Transcript for:
Vehicle Drivetrains Overview

When you're considering a new vehicle, there are several things to take into consideration. Like, should I get a small sedan or an SUV? How much technology do I want it to have? What kind of safety features are best? Vehicles come in many different sizes and styles with lots of different features, so there are many things to consider when you're ready to buy your next ride. One of the most important is to find the right drivetrain for you to find new roads. I know you've heard the term drivetrain or powertrain when shopping around for a new car. Simply put, a drivetrain is the series of parts in your car that work together to make your wheels turn. A powertrain, on the other hand, is basically a drivetrain plus the engine and some other parts. Now, when you talk about drivetrain it's possible that most of us know the types of drivetrains in cars today. But what do they do exactly? What's the difference? Which one is better out of those? Each has advantages and disadvantages, and it's important to understand each in order to make the right decision for you. The four different types of drivetrains are All-wheel drive, front-wheel drive, rear-wheel drive, and four-wheel drive. For off-roading and getting out of sticky situations, four-wheel drive and all-wheel drive may be your best choice. In nearly all cases, however, front-wheel and rear-wheel drive get the job done. But, you'll want to consider the pros and cons of your two front-wheel and rear-wheel drive options before making a decision. Front-wheel drive refers to a car in which the transmission sends the engine's power to the front wheels. Rear-wheel drive is the transmission that sends the engine's power to the rear wheels. Four-and all-wheel drive cars have power at all four corners. Now let's take a look at these drivetrains in details, starting with front-wheel drive. If a vehicle features front-wheel drive, the transmission transfers power from the engine to the front wheels. The majority of cars today have front-wheel drive layout. This setup transfers power to the front wheels, giving them the responsibility of moving and steering the vehicle. With front-wheel drive, the front wheels are pulling the car and the rear wheels don't receive any power on their own. A great thing about front-wheel drive is that it's cheaper to design and make than other drives, which means the vehicle may be less expensive for consumers. In these vehicles, the engine occupies space near the front axle. It later mates to transmission or the transaxle. This is because of the fact that it combines the functions of transmission, driveshaft, and differential. Thus, with the help of a transaxle, the engine supplies power only to the front wheels of the vehicle. Starting in 1895, the car manufacturers experimented with front-wheel-driven vehicles. Front-wheel drive surfaced during the 1900s on various prototypes, and it merged into the mainstream during the 1930s when French automaker Citroën released the traction avant, which means, literally, front-wheel drive. The most famous and most influential front-wheel drive is undoubtedly the original Mini. Small economy cars began shifting to front-wheel drive during the 1970s, and most new cars sold in 2021 use this configuration. The pros of a front-wheel drive vehicle are that they typically get better fuel economy and emit less carbon dioxide. Front-wheel drive cars are usually more stable, the engine and transmission are located directly above the front wheels, which can provide better traction when climbing hills and driving on slippery roads. They can also maintain better traction over small hills or over light snow or ice because the weight of the engine is over the front wheels. Front-wheel drive has fewer components than any other drivetrain setup, making the vehicle lighter and improving its gasoline mileage. That's why most economy-type cars are front-wheel drive. More efficient packaging and usually more passenger space. With front-wheel drive, all of the mechanics are in the front of the vehicle. That means there's more passenger and cargo space inside the car. Front-wheel drive is a simpler system, so it's easier and less expensive to maintain. The downside of an FWD vehicle is that the handling suffers somewhat. Since all the weight is located in the front of the vehicle, front-wheel drive cars tend to understeer. This means it makes handling more difficult. Front-wheel drive has worse acceleration than rear-wheel drive, which is why most sporty and race cars use rear-wheel drive. If you do a lot of driving on winding roads, you'll likely notice a difference between the two different types. Rear-wheel drive is basically the opposite of the front-wheel drive. This drive is most commonly found on sports cars and performance sedans. Vehicles that feature rear-wheel drive are a bit more complicated. Vehicles handle much better than front-wheel drive vehicles, and you will notice the difference in curves, turns, and when navigating through traffic situations. Traction won't be as good, especially in wet or snowy road conditions. A rear-wheel drive car of the same weight, power, gearing, and tire size and type will accelerate faster than an front-wheel drive car, as the weight of the vehicle is transferred off the front wheels and onto the rear wheels to improve traction. Rear-wheel drive means that the power from the engine is delivered to the rear wheels, and the rear wheels push the car forward. The front wheels do not receive any power and are free to maneuver the vehicle. The propeller shaft works to transfer the torque from the transmission to the rear wheels through a differential that distributes power between the two wheels. A rear-wheel drive arrangement needs the engine and the transmission to be mounted longitudinally. Rear-wheel drive vehicles are better for towing because the front wheels have better steering without a ton of weight on them. Plus, with the power transfer and the tongue weight of the trailer, the rear of vehicle squats, which gives the rear wheels more traction. If you get stuck, adding weight over the rear wheels may help. The rear-wheel drive system has been around for many years now, with the first example dating back to 1885. Yes, we're talking of the time when the world's first car was invented by none other than Carl Benz. 1885 Benz'patent motor wagon, which is often considered the very first car, was rear-wheel drive. In America, a vast majority of cars were rear-wheel drive through the 1970s. The configuration is becoming increasingly rare in 2020, however. Sports cars like the Toyota Supra keep it alive, and some high-end sedans, like the BMW 5 Series and the Porsche Panamera, stay loyal to it. The rear-wheel-drive cars tend to have a better balance due to a more evenly spread-out weight throughout the vehicle. Rear-wheel-drive vehicle have more flexible designs, as the engine can sit in the front, middle, or back of the car, whereas front-wheel-drive vehicles require the engine to sit at the front. Rear-wheel drives can also handle larger engines because the weight and power of that larger powertrain are less likely to burden the front wheels. You'll find that rear-wheel drive cars typically feature less interior space than its front-wheel drive equivalent, but manufacturers typically install a performance-oriented cockpit with seats that offer more support and extra gauges to better monitor the performance of the vehicle. Rear-wheel drive improves handling due to load transfer and acceleration. Maintenance cost is less. Towing load is easier because the pulling wheels are located closer to the load. There is less interior space due to more room needed for the transmission and drive shaft. It is difficult maneuvering in wet and snowy conditions. 4WD, often abbreviated as 4WD. 4WD means the power from the engine is delivered to all four wheels all of the time when 4x4s is engaged. The four-wheel-drive vehicles are usually equipped with a transfer case, which allows the car to change to rear-wheel-drive transmission in order to save fuel and get back to four-wheel-drive mode if and when required. This means you can operate your vehicle in two-wheel-drive mode in normal driving conditions. Four-wheel-drive equipped cars are called 4x4s, as the first digit here represents the number of wheels, and the second figure shows the total number of powered wheels. For example, trucks with 6 into 4 configurations have 6 wheels, out of which only 4 receive power. Most off-road-ready SUVs come with 4WD system as they offer more traction. It allows you to drive over boulders or steep hills and through deep water. There is usually a mechanical connection between the front and rear axles. The 4-wheel drive system has three main components, the differentials, transfer case, and locking hubs. Differentials, it is located between the two front wheels and one between the two rear wheels. They send the torque from the drive shaft or transmission to the drive wheels. They also allow the left and right wheels to spin at different speeds when you go around a turn. The differentials enable the speed difference between the inside and outside wheels. Next is transfer case. This is the device that splits the power between the front and rear axles. The transfer case in an all-wheel drive system contains a device that allows for a speed difference between the front and rear wheels. The transfer case on a part-time four-wheel drive system locks the front axle drive shaft to the rear axle drive shaft, so the wheels are forced to spin at the same speed. Last one is locking hubs. When four-wheel drive is not engaged, the locking hubs are used to disconnect the front wheels from the front differential. Simply from half-shaft and drive shaft, the locking hub allows the differential, half-shafts and drive shaft to stop spinning when the car is in two-wheel drive, saving wear and tear on those parts and improving fuel economy. Let's take the instance of a corner. When you are approaching a corner, then in making the turn, all four wheels spin at different speeds, but if you were to put the four-wheel drive system on, then the system would try to get all wheels spinning at exactly the same speed, which would basically make on-road cornering difficult. You shouldn't drive in four-wheel drive mode all the time. Only turn it on when it's needed, such as in rain or snow, or when you're off-roading. Speciality of these vehicles is the option to shift to high and low ratios ranges. Low provides maximum traction in an off-road environment and high is for slippery on-road conditions like snow, ice, loose sand or gravel. Using these, one can have a higher torque output to get out of a sticky situation. The four-wheel drive system was patented back in 1893 by an English engineer Brahma Joseph Diplock. He even made a four-wheel drive equipped vehicle to showcase the higher capability in off-road terrain. Of course, there was no looking back ever since, and to this day, carmakers opted for this layout for vehicles meant to go off the road. 4WD vehicle depends entirely on your driving conditions and how you intend to use the vehicle. Drivers who go off-roading or live in areas with a lot of snow may want to think about the added benefit of 4WD and how comfortable they feel driving in snow without the assistance of 4WD or all-wheel drive. Today, some good examples of four-wheel-drive cars include Mahindra Thar, Force Gurkha, Mercedes G-Wagon, Maruti Gypsy, are the most popular 4x4 vehicles which are known for their ruggedness and versatility. However, due to its rear-wheel-drive mature, a 4x4 vehicle might have less traction than its all-wheel-drive counterparts. Inherent traction advantage in all conditions, especially accelerating through turns and as engine power approaches or exceeds a level that can overwhelm two driven tires. Added cost, weight, and friction reduce efficiency in all driving situations. An all-wheel-drive arrangement works on pretty much the same principle as four-wheel drive, but in most front-wheel drive or rear-wheel drive as the primary drive mode. The general misconception is that all-wheel drive and 4x4 are the same things. While both of them have all the four wheels running, and they run on the same principles, there are some key differences which set the two apart. While most of the 4x4 send power to the rear wheels, if and when required, the all-wheel drive cars are mostly front-wheel drive or rear-wheel drive, depending upon the situation. This drivetrain employs a fornt, rear and center differential to provide power to all four wheels of a vehicle. All-wheel drive is a more expensive option and uses more parts. The big thing that an all-wheel drive system usually includes is center differential, which set of gears that divides the transmission power to the rear and front axles. The engine runs into a transmission and then back to the differential. Usually the engine is longitudinally mounted. Instead of connecting to the rear differential like in rear wheel drive vehicle, the drive shaft connects to the center differential. All wheel drive system will usually have wheel sensor that can tell if the tires are losing speed or traction. If the sensors detect that a wheel is not performing correctly, it will say to the vehicle's computer to provide extra power as needed. All-wheel-drive cars aren't as capable off the road as four-wheel-drive ones, but they do help increase the traction, which is something that leads to improved handling capabilities on the tarmac. Again, all-wheel-drive isn't too good off the road, but it can definitely help a vehicle get out of a sticky situation. In the best-case scenario, all-wheel-drive SUVs can be used for mild off-roading. All-wheel drive system was invented in 1903, a few years after the four-wheel drive model broke covers. It was the invention of Dutch brothers Jacobus and Henrik Jan Spiker and was unveiled through a hill climb racer called Spiker 60 HP four-wheel drive. While it was promoted as a four-wheel drive, it was nothing but an all-wheel drive layout. Better acceleration with all four-wheel putting power usually gain more speed is easier. Better grip in slippery condition, whether there is snow on the ground or heavy rain coming down. All-wheel drive will make the wheel grip more when accelerating or maintaining speed. Less fuel efficient, sending power to both axles makes the vehicle less fuel efficient. More parts means more weight. Weight makes the vehicle perform worse and use more fuel, more parts means more thing that can break. All-wheel drive vehicles generally cost more to start with services and repairs may cost more down the road as well. While all-wheel-drive system are very similar to four-wheel-drive systems, they are not exactly the same, but both system do activate all four wheels simultaneously, but differ on how they get to that point. To be classified as all-wheel-drive cars, both axles must be able to rotate simultaneously, but at different speeds. While four-wheel-drive vehicles have a transfer case, all-wheel-drive has a center differential that forces both axles to spin at the same speed. The gear and transfer case usually divide the power between the front and rear axles, so both axles deliver the maximum possible amount torque. Which is better? That's one of the most loaded questions in the automotive world, and the answer largely depends on who you ask. The truth is, it largely depends on the situation and the application of the system, and there is no right or wrong answer. While front-wheel-driven cars provide better traction due to the weight in the front, they also tend to understeer more often. The RWD vehicles have less costly maintenance than their counterparts, but then the additional materials lead to a higher purchase price. Any type of four-wheel-drive system is perceived as superior in low-traction situations. That makes it most favorable for those who live in regions where it snows quite a bit or where paved roads are a luxury. More recently, all-wheel drive has become more prominent in performance applications as a way to increase traction. So what do you think of these drivetrains? Which drivetrain system is in your car or which one are you looking to buy? Tell me in the comments. Do you know that ABS system is really good for your car in case of emergency braking? Watch this video and find out how different braking systems work.