When buying a car, modern consumers, as a rule, long pondered the question of whether to give preference to the vehicle with the front or rear wheel drive. Most have exclusively focused on the acquisition of those vehicles, which are used all-wheel drive system. However, it is important to remember that these systems are significantly different from each other, and to make reasonable choice, you can only if you know exactly what are the types of wheel drive systems as how they act themselves on the road, and which vehicles are equipped with them. Let’s try to review each of the issues in more detail.
Part time AWD
This is the most common type of all-wheel drive system, which today is used in many low-cost cars. It is often put, for example, on Ford and some models of Nissan. And the distinctive feature of any of the vehicle with part-time AWD that it cannot work in a four-wheel drive mode for a long time. After all, the system does not include a center differential, which would compensate the difference of rotation speeds between the axes of the car. And therefore, if you will turn on all-wheel drive mode continuously, the transmission very quickly fail. This system is suitable in the first place, for those car owners who are going to travel off the road. But for the urban environment, it is not intended – in fact while traveling on a flat, hard surface, you’ll need to keep switched on only rear-wheel drive, using all the capabilities of the system only in extreme cases. It is suitable to turn on the system for a short time only to overcome the dangerous sections of the road.
Full time AWD
A better option for modern SUVs is permanent four-wheel drive – TOD or other well-proven system. After all, this system has a reliable center differential, which allows you to use it without restrictions both on city streets and off-road. However, it is important to remember that the design of the joints between the front and rear axles, allowing them to freely slide. This somewhat limits the possibilities of use of the vehicle off the road, but for the urban environment makes it just unbeatable. It should be noted that the system of active Full Time AWD virtually eliminates the possibility of all the cars forced connection or front or rear axle. As for the interaxal bridge management in modern vehicles is carried out directly by electronic devices. So all-wheel drive vehicles that run on this system is quite simple and nice – they give you the ability to move with maximum comfort and safety on any kind of surface. In this vein, it should be noted that every modern intelligent AWD system allows different proportions of distributing the torque between axles. In the classic version torque between the axles is distributed to 50:50 ratio, however, if there is slippage of one of the axes, the system will transfer immediately most of the load on the axle, which has better traction. Due to such characteristics, the car can perfectly adjust to any type of surface. Furthermore, some models have drive system which allows to shift a maximum torque of not only the front or rear axles, but also directly to the wheels – and this significantly increases the performance of the vehicle. The most common Full Time AWD systems finds application in Audi and Subaru cars, but it can also be used in vehicles sold under other brand names.
Full time AWD on demand
This system operates substantially the same way as the previous one, but it is not necessary to turn it on by hand – the system starts to operate automatically when needed. For example, if there is a slip of one of the axles, the vehicle immediately goes into four-wheel drive mode and the torque is transmitted directly to both axes (and proportions can be very diverse). In addition, the consumer’s attention is often offered automated wheel-drive system, in which the torque can be fed directly to the individual wheels. And a good example in this case is able to serve as the All Mode 4×4 system, which is one of the most popular on the market today.
The advantages of automated wheel-drive systems, which are equipped with many modern cars are:
- The ability to self-distribution of torque between the axles (not present in all systems);
- The ability to switch to front-wheel drive;
- Significant savings of fuel (as all-wheel drive mode does not work all the time, and you do not need to switch it manually, the car uses a minimum amount of fuel).
Thus, we can conclude that the system of Full Time On Demand ideally suited for operation in both city and suburbs, as it is able to very quickly adapt to the specifics of the surface. But of Full Time and Part Time do not differ so versatile – the first is better suited for urban roads, and the second should be used in off-road conditions.