As the population grows, the demand for cars and other automobiles increase. Each car-maker makes new car models with loads of features and innovative functions every year. The modern-day cars are changing and evolving as the world does. Some people can’t keep up. Some are still hung-up on hearsays or old habits and myths about vehicles. It is understandable since most of the time the language that the automotive world is using is too complex to understand.
While some car-enthusiasts really know the details and the driving capabilities of their car, some people don’t. Then there’s this topic about drivetrains. People usually know the different types of drivetrains, but what are they for and how do they function?
The front-wheel drive and rear-wheel drive drivetrains are easy to understand how they work since their names say it all. The all-wheel drive and four-wheel drive however, are synonymous if we base it on their names alone. But what exactly are these drivetrains? Are they interchangeable? Let us all find out the differences between the All-wheel drive and the Four-wheel drive.
DRIVETRAIN, TORQUE, and TRACTION
First things first, let us refresh our automotive vocabulary. The drivetrain is a group of components that sends power to the wheels. This group of components work together with the engine that produces power to move the wheels and other parts of the vehicle and put it into motion. It is not to be confused with the powertrain. The powertrain is all the components that make the car move including the engine.
A powertrain is basically a drivetrain plus the engine. Torque on the other hand, is the amount of turning power the car has. Its role is to make the car accelerate. It also makes the car accelerate faster when the car is beginning to start or is starting to pick up speed. As the vehicle goes larger and heavier, more torque will be needed to make the larger vehicle start moving.
The torque just usually goes where the spinning wheels are and that’s what keeps the car moving. Now, drivetrains like the All-wheel drive and the front-wheel drive have special features that divide and distribute the torque to the wheels that need it most. The right amount of torque is being delivered to the right wheel and at the right time. Then there’s traction. Traction is the maximum amount of force the wheels can apply against the ground. It is the grip of the tire to the ground or any given surface.
The All-Wheel Drive or AWD system delivers power to the front and rear wheels all the time but not in an equal amount. The amount of torque sent to the wheels varies since some all-wheel drive systems are front-biased and some is rear-biased. The front-biased sends more torque to the front wheels while the rear-biased sends more to the rear wheels. Usually, the AWD needs no buttons to press. It does not require any input from the driver. The system is always functioning and always active. There are two types of AWD, the part-time and the full-time AWD. The part-time AWD sends torque to two wheels, either the front or rear depending on the car model. When a slippage has been detected or a certain road condition needs additional traction, the system automatically engages its other set of wheels. The full-time AWD system drives both sets of wheels all the time.
The Four-Wheel Drive or 4WD system also can power all the four wheels of the vehicle just like the AWD but it typically requires to be engaged or activated when it is needed. When the 4WD is engaged, all wheels will be powered and when disengaged, the vehicle switches to two-wheel drive. The 4WD system also has a front and rear driveshaft that can be locked together. This allows the front and rear driveshaft to move together and delivers the same amount of torque to all the wheels.
Just like the AWD, the 4WD also has part-time and full-time systems plus the on-demand 4WD. The part-time 4WD is often found in trucks and SUVs that are built to withstand extreme conditions. It usually drives using its rear wheels and when the driver needs the other set of wheels, the driver can engage the 4WD by pulling a lever or by pushing a button.
The full-time 4WD or the permanent 4WD works just like the full-time AWD with all the four wheels continuously receiving power. The full-time 4WD sends 25% of power to the four wheels all the time. The on-demand 4WD is similar to the part-time 4WD that works in two-wheel drive but when an additional traction is needed, it automatically engages the other two wheels to help. There are also some models that have an option to control the power being sent to the wheels.
In a 4×4 vehicle, you can often see a dial, lever, or buttons with different driving configurations. It has these options that include 2H, 4H, and 4L. Always keep in mind that each of the options is to be used only when needed and only for its intended purpose. If it is not used properly, it could cause some damage on your vehicle. 2H stands for Two High and it means that the two-wheels are engaged in high range.
It is to be used under normal driving conditions on hard surfaces. The 4H is for Four High which means that the four wheels are engaged in high range gear and only to be used when the driver needs additional traction in a speed at about 30-50mph. The 4L stands for Four Low that means the four wheels are engaged in a low range gear. This is only to be used when the driver needs the maximum amount of torque and traction like when you are stuck on mud or sand and when you are climbing or going down from a steep slope.
The AWD and the 4WD almost have identical features with its torque and traction abilities, but they do not have the same capabilities in terms of the terrain they are driving. Both AWD and 4WD have their strengths and weaknesses.
City and Highway Driving
When it comes to city driving, the best choice will be the AWD as it offers more important safety benefits to the city drivers. The AWD is also great on the road as it is less complicated to use. It is cheaper and it is lighter. It is perfect for road-use as it purposely delivers power to the wheels that need it the most.
4WD does not offer much when it comes to city driving. It is generally heavier than AWD and its fuel consumption is normally higher. If 4WD is used on the road or pavement for a long period, it can cause wear and tear on the vehicle and might cause serious damage caused by an axle binding. 4WD is also difficult to manoeuvre when cornering as the wheels on the vehicle spin at the same speed. The tires might slip and spin as they try to maintain a steady rotation. The AWD doesn’t have this problem since it relies more on differential and not on the transfer case.
Off-roads belong to the 4FD or 4×4’s territory. Traction and power are some of the benefits you can get from a 4WD. It is also heavier and generally bigger in size. 4WD is sturdy and is known to withstand the worst off-road surfaces you can possibly encounter. It usually has an option for high-range and low-range gearing. Low gear makes it easier to crawl over rocks at slow speeds or climb over steep terrains.
Overall, it has the needed equipment for off-road terrains like the suspension, gearing, and ground clearance. The AWD on the other hand fell short on the needed ground clearance that is necessary when driving on off-roads. The lack of it makes the AWD vulnerable to obstacles like rocks, tree stumps, and deep surfaces that can damage the undercarriage of the vehicle. The AWD can work through light off-roads though. On surfaces like gravel tracks, desire paths, flattened trails, and firm sands.
Snow and Ice
Driving in the snow or ice can be very tricky since you can lose grip or traction and can spin out regardless of what drivetrain you use. The determining factor is the speed, the tires you use and the much needed traction. With the AWD system that sends power simultaneously to all four wheels, or engages the torque automatically to all the wheels at the right time, the driver can just focus on driving and does not have to guess when to engage it. It is important because when you are driving in cold weather, there is a possibility that you will encounter different road surfaces that rapidly change as you drive along. You can be driving on soft snow at first, driving on hard ones next then on thin slippery ones but no matter how unpredictable the driving condition is, the AWD can react immediately and engage the torque automatically faster than the driver could to handle those tricky surfaces. For that reason, AWD makes a better choice when driving on slippery roads caused by snow and ice.
Driving in deeper snow and navigating through extreme winter conditions is another story. For the extremes, a 4WD is the solid option. It has a higher ground clearance that is very important for deep snow traction. It has been established earlier that the tires you use can determine the outcome of snow driving.
Be sure to use the right winter tires and learn by heart the proper driving techniques of tough winter conditions. Deep snow can hide obstacles such as rocks, tree branches and frozen puddles. Keep the momentum up and drive at a reasonable pace and when you need a greater control, use low range gears. The 4WD has the necessary equipment and power to help you get unstuck from a snowdrift easily and lets you drive through roads that haven’t been plowed.
Advantages and Disadvantages
As great as they are, the AWD and the FWD have their fair share of advantages and disadvantages.
All-Wheel Drive Advantages
The AWD provides best traction. Even on slippery roads, you can trust the AWD to drive you home safely. It also has better handling and is more stable when cornering. It is also an advantage that the AWD system is widely available on many car models.
All-Wheel Drive Disadvantages
The Disadvantages Include A not-so-efficient fuel economy, the cost for repairs and maintenance is not that affordable. It is not an ideal vehicle for the off-roaders.
Four-Wheel Drive Advantages
The 4DW improves the traction when in extreme driving conditions. It is a trusted vehicle that gets you through any difficult situation. Its weight that is heavier than other vehicles provides a better grip on the surface.
Four-Wheel Drive Disadvantages
Its added weight and power means it consumes more fuel than the other drivetrains. The added weight also means that it is hard to make a complete stop as it requires an increased braking distance. Just like the AWD, the FWD is also expensive to maintain.
Which is better?
The AWD and 4WD have lots of similarities and both have almost equal points on their strengths and weaknesses, it is really hard to judge. The answer just depends on where you live, how you intend to use it, what driving conditions you usually encounter, and even on your personal preference.
The AWD system is usually found on cars, SUVS or crossovers, while the 4WD is on trucks and off-road vehicles. But most of the car brands today also offer these two drivetrains in their line-ups for an extra cost. No matter what you choose, always keep in mind that using these drivetrains on any extreme driving conditions must not be taken lightly. Do not be overconfident because you are driving a powerful vehicle. It is better to be safe and alert all the time.