DRIVETRAINS: the driving force in your vehicles
As a child, I used to wonder what the “4X4” meant on those SUVs. Was it a challenge to mathematicians? Was it a note telling us about the dimensions of the vehicle? By the end of this piece, you’ll be able to discuss drivetrains and differentiate between different drivetrains of different vehicles, and also be able to make informed decisions when buying a car, as you’d know a little something many people don’t.
According to Wikipedia, “A drivetrain is the group of components that deliver mechanical power from the prime mover to the driven components”.
Simply put, a drivetrain is a group of parts on a vehicle that helps distribute power coming from the engine to the wheels. These comprise transmission, differential, driveshaft, axles, CV joints, and the wheels(yeah, the wheels too). Some might wonder why we don’t hook the wheels up directly to the engines. Well, drivetrains ensure your ability to adjust your speed while driving, instead of your vehicle having a constant speed from the moment it starts till the moment you turn off power. This is the effect of your transmission system, a very important component of your drivetrain.
TYPES OF DRIVETRAIN
The most common drivetrains are;
- Rear Wheel Drive (RWD)
- Front Wheel Drive (FWD)
- Four-Wheel Drive (4WD)
- All-Wheel Drive (AWD)
Rear Wheel Drive (RWD)
In an RWD system, the engine sends power directly to the rear wheels, usually through a mechanism called the “drive shaft”. This makes the rear wheels the dominant wheels of the vehicle.
This type of drivetrain is mostly favored by racers and car enthusiasts as it has some perks, which include the following:
- Provides power and control around fast corners
- More balanced, compared to Front wheel drive vehicles.
- Maneuverable in different terrains
- Better weight distribution compared to FWD vehicles
- Better ascent up a slope, as the weight distribution helps the rear wheels move the vehicle easily, while the front wheels are used for steering.
One disadvantage of RWD would be;
- Loss of power, due to the multiple parts between the engine and the rear wheels. This could be up to 30% power loss.
Popular RWD vehicles include; Chevrolet Camaro, Ford Mustang, Dodge Challenger, etc
Front Wheel Drive (FWD)
In an FWD vehicle, the engine sends power directly to the front wheels only.
This design is mostly used in city cars and the types of vehicles we call “family cars”. Some of its advantages are;
- Fuel efficiency: since the engine, drivetrain and driven wheels are all in the same end, the car has reduced weight and wouldn’t lose power due to friction from multiple moving parts.
- Reduced production cost, compared to rear-wheel-drive vehicles.
- It also has improved traction since the engine weight is directly over the driven wheels.
Disadvantages include:
- Worse acceleration compared to rear-wheel-drive vehicles.
- Handles worse, compared to rear-wheel drive.
- CV(constant velocity) joints wear out faster, compared to rear wheel drive vehicles.
A constant-velocity joint (also called a CV joint) is a mechanical coupling which allows the shafts to rotate freely (without an appreciable increase in friction or blacklash) as the angle between the two shafts moves within a certain range. (Reference: Wikipedia)
popular front wheel drive vehicles include; the Toyota Corolla, Toyota Camry, and Ford Edge.
Four Wheel Drive (4WD)
Four wheel drive, also written as “4x4” or “4WD”. This is a two-axled vehicle drivetrain capable of providing power to all wheels simultaneously. This could be full time, or on-demand, depending on the driver’s preference.
These are all-purpose vehicles, they provide improved traction when you’re driving on rocks, snow, sand, ice, and other scenarios that can make control difficult. Some of the advantages of this drivetrain are;
- The extra weight of the vehicle improves the grip on the roads.
- A great choice for off-road driving.
- Can be used for towing and moving trailers of reasonable size.
Disadvantages include:
- Added cost for purchase, maintenance, and fueling of the vehicle.
- 4WD vehicles can lead to overconfidence in drivers, causing them to land in awkward situations like getting stuck.
A great member of the 4WD family is the Jeep Wrangler.
All Wheel Drive (AWD)
This is a drivetrain setup usually confused for 4WD. In this drivetrain, the vehicle has control over all wheels as well. Though, one important difference is that AWD can be controlled by the computer in your car and can automatically send power to the wheels.
In part-time or automatic AWD vehicles, the car would only send power to a set of wheels, maybe rear or front wheels, until a situation arises, where extra traction is needed. This way, the vehicle helps economize fuel consumption as it’s not always on four wheels and helps you avoid putting unnecessary strain on your machine.
Advantages of AWD vehicles include:
- Better traction control, compared to some of the other drivetrains mentioned above.
- AWD vehicles can perform better than the other drivetrains.
- AWD vehicles have better weight distribution; thus, they don’t throw you off balance when you make that sharp turn or decide to do a little donut.
- AWD vehicles are capable of moving on rugged and muddy terrain, too.
Disadvantages include:
- Fuel efficiency — since your vehicle is going to be sending power to four wheels some or most of the time, it’s going to make a huge difference in the fuel efficiency compared to, for example, a front-wheel-drive vehicle.
- False sense of security — AWD vehicles tend to give people the confidence that nothing can go wrong, so some people start driving recklessly and learn a hard lesson.
- Increased cost and complexity — in AWD vehicles, there are more parts, compared to, let’s say, front-wheel-drive vehicles. That’s got to cost you some extra cash.
Popular All-wheel-drive vehicles include; the Mercedes C300 and the Audi A4.
Also, there are other drivetrains not mentioned in this article. For example; 6-wheel-drive, 8-wheel-drive, and 16-wheel-drive (usually found in trucks).
Thanks for your time, and see you next time.
