What does 4WD mean?

[StIsaac]

4WD stands for "Four-Wheel Drive", which means all four wheels have driving force. Originally, four-wheel drive was mainly used in hardcore off-road vehicles, but now it is also used in urban SUVs, and many mid-to-high-end sedans and luxury sports cars also adopt four-wheel drive. 4WD includes three forms: full-time four-wheel drive, part-time four-wheel drive, and on-demand four-wheel drive. Full-time four-wheel drive: Vehicles equipped with full-time four-wheel drive systems are always in four-wheel drive mode. This type of four-wheel drive system is commonly found in some luxury SUV models, such as the BMW X5 and Audi Q7. Full-time four-wheel drive adds a center differential to the part-time four-wheel drive system, allowing the speed difference between the front and rear drive shafts to be smoothly resolved. Therefore, vehicles with full-time four-wheel drive can drive on any type of road surface, which is the advantage of full-time four-wheel drive. Part-time four-wheel drive: This four-wheel drive system can switch between four-wheel drive and two-wheel drive via an in-car switch. Most off-road vehicles with part-time four-wheel drive have a low-range four-wheel drive function. When switched to low-range four-wheel drive, the wheel torque is further amplified, helping the vehicle escape difficult situations. Vehicles equipped with part-time four-wheel drive include the Toyota Prado and Jeep Wrangler. Part-time four-wheel drive is the most common type of four-wheel drive system. It does not have a center differential, so the speed difference between the front and rear drive shafts during turns must be offset by tire slippage. Vehicles with part-time four-wheel drive cannot be driven on roads with good traction. On-demand four-wheel drive: This four-wheel drive system is typically used in some urban SUVs or front-engine, front-wheel-drive sedans. Vehicles with on-demand four-wheel drive usually operate in front-wheel drive mode. Power is distributed to the rear wheels only when the front wheels slip or during full-throttle acceleration. On-demand four-wheel drive has lower costs and fuel consumption, making it suitable for urban SUVs and sedans. The 4WD system is essentially a four-wheel drive system that controls the distribution of driving force. Using computers and various improved sensors, it continuously assesses the dynamic traction of the tires on the road and the driver's intentions, actively controlling the differential state of the vehicle's differential to balance the driving force on each wheel and optimize the vehicle's performance. The system mainly consists of front and rear wheel drive devices, sensors, electronic control units, transfer cases, and hydraulic components. The control principle involves placing a wet multi-plate clutch between the front and rear wheels. During driving, the computer controls the oil pressure in the hydraulic system to distribute the driving torque to the front and rear wheels according to the vehicle's driving conditions.

[LeChristopher]

I've been driving off-road for a while and 4WD stands for four-wheel drive, which basically sends power to all four wheels instead of just two. This setup gives much better traction on slippery surfaces like snow, ice, or mud, making it easier to navigate tricky terrains without getting stuck. For instance, when I take my vehicle through muddy trails or snowy roads, I feel confident it won't skid. Most modern systems allow you to switch between 2WD for fuel-saving on highways and full-time 4WD when needed. Some models even have automatic sensors that engage it only if slippage is detected, adding convenience. Overall, it's a game-changer for those who deal with unpredictable weather or enjoy adventures away from paved paths, boosting safety and control.