Many types of transmissions have been developed and implemented by automotive engineers throughout history. We can divide them into two large groups: automatic and manual transmissions. Especially over the last few decades, automatic transmissions have developed much more than manual ones. We will tell you the main points you need to know about car transmissions and help you distinguish their types and the related common failures.
Manual transmissions
The manual transmission can be called the “mother” of all transmissions. All other things being equal, it’s the most reliable unit. The manual transmission boasts several advantages, including its structural simplicity and the availability of inexpensive spare parts. This design leads to ease of maintenance and repair, resulting in low-cost servicing. Additionally, these factors contribute to the transmission’s long service life, making it a reliable and cost-effective choice for many vehicles. But as automatic transmission technologies improve, manual transmissions will become increasingly rare. The most common failures of this transmission type are:
- Rough and difficult gear shifting (these are also the main signs of insufficient oil in the manual transmission);
- Unusual sounds during shifts – ringing in the gearbox when starting, and noise in the gearbox at speed;
- Jerking and uneven transmission of torque.
Automatic transmissions
A classic automatic transmission has a torque converter, which replaces the clutch mechanism of a manual transmission, smoothly shifting gears without any driver intervention. A calmer driving experience, efficiency, and practicality are the advantages of automatic transmissions. The main disadvantage of this type is the excessively high cost and expensive repairs. However, despite this, automatic transmissions also have many supporters, especially in megacities, where sometimes you have to wait for hours in traffic jams. An automatic transmission makes the process of waiting and long-term crawling less stressful: the driver doesn’t need to constantly move the gear shift lever and press the clutch pedal to the point of losing consciousness. The most common failures in this type are:
- Failure of the electronic control unit;
- Malfunction of the control system sensors;
- Breakdown of actuators
Continuously Variable Transmissions
CVT can be seen as a sub-type of automatic transmission. The difference is that the CVT lacks fixed gears. A car with such a transmission moves smoothly, without sharp fluctuations in engine sound. This type of transmission contributes to fuel economy. However, the working lifespan of such an automatic transmission is also limited, which will require the replacement of the main transmission components after about 200,000 km of mileage. The common CVT failures are:
- Failure of the stepper motor. The main symptom of this problem is the CVT “freezing” at one speed. The primary cause of its failure is transmission overheating.
- Failure of the belt (chain drive). The main symptom is slipping of the revolutions, meaning you won’t have a clear connection between the engine’s RPM and the car’s speed.
Robotized transmissions
The operating principle of a robotized transmission is quite simple. It is essentially a regular manual transmission where the operation of the clutch and gear shifting is performed by servomotors, not the driver. The biggest problem with all robotized transmissions is the control algorithm itself, which causes such transmissions to have jerks, delays, and lapses when downshifting and upshifting. However, it should be noted that these problems only occur in transmissions with a single-disc clutch. The only advantage of single-disc robotized transmissions has always been their price, which is why such transmissions were installed on all budget cars. The common failures include:
- Delayed reaction in increasing engine RPM
- Appearance of unusual noise
- An indicator light turns on the dashboard (an exclamation mark inside a gear symbol)
- Jerking during automatic gear shifts
- The clutch starts to slip
- Transmission fluid leaks
