1. Overview
all-wheel drive (4WD system) is the driving force of the engine from the transmission 2wd two transmission system becomes four. 4wd system and are included in active safety systems, mainly 4wd system is more excellent than 2wd engine driving force application efficiency, achieve better tire traction and steering effective force. On security for, 4wd tire traction and steering system for better application of force, resulting in good driving stability and tracking of. In addition to more 2wd 4wd system does not have off-road.
2. Category
four-wheel drive (Part-time 4WD)
This is a driver can manually select between two drive and four-wheel-drive wheel drive system, according to road conditions by the driver, by turning on or off the splitter be varied two-wheel drive or four wheel drive mode, which is typically four-wheel drive off-road vehicle or SUV most common driving mode. The most significant advantage is that the driving mode can be selected according to the actual situation, more economical. 2.8 breeze displacement of the four-wheel drive SUV is a typical example, which has three drive mode selection: 2H use with high-speed two-wheel drive on the road profile; when encountered snow road, 4H select high-speed driving, enhanced the adhesion and handling of the vehicle: the challenge while poor road conditions, may be employed 4L breeze and low four-wheel drive, so that force acting on all four wheels, thereby reducing the requirements for each tire adhesion, It minimizes the possibility of wheel slip during turning. Engine braking ability can be enhanced, greatly improves the controllability of the throttle in the case of the sudden closure of the vehicle is traveling over rough or smooth surfaces. In 2003, on the 2004 national cross-country venue, Landwind 2.8 diesel four-wheel displacement, regardless encounter bumpy stone road, or very steep angle of the V-shaped grooves, deep muddy after heavy rains abnormal, even half a man deep the large pond, can easily deal with, Yiqijuechen, won numerous races and even the national finals of the championship, it can be said to describe fourWheel drive most heroic performance. AWD (Full-time 4WD)
The drive system is not required to select the driver operation, front and rear wheels will always maintain four wheel drive mode, the engine output torque when the driving set around 50:50 wheel, so that the front and rear wheels to maintain the same amount of torque. Full-time drive system has a good driving handling and tracking of travel, with full-time four-wheel drive system, you can successfully driving on paved roads covered. But its disadvantages are also obvious, and that is a comparison of fuel consumption, the economy is not good enough. Moreover, there is no device to control the vehicle tire speed difference, once a tire off the ground, tend to make you stuck in there, we can not move forward. Timely drive (Real-time 4WD)
The drive system uses timely vehicle driving mode selection may be controlled by the computer for the current situation. In normal road, rear-wheel drive vehicles generally the way. Once the wheel slip or poor road surface conditions encountered, the computer automatically detects the engine output torque is immediately assigned to the two front wheels and four-wheel drive is switched to the natural state, eliminating the driver’s judgment and manual operation, application easier. However, compared with the computer brain, slow reaction after all, and in so doing, also they lack the sense of conquest that everything is under control and driving pleasure.