Rolling-element bearings help rotating parts run smoothly by providing support and alignment while reducing noise, vibration, and wear. They consist of a series of ball or roller elements that ride along the internal surface, or raceway, of the bearing's inner and outer rings. Ball bearings have a smaller contact surface with the bearing raceway which reduces friction and allows the bearing to run at higher speeds at lower load capacity than roller bearings. Roller bearings have cylinder-shaped rolling elements that have a wide contact surface with the raceway allowing them to support heavy loads. Mounted rolling-element bearings have a housing or flange that mounts to a surface and supports the shaft running through the bearing. Thrust bearings support axial loads in a single direction and mount perpendicular to the shaft to support light-load rotating parts to reduce misalignment. Combination bearings handle radial and axial loads in installations where multiple bearings take up too much space, or the axial loads and speeds are too high.