U-Joints

U-joints, or universal joints, transmit rotational power through an angle between two shafts. Commonly found in driveshafts connecting the transmission to the differential in rear-wheel and four-wheel drive vehicles, they accommodate misalignment caused by suspension movement and differing component positions. These joints utilize yokes, a cross, and needle bearings to facilitate smooth rotation while allowing for angular displacement. Constant-velocity (CV) variants minimize speed fluctuations and vibration compared to traditional single U-joints. Failure modes typically involve bearing wear, yoke damage, or cross failure, resulting in driveline vibration and potential loss of power.