Automotive vocabulary can be quite confusing at times particularly when you are buying a new car. If you are planning to buy an SUV, it is highly possible that you come across a few terms like all-wheel drive and 4-wheel drive. These technologies may seem familiar but it is not the case. This article covers in detail the differences between these systems.
What is All-Wheel Drive?
Starting from the basics, it is a kind of recent system. All-wheel drive systems power both the front and rear wheels all the time. In actuality, there are two kinds of drivetrains. One which drives the wheels endlessly, some manufacturers may refer to it as full-time AWD. The other one is known as the part-time AWD or the automatic AWD mostly operates in one the rear wheel drive or the front wheel drive based on the drive system of the vehicle. The power is delivered to all four corners only if additional traction is required.
In an AWD system, all four wheels can gain traction individually. 4WD can be usually found in trucks. AWD is mostly found in cars and SUVs. AWD can be integrated into the car by giving three differential or gearboxes in various car parts. A differential contains the AWD gearbox with developed engineering. It takes power from the car’s transmission and delivers it evenly to the right axles. There will be three gearboxes on the front, rear, and center of the car. Having these differentials enables the four tires to have independent traction. This results in superior traction and it can bear all kinds of weather situations.
The mechanical AWD utilizes the differential-based method. The SUVs of 2015/2016 require computerized electronic AWD in the systems. The wheel of the car has sensors that are there for the traction and speed of the wheel. The data is utilized by the ECU in order to decide where the power is delivered based on which wheel has the most grip. Electronic AWD is generally called ‘torque vectoring’
The most innovative all-wheel drive is used in Ford’s Intelligent All Wheel Drive(iAWD). It is available in a few new Ford models. They provide a greater grip even on wet surfaces or snow. It also delivers enhanced responsiveness, handling, and fuel efficiency at various speeds.
What are the Benefits of All Wheel Drive?
AWD system is quite complex and it is utilized in most modern cars. It can enhance road safety to a greater extent.
● Provides Greater Grip on Wet Roads/Snow
It provides a greater grip on wet roads or slippery areas. It distributes the traction evenly and fast to the right wheels. This helps your car to be stabilized in an adverse situation.
● Enhanced Handling
The recent AWD system utilizes smart torque vectoring to enhance handling. The traction and speed are kept under control with the help of ECU. It enables uneven driving surfaces easier to withstand.
● Working 24/7
The AWD system is activated as the car is started while the 4-Wheel drive can be activated by the driver.
● Greater Handling and Traction
With all-wheel drive, your SUV can withstand tight cornering and increase performance, handling, and traction. A lot of popular car brands like Ford and Nissan have upgraded from 4x4 to all-wheel drive. The 2016 Nissan GT-R uses this to enhance the acceleration on the track.
Disadvantages of all-wheel drive
There are a few disadvantages of all-wheel drive as well which are stated below:
● It increases the cost of the vehicle due to its complex design
● It is not recommended for serious off-roading as the driver would have no control over it
● It lessens the fuel economy
How does All-Wheel drive work?
Both the full-time and part-time AWD system work without having to get any input from the driver. It evenly distributes the power through a center differential which then splits the torque into 4 wheels. The 4 wheels are powered all the time simultaneously. If the surface is slippery with lesser traction, the power is distributed accordingly. Part-time AWD system drives two wheels only. It can be a front or rear wheel based on the car model. More traction is needed for wet conditions. Therefore, the system sends the power accordingly. Electronic sensors are used in the automatic all-wheel-drive system to identify the loss of traction. The computer onboard is in the control of transmission of power to each wheel.
All-wheel drive example
Driving on highways requires a lot of traction. Part-time AWD delivers power to the front wheel and rear wheel. If you experience a bad patch in the road, the system identifies the traction loss and delivers power to all the wheels. The computer makes the necessary adjustments provided there is no human intervention.
In a full-time AWD system, the car is always going to stay in AWD mode. This implies that the power is delivered to the four wheels constantly. If you drive around the corner, the system detects that more traction is required for the outer wheels than the inner wheels. The power is adjusted accordingly. The same happens when considering a slippery or wet road. The system delivers more torque to the wheel having reduced traction.
What is Four Wheel Drive?
Four-Wheel Drive is a conventional system as compared to AWD. It delivers an equal amount of power to all four wheels. It requires input from the driver in order to drive the front and rear wheels. It transmits power to the wheels through a transfer case acting as a locked differential.
It goes well for situations that include extreme off-roads/heavy hauling because of all the wheels spinning at the same speed. That is why it is typically found in pickup trucks. The wheel having traction can get the car out of a difficult situation. Some of the 4WD vehicles come with high and low-range gear. It can be selected by the driver.
What are the Benefits of Four Wheel Drive?
Gear up for off-road adventures
4 Wheel drive systems are best suited for off-road adventures including various tracks and trails. They offer better grip and traction aiding you to plough through difficult terrain. They can power ahead even if one wheel is touching the ground. It has a greater benefit when you are trying to find the rugged terrain that leaves one more wheel off the ground.
If you are searching for the best vehicle for the adventure, 4WD is the best choice. The Land Rover Defender will be an iconic choice, having an iconic boxy design along with serious off-road capabilities. You need to have the right skill set if you are choosing the 4WD system to explore.
Reduced Fuel Consumption
The new models of the 4WD systems are fuel efficient because of innovative engine technologies. They provide better fuel efficient than the older 2WD models. If you upgrade it to a plug-in hybrid, its efficiency will be increased a lot. An example is the Mitsubishi Outlander which is considered to be one of the best PHEVs in the UK and increases fuel economy by 139.7mpg, and CO2 emissions by just 64g/m. It comes with an attractive price tag. The Volvo XC60 is a brilliant example of having excellent eco credentials and luxurious manufacturing.
Flexible All-Terrain
4WD systems are not only for off-road usage but numerous models are designed considering urban driving in mind. Mercedes Benz GLS has exceptional power but there are additional compact choices in the market that can deliver the advantages of 4WD without the bulk.
Some models have innovative designs like the MINI Countryman compact is designed in a way which is urban-friendly and has a 4WD grunt. It has a high suspension along with an optional 4WD system making it comfortable on the motorway as well as it is off-road.
Better Traction In Difficult Situations
Producing power from the 4 wheels enhances the traction. It also improves control in difficult driving conditions like ice or snow. 4WD is preferable for more safety considering families and young kids. If your area has a lot of snow or ice on the roads, it means that the 4WD can be considered the right model to stay safe. 4 wheel drivers are relatively heavier than the 2WD counterparts translating for improved grip in wet/icy circumstances.
Improved Driving Position
4WD vehicles are elevated as compared to their 2WD counterparts meaning they will have a taller driving position. This enhances the visibility on road and can aid you to feel safe and comfortable behind the wheel.
Towing Power
The 4WD system features larger builds and generates additional power from each wheel. Due to this, the towing capacity is greatly increased. If you are searching for an automobile with greater power to tow a trailer or caravan, you should go for 4WD. There are a few models like the Jeep Grand Cherokee, Land Rover Defender, and Mitsubishi Shogun that have to deliver some of the best capacity credentials available in the market. They can efficiently tow caravans weighing greater than 3500kg.
Disadvantages of four-wheel drive
A few disadvantages of the 4-wheel drive system can be:
● It offers a stiffer ride as compared to a 2WD vehicle
● The price of vehicles is increased. Maintenance costs are also increased
● It hinders the fuel economy
How does Four-wheel drive work?
A 4WD system is similar in a sense to the 4WD system considering it delivers power to all 4 wheels. A full-time 4WD car receives the power consistently. In a few vehicles, the driver has the option of regulating the power ratio delivered to the front and rear axles. In a part-time 4WD system, the vehicle run on 2WD mode as a default mode. If the traction is low the driver can give an input to the system and engage with the system with the help of a lever or button. A few systems also enable the driver to lock differentials for additional traction.
Four-wheel drive example
Now let’s consider a 4x4 SUV. If you drive it on the road with improved traction, it will be in the default i.e. 2WD drive. Engaging 4WD on paved roads is not preferable because it locks the difference. All four wheels travel at a similar speed.
Driving on corners becomes hard when the 4WD system is considered. The vehicles will lose traction because of the 4 wheels spinning at the same speed. Therefore, the 4WD drive is used when required.
If you are interested in extreme off-roading, you can engage with the system manually. You can choose the high or low gear. The low mode can be aided in extreme off-roads as it delivers additional torque to all 4 wheels. The high mode is well sufficient for light off-roading.
Different Types of All-Wheel Drive
With the help of all-wheel drive, drivers have better control and reliability with greater safety and performance. There are different types of AWD. The manufacturers can use different terminology for the same technology. Some of the most common types of all-wheel drive and what they offer are given below:
Part-Time AWD
Part-time AWD is mostly observed on trucks. This enables a driver to select while an AWD system is involved especially when turning from a 2WD into a 4WD through the transfer case. The wheels tend to rotate at the same speed as it does not have a center differential. It is a manual choice that can be mechanically engaged. The vehicle does not do good around the corners. A vehicle shouldn't be driven in this mode under normal circumstances. It can result in transmission windup along with a certain level of damage. It is better for those who find themselves in tough driving situations and someone skilled in engaging and driving the system.
● Full-Time AWD
Full-time AWD means that all the wheels are utilized in the driving and are always getting some torque. Manufacturers resolve the windup issues in different ways. The wheel spin is able to spin at different speeds and sustain traction as required. One way to utilize the center differential having a traction control device like viscous coupling or multi-plate hydraulic clutch. Some of the well-known systems are the Torsen and Haldex. Torsen is mechanically utilizing a pre-calculated torsion force to find out the torque transfer.
Creative braking can be an additional solution. If a wheel slips, the ECU identifies it and uses the ABS to get control of the system. It delivers more torque to the wheels having traction. Full-time AWD is really helpful because of its responsiveness and it is always on.
● Automatic
Automatic AWD is kind of similar to part-time in the way that it defaults to 2WD. The difference between the two systems is that the driver does not have a hold of selection when the AWD system kicks in. The advantage of the system is that it is relatively efficient compared to full-time. There is no need for a center differential due to this system. If there is an immediate need for traction in one of the drive wheels, a traction control device can be utilized. It automatically gets activated and delivers torque to the wheels and the other axle according to the requirement. If it is not needed anymore, the system goes back to 2WD. This can happen really fast utilizing algorithms and technology. The process is getting more predictive utilizing sensors and driving patterns.
● Electric and Hybrid
Some of the vehicles are coming with electric solutions as well and the number will keep on increasing in the future. These automobiles use electric motors with sensors to deliver torque when required. Automobiles also utilize electromagnetic couplings. A few vehicles have an electric motor that powers a set of wheels. A gasoline engine is used to power the other. The electric-driven set can get activated when the computer system of the car tells it to do. The instruction is based upon a number of factors. Die-hard off-roaders will have a deeper dive into what 4WD has to deliver. This can be a good start for anyone.
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