Today I will talk to you about the four-wheel drive system. The common four-wheel drive of SUVs currently on the market can be divided into three categories: part-time four-wheel drive, timely drive, and full-time four-wheel drive.
1. PART-TIME 4WD
The driver can switch between two-wheel drive and four-wheel drive by operating the transfer case. This process requires the driver to change the two-wheel drive or four-wheel drive by turning on or off the transfer case according to the road conditions. The four-wheel drive mode is the most common driving mode for hardcore off-road vehicles.
Advantages: simple structure, high stability, strong and durable.
Disadvantages: Because the part-time four-wheel drive does not have a central differential, the four-wheel drive system cannot be used on hard ground (pavement), especially on curves. The overall fuel consumption is relatively high.
Common models:
Jeep Wrangler
Mitsubishi Pajero Jinchang
Haval H5
2. Timely drive
Timely drive is a four-wheel drive system that only appears at the right time, and it is still a two-wheel drive system under normal circumstances. Its appearance not only reduces the cost of building four-wheel drive vehicles, but also brings good fuel economy to users (the most urban SUVs are timely four-wheel drive).
Advantages: Compared with the full-time four-wheel drive structure, it is simpler, which not only reduces production costs, but also effectively reduces the weight of the vehicle. It is beneficial to expand the space inside the car, with higher transmission efficiency, less noise from the window opening, and stronger vehicle comfort. Compared with the other two types of four-wheel drive, timely four-wheel drive is more fuel-efficient.
Disadvantages: Most of the timely four-wheel drive will be subject to structural defects when transmitting power to the front and rear axles, and cannot transmit more than 50% of the power to the rear axle, which makes it no full-time four-wheel drive in terms of active safety control. The adjustment range is so large; at the same time, compared with the time-sharing four-wheel drive, when it deals with bad roads, the physical structure limit of the four-wheel drive is lower. (To put it simply, the ability of four-wheel drive to get out of trouble is slightly worse than that of part-time four-wheel drive and full-time four-wheel drive)
Common models:
Tiguan
X-Trail
3. Full-time four-wheel drive AWD (short for All Wheel Drive)
Full-time all-wheel drive means that any time the car is in motion, all the wheels move independently. Full-time all-wheel drive vehicles will have a better and safer driving foundation than two-wheel drive vehicles (2WD), especially when encountering extreme road conditions or intense driving. In theory, AWD will have better traction than 2WD. The driving of the car is based on its continuous and stable traction, and the stability of traction is mainly determined by the driving method of the car. The engine power output is distributed to the four tires through the transmission system. Compared with assigning to two tires, the result is that the controllability, passability and stability of AWD will all be improved.
Advantages: Improve driving safety, stronger ability to get out of trouble than timely four-wheel drive, but the operation is not as complicated as part-time four-wheel drive, so that people with little technology can easily have a relatively strong off-road ability
Disadvantages: The structure is complicated and the cost is high. Generally, only luxury cars are equipped with it. The reliability is not as high as that of part-time four-wheel drive.
Common models:
bmw x5
Audi Q7
Land Rover Range Rover
Source of pictures and texts: Original article by SUV Master, author Li Xincheng.
