A universal joint, often shortened to u-joint, is a flexible coupling that allows for power transmission between two rotating shafts that are not perfectly aligned. These joints are crucial components within drivelines, connecting the transmission to the differential. They accommodate the vertical movement of the rear axle relative to the transmission, especially important in vehicles with suspensions that allow for significant wheel travel. A typical driveline uses two or more of these joints.
These components are essential for smooth power delivery in vehicles. Without them, vibrations and binding would occur, especially during acceleration or when the suspension articulates. Their development enabled the practical use of rear-wheel and four-wheel drive systems. Historically, simpler, less flexible couplings were used, but they were often prone to failure under the stresses of varying angles and speeds. Universal joints provided a more robust and efficient solution, greatly improving vehicle drivetrain reliability and performance.
