How to drive a car?

Highway traffic

The movement of the car is the gravitational effect on the car. Whether a car is moving or stationary depends on the force of gravity or gravity. Gravity pushes the wheels of the car towards the road. The result of this force is at the center of gravity. The distribution of the weight of the car along the axes depends on the location of the center of gravity. The closer the center of gravity is to one of the axles, the greater the load on that axle. On cars, the axle load is distributed approximately equally. Of great importance for the stability and controllability of the car is the location of the center of gravity, not only in relation to the longitudinal axis, but also in height. The higher the center of gravity, the less stable the machine will be. If the vehicle is on a level surface, gravity is directed vertically downwards.

The movement of the car on an inclined surface

On an inclined surface, it splits into two forces. One of them presses the wheels against the road surface, and the other, as a rule, capsizes the car. The higher the center of gravity and the greater the angle of inclination of the car, the faster stability is violated and the car may tip over. While driving, in addition to gravity, a number of other forces that require engine power affect the car. The forces acting on the car while driving. They include. Rolling resistance is used to deform tires and roads, friction between tires, friction of drive wheels and much more. Resistance to rise depending on the weight of the car and a tilt angle. The resistance force of air, the value of which depends on the shape of the car, the relative speed of its movement and air density.

Centrifugal force machine

The centrifugal force that occurs when the car is moving in a bend and is directed in the opposite direction from the bend. The force of inertia of movement, the value of which consists of the force necessary to accelerate the mass of the vehicle during its forward movement. And the force necessary for the angular acceleration of the rotating parts of the car. The movement of the car is possible only on condition that its wheels will have sufficient adhesion to the road surface. If the traction is not enough, less traction drive wheels, then the wheels slip. Traction depends on the weight of the wheel, the condition of the road surface, tire pressure and tread. To determine the impact of road conditions on traction, a traction coefficient is used, which is determined by dividing the traction by driving wheels of the car.

Car adhesion coefficient

And the weight of the car on these wheels. The adhesion coefficient depending on the coating. The coefficient of adhesion depends on the type of road surface and its condition, such as humidity, dirt, snow, ice. On asphalt roads, the coefficient of adhesion decreases sharply if there is wet dirt and dust on the surface. In this case, the dirt forms a film, drastically reducing the adhesion coefficient. Oily film with protruding bitumen appears on hot asphalt roads in hot weather. Which reduces the coefficient of adhesion. A decrease in the coefficient of adhesion of the wheels to the road is also observed with increasing speed. So, with increasing speed on a dry road with asphalt from 30 to 60 km / h, the coefficient of adhesion decreases by 0,15. Engine power is used to drive the driving wheels of the car and to overcome the frictional forces in the transmission.

Kinetic energy of a car

If the amount of force with which the drive wheels rotate, creating traction, is greater than the total drag force, then the car will move with acceleration. Acceleration is the increase in speed per unit of time. If the traction force is equal to the resistance forces, then the car will move without acceleration at the same speed. The higher the maximum power of the engine and the lower the total resistance, the faster the car will reach a certain speed. In addition, the amount of acceleration is affected by the weight of the car. Gear ratio, final drive, number of gears and car rationalization. While driving, a certain amount of kinetic energy is accumulated, and the car acquires inertia.

Car inertia

Due to inertia, the car can move with the engine off for some time. Costing is used to save fuel. Stopping a car is of great importance for driving safety and depends on its braking properties. The better and more reliable the brakes, the faster you can stop a moving car. And you can move faster, and therefore its average speed will be higher. During the movement of the car, the accumulated kinetic energy is absorbed during braking. Braking contributes to air resistance. Resistance to rolling and lifting. On the slope there is no resistance to lifting, and a weight component is added to the inertia of the car, which makes it difficult to stop it. When braking between the wheels and the road there is a braking force opposite to the direction of traction.

Workflow when the machine is moving

Braking depends on the relationship between braking power and traction. If the traction force of the wheels exceeds the braking force, the car stops. If the braking force is greater than the tractive effort, then when braking, the wheels will slide relative to the road. In the first case, when the vehicle stops, the wheels rotate, gradually slowing down, and the kinetic energy of the car is converted into thermal energy. Heated pads and discs. In the second case, the wheels stop spinning and slide along the road, so most of the kinetic energy will be converted to the heat of friction of the tires on the road. A stop with wheels stopped disrupts traffic, especially on slippery roads. The maximum braking force can be achieved only when the moments of stopping the wheels are proportional to the loads caused by them.

Proportionality in car movement

If this proportionality is not observed, the braking force of one of the wheels will not be fully used. The braking efficiency is calculated as a function of the braking distance and the amount of deceleration. The braking distance is the distance that the car travels from the start of braking to full braking. The acceleration of a vehicle is the amount by which the speed of a vehicle decreases per unit of time. Driving a car is understood as its ability to change direction. The stabilizing effect of the angles of the longitudinal and transverse tilt of the axis of rotation of the wheel. When the vehicle is moving in a straight line, it is very important that the steered wheels do not rotate randomly and that the driver does not have to exert effort to keep the wheels in the correct direction. The car provides stabilization of the steered wheels in the forward position.

Machine Specifications

What is achieved due to the longitudinal angle of inclination of the axis of rotation and the angle between the plane of rotation of the wheel and the vertical. Due to the longitudinal inclination, the wheel is adjusted so that its fulcrum is transmitted relative to the axis of rotation, and the operation is similar to the roller. On a transverse slope, turning the wheel is always more difficult than returning it to its original position by moving in a straight line. This is due to the fact that when the wheel turns, the front of the car rises by a value of b. The driver makes relatively more effort to the steering wheel. To return the steered wheels in a straight line, the weight of the car helps to turn the wheels, and the driver puts a little force on the steering wheel. On cars, especially those where the air pressure in the tires is low, lateral tension is observed.

Driving Tips

Lateral retraction occurs mainly under the influence of a transverse force causing lateral deflection of the tire. In this case, the wheels do not roll in a straight line, but move sideways under the influence of transverse force. The two wheels on the front axle have the same steering angle. When the wheels are driven, the turning radius changes. What increases by reducing the steering wheel of the car and the stability of the movement does not change. As the wheels of the rear axle are removed, the turning radius decreases. This is especially noticeable if the angle of inclination of the rear wheels is greater than the front, the stability deteriorates. The car begins to fall, and the driver must constantly adjust the direction of movement. To reduce the influence of the drive on driving, the air pressure in the tires of the front wheels should be slightly lower than that of the rear wheels.

Wheel grip on the road

Sometimes sliding can cause the car to rotate around its vertical axis. Slippage can result from a number of reasons. If you sharply turn the steered wheels, it may turn out that the inertia forces become larger than the traction force of the wheels. This is especially common on slippery roads. In the case of uneven pulling or braking forces applied to the wheels on the right and left sides, acting in the longitudinal direction, a turning moment occurs, leading to slippage. The immediate cause of slippage during braking is the uneven braking force on the wheels on the same axle. Uneven adhesion of wheels on the right or left side of the road or improper placement of cargo relative to the longitudinal axis of the vehicle. The reason for the car to slip in a bend can also be its stop.

Driving recommendations

That the car did not slip, it is necessary. Stop the brakes without releasing the clutch. Turn the wheels in the slip direction. These techniques are performed as soon as the descent begins. After the engine stops, the wheels should be aligned so that the motorcycle does not start in the other direction. Most often, slippage occurs when a sudden stop on a wet or icy road. And at high speeds, gliding increases especially quickly, so on slippery or icy roads and corners, you should slow down without applying braking. The off-road ability of a car lies in its ability to drive on poor roads and off-road conditions, as well as overcome various obstacles encountered on the road. Patency is determined. Ability to overcome rolling resistance with wheel traction.

4x4 car traffic

Overall dimensions of the car. The ability of a vehicle to overcome obstacles encountered on the road. The main factor characterizing patency is the ratio between the maximum traction force used on the drive wheels and the drag force. In most cases, vehicle maneuverability is limited by insufficient traction. And, therefore, the inability to use maximum traction. To assess the ability of the vehicle to move on the ground, the coefficient of adhesion of the mass is used. It is determined by dividing the weight due to the drive wheels by the total weight of the vehicle. All-wheel drive vehicles are the greatest off-road ability. In the case of trailers that increase the total weight, but do not change the weight of the traction, the ability to cross rails is sharply reduced.

Traction of driving wheels when driving a car

The specific tire pressure on the road and the tread pattern have a significant effect on the traction of the drive wheels. The specific pressure is determined by the pressure of the wheel weight for the tire print area. On loose soils, vehicle patency will be better if the specific pressure is lower. On hard and slippery roads, the ability to cross long-distance roads improves with higher specific pressure. A tire with a large tread pattern on soft soils will have a larger footprint and lower specific pressure. While on hard soils the footprint of this tire will be less and the specific pressure will increase.