In brief, a four-wheel drive provides the four wheels of the car with their own rotations per minute when a car needs to make a turn. This is mainly achieved by the differential which apportions the torque or rotation power provided by the drive shaft between the left and right wheels of a car. There is a differential for the rear tires and a differential for the front tires.
As mentioned, when a car turns to the right, the right wheels need to make more rotations per minute than the left wheels. If a car is turning to the left, the opposite is true. The differentials at the center of the front and back axles make this difference in rotation rate or torque possible.
The differentials are sensitive to resistance and distribute the rotation power in inverse proportion to the resistance it feels from the left and right wheels. In negotiating a turn, the inner front wheel exerts resistance because it needs to rotate less. Sensing this, the differential at the center of the axle distributes more torque or rotating power to the outer wheel. This is the mechanism found in standard four-wheeled drives.
But because the basic movement of turning pivots the front end of the car around the back end, the front end needs to rotate more than the back end. Basic four-wheeled drive systems do not have a mechanism for distributing torque proportionately between front and back ends of the car. Therefore, when negotiating tire-gripping smooth pavements, basic four-wheel drive vehicles tend to under-rotate because the system is not equipped with the mechanism to allow for proportionate distribution of rotating power to both ends. In simpler terms, it cannot convert the resistance offered by the back of the car to rotating power for the front of the car.
Of course, this fact, causes strain on the differentials and associated parts of the vehicle.
It is for this reason that standard four-wheeled vehicles are hardly used on flat and dry pavement. They are more often used for roads with less traction, like gravel and sandy roads, roads filled with mud or snow. Standard four wheeled vehicles those vehicles that are made for off-the-pavement trips.
To enable the four-wheel-drive car to run on smooth pavement, manufacturers inserted an additional differential near the center of the drive shaft. Incidentally, the drive shaft is the long bar connecting the front and back axles through the middle of the car. This effectively made the drive shaft function like a pair of axles, this time connecting the front and the back ends of the car.
In this formation, which later became known as the full-time four wheel drive, cars with front and back axles could run on flat surfaces providing lots of traction or grip as well as on dirt roads which grip the tires less.
Standard four wheel drive systems can shift the driving mechanism to two-wheel or four-wheel.
Two-wheel drives funnel the rotating power given by the used car engine to either front or back wheels. In this setup, the other set of wheels passively conforms its rotations to the actively rotating set and are not directly supplied with rotating power from the engine of the car. Because the wheels without differentials don't receive a portion of the torque (rotating power) from the engine of the car, these vehicles are suited for gravel as well as for pavement roads.
More people are discovering the advantage of using full-time four wheeled technology because they don't need to be adjusting the setting of the driving mechanism for negotiating low-traction roads on one hand and high traction roads on the other.
As mentioned, when a car turns to the right, the right wheels need to make more rotations per minute than the left wheels. If a car is turning to the left, the opposite is true. The differentials at the center of the front and back axles make this difference in rotation rate or torque possible.
The differentials are sensitive to resistance and distribute the rotation power in inverse proportion to the resistance it feels from the left and right wheels. In negotiating a turn, the inner front wheel exerts resistance because it needs to rotate less. Sensing this, the differential at the center of the axle distributes more torque or rotating power to the outer wheel. This is the mechanism found in standard four-wheeled drives.
But because the basic movement of turning pivots the front end of the car around the back end, the front end needs to rotate more than the back end. Basic four-wheeled drive systems do not have a mechanism for distributing torque proportionately between front and back ends of the car. Therefore, when negotiating tire-gripping smooth pavements, basic four-wheel drive vehicles tend to under-rotate because the system is not equipped with the mechanism to allow for proportionate distribution of rotating power to both ends. In simpler terms, it cannot convert the resistance offered by the back of the car to rotating power for the front of the car.
Of course, this fact, causes strain on the differentials and associated parts of the vehicle.
It is for this reason that standard four-wheeled vehicles are hardly used on flat and dry pavement. They are more often used for roads with less traction, like gravel and sandy roads, roads filled with mud or snow. Standard four wheeled vehicles those vehicles that are made for off-the-pavement trips.
To enable the four-wheel-drive car to run on smooth pavement, manufacturers inserted an additional differential near the center of the drive shaft. Incidentally, the drive shaft is the long bar connecting the front and back axles through the middle of the car. This effectively made the drive shaft function like a pair of axles, this time connecting the front and the back ends of the car.
In this formation, which later became known as the full-time four wheel drive, cars with front and back axles could run on flat surfaces providing lots of traction or grip as well as on dirt roads which grip the tires less.
Standard four wheel drive systems can shift the driving mechanism to two-wheel or four-wheel.
Two-wheel drives funnel the rotating power given by the used car engine to either front or back wheels. In this setup, the other set of wheels passively conforms its rotations to the actively rotating set and are not directly supplied with rotating power from the engine of the car. Because the wheels without differentials don't receive a portion of the torque (rotating power) from the engine of the car, these vehicles are suited for gravel as well as for pavement roads.
More people are discovering the advantage of using full-time four wheeled technology because they don't need to be adjusting the setting of the driving mechanism for negotiating low-traction roads on one hand and high traction roads on the other.
