Types of Transmissions and How They Work

Types of Transmissions

A transmission history is very long, it is almost impossible to track all the evolution process. The main concept has changed over the years from manual transmissions to electronically controlled automatic or semi automatic. They are becoming more and more complicated, at the same time, it is becoming easier to use them. Sometimes, the complexity brings more harm than goodness and transmissions may suffer numerous minor or severe problems.

In this guide you will find out the internal structure of all transmission types and will see the advantages and disadvantages of each type.

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Manual Transmissions

It becomes clear from its name that gear changing is accomplished by manual shifting the mechanism that switches off one gear and engages another. Usually, manual transmission has 5-6 forward and only one reverse gear.

The manual transmission is engaged via a clutch, which is deactivated by pressing the pedal. When the clutch is connected to the transmission, power is transferred to the transmission through a shaft which is separated from a cluster and can rotate in different speed modes. The cluster is a complicated mechanism that consists of gears that can be engaged or disengaged from the fixed gears that are situated on the secondary shaft and supported with roller bearings.

Gear selection

The input shaft has only one gear that is connected via gears with secondary shaft. When it is working and the clutch is connected, the transmission box is in a neutral position, because no gears are activated on the secondary shaft. When you are shifting, the primary shaft is getting slow and aligned with another gear on the secondary shaft. The current gear is always separated till the moment another one is becoming engaged. When the clutch is reconnected the energy is transferred from the transmission to the axles.

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Advantages of Manual Transmissions

  • Easy to service and is relatively reliable.
  • Cheap to service
  • Can cope with the high load.
  • Is the best choice for the off-road environment because of a solid engine link and an ability to use engine braking.

Disadvantages of Manual Transmissions

  • It may be quite challenging for drivers that are used for an automatic transmission.

Fully Automatic Transmissions

The main difference between the manual transmission and fully automatic one is the computer that controls transmission system electronically instead of using a clutch. There are only 3 positions for the driver:  (P) park, (D) Drive, (N) Neutral. All gears will be shifted perfectly without any efforts from a driver, of course, the right to change programs and modes is up to the drivers choice.

Gear shifting in fully automatic transmissions occurs when all required conditions are sustained, these are a vehicle and engine speed, mode and its influence on traction control, stability, automatic braking and cruise control.

If all requirements are set and there is a connection between the EM (engine management) and the TCs (transmission control system), transmission fluid will be injected and under the pressure, it will active the mechanism of gears and clutches.

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Advantages of Fully Automatic Transmissions

  • Simple
  • The best choice for inexperienced drivers
  • Up to date, transmissions are as economical and reliable as manual ones.

Disadvantages of Fully Automatic Transmissions

  • Such kind of transmissions suffers from the numerous troubles
  • Expensive to repair and to service
  • Expensive to maintain
  • It is not a good choice for off-road environments because of the absence of engine braking

The eternal struggle between manual and fully automatic transmission owner lasts for years. Here is the comparison table, it is quite subjective but it has a seed of sense.

CriteriaFully automatic Transmission against Manual
Option for cruise controlMost manuals don’t have cruise control.
ControlManual provides with more control.
Vehicle costPrices for fully automatic are higher approximately on 1000$
Fuel EconomyCars with manual transmission are more economic, they consume 5%-15% less fuel depending on road conditions and driving habits
MaintenanceManual transmission doesn’t need as much maintenance as automatics and the repair costs are much cheaper.
EfficiencyEvery time has its plusses and minuses depending on the model, circumstances, and requirements.
Heavy TrafficFully automatic wins this round: it’s much easier to drive in stop-and-go traffic with an automatic
“Feeling”If you want to impress your girlfriend or have a race, the answer is manual.
WeightManual transmission boxes are lighter than automatics.
CoolingIt’s much easier for a fully automatic transmission to get overheated.

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Semi Automatic Transmissions

Semi automatic transmissions may be called as a hybrid that combines automatic and manual transmission, so it is also known as “clutchless manual” or “automatic manual”.

As well as manual transmissions semi automatic change its gears via shifter or paddles which are usually located behind the steering well. In contrast to the manual one, semi automatic transmission system has no clutch pedal. To switch gears smoothly there are different sensors, computers, and actuators which do their job as soon as the shifting signal comes.

The semi automatic systems are usually used in heavy vehicles in a commercial sphere. The latest models provide owners with a lightning speed shifting, you might even not spot how and when you have changed the gear.

The design may vary from model to model, however, the main principle remains: semi automatic transmissions rely on numerous computers and microprocessors to control the shifting process. This was adjusted to sport and supercars at first because of their cost, however, last time manufacturers started to implement semi automatic transmissions in the mid-range cars.

Advantages of Semi Automatic Transmissions

  • Perfect shifting
  • Easy to study and drive
  • Engine doesn’t lose energy while changing gears

Disadvantages of Semi Automatic Transmissions

  • Suffers from numerous failures, may be easily damaged
  • Requires more time and efforts to repair
  • An expensive service. It may happen so that changing the transmission is cheaper than getting it repaired

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Continuously Variable Transmissions

The Continuously Variable Transmissions is a totally unique system in comparison with previously mentioned. Continuously Variable Transmissions have no gears for power transfer, instead of them, there are rubber belts or metal ones that are running over pulleys and can change the effective diameter. Pulley can change their effective diameters in order to keep the belt on the optimum tension, it becomes the same as the effect produced by engaging two gears of different diameters.

Advantages of Continuously Variable Transmissions

  • You don’t need to think about shifting
  • Better fuel consuming
  • It doesn’t lose energy thanks to the belt
  • Faster reaction to the driving conditions changing
  • Smooth drive

Disadvantages of Continuously Variable Transmissions

  • High cost
  • Limited amount of torque
  • No engine braking

If there are still some questions about Fully Automatic Transmissions, Semi Automatic Transmissions or Continuously Variable Transmissions, leave comments and we will try to help you.

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