軸齒輪花鍵傳動(dòng)軸。 一些重型差速器包含四個(gè)行星齒輪和兩個(gè)半軸齒輪軸。在這個(gè)設(shè)計(jì)中，有一個(gè)中心孔中的一個(gè)軸。另一根軸穿過它。半軸齒輪花鍵傳動(dòng)軸。有些差異。參見圖16-11。 行星和半軸齒輪錐齒輪。功率傳遞通過錐齒輪使他們被迫遠(yuǎn)離對(duì)方。這導(dǎo)致高推力的齒輪的背面，在那里他們接觸差速器殼。硬化鋼墊圈通常安裝在齒輪的后面和殼體之間。這些墊圈提供滑動(dòng)表面，減少磨損。圖16-12。 圖16-13顯示差而直線行駛和轉(zhuǎn)彎時(shí)的駕駛操作狀態(tài)。圖16-13a，車輛行駛前方，車輪行駛在相同的速度。蜘蛛和側(cè)齒輪旋轉(zhuǎn)的情況下，但不移動(dòng)有關(guān)。整個(gè)外殼組件作為單元旋轉(zhuǎn)。 當(dāng)車輛轉(zhuǎn)彎時(shí)，車軸和半軸齒輪開始以不同的速度轉(zhuǎn)驅(qū)動(dòng)左右后輪，在右轉(zhuǎn)彎的情況下轉(zhuǎn)快于內(nèi)輪，左側(cè)齒輪轉(zhuǎn)快于右側(cè)齒輪。參見圖16-13b。由于各軸的速度，蜘蛛齒輪開始旋轉(zhuǎn)。左側(cè)齒輪，這是移動(dòng)速度比右側(cè)齒輪，驅(qū)動(dòng)蜘蛛齒輪，使他們旋轉(zhuǎn)，或走動(dòng)，右側(cè)齒輪。 注意差速器差速器的轉(zhuǎn)速是半軸齒輪速度的平均值。這是因?yàn)橐粋€(gè)側(cè)面齒輪的轉(zhuǎn)速比殼體快，而另一側(cè)齒輪的旋轉(zhuǎn)速度比殼體慢。圖16-14，車輛轉(zhuǎn)彎時(shí)，差速器的作用使外側(cè)車輪在情況下轉(zhuǎn)速增加110%，而內(nèi)輪轉(zhuǎn)速減90%差速器殼體轉(zhuǎn)速。這些百分比隨轉(zhuǎn)彎半徑而變化。 鎖止差速器 對(duì)稱差速器在大多數(shù)在非常滑的表面，如結(jié)冰或泥濘的路面，缺乏牽引力會(huì)導(dǎo)致后輪打滑。這是因?yàn)闃?biāo)準(zhǔn)差將給驅(qū)動(dòng)車輪最少的牽引力。 如果一個(gè)驅(qū)動(dòng)輪在干燥的路面上，另一個(gè)是在冰或泥上，那么環(huán)形齒輪和差速器殼就會(huì)驅(qū)動(dòng)行星齒輪。然而，行星齒輪不會(huì)驅(qū)動(dòng)兩側(cè)半軸齒輪。當(dāng)行星齒輪由差速器殼驅(qū)動(dòng)時(shí)，它們將在干燥的路面上繞到與車輪有關(guān)的半軸齒輪上。因此，行星齒輪驅(qū)動(dòng)滑動(dòng)輪，車輛不會(huì)移動(dòng)。 為了克服這個(gè)問題，使用鎖速差克服牽引問題，通過發(fā)送一些強(qiáng)制信號(hào)給兩個(gè)車輪，同時(shí)使車輛作出正常的轉(zhuǎn)向。有幾種不同類型的鎖止差速器，包括防滑、棘輪、和托森式。 兩種最常見的限滑差速器是離合器盤差速器和錐差速器。離合器片的鑒別使用幾個(gè)摩擦盤看起來像小手動(dòng)離合器盤。錐差采用錐形離合器嚙合匹配錐形插座。限滑差類型有不同的品牌名稱，包括積極的牽引，確保抓地力，反旋，牽引樂。許多技術(shù)人員參考限滑差為差異，盡管這實(shí)際上是一個(gè)通用的品牌名稱可以追溯到20世紀(jì)50年代。 由于其結(jié)構(gòu)復(fù)雜和更高的成本，有限的滑差鎖僅用于高性能版本的后輪驅(qū)動(dòng)汽車?，F(xiàn)代卡車和越野車常見的限滑差速器。許多越野車和一些卡車在前后車軸上有有限的滑差。有些公司制造售后限滑差速器，以取代原有的設(shè)備設(shè)計(jì)或轉(zhuǎn)換標(biāo)準(zhǔn)差，以有限的滑移單位。 一個(gè)常見的離合器片鑒別實(shí)例圖16-15所示。這種限滑差速器和一個(gè)標(biāo)準(zhǔn)差之間最明顯的區(qū)別是離合器放側(cè)齒輪和差速器殼之間。 離合器摩擦片由用摩擦材料覆蓋的鋼制成。離合器片是鋼制的。盤板交替花鍵的齒側(cè)和頑強(qiáng)的（意思是片裝入槽）的差異的情況下，圖16-6。在盤或板槽是為了更好的抓取能力。 圖16-17顯示離合器片微分運(yùn)動(dòng)部件。行星齒輪，半軸齒輪，和其他部分是非常相似的標(biāo)準(zhǔn)差。 圖16-17顯示離合器片微分運(yùn)動(dòng)部件。蜘蛛齒輪，側(cè)齒輪，和其他部分是非常相似的標(biāo)準(zhǔn)差。的限滑差速器的微分的情況常常是兩部分，使離合器的去除，如圖所示的16-18。 盤和板由預(yù)緊彈簧和側(cè)齒輪上的行星齒輪的機(jī)械壓力施加。由于行星和半軸齒輪是錐齒輪，他們的牙齒試圖退出時(shí)，差分傳遞發(fā)動(dòng)機(jī)扭矩。 在側(cè)向齒輪上推動(dòng)作用下迫使它們向外擠壓。側(cè)面齒輪的外壓力將摩擦盤和鋼板連接在半軸齒輪和箱體之間。當(dāng)盤和盤被壓在一起的時(shí)候，襯里和緊固連接確保半軸齒輪和差動(dòng)箱被鎖在一起。 圖16?-?19顯示了離合器片式差速器的工作原理。當(dāng)車輛前行時(shí)，離合器片式差速器與普通差速器以相同的方式工作，如圖16?-?19a。后輪和差速器箱以相同的速度轉(zhuǎn)動(dòng)。離合器片雖然被設(shè)置，但此時(shí)不工作。 當(dāng)汽車轉(zhuǎn)動(dòng)時(shí)，會(huì)失去對(duì)一個(gè)輪胎的牽引力，造成輪胎滑摩。如圖16-19A所示， 一旦輪胎滑摩，行星齒輪將不會(huì)緊緊地壓在打滑一側(cè)的齒輪，這邊的齒輪也不能對(duì)箱體產(chǎn)生壓力。打滑一側(cè)的離合器片也不會(huì)緊緊地壓在一起。 在負(fù)載下，此邊齒輪有離開行星齒輪的趨勢(shì)，另一個(gè)側(cè)齒輪也向外移動(dòng)并會(huì)遠(yuǎn)離行星齒輪。半軸齒輪在負(fù)載下，因?yàn)榕c它相對(duì)應(yīng)的車輪有牽引力。這側(cè)齒輪的壓力導(dǎo)致相關(guān)的離合器片被緊緊地?cái)D壓在一起。半齒輪是由于離合器片被鎖在一起了，牽引力能傳遞到車輪上。 離合器片的設(shè)計(jì)是為了在達(dá)到一定的扭矩值時(shí)方式滑動(dòng)。當(dāng)車輛轉(zhuǎn)彎時(shí)，一個(gè)大扭矩，由外輪轉(zhuǎn)動(dòng)的速度快于這個(gè)情況，導(dǎo)致離合器打滑。這樣，在做轉(zhuǎn)彎時(shí)，離合器片式的差速器就可以于普通差速器相同的方式工作，。閥瓣和碟片相互滑動(dòng)，用半軸齒輪進(jìn)行旋轉(zhuǎn)，板材旋轉(zhuǎn)，以允許半軸齒輪以不同旋轉(zhuǎn)速度，因此，在后輪之間。 圖16-20展示了一個(gè)錐式的差速器，這是另一種限滑差速器，在離合器片的位置，使用摩擦錐襯片，工作原理以摩擦片式的相同。預(yù)裝彈簧和側(cè)齒輪壓力迫使錐形片產(chǎn)生凹陷。在摩擦力的作用下鎖定錐體，因此，側(cè)齒輪傳遞動(dòng)力驅(qū)動(dòng)車輪。圖16-21是其爆炸圖。 在這里要注意，摩擦片式的或錐式的差速器都需要一種特殊的限滑齒輪油，如果使用普通的潤滑油，會(huì)造成零件的損壞。 棘輪式的差速器，別名叫底特律鎖，使用一系列的凸輪和坡度來直接將動(dòng)力力驅(qū)動(dòng)到車輪上。它的運(yùn)行取決于相對(duì)的車輪速度，而不是車輪牽引力。棘輪的差動(dòng)通過一組可以嚙合和分離的牙齒來傳輸動(dòng)力。這種可分離的牙齒系統(tǒng)有時(shí)被稱為狗牙式離合器。這一系列的凸輪和坡道使牙與一側(cè)車輪傳遞斷開 ，其結(jié)構(gòu)如圖16-22所示； 對(duì)于直行的情況下，兩套牙齒都是嚙合的，而差速器殼和車輪的轉(zhuǎn)動(dòng)速度是相同的，16?-?22a。在轉(zhuǎn)向時(shí)或當(dāng)一個(gè)輪子失去牽引力時(shí)，車輪之間的速度差會(huì)導(dǎo)致內(nèi)部凸輪和坡道使齒分離，使移動(dòng)的輪子更快，圖16?-?22b和16?-?22c。然后，所有的動(dòng)力都通過另一個(gè)輪子傳送。 因?yàn)楦斓囊苿?dòng)輪總是在滑動(dòng)。動(dòng)力隨著牽引力而進(jìn)入車輪。在轉(zhuǎn)向的情況下，對(duì)外輪的功率損失是不明顯的。這種設(shè)計(jì)是耐用的，不需要特殊的齒輪機(jī)油，但在操作上通常是粗糙和嘈雜的。它通常用于越野車輛和賽車。 托爾森差速器是一種使用復(fù)雜的蝸輪結(jié)構(gòu)鎖定。齒輪裝置包括半軸渦輪(傳動(dòng)齒輪)和行星蝸輪(傳動(dòng)齒輪)。自上世紀(jì)60年代以來，蝸輪一直是普通差速器的高性能替代品。它現(xiàn)在被作為原始設(shè)備一些歐洲汽車上。這種結(jié)構(gòu)的基本原理是，當(dāng)行星蝸輪可以驅(qū)動(dòng)半軸蝸輪時(shí)，半軸蝸輪無法驅(qū)動(dòng)行星蝸桿。 如圖16?-?23所示，蝸輪式差速器有兩個(gè)半軸蝸輪。為了清晰起見，這些將被稱為軸齒輪。一個(gè)軸齒輪連接在每個(gè)軸上。蝸輪行駛，由輪軸齒輪驅(qū)動(dòng)。蝸輪由差速器殼固定。齒輪嚙合在蝸輪的兩端嚙合，形成了兩個(gè)軸系之間唯一的連接。發(fā)動(dòng)機(jī)驅(qū)動(dòng)差速器殼，而由箱子所控制的蝸輪轉(zhuǎn)動(dòng)。蝸輪不能轉(zhuǎn)動(dòng)軸齒輪，所以它們把自己鎖在齒輪上。在這種情況下，軸齒輪和軸與箱子是鎖著的，并與它一起旋轉(zhuǎn)。 在直行的操作過程中，其運(yùn)行就像一個(gè)標(biāo)準(zhǔn)的差速器裝置，所有的內(nèi)部齒輪都是一個(gè)單位旋轉(zhuǎn)。當(dāng)車輛轉(zhuǎn)彎時(shí)，或當(dāng)一個(gè)驅(qū)動(dòng)輪在滑動(dòng)時(shí)，驅(qū)動(dòng)輪的相對(duì)速度，因此，軸突的相對(duì)速度變化。這個(gè)速度差從較快一側(cè)的軸傳到慢的一側(cè)。 快軸上的軸齒輪可以驅(qū)動(dòng)各自的蝸輪。這種驅(qū)動(dòng)力從齒輪的齒輪轉(zhuǎn)到減速輪上。發(fā)動(dòng)機(jī)功率通過齒輪的相互作用從較快的蝸輪轉(zhuǎn)向較慢的蝸輪。在較慢的一側(cè)的蝸輪仍然不能驅(qū)動(dòng)較慢的輪軸齒輪，但它可以將增加的轉(zhuǎn)矩從更快的輪子轉(zhuǎn)移到壓力。這種壓力增加了輸送到較慢軸齒輪和軸的功率。它不給軸齒輪，但它允許它以更多的力轉(zhuǎn)動(dòng)。 液壓差速鎖式的差速器 有一些較晚的越野車模型具有由液壓系統(tǒng)操作的差速器。它可能被稱為水合鎖，變鎖，或Georotor系統(tǒng)。液壓鎖定差速器由一個(gè)內(nèi)部和外部齒輪泵，一個(gè)環(huán)形壓力隔膜，和一個(gè)離合器片，類似于一個(gè)傳統(tǒng)的鎖定摩擦片式差速器，如圖16?-?24a所使用的離合器包。操作液壓系統(tǒng)的齒輪油來自后軸總成。不需要特殊的油。同樣的油用于后軸潤滑，液壓系統(tǒng)也不需要由其他后軸部件密封。 這種泵類似于轉(zhuǎn)子發(fā)動(dòng)機(jī)油泵，有一個(gè)6點(diǎn)外部齒輪，內(nèi)部齒輪有7個(gè)腔。泵的內(nèi)部和外部齒輪之間的間隙在任何時(shí)候都充滿齒輪油。當(dāng)齒輪移動(dòng)時(shí)，氣泵入口側(cè)的空間打開并吸入齒輪油。流體被輸送到泵的輸出端，在那里空間開始關(guān)閉。 空間產(chǎn)生的壓力可以用來操作差速器的其他組件。圖16?-?24b顯示了轉(zhuǎn)子泵的操作。止回閥確保壓力總是產(chǎn)生，不管泵的旋轉(zhuǎn)方向是什么。 內(nèi)部齒輪連接在一個(gè)側(cè)軸上。外部齒輪連接在另一側(cè)的軸上。當(dāng)兩個(gè)輪子都有相等的牽引力時(shí)，兩邊的軸都以相同的速度轉(zhuǎn)動(dòng)。因此，內(nèi)部和外部的泵齒輪相互之間不會(huì)移動(dòng)，也不會(huì)產(chǎn)生壓力。當(dāng)車輛在一個(gè)輪子上失去牽引力時(shí)，其中一個(gè)側(cè)軸開始以比另一個(gè)更快的速度轉(zhuǎn)彎。軸轉(zhuǎn)速的差異導(dǎo)致內(nèi)部和外部的泵齒輪移動(dòng)。這種壓力被傳送到環(huán)隔膜上，它擴(kuò)展到離合器包。將離合器包應(yīng)用后，側(cè)軸將鎖在一起，作為一個(gè)單位轉(zhuǎn)動(dòng)。當(dāng)車輪以相同的速度轉(zhuǎn)動(dòng)時(shí)，內(nèi)部和外部齒輪之間不會(huì)移動(dòng)，也不會(huì)產(chǎn)生壓力。由于沒有產(chǎn)生泵壓力，環(huán)隔膜減壓并釋放離合器。如果一個(gè)輪子再次開始滑動(dòng)，泵又開始運(yùn)轉(zhuǎn)，系統(tǒng)重新應(yīng)用離合器。當(dāng)車輛轉(zhuǎn)彎時(shí)，泵的齒輪相對(duì)另一個(gè)齒輪會(huì)輕微地移動(dòng)。然而，施加足夠的壓力來應(yīng)用離合器。因此，在正常轉(zhuǎn)向情況下，差速器不會(huì)試圖鎖定。 一些鎖止差速器是由連接在車軸上的電機(jī)驅(qū)動(dòng)的。注意標(biāo)準(zhǔn)后軸上安裝的附加部件，圖16?-?25。移動(dòng)叉軸和移動(dòng)叉由馬達(dá)操作并移動(dòng)軸套。軸套有條樣條，可以分離行星齒輪和半軸齒輪。在正常的非鎖止操作中，位移叉軸和軸叉可以保持轂套的脫離。軸套對(duì)差動(dòng)操作沒有影響。 為了鎖定差速器，馬達(dá)會(huì)將變速叉軸和換向叉移動(dòng)。花鍵將軸套、差速器和側(cè)齒輪鎖定為一個(gè)單元。將載波和側(cè)齒輪鎖定在一起防止其他差動(dòng)齒輪轉(zhuǎn)動(dòng)。差動(dòng)總成變成一個(gè)單元。為每個(gè)驅(qū)動(dòng)輪提供相等的功率。 309Chapter16Rear Axle AssemblyConstruction andOperationTechnical TermsSolid-axle rear suspensionIndependent rear suspensionDifferential drive gearsDrive pinion gearPinion bearingCollapsible spacerJam nutPinion shimRing gearWheel hopStandard differentialDifferential caseAfter studying this chapter,you will be able to:Explain the purpose of a rear axle assembly.Identify the major parts of a rear axle assembly.Describe the differential drive gears and related parts.Calculate rear axle ratio.Compare differential and rear axle assembly design variations.Describe the operation of a standard differential and of the various types of locking differentials.Spider gearsSide gearsLocking differentialLimited-slip differentialClutch-plate differentialCone differentialRatchet differentialTorsen differentialHydraulic locking differentialDifferential carrierAxle tubeRemovable carrierPinion pilot bearingSide bearingsIntegral carrierSolid drive axleAxle flangeAxle bearingAxle collarAxle retainer plateSemi-floating axleAxle shimFull-floating axleIndependently suspended drive axleThis sample chapter is for review purposes only.Copyright The Goodheart-Willcox Co.,Inc.All rights reserved.IntroductionThe rear axle assembly is used on rear-wheel drivevehicles.This assembly is the final leg of the drive train.Itis often called the final drive or rear end.The rear axleassembly is often mistakenly called the differential.Thedifferential is only part of the rear axle assembly.The basic design of rear axle assemblies has beenadopted by all manufacturers for many years.There areseveral variations,but all operate according to the samebasic principles.The major difference between rear axleassemblies depends on whether the vehicle has solid-axlerear suspension or independent rear suspension.Solid-axlerear suspension incorporates rigid and nonflexing driveaxles and axle tubes;both wheels move as one solid unitin response to bumps and potholes.Independent rearsuspension incorporates jointed drive axles(no axle tubes)that allow for flexibility and independent axle movement.This chapter is designed to identify and explain the con-struction and operation of various rear axle assemblies.Thematerial in this chapter provides a basis for understandinghow to properly troubleshoot and repair rear axle assemblies.Construction and Operation Overview The rear axle assembly includes the differentialassembly,the rear drive axles,and the rear axle housing.Rear axle assemblies are subjected to heavy loads from theengine and road.They are ruggedly constructed andseldom fail.The most common rear end failures are axlebearing failures.A typical rear axle assembly is shown inFigure 16-1.In a rear axle assembly,engine power enters the drivepinion gear from the drive shaft assembly and differentialpinion yoke/flange.The drive pinion gear,which is inmesh with the ring gear,causes the ring gear to turn.Theinteraction of the ring and drive pinion gears turns thepower flow at a 90 angle.The difference in the number ofteeth on the ring and pinion gears causes a reduction gearratio.This reduces turning speed,while increasing torque.Power from the ring gear flows through the differentialcase,spider gears,and side gears to the drive axles.Thedrive axles transfer power from the differential assembly tothe rear wheels.The bearings and rear axle housing are key com-ponents of the rear axle assembly.They are designed tosupport and align the differential assembly and the driveaxles.Notice that the bearings and axle housing are large,heavy-duty parts.This is to ensure they will stand up underhard usage.Seals and gaskets are also very important to theoperation of the rear axle assembly.Seals are used at thedifferential pinion yoke/flange and at the outer drive axles.Gaskets are used at housing interfaces,such as betweenthe differential cover and the housing,to provide a tightseal from the outside.Figure 16-2 is an exploded view of a common type ofrear axle assembly.Notice the relationship of the internalparts to the housing and to each other.Note that the rear310Manual Drive Trains and AxlesWheel,oraxle,bearingAxle sealAxleflangeSidebearingsDifferentialcaseInspection coverRing gearDrive axlePinionbearingsCompanionflangeDrivepinion gearPinion orspider gearsSide gearsRear axlehousingDriveaxleFigure 16-1.Most rear axle assemblies contain the same parts as shown in this cutaway.Note that some drive axles differ from thisbasic design.(Ford)Chapter 16Rear Axle Assembly Construction and Operation311BoltInspection coverThrustwasherSpidergearRetainingwasherSide gearThrust washerThrustwasherSidegearPinion shaftlock pinShimCupSidebearingPinionshaftSpidergearThrustwasherSidebearingCupShimDrivepinion gearRing and pinionassemblyPinionshimBoltBoltDifferential caseDifferentialcapPinionbearingPinionbearing cupBoltDifferentialcarrierRear axlehousingAxle tubeFiller plugBearingcupPinionspacerPinion bearingassemblyPinion sealPinion nutPinionflangeSlingerBoltAxlebearingSealNutDriveaxleRing gearBrake assemblyFigure 16-2.Exploded view of a rear axle assembly shown in Figure 16-1.(Ford)axle housing and drive axle designs will be different whenthe vehicle has independent rear suspension.Also,whenthe rear axle assembly is equipped with a limited-slipdifferential,it will contain more parts.These features willbe discussed later in this chapter.Differential AssemblyThe differential assembly in a rear-wheel drive vehiclehas three functions.The first,and most obvious,is toredirect the power flow to drive the rear wheels.Thepower flow must make a 90 turn between the drive shaftassembly and the rear wheels.This is accomplished in thedifferential assembly by the drive pinion and ring gears.The second function of the differential assembly isto multiply engine power,reducing speed at the outputin the process.If there were no gear reduction(1:1 gearratio),the vehicle would accelerate very slowly.In somecases,the engine would be unable to move the vehicle.At the very least,gas mileage would be harmed,sincethe engine would not reach its most efficient rpm range.For this reason,the ring and drive pinion assembly,bydesign,provides a reduced speed at its output.Thereduction is between 2:1 and about 5:1,depending onthe engine size,vehicle weight,and intended use of thevehicle.The third function of the differential assembly is toallow the vehicle to make turns.If the assembly did notmake allowances for the different speeds of the rear wheelsduring turns,one tire would lose traction with the groundas the vehicle turned corners.The differential assemblyallows the vehicle to make smooth turns.The differential assembly consists of numerous parts,including the differential drive gears(ring and drivepinion gears),pinion bearings,differential case,spiderand side gears,and side bearings.See Figure 16-3.Theseparts and their function are described in detail in thefollowing section.Differential Drive GearsThe differential drive gears also called the ring andpinion gearset,consist of the ring and drive pinion gears,Figure 16-4.These hypoid gears redirect power flow by90 and multiply engine power.The number of teeth in thering gear compared to the number of teeth in the drive pin-ion gear sets the rear axle ratio.For instance,if the ringgear has 40 teeth and the pinion gear has 10 teeth,theratio is 40:10,or 4:1.The ring gear always has more teeththan the drive pinion gear.Rear axle ratios can always bedetermined by dividing the number of teeth on the ringgear by the number of teeth on the drive pinion gear.Drive pinion gearThe drive pinion gear is a hardened-steel gear with anintegral shaft,Figure 16-5.It is machined to mesh with androtate the ring gear.The end of the shaft opposite the gearhas external splines that fit the internal splines of the differ-ential pinion yoke/flange.The gear is supported by twotapered roller bearings,called pinion bearings.By design,the axial centerline of the drive pinion gearlies below that of the ring gear.With this design,the piniongear is placed lower in the rear axle housing.This is doneto lower the drive shaft and,therefore,the drive shaft humpin the vehicle passenger compartment.The spiral design ofthe gear teeth allows the gears to mesh with a slidingmotion,creating a smooth power transfer.As a result of thesliding action,the gears must have a good supply of theproper lubricant.Gears of this type are called hypoid gears.312Manual Drive Trains and AxlesPinion bearingDrivepinion gearAdjustingnutSidebearingSide gearsRing gearSpidergearsDifferentialshaftCaseSide bearingAdjustingnutFigure 16-3.Relative positions of parts of a differential assembly.The interaction of the various parts of the differential may bemore easily understood by studying this illustration.(Subaru)Rear axlehousingPinionpreload shimDifferentialpinion yokePinionbearingsPinion depth shimDrivepinion gearRinggearSidebearingDifferentialcaseDifferentialbearing shims(endplay/preload)SidebearingFigure 16-4.The positions of the drive pinion gear and the ringgear are always about the same.The two pinion bearings andtwo side bearings are always tapered roller bearings that mustbe carefully adjusted.Some drive pinion gears have a thirdbearinga pinion pilot bearingfor support.Bearings andadjusting devices(shims or adjusting nuts)are usually locatedas shown.(DaimlerChrysler)The rear pinion bearing is pressed onto the drivepinion gear shaft at the gear end.The front pinion bearingis often a slip fit on the smaller end of the shaft.The outerraces,or bearing cups,of both bearings are pressed intothe rear axle housing.Either a solid spacer or a collapsible spacer(crushwasher)is used to set the pinion bearing preload.Thecollapsible spacer is designed to be slightly compressedwhen the drive pinion gear is installed in the rear axlehousing.The spacer maintains a mild pressure betweenthe front and rear pinion bearings,making it possible toaccurately adjust the bearing preload.The differential pinion yoke/flange has internalsplines that fit the external splines on the drive pinion gearshaft.See Figure 16-6.The rear of the yoke/flange,whereit fits into the rear axle housing,is machined smooth.Thisis the sealing surface for the pinion seal.The yoke/flange isheld to the drive pinion gear shaft by a large nut and washerthat threads onto the shaft.This nut is a type known as ajam nut.The top threads of the nut are deformed to tightlygrip the threads on the drive pinion gear shaft.This is aninterference fit.Tightening the nut also adjusts the pinionbearing preload.The pinion yoke is machined to accept the bearingcups of the rear universal joint.The cups are either pressedin and held with snap rings,or they are attached to theyoke with U-bolts or bolted-on straps.Pinion flanges are simply a two-piece yoke joined bymating flanges.The outer section has the yoke;the innersection has the external splines for the pinion gear shaft.These companion flanges,as they are also called,wouldbe separated at the flanged section to remove the driveshaft assembly,Figure 16-7.The position of the drive pinion gear relative to thering gear must be set exactly.Otherwise,the gears will benoisy and will wear out quickly.The position of the drivepinion gear in the housing must be carefully adjusted sothat it contacts the ring gear at exactly the right toothdepth.To make this adjustment to the ring and drive pinionclearance,a pinion shim is installed in the housing,behindthe rear bearing cup.The thickness of this shim determinesthe depth of the drive pinion gear in the housing.This shimis installed at the factory when the rear end is assembled.It must be checked for proper thickness whenever the drivepinion gear is removed.Figure 16-8 shows the position of the pinion shim onmost rear axle assemblies.This figure also shows the rela-tive position of the collapsible spacer.Ring gearThe ring gear,Figure 16-9,transfers power from thedrive pinion gear to the differential case.Both the ring gearand the case are machined to fit together tightly.Bolts areChapter 16Rear Axle Assembly Construction and Operation313Threads foryoke nutDrive pinionsplinesCollapsiblespacerDrive pinion gearRear pinionbearingDrive piniongear shaftFigure 16-5.A typical drive pinion gear.The rear pinion bear-ing is pressed on the drive pinion gear shaft.A collapsiblespacer is used to aid in pinion bearing installation.Threads andsplines at the front of the drive pinion gear shaft are used forinstalling the differential pinion yoke.(General Motors)Differentialpinion yokeDifferentialseal surfaceSplines lockgear to yokeDrivepinion gearDrive piniongear shaftFlat washerPiniongear nutHole forU-jointFigure 16-6.The differential pinion yoke slides over the drivepinion gear shaft and is secured by the pinion gear nut.Thetightening nut also preloads the pinion bearings.The outer sur-face of the drive pinion gear shaft seals against the front oil seal.U-jointRear axleassemblyCompanionflangesFlange boltsDrive shaftFigure 16-7.Some differential pinion yokes are two-pieceflanged assemblies,as shown here.This type of design isreferred to as a differential pinion flange,or companion flange.(Ford)used to hold the ring gear to the case.The bolts passthrough holes in the case and are threaded into tappedholes in the back of the ring gear.Since the ring and drive pinion gear teeth must meshaccurately to transmit motion without noise or damage,the position of the ring gear is important.Automotive tech-nicians should be familiar with gear terminology that willbe encountered while adjusting the differential assembly toobtain correct gear positions.The convex side,or driveside,and the concave side,or coast side,of the ring gearare pointed out in Figure 16-9A.These terms will be usedwhen differential gears are adjusted.The tooth parts thatmust be carefully adjusted are identified in Figure 16-9B.The terms heel and toe will be used extensively for ringand pinion gearset adjustment.Differential Case AssemblyWhen a vehicle makes a turn,the outer wheel travelsa greater distance than the inner wheelthe arc(orradius)of the turn is greater at the outer wheel.If the reardrive axles were simply connected together,both wheelswould have to travel an arc of the same length during aturn.Since this is impossible,one of the tires would losetraction,or slip,during the turn.If the tire did not slip,itwould skip over the road surface.This condition is calledwheel hop.The purpose of the differential case assembly is toallow the vehicle to make turns without slippage or wheelhop.It does this with an arrangement of gears that allowsthe rear wheels to turn at different speeds.Two basic typesof differential case assemblies used to accomplish this taskare the standard differential and the locking differential.Standard differentialThe standard differential,also called a single-pulldifferential,is composed of meshing spider and side gearsenclosed in a differential case.See Figure 16-10.The standard differential case is usually a one-pieceunit.The ring gear is bolted to the case.The case is usuallymade of cast iron.Occasionally,it is made of aluminum.Side bearings are usually pressed onto the case.The spider gears are made of hardened steel and areheld in place by a steel shaft called the pinion shaft.Thepinion shaft passes through the differential case and thecenter of the spider gears.It is attached to the case with abolt.Spider gears are also called pinion gears.Spider gears mesh with side gears,which are alsomade of hardened steel.When the ring gear and differen-tial case turn,the spider and side gears also turn.Powerflow is through the case,into the spider gears,and on intothe side gears.The side gears are splined to the drive axles.314Manual Drive Trains and AxlesRear U-jointFront pinionbearingPinionshimPiniongear nutDifferentialpinion yokeCollapsiblespacerRear pinionbearingFigure 16-8.Pinion shim and preload spacer locations.Properpinion adjustment is critical.The adjusting nut,preload spacer,and depth shim are all critical to proper pinion adjustment.(DaimlerChrysler)CorrectpatternToeConcave side(coast)Convex side(drive)HeelTop landProfileRootToeHeelLengthwisebearingarcABFigure 16-9.When installed,the ring gear is bolted to the differential case and meshes with the drive pinion gear.AThe ring gearhas convex and concave sides.The convex side is the drive side.It contacts the drive pinion gear when the vehicle is accelerating.The concave side is the coast side.It contacts the drive pinion gear when the vehicle is decelerating.BGear terminology will beimportant when the differential assembly is serviced.Proper heal and toe contact is critical to quiet operation and long life.(General Motors,DaimlerChrysler)They transfer power to the drive axles and rear wheels.Side gears are also called axle end gears.Some heavy-duty differentials contain four spidergears and two pinion shafts.In this design,there is a centerhole in one of the shafts.The other shaft passes through it.The side gears are splined to the drive axle.On somedifferentials,the side gears contain C-locks,which holdthe axles in place.See Figure 16-11.The spider and side gears are bevel gears.Powertransfer through the bevel gears causes them to be forcedaway from each other.This causes high thrust forces on thebacks of the gears,where they contact the differential case.Hardened-steel washers are usually installed between theback of the gears and the case.These washers provide asliding surface and reduce wear.See Figure 16-12.Figure 16-13 shows the operating states of the differ-ential while driving straight ahead and while drivingaround a corner.In Figure 16-13A,the vehicle is movingstraight ahead and both wheels are traveling at the samespeed.The spider and side gears rotate with the case butdo not move in relation to it.The entire case assemblyrotates as a unit.When the vehicle makes a turn,the axles and the sidegears begin turning at different speeds.The outer wheelthe left wheel,in the case of a right turnturns faster thanthe inner wheel,and the left side gear turns faster than theright side gear.See Figure 16-13B.As a result of thedifferent axle speeds,the spider gears begin to rotate.Theleft side gear,which is moving faster than the right sidegear,drives the spider gears,causing them to rotate on,orwalk around,the right side gear.Note that the differential case speed on turns is theaverage of the side gear speeds.This is because one sidegear is rotating faster than the case and the other side gearis rotating slower than the case.In Figure 16-14,when thevehicle makes a turn,the action of the differential allowsthe outer wheel to turn at 110%of case speed,while theinner wheel turns at 90%of differential case speed.Thesepercentages will vary with the radius of the turn.Locking differentialThe standard differential works well in most situa-tions.However,on very slippery surfaces,such as icy ormuddy roads,lack of traction can cause the rear wheels toslip.This is because the standard differential will drive thewheel with the least traction.If one drive wheel is on dry pavement and the otheris on ice or mud,the ring gear and differential case willdrive the spider gears.However,the spider gears will notdrive both side gears.When the spider gears are driven bythe differential case,they will walk around the side gearrelated to the wheel on dry pavement.As a result,thespider gears drive the slipping wheel,and the vehicle willnot move.The standard differential sends almost all enginepower to the slipping wheel.To overcome this problem,locking differentials areused.Locking differentials overcome traction problems bysending some power to both wheels,while allowing thevehicle to make normal turns.There are several differenttypes of locking differentials,including limited-slip,ratchet,and Torsen differentials.The two most common types of limited-slipdifferential are the clutch-plate differential and the conedifferential.The clutch-plate differential uses several fric-tion discs that look like small manual clutch discs.Thecone d