It worked, but the Benz Patent Motorwagen offered a slow and jerky ride. 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. Still, since the engine was so small, it was an acceptable compromise. Eventually, 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.
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.
Basically, a manual transmission is a gear box that enables the driver to choose between different gear ratios to drive the car. Lower gear ratios offer more torque, but less speed, while higher gear ratios offer less torque, but higher speed. At its simplest, the manual transmission consists of three shafts with constantly-intermeshed gears of different sizes.
The input shaft connects to the engine, via the clutch. The countershaft is constantly meshed with the input shaft and has multiple gears.
The output shaft connects the countershaft to the driveshaft and eventually the wheels. In four-wheel drive and all-wheel drive vehicles, the output shaft connects to the transfer case first. Reverse gear is usually on a fourth shaft to effect a change in direction. Sign up for our Newsletter! Mobile Newsletter banner close. Mobile Newsletter chat close. Mobile Newsletter chat dots.
Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. Under the Hood. How Manual Transmissions Work. Today's car transmissions come in standard, manual, CVT and even automated manual. Where Have the Manuals Gone? Continuously Variable Transmissions " ". A Very Simple Transmission " ". The green shaft comes from the engine through the clutch. The green shaft and green gear are connected as a single unit.
The clutch is a device that lets you connect and disconnect the engine and the transmission. When you push in the clutch pedal, the engine and the transmission are disconnected so the engine can run even if the car is standing still. When you release the clutch pedal, the engine and the green shaft are directly connected to one another.
The green shaft and gear turn at the same rpm as the engine. The red shaft and gears are called the layshaft. These are also connected as a single piece, so all of the gears on the layshaft and the layshaft itself spin as one unit.
The green shaft and the red shaft are directly connected through their meshed gears so that if the green shaft is spinning, so is the red shaft. In this way, the layshaft receives its power directly from the engine whenever the clutch is engaged. The yellow shaft is a splined shaft that connects directly to the drive shaft through the differential to the drive wheels of the car.
If the wheels are spinning, the yellow shaft is spinning. The blue gears ride on bearings, so they spin on the yellow shaft. If the engine is off but the car is coasting, the yellow shaft can turn inside the blue gears while the blue gears and the layshaft are motionless. The purpose of the collar is to connect one of the two blue gears to the yellow drive shaft. The collar is connected, through the splines, directly to the yellow shaft and spins with the yellow shaft.
However, the collar can slide left or right along the yellow shaft to engage either of the blue gears. Teeth on the collar, called dog teeth, fit into holes on the sides of the blue gears to engage them. Shifting Into First Gear " ". When you make a mistake while shifting and hear a horrible grinding sound, you are not hearing the sound of gear teeth mis-meshing.
As you can see in these diagrams, all gear teeth are all fully meshed at all times. The grinding is the sound of the dog teeth trying unsuccessfully to engage the holes in the side of a blue gear. The transmission shown here does not have "synchros" discussed later in the article , so if you were using this transmission you would have to double-clutch it.
Double-clutching was common in older cars and is still common in some modern race cars. In double-clutching, you first push the clutch pedal in once to disengage the engine from the transmission.
This takes the pressure off the dog teeth so you can move the collar into neutral. Then you release the clutch pedal and rev the engine to the "right speed. The idea is to get the blue gear of the next gear and the collar rotating at the same speed so that the dog teeth can engage. Then you push the clutch pedal in again and lock the collar into the new gear.
At every gear change you have to press and release the clutch twice, hence the name "double-clutching. The gear shift knob moves a rod connected to the fork.
The fork slides the collar on the yellow shaft to engage one of two gears. A Real Transmission " ". First gear provides the most pulling power but the least potential for speed, whilst fifth gear which provides the least pulling power allows the greatest range of speed.
The following table indicates typical speed and revs for changing gears up or down. As the car increases speed, change up through the gears. When you want to slow down, use the foot brake. Selective gear changing means you sometimes miss out gears, for example, by changing from fifth or fourth gear to second gear. There are also times when you might selectively change up, for example if you have used a lower gear such as third for better acceleration you might be able to change to fifth gear when you have reached your intended cruising speed.
You can practice this when the car is stationary and the engine is switched off, but make sure that you keep the clutch pedal pressed down to the floor. The gear lever will automatically spring to the central neutral position when not in a gear. This is very useful when trying to find and select third or fourth gear.
To select first gear place your left hand onto the gear lever, palm away from you. Cup your hand around the gear lever and move it across to the left and forward.
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