“There is no rear-wheel drive, not a luxury!” This slogan Cadillac I do not know how many people wash the brain. But think about it, it seems really is such a thing! After all those rich people’s car, not a few are really front-drive. After that what drove over the previous drive strong where it? Why prefer expensive cars are rear-wheel drive form it? Today I will fully analyze a wave for everyone!
In modern automotive design, there is a very important parameter, that is, “non-famous” Code: L113. Just from the literal point of view, you really hard from a letter plus three numbers to see what, but this simple code but largely determine the degree of aesthetic appearance of the car. Codenamed L113, in fact, represents the front wheel axis to the distance between the driver’s toes, that is, we often say “before the turn of the length of the front door.”
and the rear-wheel drive models, are used because of the relationship between longitudinal engine, front-wheel drive compared to the general model transverse engine, the engine nacelle inner longitudinal space will be occupied by more nacelle will naturally have a length requirements. Further, since the front transverse engine to drive the front axle, and the gearbox, the engine remains in the same vertical plane, so the position of the wheel will inevitably closer to the cab, so that the length L113 is bound to be shortened. After the longitudinal engine drove the other hand, since the transmission will be placed in a position after the front axle, the front wheel can be disposed at a position close to the natural front of, and thus increase the length L113.
and L113 longer distance, they can at the same time lengthen the front, so that the position of the cockpit after the shift. As a result, the whole front of the car, in the proportion of three parts will be more coordinated and stretch, while the vehicle’s visual center of gravity will be closer to the rear, the car looks sportier look and feel.
minimum turning radius, which is the need to take how many lanes when a car turned around for everyday through the city people are particularly important. In general, the length of a trolley, significantly affect the minimum turning radius of the vehicle.
Therefore, if the turning radius of the vehicle in order to improve the problem of excessive, it only by shortening the body, or by increasing the pivot angle of the front wheels. However, if a car in order to get more interior space, and that the length of the body is bound to have to increase the job. That in this case, we can only by increasing the front-wheel steering angle to solve.
Unfortunately, the front wheel drive because they have responsible for driving the wheels of universal joints exist, so the maximum swing angle of the front wheels is directly locked out. In other words, it is impossible to have too much front-drive steering angle. At the same time, due to the four-wheel-type universal joint of the front wheels also need to transmit power, even if it is based on the four-wheel drive to build its vehicles compared to the same rear-wheel drive version, the turning radius is to be greater.
Then the front wheel drive type, since the absence of the joint, the front wheels can reach even approximately 90deg; steering angle. That is why, after the body longer luxury car, in order to reduce the minimum turning radius as possible, will use the drive as a basic form of driving the vehicle.
When the driving limit, the front drive wheel brakes to be completed substantially at the same time, vehicle steering and traction three action. Unfortunately, due to the lateral and longitudinal traction tire traction only the sum is less than equal to “1”, so that if the limit of the tire grip 1 is then assumed at the time spent turning 0.5, then the traction drive out of the corners of the front case only a maximum 0.5. This leads to drive at the limit before driving out of the corners, not simply play the full power of the engine.
However, after the drive would not have this trouble, as compared to the predecessor model, the rear-drive the front wheels only need to be responsible for steering and braking can be. So after driving when accelerating out of bends naturally has a unique advantage.
after
In addition to the advantages of drive acceleration in the outside bend, due to a more neutral pH before and after the weight ratio of (e.g. around 50:50), the rear-drive limit when cornering, rear wheel realOn the occasion can also help to share the front part of the lateral grip, thereby enhancing the vehicle cornering limit.
At this time the front drive other hand very awkward, since the front drive pressure most of the weight relationship are front of the vehicle. So when cornering limits, the rear wheels of the vehicle allocated almost see much of axle load weight, pressure between the tire and the ground to such a naturally inferior to the drive, the resulting grip certainly can not be compared with the drive . More to the point, it is because not provide enough grip, so the first rear-wheel drive will often encounter problems operating temperature not compliance, and further affect the rear grip.
during rapid acceleration of the vehicle will cause the rear wheel Because inertia assume more axle load, i.e. rear wheel pressure between the ground will be higher than the rest. This means that, after the drive during acceleration, the rear wheels of the vehicle will have more grip than the rest or constant speed, so naturally much less prone to slipping during hard acceleration, avoiding the loss of power to some extent, .
while the front drive, although it will produce the same axle load transfer at the time of acceleration, but since the front drive wheels in the front, so that when the rapid acceleration of the vehicle wheel grip actually not as static. Thus, the front wheel drive during rapid acceleration slip idling state prone to ultimately affect the acceleration time. And this problem is particularly evident in the more than 150 horsepower models, which is why only a power rear-wheel drive BMW 3 Series 184’s, one of the reasons can accelerate so fast up.
Typically, the drive will use longitudinal engine layout, which is vertically placed in an engine nacelle. This layout form the vertical position, compared to the previous transverse drive layout is more often used, the lateral space is significantly more comfortable.
and the open cabin space laterally, to the selected design of the suspension and leaving more space. As we all know, the reason why most of the precursor civilian car with McPherson suspension, the most critical factor is the cabin space occupied McPhersonsmaller. Then drove there will be no such problems, whether it is a double-wishbone, or a more complex multi-link, longitudinal engine models have a more ample space for the suspension. So, compared to the predecessor model, the rear-drive tend to be more advanced form of the suspension to improve handling and shock filter of the vehicle.
before the drive transverse engine layout represented by models, though they have lower manufacturing costs, good interior space performance, but this form but then tap the size of the engine has a very stringent requirements. Since the engine is placed across the cabin relationship, so the length of the engine certainly will be limited, basic inline six-cylinder engine is the limit of the car tapped. However, if the width from the start, which is a V-type engine, and that the tank be arranged in the vehicle cooling high demands. So, most of the precursor models will adopt a smaller volume inline-four engine as a power source.
After the drive represented longitudinal engine models would not have this concern. Because of the relationship between longitudinal engines, as long as the design of the front long enough, even a twelve-cylinder in-line would not have any problems. At the same time, that would otherwise be restricted to the width of the engine nacelle length, in the longitudinal engine then becomes a relatively narrower width of the engine, so that even very close to the square W12 into the engine is not a problem. So, compared to the transverse front-drive, the use of the posterior longitudinal drive home can often be put down in the form of a larger engine with more horsepower.
Since the transmission position transverse precursor is not located in the middle of the vehicle cabin of the vehicle, the engine power after transmission through the output point is not in the middle position of the nacelle. Thus, the length of the front axle of the left and right sides will be different. Then the relationship of the principle of leverage, a shorter side of the axle tend to get more torque on the wheel. And this feature not only make faster breakthroughs side of the tire grip limit, affecting vehicle acceleration performance, while the former will lead to the infamous drive torque steer issues.
The drive shaft then is due, then the left and right rear wheel axle shaft length, etc. will naturally extend rearwardly from the center of the vehicle length. At this time, the same adhesive force as long as the sides of the tire, both ends of the left and right that can obtain the same power, so that the adhesion to maximize the limit of the two tires.
As we all know, can be done only after the drive was a real power shift. As for front-drive, due to the relationship between the drive wheels in front, even through the handbrake, pendulum and other ways to break through the rear grip limit, it is only to make only brief action flick. At the same time, the drive drift compared to the loss of cornering speed, the front-drive drift will not only lose out even more speed, and no spectator at all.
sure a lot of people are wondering why the low-end post-hardcore off-road vehicles without four-wheel drive, the drive will be used to as the drive forms. In fact, this is mainly because of axle load transfer caused. Because for off-road vehicles, the hardest thing uphill turnaround. Then the vehicle uphill process, the weight of the car will actually be more pressure on the rear wheel shaft caused by charge transfer acceleration Plus, the rear-drive the rear wheels will naturally have more traction to help the rescue vehicle. This is why hardcore off-road vehicles rear axle differential lock the front axle is more important than reason.
Many people often Tucao rich “only expensive, do not buy right” such consumption concept is malformed. But think about it for commodities, it is often the most expensive to ah! Before you can say drove the use of low cost, but the problem is the poor people left with money; you can say that a large front-drive space, but people can solve the space problem that way by buying a larger car; you can also say the car too big bad open, people waved back, then quietly got into the back seat …… Maybe the boss, the rich life is so plain and boring now. By the way, why do not buy after drive it?