The history of bearings
The prototypes of the modern bearings greatly facilitates the lives of people in ancient times. The device is vaguely reminiscent of the bearings, found during archaeological excavations, which have for the Neolithic period. During this period, people just learned how to make holes in the stone rocks. Material for their manufacture of course was the stone used simple fixture for drilling and hand-spinning. Later found application in more complicated mechanisms: carts, pottery wheels, windmills.
It is believed that the first device, which is a precursor of bearing, invented in Ancient Greece, 330 years B. C. E. the Author was a military engineer and inventor Dyad. The design was a ramming mechanism for the destruction of the fortress walls. It was located on the rollers, which movement was carried out through grooves located in the bottom of the device.
Analog ball bearing was born during the reign of Roman Emperor Caligula. During the excavation belonging to this period, archaeologists found the ship, which found mechanisms with rotating discs. In the first case the rotation of one of the circle was carried out with a focus on wheels, fixed in the circumference of the other. In the second device instead of wheels used balls, each attached to a rotating axle. In the third case, the use of rollers of wood, its form resembled a truncated cone. The design of the turntable with spherical elements was much cheaper compared to cylindrical. The find is the earliest version of modern bearing constructions.
During the construction of the windmill in the late 18th century English Sprowston was constructed mechanism, which was the first representative of a metal bearing. The device comprised two cast-iron roller path. Between them is forty bullets cast from the same material.
By 1945 can be attributed to the emergence of oil-free bearings based on the application of the cermet. They were made of porous metal, nadyshavshis special grease, or bronze with graphite. Devices of this type can for a long period work properly in small machines and mechanisms.
The next step in the improvement of design characteristics has been the development of hybrid systems. Usually, to improve the strength characteristics of high-speed bearings, used grooved beads, and the beads are light weight. An alternative option may be the possibility of combining the ball and the hydrostatic mechanism in which the load is taken by a thin layer of liquid. The load in this design is distributed equally between work items. This ratio can lead to a tenfold increase in the strength characteristics of such a device in comparison with a conventional bearing under the same operating conditions.
- Until the end of the 20th century. the main material used for the production of bearings were steel. The metal had gone through various stages of modification due to the constantly growing requirements. It should be noted that the scope of steel products was limited to certain conditions, which determined the physical properties of the metal:
- thermal expansion;
- low corrosion resistance;
- a high coefficient of friction.
Additional impulse for development has provided a synthetic ceramic silicon nitride. First, it applied only to rolling elements. After some time it started construction of bearings that are made completely from ceramic materials.
High-speed single-row cylindrical bearing is a Prime example of such a device. It has a top speed almost 2 times more than its metal prototype.