【正文】 synchronizers assemblies is in neutral and the reverse idler gear is not in mesh, power is not able to get from the input shaft to the intermediate shaft. The input shaft and the speed gears can rotate, but the intermediate shaft will not be driven. All synchros. are in neutral, center position 1st Gear This is the lowest gear ratio with the smallest gear on the input shaft driving the largest gear on the intermediate shaft. In this example a 12 tooth gear drives a 42 tooth gear. 42 247。 14 = 2nd Gear, Driving 2nd Gear, Driven 12 Synchro., Shifted to 2nd 3rd Gear With the 12 synchronizer in neutral, the 34 synchronizer is moved to engage the 17 tooth speed gear. It drives a 21 tooth gear. The ratio is 21 247。 19 = :1. Note that this is an overdrive ratio so the intermediate shaft will rotate faster than the input shaft. 4th Gear, Driving 4th Gear, Driven 34 Synchro. Shifted to 4th 5th Gear The 5th gear synchronizer is moved to engage the 15 tooth 5th speed gear. It is driven by a 20 tooth gear so the ratio is 15 247。 12 = :1 Rev. Gear, Driving Rev. Gear, Driven 5Rev. Synchro. Shifted to Rev. Rev. Idler Gear Other Reverse Types Some transaxles construct the 12 synchronizer sleeve with the reverse gear teeth surrounding it. The reverse idler gear is shifted into mesh with the reverse drive gear and the driven gear on the synchro. Sleeve. This is difficult to illustrate because the idler gear and shaft are positioned behind the other gears. Rev. Idler Gear Rev. Drive Gear 12 Synchro. + 1st amp。 20 = 4:1 Pinion Gear Ring Gear Diff. Side Gear Diff. Pinion Gear CV Joint Overall Ratios The overall ratio between the engine and the drive wheels is effected by both gear ratios. These ratios bee: 1st gear: X 4 = 14:1 2nd gear: X 4 = 10:1 3rd Gear: X 4 = :1 4th Gear: X 4 = :1 5th Gear: X 4 = 3:1 Reverse: X 4 = 14:1 二、兩軸式變速器 ? 應(yīng)用： FF RR ?特點： 輸入軸與輸出軸平行，無中間軸。 ? 二軸：一、二檔齒輪與通過軸承連接；三、四檔齒輪與軸一體。 換檔原理 一軸 中間軸 二軸 三軸式變速器結(jié)構(gòu)圖 掛檔方向 傳動方向 結(jié)合齒圈 結(jié)合套齒 花鍵轂 ? 跳檔方向 四、防止自動跳檔的措施 （ 1）切薄齒式 利用接合套換檔的變速器，由于接合套與齒圈的接合長度較短，同時汽車行駛時需要經(jīng)常換檔，頻繁撥動接合套將使齒端發(fā)生磨損。 （ 2）斜面齒式 結(jié)合齒圈 結(jié)合套齒 花鍵轂 結(jié)合齒圈 傳動方向 接合套和接合齒圈的齒端制成倒斜面 （ 3）接合套的齒端制成凸肩 五、組合式變速器 5Speed Manual Transmission Purpose A manual transmission is used in many RWD and 4WD vehicles. It provides the various gear ratios that are necessary to transfer power from the engine and clutch to the drive shafts and wheels. Engine Clutch Transmission Driveshaft Drive Axle Construction Manual transmissions have three major shafts: an input shaft/ main drive gear that connects to the clutch disc, a counter shaft that is monly called a cluster gear, and the main shaft/output shaft with the driven gears and synchronizers. Main Shaft Input Shaft Cluster Gear Bearings The main drive gear and main shaft are each supported by a ball or roller bearing with a pilot bearing where the main shaft fits into the main drive gear. The cluster gear is supported by a pair of bearings. These bearings are colored orange. Cluster Gear Bearings Main shaft bearing Pilot Bearing Main Drive Gear Bearing Speed Gears amp。 15 = :1 Reduction, 1st Gears: 3:1 1st Gear Ratio: X 3 = :1 1st Gear The 12 synchronizer is moved to engage the clutching teeth on the 45 tooth 1st speed gear. It is driven by a 15 tooth gear on the cluster gear. The 1st gear ratio is :1. 12 Synchro. Shifted to 1st 1st Speed Gear, Driven 1st Gear, Driving 2nd Gear The 12 synchronizer is moved to engage the 40 tooth, 2nd speed gear. It is driven by a 20 tooth gear on the cluster gear. The cluster to main shaft ratio is :1, and the 2nd gear ratio is 2:1 X :1 = :1. 2nd Speed Gear, Driven 2nd Gear, Driving 12 Synchro. Shifted to 2nd 3rd Gear The 34 synchronizer is moved to engage the 20 tooth 3rd speed gear. It is driven be a 15 tooth gear on the cluster gear. The gear ratio is: :1 X :1 = :1. 34 Synchro. Shifted to 3rd 3rd Gear, Driving 3rd Gear, Driven 4th Gear The 34 synchronizer is moved to engage the clutching t