The various gears in the transmission and differential multiply the torque and split it up between the wheels. More torque can be sent to the wheels in first gear than in fifth gear because first gear has a larger gear-ratio by which to multiply the torque.
The bar graph below indicates the amount of torque that the engine is producing. The mark on the graph indicates the amount of torque that will cause wheel slip. The car that makes a good start never exceeds this torque, so the tires don't slip; the car that makes a bad start exceeds this torque, so the tires slip. As soon as they start to slip, the torque drops down to almost zero. The interesting thing about torque is that in low-traction situations, the maximum amount of torque that can be created is determined by the amount of traction, not by the engine.
Even if you have a NASCAR engine in your car, if the tires won't stick to the ground there is simply no way to harness that power. For the sake of this article, we'll define traction as the maximum amount of force the tire can apply against the ground or that the ground can apply against the tire -- they're the same thing. These are the factors that affect traction:. The weight on the tire -- The more weight on a tire, the more traction it has.
Weight can shift as a car drives. For instance, when a car makes a turn, weight shifts to the outside wheels. When it accelerates, weight shifts to the rear wheels. See How Brakes Work for more details.
The coefficient of friction -- This factor relates the amount of friction force between two surfaces to the force holding the two surfaces together. In our case, it relates the amount of traction between the tires and the road to the weight resting on each tire.
The coefficient of friction is mostly a function of the kind of tires on the vehicle and the type of surface the vehicle is driving on. The coefficient of friction for that same tire in mud would be almost zero. By contrast, huge, knobby, off-road tires wouldn't have as high a coefficient of friction on a dry track, but in the mud, their coefficient of friction is extremely high. Wheel slip -- There are two kinds of contact that tires can make with the road: static and dynamic.
But there are also other situations when friction is fundamental for making the vehicle behave the way you want:. In these situations, it is crucial that the static frictional force exceeds other forces, e. Otherwise you lose road grip. So, what will influence your road grip? In a typical driving situation, the first three factors are rather constant; our vehicle has a certain weight and certain tyres, and we drive on a long road.
Accordingly, we adapt our driving style to these given factors. But all of a sudden, there could be a heavy rain, and everything changes…. In certain conditions, there may appear something else between the tyre and the road surface — rain water for example.
The water works as a lubricant between the rubber and the asphalt, and the static friction is reduced as a result. Even worse, the road could be icy.
When accelerating on ice, if the applied force the driving force on the wheels exceeds the static friction, the wheels will lose grip and spin. What actually happens here is that, when static friction is exceeded, another kind of friction takes over; the kinetic friction, which is also known as dynamic or sliding friction. The vehicle will slide until this kinetic friction eventually makes it stop. How far a vehicle will slide and how slippery the road is, is determined by the coefficient of friction.
Different materials and textures provide different friction. The coefficient of friction is a measure for how much friction a material or texture provides. While friction is a general physical expression, vehicle traction can be defined as the friction between a drive wheel and the road surface.
If you lose traction, you lose road grip. Now you know that it all comes down to friction. Select your state to get started. Get ready for the permit test with DriversEd. Wet road surfaces can cause tires to hydroplane skim on a thin layer of water.
This could result in loss of control and steering ability. Hydroplaning is caused by a combination of standing water on the road, car speed, and under-inflated or worn-out tires.
If it feels like your tires have lost traction with the surface of the road and your vehicle is hydroplaning, take your foot off the accelerator and let the vehicle slow down. Do not try to stop until your tires are gripping the road again. To reduce the chances of hydroplaning, use tires with adequate water-channeling treads and check them regularly. Remember the other important factor is speed control—always slow down when water is on the road.
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