An overview of car transmission system

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Every car we see on the road comprises of thousands of parts. However, some systems are largely responsible for the running of a car and these systems are definitely more important compared to others. The transmission is amongst the most important systems in a car. Without this critical system, the power generated by the engine would never reach the vehicle’s wheels. Otherwise, your favorite car with its lift kit from Offroad Power Products would be of no use. 

Types of Transmission

Automatic and manual are the two major types of transmission systems found in most of the cars. However, in recent years, some other transmissions types have also gained ground. The functioning principle of the dual-clutch transmission is similar to that of the manual transmission. However, it bridges the gap between manual and automatic transmission with computer control. On the other hand, the continuously variable transmission (CVT) eliminates individual gears to ramp up its ratio of power transmission as per a set of rules. Also, most of the modern-day electric vehicles don’t have any transmission at all. 

Before discussing the functioning of manual and automatic transmissions, it is important to understand some basic terminologies.

Some Key Terms

  • Gear: In the context of transmission, gear can be defined as a set of toothed wheels working in tandem to alter or determine the relationship between the speed of a car’s engine and wheels. In terms of functionality, each of the gears selected by the drivers is a ratio of the selected gears on the output and input shafts.
  • Gear Ratio: This is the input and output rotation rates of a set of gears
  • Clutch: This is the mechanism that connects and disconnects a car from its transmission system.
  • Transmission: A mechanism that transmits power from the engine of a vehicle to its wheels.
  • Shift Lever: This is a control lever used by the drivers to manage the gear range or current gear of a car’s transmission.

Having discussed the key terms related to transmission, let us now figure out how the two most common types of transmissions work. 

Manual Transmission

This is the simpler of the two in terms of construction and function. The most basic form of a manual transmission is equipped with a gear set along with a pair of shafts and input as well as output shafts. The gears in one of the shafts engage with the ones on the other shaft. The overall gear ratio is determined by the resulting ratio between the selected gear on the input shaft and the engaged gear on the output shaft. 

In a manual transmission, the gear is selected by the driver by moving a shift lever. This engages a linkage capable of controlling gear movement along the input shaft. It is possible to select any of the two gears on any linkage by moving the lever forward or rearward. 

The driver pushes in the clutch pedal for engaging a gear. This disconnects the engine from the transmission’s input shaft. As a result, the gears on the input shaft are freed to move. Once power is disconnected from the engine, the drivers can select the gear that is appropriate and re-engage engine power. 

Automatic Transmission

The same essential process is followed within the transmission in an automatic transmission system. However, unlike manual transmission, automatics don’t use clutches. Instead, it makes use of a torque converter for the purpose of de-coupling the engine and the gear set. 

The functioning of the torque converter is based on the principles of fluid dynamics. As the transmission input’s connection from the engine is handled by the torque converter, the gears can perform their work without the direct intervention of the drivers. Unlike manual transmission’s gears arrayed along two parallel shafts, the automatic transmission uses just one concentric shaft with gear sets in a planetary arrangement.

These were just some basic discussions related to car transmission systems.

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