Graduates of auto mechanic courses know that when a gas-powered car is running, its engine rotates very quickly—too quickly for the car’s wheels. A transmission serves as an intermediary between the engine and the car’s wheels, transferring power at a reduced, more manageable level. This allows the wheels to turn.
There are several different kinds of transmissions used in modern cars, each with a slightly different functionality as well as its own pros and cons.
Here’s a quick guide to common transmissions often seen in careers in the auto industry.
A Mechanic’s Guide to Different Transmissions
There are several kinds of transmissions:
- Manual
- Automatic
- Dual-Clutch
- Continuously Variable
Most transmissions work by using a system of gears.
The gears change the amount of power going from the engine to the wheels.
Here’s how the most common kinds of transmissions work.
Manual Transmission
Switches between individual gears to change power throughput
Most manual cars have 4-6 gears
High-end sports cars sometimes offer 8 gears
Manual transmissions require more work from the driver
How it works:
- 1. The driver presses the clutch pedal to detach the engine from the selected gear
- 2. The driver uses a stick shift to select a new gear
- 3. The driver releases the clutch to reattach the engine to the new gear
9% of cars sold in Canada have manual transmissions
Automatic Transmission
Uses a “planetary gear system” that changes power throughput automatically
How it works:
- 1. The driver drives.
- 2. The car’s sensors detect acceleration and speed
- 3. The car’s torque converter changes the gear system’s throughput
Did you know? Automatic cars are now just as fuel efficient as manual cars.
Dual-Clutch Transmission
Like a combo between manual & automatic
How it works:
- 1. The driver drives with the first clutch attached to a gear
- 2. The second clutch prepares to engage with the next gear
- 3. When sensors detect the gears should switch, they do
Zoom zoom: Dual clutch cars can change gears in 8-200 milliseconds.
(A regular automatic takes half a second!)
Continuously Variable Transmission (CVT)
Gearless transmission system increasingly used in cars
How it works:
- 1. The driver drives
- 2. Two pulleys connected by a belt transfer power from the engine to the wheels
- 3. The pulleys adjust their size to smoothly change the amount of power transferred
Fun fact: CVT is the most efficient transmission for frequent starts and stops
Electric Transmissions
Exclusive to cars that can run off of battery power
Electric motors don’t need a lot of help transferring power to the wheels
Some experts claim electric cars don’t really have a transmission
How it works:
- 1. The driver drives
- 2. A single gear transfers power from the motor to the wheels
- 3. That’s it!
Fun fact: Electric cars typically accelerate faster than other cars
Sources:
https://www.theglobeandmail.com/globe-drive/news/industry-news/the-shift-from-manual-why-the-demise-of-stick-shift-is-accelerating/article26795936/
https://www.edmunds.com/fuel-economy/five-myths-about-stick-shifts.html
https://www.digitaltrends.com/cars/auto-manual-dct-cvt-whats-the-best-type-of-transmission-for-you-and-your-car/
http://www.nrcan.gc.ca/node/16769
https://www.carthrottle.com/post/how-do-electric-vehicles-produce-instant-torque/
