allhjulsdrift

Allhjulsdrift, or all-wheel drive, is a drivetrain configuration that sends power to all four wheels in a vehicle. It is designed to improve traction, stability and handling on surfaces with limited grip, such as wet, snowy or uneven roads. Allhjulsdrift is commonly found in passenger cars, crossovers and some light SUVs. In Swedish automotive terminology, fyrhjulsdrift is often used to describe more rugged off-road four-wheel-drive systems, while allhjulsdrift typically refers to on-road AWD setups, though the distinction varies by manufacturer.

How it works

Most allhjulsdrift systems transmit engine torque from the transmission to both axles via a center transfer mechanism or differential. Permanent AWD uses a center differential to allow front and rear wheels to rotate at different speeds while sharing torque. Some systems use an electronically controlled clutch or multi-plate mechanism to vary torque distribution in real time. On-demand AWD engages the second axle automatically when slip is detected, while the vehicle remains primarily driven by two wheels under normal conditions. Modern systems often integrate with stability control and may include torque vectoring to improve cornering response.

Technologies and configurations

Common approaches include mechanical center differentials (e.g., Torsen), viscous couplings and electronically controlled clutch packs (such as Haldex-type systems). Torque vectoring and sophisticated control algorithms further adjust power between axles to optimize grip and handling. The choice of system influences efficiency, on-road feel, and capability in low-grip conditions.

Advantages and considerations

Benefits include improved traction, acceleration and braking in adverse conditions, and enhanced cornering stability. Drawbacks can include higher weight, greater mechanical complexity, potential impact on fuel economy, and varying levels of off-road capability. Maintenance may involve periodic checks of fluids in differentials or transfer mechanisms.