4WD stands for “four-wheel drive,” which is a drivetrain configuration commonly used in vehicles, especially off-road vehicles and trucks. Here are some main facts about 4WD:

1. Drivetrain Configuration: A 4WD vehicle is designed to deliver power to all four wheels simultaneously. It typically consists of a transfer case, which distributes power from the engine to both the front and rear axles.
2. Traction and Off-Roading: The primary purpose of 4WD is to improve traction and handling in challenging terrain, such as off-road trails, snow-covered roads, or slippery surfaces. By powering all four wheels, a 4WD vehicle can distribute torque more evenly, reducing the chances of getting stuck or losing control.
3. Selection Modes: Most 4WD systems offer different operating modes to adapt to various conditions. Common modes include:
   • 2H (Two-Wheel Drive High): Power is sent only to either the front or rear wheels, providing better fuel efficiency during regular driving conditions on paved roads.
   • 4H (Four-Wheel Drive High): Power is distributed to all four wheels, allowing increased traction. This mode is suitable for off-road driving or when additional traction is required on slippery surfaces.
   • 4L (Four-Wheel Drive Low): This mode provides maximum torque and is intended for extreme off-road conditions, such as steep inclines or deep mud. It reduces the vehicle’s speed but increases its pulling power.
4. Differential Lock: Some 4WD systems offer differential lock functionality, which helps improve traction even further. When engaged, the differential lock ensures that power is evenly distributed between the left and right wheels on each axle, preventing wheel spin.
5. Fuel Efficiency and Handling: 4WD vehicles typically consume more fuel than their two-wheel drive counterparts due to the added mechanical components and power distribution to all wheels. However, advancements in technology have led to the development of more efficient 4WD systems, reducing the fuel consumption gap between 2WD and 4WD vehicles. Handling and maneuverability can be slightly affected in 4WD mode, particularly on paved roads, due to the increased weight and drivetrain complexity.
6. All-Wheel Drive (AWD) vs. 4WD: While 4WD and all-wheel drive (AWD) are often used interchangeably, there is a technical distinction. AWD systems are typically designed for on-road use and continuously vary the power distribution between the front and rear wheels based on traction conditions. On the other hand, 4WD systems are typically manually selectable and intended for off-road use, providing more control over power distribution.

It’s worth noting that specific details and features of 4WD systems can vary between different vehicle manufacturers and models. It’s always recommended to consult the vehicle’s owner’s manual or manufacturer’s information for precise operating instructions and specifications.