Fyrhjuls

Fyrhjuls is a Swedish term associated with the configuration and drivetrain in which torque is delivered to all four wheels of a vehicle. In common automotive usage, the term is closely linked to fyrhjulsdrift, or four-wheel drive (4WD), and is used to describe systems designed to improve traction on slippery or uneven surfaces compared with two-wheel-drive configurations.

Originating from the Swedish words fyr (four) and hjul (wheel), the compound is used in phrases such as fyrhjulsdrift and fyrhjuls. In everyday language, fyrhjuls often appears as part of these terms rather than as a standalone drivetrain label.

Most four-wheel-drive systems use a transfer case to distribute torque between the front and rear axles. Permanent four-wheel-drive keeps torque distributed at all times; part-time or on-demand systems engage four-wheel drive when slip is detected. Distribution can be equal or biased, often toward the front axle. Some systems use center differentials, viscous couplings, or electronically actuated clutches to vary torque.

Found in passenger cars, SUVs, trucks, and off-road vehicles, four-wheel-drive systems provide benefits such as improved grip in rain, snow, and mud, as well as advantages in towing. Downsides include increased weight, mechanical complexity, potential for higher maintenance costs, and slightly worse fuel efficiency when four-wheel drive is not needed.

In Sweden and other Nordic countries, four-wheel drive has been popular for winter driving conditions. Related terms include framhjulsdrift (front-wheel drive) and bakhjulsdrift (rear-wheel drive).