Do you want to know such devices as straight pulleys and electric motors, why can you rotate quietly and smoothly? The answer lies in a small mechanical device - bearing.
The bearings allow our daily machines to function properly. If there is no bearing, we may need to constantly replace those parts that are easy to wear. In this paper, we will understand the working principle of bearings and various types of bearings, explain its general purpose, and explore other related applications of bearings.
Bearing the principle of bearing
The principle of the bearing is very simple: the object rolling is easier than sliding. Car wheels are like large bearings. If you use a sled instead of a wheel, it is much harder for the car to move on the road.
This is because when the object slides, the friction between the two objects produce friction to slow the sliding speed. But if the two objects can roll each other, the friction will be greatly reduced.
The bearings use smooth metal balls or rollers as well as lubricated inner and outer metal surfaces to reduce friction. These balls or rollers "carry" the load so that the device can rotate smoothly.
Bearings usually carry two loads, radial loads and axial thrust loads. Depending on the position of use, the bearing may be subjected to radial load, axial thrust load, or a combination of both.
The electric motors and the bearings used in the pulleys shown above only carry radial loads. In this case, the main load comes from the tension of the strap connecting the two pulleys.
The bearings in the figure above are similar to those used in bars and high stools. Only in the axial load, all the load from the weight of the person sitting on the stool.
The bearings in the figure above are similar to those used for automotive wheels. This bearing needs to support radial load and axial thrust load. The weight of the vehicle produces a radial load, and the steering force at turn produces an axial thrust load.
There are many types of bearings, each with its own different uses. Including ball bearings, roller bearings, thrust ball bearings, thrust roller bearings and thrust tapered roller bearings.
As shown below, the ball bearing may be the most common type of bearing. From the straight pulley to the hard drive, many items are used in ball bearings. This bearing can carry radial load and axial thrust load, usually used in the case of relatively small load.
In the ball bearing, the load from the outer ring to the ball, and then from the ball to the inner ring. Because the ball is spherical, with the inner and outer ring contact point is very small, which helps to smooth rotation. But this also means that there is not much contact area to bear the load, so if the bearing overload, the ball will be deformed or flattened, resulting in bearing damage.
As shown in the figure below, the roller bearings are used in the conveyor belt to carry a very heavy radial load. In these bearings, the roller is a cylinder, so the contact between the inner and outer rings is not a point but a line. This will load the load to a larger area, the bearing can carry a much larger load than the ball bearing. However, the design of such bearings can not be used to carry a large axial thrust load.
A variant of this type of bearing is called a needle roller bearing, using a very small diameter cylinder. In this way, the bearings can be installed in a limited space.
Thrust ball bearings
As shown below, thrust ball bearings are often used for low-speed rotation, can not carry a large radial load. Bar high stool and Lazy Susan turret are used in such bearings.
As shown in the figure below, the thrust roller bearing can carry a large axial load. Commonly used between gears and between gears and gears, such as automotive transmissions. The teeth of the helical gears used in most transmissions have a certain angle - the resulting axial thrust must be supported by the bearing. Thrust roller bearings
Thrust tapered roller bearings can carry large radial loads and axial thrust loads. The following figure shows a cross-sectional view of the thrust spherical roller bearing (left) and radial tapered roller bearing (right). Thrust tapered roller bearings
Tapered roller bearings are used in automotive axles and are usually mounted in pairs in reverse direction to carry thrust in both directions.
Special type of bearing
The following will introduce you to several different bearings, each with its associated applications, including magnetic bearings and large roller bearings.
Some very high speed devices, like advanced flywheel energy storage systems, will use magnetic bearings. This type of bearing allows the flywheel to be suspended in the magnetic field generated by the bearing.
Some flywheels rotate at a high speed of 50,000 rpm (rpm) per minute. Ordinary roller bearings or ball bearings will melt or explode at this speed. Magnetic bearings have no moving parts and are therefore able to withstand such fast speeds.
Large roller bearings
The earliest use of this bearing back to the Egyptian construction of the pyramid. They put the logs under a heavy stone and then rolled the logs to transport the stones to the building site.
Now this method is still in use for moving large, heavy objects such as the Hartlas Point Lighthouse.
The new San Francisco International Airport uses many advanced building technologies to enable buildings to prevent earthquakes. One of the technologies includes a large ball bearing.
Support the airport weight of 267 cylindrical, each are erected in the diameter of 1.5 meters on the ball bearing. The steel balls are located in a concave base connected to the ground. In the event of an earthquake, this device allows the ground to move 51 cm in any direction. The cylinders above the balls move smaller than this distance because they roll around the base, which helps protect the building from ground movement. After the end of the earthquake, gravity will pull the cylinder back to the center of the base.