Really, the only thing a manual transmission needs is an occasional gear oil change – usually every 30,000 to 60,000 miles, depending on conditions and driver habit. In comparison to an automatic transmission, a manual transmission is simple in operation and maintenance, and they are known to last hundreds of thousands of miles. Synchronizer rings are like tiny clutches, using friction to bring the locking collar and the gear to the same speed, at which point they easily mesh and power can be reapplied. Changing to 3 rd gear involves using a second shift linkage, shift fork, and locking collar, this one between 3 rd and 4 th gears.īecause the countershaft and output shaft turn at different speeds, moving from 1 st to 2 nd gear, trying to engage a higher gear while the vehicle is moving slower would be like trying to turn the shaft at two different speeds, which is impossible. Releasing the clutch engages the input shaft again, this time routing power through 2 nd gear. The shift shaft moves the shift fork to disengage 1 st gear and engage 2 nd gear. Now, when the clutch is released, engaging the input shaft, the output shaft turns because 1 st gear is locked to the output shaft by the locking collar.Īs the driver speeds up, selecting 2 nd gear simply involved repeating the process, but moving the shift lever to 2 nd gear. Using the shift lever, the driver selects first gear, and the linkage moves the shift fork to connect the 1 st-2 nd locking collar with 1 st gear, locking it to the output shaft. To effect a gear change, selecting first gear, for example, the driver depresses the clutch, disengaging the input shaft. In “neutral,” with no gear selected and the clutch released, the input shaft and countershaft are spinning, as are the output shaft gears, but the output shaft doesn’t move because none of the locking collars are engaged. Locking collars, on the other hand, rotate with the output shaft and can shift or slide back and forth to engage one of the gears. The gears themselves are not fixed to the output shaft, but freewheel. Reverse gear is usually on a fourth shaft to effect a change in direction. In four-wheel drive and all-wheel drive vehicles, the output shaft connects to the transfer case first. The output shaft connects the countershaft to the driveshaft and eventually the wheels. The countershaft is constantly meshed with the input shaft and has multiple gears. The input shaft connects to the engine, via the clutch. Different gear ratios are often referred to as “speeds,” so a “six-speed” manual transmission has six forward gear ratios.Īt its simplest, the manual transmission consists of three shafts with constantly-intermeshed gears of different sizes. Lower gear ratios offer more torque, but less speed, while higher gear ratios offer less torque, but higher speed. What Is a Manual Transmission?īasically, a manual transmission is a gear box that enables the driver to choose between different gear ratios to drive the car. The Benz Patent Motorwagen had a single-speed manual transmission with no reverse, but most of today’s manual-transmission vehicles are equipped with at least four or five forward gear ratios, and some vehicles are available with six- and seven-speed manual transmissions. Additionally, because the internal combustion engine is most-efficient and most-powerful at different speeds, multiple gear ratios are necessary to extract the most usable power or best fuel economy, depending on driver demand. Still, since the engine was so small, it was an acceptable compromise.Įventually, with the development of more powerful engines, multiple gear ratios were required, reducing the jerky takeoff and enabling higher speeds and even a reverse gear. The vehicle would lurch forward as soon as the single drive belt was engaged, and speed was slightly variable, depending on engine speed, but going even faster would damage the engine. It worked, but the Benz Patent Motorwagen offered a slow and jerky ride. When the first automobile was built, the tiny engine was connected directly to the driveshaft.
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