How roller bearings differs from ball bearings?

Have you ever wondered what the difference was between roller bearings and ball bearings? At first glance they may not seem all that different. However, these seemingly similar style bearings have very different uses. 

 

Why we need bearings?

A shaft is used to transfer power from one point to another. For example, one end of the shaft is connected to an electric motor and the other end to a belt or any other component where you want to transfer the power. Because of the movement, the shaft would be under different kinds of loads like axial load and radial load. There would be possible up and down deflection of the shaft and jerks while moving. Due to this vibration, the load transfer does not happen properly. To resolve this issue what we need is a continuously moving support, which is called bearings.
Bearing is a machine component that supports the machine element and permits relative motion between the contact surfaces of the members while carrying a load.

Bearings all essentially consist of a set of rolling elements fitted between the two rings, inner and outer. This arrangement allows the bearing to take up the load while in operation. The bearing will rotate or roll when the load is applied in case of radial load and it can take up thrust load too.
Being in use for many years, bearings are evolved into many different types depending upon the requirement of the machine and the operation. When the loading is perpendicular to the axis of the shaft it is called a Radial load. When loading acts parallel to the axis of the rotating shaft, it is Axial /Thrust load.

 

 

Ball Bearings

Ball bearings are most common type of bearing and can handle both radial and thrust loads. Ball bearings are also known as deep-groove single-row or Conrad bearings. The inner ring is typically fastened to the rotating shaft and the groove on the outer diameter provides a circular ball raceway. The outer ring is mounted onto the bearing housing. The ball bearings are housed in a race and when the load is applied, it is transmitted from the outer race to the ball and from the ball to the inner race. The raceway grooves have typical curvature radii of 51.5% to 53% of the ball diameter. Smaller curvature raceways can cause high rolling friction due to the tight conformity of the balls and raceways. Higher curvature raceways can shorten fatigue life from increased stress in the smaller ball-race contract area.