We are back with another theme for today’s Automobile Technology Section. The aim of this section is to explain the complex technical aspects and technologies of automobile engineering in a simple and easy-to-understand language. There are plenty of automobile enthusiasts out there who would like to expand their knowledge with regards to the proper functioning of their vehicles. This might include modern features or processes inside the engine. If you are interested in such kinds of articles, do visit Car Blog India and go to the Automobile Technology Section directly. Let us get into today’s theme of Torque Vectoring, Torque Steer, Understeer and Oversteer, which you must have heard before.
Torque Vectoring – Principle
The phenomenon of Torque Vectoring is very prevalent in performance and high-end luxury cars. It could be used in front-wheel-drive as well as all-wheel-drive vehicles. Essentially, the ability of the car to supply variable torque to all four wheels or both wheels (in the case of front-wheel-drive cars) is known as Torque Vectoring. Alternatively, one can also say that the ability to supply torque to individual wheels independently, according to the situation, is known as Torque Vectoring. There are sophisticated systems and components in place to achieve this. This is especially prevalent in four-wheel-drive vehicles. The purpose of all-wheel drive cars is to make the car capable of handling any type of terrain or road conditions to start with. Add to that the sophistication of delivering torque independently to individual wheels, enhances the capability for off-roading or traction control tremendously. Additionally, for regular front-wheel-drive cars, the Torque Vectoring comes in handy while cornering. The stability that this method extends to the cars improves the handling capabilities of the car greatly. The driving dynamics of the car are raised to another level.
Torque Vectoring – Components and Working
In the Differential Assembly, there is an additional Clutch Pack, which can be engaged or disengaged according to the needs. When the clutch is disengaged, there is a 50-50 torque split between the two wheels (right and left). However, once the clutch is engaged, depending on the traction or slippage, a large chunk of the overall torque can be directed towards one particular wheel. This will help the vehicle to come out of the corner with more stability or get the car out of an uneven surface with limited traction easily. This clutch assembly can be operated through an electric or hydraulic setup. Depending on the need, the electric motor, for instance, engages the gear to the differential housing and ensures more torque to one wheel than the other.
Torque Steer is a phenomenon that is generally found in cars with a ton of power and torque. Many times, these are relatively smaller cars, for instance, the performance-oriented hardcore hot-hatches around the world like the Honda Type-R, Volkswagen Polo GTI, Hyundai Veloster N, etc. Some of these hatchbacks have power figures in excess of 300 hp and torque figures in the regions of 400 Nm. That is a lot of power and torque for a hatchback. What ends up happening is that the torque at the launch of the car from a standstill ends up being too much for the wheels to handle. As a result of this, the car might go in one direction unintentionally. This can also be because of the length of the drive shafts connecting the rack and pinion assembly to the wheels. Also, while cornering, there may be instances where the steering characteristics work autonomously at times as a result of strong throttle inputs during the corners. These scenarios are not uncommon with cars like these. Therefore, the car manufacturers take multiple measures to combat this including the reduction in Scrub Radius, Brake Application on one wheel or torque vectoring, etc.
This is something a lot of you must’ve heard and also experienced some time. As the name suggests, when the car doesn’t steer enough according to the driver’s input during a corner, it is known as understeer. There can be a ton of factors for this. For example, in front-wheel-drive cars, the duties of power, torque and steering are handled by the front wheels alone. There are enormous amounts of forces and pressure acting on these two wheels. If the driver applies brakes or acceleration while the wheels are already turned in a particular direction, the wheels have not enough surface area in contact with the road. Therefore, slippage increases as the wheels are not able to implement the driver’s wish due to lack of traction. Hence, the vehicle keeps moving forward or doesn’t turn enough around the corner. The more the driver turns the steering wheel, the more slippage occurs. Most cars are designed for understeer because it is easy to predict and correct.
The most potent way to overcome understeer is to release the brake or the accelerator pedal or reduce the steering lock. All these methods allow the wheels to gain back traction and grip and the car can become stable again and ready to follow the driver’s instructions once again. Also make sure not the go into the corners with high speeds or hard braking, to begin with.
As the name suggests, when the car steers more than the input given by the driver, it is known as an oversteer. This happens when the rear wheels of the car get locked up and start to slip. The rear end comes out and the car goes into spiral motion. This is a more dangerous situation compared to understeer because the driver can lose entire control of the car easily and there are no corrective measures that are very effective. This happens when you drive too fast into the corner or suddenly lift your foot off the accelerator pedal to go into the corner. The entire weight of the car gets thrown forward and the rear end kind of becomes loose and the car begins to lose grip from the rear end. Some experienced drivers also love doing this and do this on purpose but these are risky maneuvers and should be avoided. To combat the effects of oversteer, one must steer the car in the opposite direction known as countersteering. Also, a gradual decrease in the accelerator pressure also helps avoid oversteer.
Image Credit: Research Gate