Most common cars have a long drive shaft. The engine drives the rear wheels to rotate through this shaft to make the car move forward. This is called rear-wheel drive. Why does the engine not directly drive the front wheels. Isn’t this more convenient? Most trucks use rear-wheel drive for two reasons:
First, the traction of a car is essentially the friction of the ground against the car. The friction is not only related to the conditions of the wheels and the road surface (that is, the roughness of the contact surface), but also related to the pressure of the wheels on the road. The greater the pressure, the greater the friction, that is, the greater the traction of the car; On the one hand, the pressure of the wheels on the road is not only related to the load capacity, but also related to the position of the cargo on the vehicle. In general, the cargo is in the back half of the car, and the pressure on the front wheel of the car accounts for 1/4 of the car's load. The pressure on the rear wheels accounts for 3/4 of the car's load. Even if the cargo is placed close to the front wheel, the cargo on the car will generally move backward due to inertia, which automatically increases the pressure of the rear wheel on the ground. Therefore, rear-wheel drive for automobiles can increase the traction of the automobile.
Second, if the car is driven by the front wheels, the front wheels need to be steered and driven. It is complicated to combine the transmission and direction of the car, and it is troublesome, laborious and inconvenient for the driver to manipulate the steering wheel. Therefore, front-wheel drive is rarely seen.
Cargo loaders generally use front-wheel drive and rear-wheel steering. This is because the load bucket of the loader is at the front, and the pressure of the front wheels on the ground is much greater than that of the rear wheels. Some vehicles, such as off-road vehicles. Wheeled tractors, etc. In order to obtain greater traction, the front and rear wheels are simultaneously driven. But the roads are not particularly bumpy and muddy. These vehicles still use rear-wheel drive, which can increase the speed of travel.