Bearings is to prevent direct metal to metal contact between two elements that are in relative motion. This prevents friction, heat generation and ultimately, the wear and tear of parts. It also reduces energy consumption as sliding motion is replaced with low friction rolling.
They also transmit the load of the rotating element to the housing. This load may be radial, axial, or a combination of both. A bearing also restricts freedom of movement of moving parts to predefined directions as discussed above.
Rolling Element Bearings
Rolling element bearings contain rolling elements in the shape of balls or cylinders. We know that it is easier to roll a wheel than slide it on the ground as the magnitude of rolling friction is lower than sliding friction. The same principle is in work here. Rolling element bearings are used to facilitate the free movement of parts in rotational motion.
Even when we need linear motion in applications, it is easy to convert rotational motion to sliding motion. Consider an escalator or a conveyor. Even though the motion is linear, it is powered by rollers that are driven by motors.
Advantages of ball bearings:
- Good wear resistance
- Do not need much lubrication
- Provide low friction, thus little energy loss
- Long service life
- Easy to replace
- Small general dimensions
- Comparatively cheap
- Can handle thrust loads
Disadvantages of ball bearings:
- May break due to shocks
- Can be quite loud
- Cannot handle large weights