In the world of our daily life, behind almost all objects that can rotate, there is an unknown yet crucial mechanical component – the bearing. From the high-speed wheels of Mercedes Benz cars, the rapid operation of computer hard drives, to the gentle breeze of household fans, and even children’s scooters and toy four-wheel drive cars, bearings are everywhere. It may seem simple, but with its ingenious working principle, it greatly reduces friction and carries loads, making it the cornerstone of modern industry. So, how do bearings actually work?
1、 Core mission: Replace “sliding” with “rolling”
To understand the working principle of bearings, we first need to understand the fundamental problem they aim to solve: friction.
Imagine what it would be like if there were no bearings and a heavy wheel were directly rubbing against a metal shaft to rotate? It requires tremendous force to start, and a large amount of heat and wear will be generated during operation. Not only is the efficiency extremely low, but both will also be quickly scrapped.
The birth of bearings is precisely to solve the huge resistance of “sliding friction”. Its core idea is very clever: using “rolling friction” instead of “sliding friction”. The resistance of rolling friction is much lower than that of sliding friction, which can significantly reduce energy loss, minimize wear, and allow equipment to operate at higher speeds.
2、 Basic structure and classification of bearings
A typical rolling bearing (such as a deep groove ball bearing) typically consists of four basic parts:
Outer ring: Installed on the bearing seat or housing, usually fixed and immovable.
Inner ring: installed on a rotating shaft and rotates together with the shaft.
Rolling element: It is a component located between the inner and outer rings that truly achieves “rolling”. They can be different shapes such as balls (steel balls), cylindrical rollers, tapered rollers, or needle rollers. The type of rolling element determines the main type and load-bearing characteristics of the bearing.
Retainer: Used to evenly separate the rolling elements, prevent them from colliding and rubbing against each other, and guide the rolling elements to move on the correct track.
According to the different rolling elements, bearings are mainly divided into:
Ball bearing: The rolling element is spherical. Strong universality, suitable for withstanding radial loads (forces perpendicular to the axis) and certain axial loads (forces along the axis, also known as thrust), with good high-speed performance.
Roller bearings: The rolling elements are cylindrical, conical, or drum shaped. Compared with ball bearings, they have a larger contact area with the raceway, so they can withstand heavier radial loads, but their high-speed performance is slightly inferior.
3、 Detailed analysis of working principle
The working process of bearings is a precise mechanical collaboration:
1. Load bearing capacity:
When the shaft is subjected to force from equipment such as wheels or gears, this force is transmitted to the inner ring of the bearing. The inner ring transmits force to the outer ring through the rolling elements, and ultimately distributes it to the entire machine structure through the outer ring and bearing seat. This process smoothly supports the rotating components.
2. Reduce friction:
This is the most exciting part. When the shaft drives the inner ring to rotate, the inner ring does not directly rub against the outer ring, but rather presses the rolling elements to drive them to roll along the carefully polished raceways (smooth grooves) on the inner and outer rings.
Due to rolling, the frictional resistance becomes very small.
The cage ensures even distribution of rolling elements, avoiding congestion and mutual sliding, further reducing friction.
3. Ensure accuracy and smoothness:
High precision bearings have extremely small machining errors in the raceways and rolling elements of their inner and outer rings. This ensures that the center position of the rotating shaft is very stable, without severe shaking or eccentricity, thus achieving smooth and quiet operation, which is crucial for precision machine tools, hard disk drives, and other equipment.
4、 Not just rotation: other functions of bearings
In addition to the core functions of reducing friction and supporting loads, bearings also undertake other important responsibilities:
Transmission of power: In equipment such as gearboxes, bearings ensure that gears remain in the correct position and mesh, thereby efficiently transmitting power.
Reduce wear and extend lifespan: By protecting the shaft and bearing seat from direct wear, bearings greatly extend the lifespan of the entire equipment.
Bearing axial force: For example, thrust bearings are a type specifically designed to withstand strong axial forces, commonly found in scenarios such as automotive transmissions and ship propeller shafts.
Conclusion
In summary, the working principle of bearings is a model of “four or two strokes of a thousand pounds” in ergonomics. It does not use complex technology, but instead adopts a clever idea of “rolling instead of sliding”, which transforms harmful friction into efficient rolling through the clever combination of inner and outer rings, rolling elements, and retainers. It is this tiny rolling that carries the enormous load of modern industry, enabling our world to operate smoothly and efficiently. It is undoubtedly one of the greatest inventions hidden inside the machine.
