Bearings

Bearings we call machine parts, whose task is to support axles and shafts or moving parts mounted on them. Bearings reduce the frictional force between a rotating axle or shaft and the seat, in which they are embedded. Each bearing consists of two essential components: body and a seat properly seated in it, which is used to support the pin. A distinction is made between resting and motion bearings, these, in turn, can be sliding or rolling. In slide bearings, the surfaces slide at the contact point of the journals and seats. In rolling bearings between the surfaces of journals and seats there are rolling elements in the shape of balls or rollers.

Depending on the direction of the transferred forces, the bearings are divided into transverse ones (radial) and longitudinal (thrust) and transverse-longitudinal (radial-thrust).

W plain bearings the axle and shaft journals rest in separate pieces, called panes, seated in the bearing seats. Lord knows they can be completely made in the form of bearing sleeves, bipartite or consist of several parts.

Plain bearings: a) transverse (radial) shared, b) transverse-longitudinal horizontal (radial-thrust), c) transverse-longitudinal vertical with a stop plate.

In machine bearings with low rotational speeds and transmitting small moments of force, working periodically, the bushings can be turned directly into the material of the machine hull, poured with the correct alloy (most often bronze) or bolted to the hull with bolts. Such bearings are called non-split. If the shaft rotation is continuous, split bearings are used. Such bearings have a horizontal parting plane and the cover is connected to the body by bolts. The disadvantages of plain bearings are: considerable dimensions in the direction of the shaft length, high lubricant consumption and high power losses to overcome frictional resistance, the advantage is their simple structure. Shaft shells and journals wear in plain bearings. Split bushes are most often made of cast iron, cast steel or forged steel, and the small bushings - from the so-called. yellow alloy. The bush is poured with a tin bearing alloy (80% Sn, 10% With i 10% Sb), lead acid (5% Sn, 15% Sb, 1,5% Cu i reszta Pb) or zinc. Special bearing bronzes are used for the production of non-split bushings. The bushes are poured with a thin layer of alloy, in the order of a few mm, which makes it possible to carry heavy loads. The bearing alloys are abrasion resistant, have a low coefficient of friction in cooperation with steel, and their mechanical properties do not change under the influence of temperature increase.

Rolling bearings depending on the shape of the rolling elements, it is divided into ball and roller, the term rollers is understood as meaning elements with shapes: cylindrical, conical, barrel or needle roller.

Types of rolling bearings: a) single-row cross ball bearings, b) oblique single row ball bearings, c) double row self-aligning ball bearings, d) thrust ball bearings, e) ball and thrust pivoting, f) cylindrical, g) barrel, h) transverse-longitudinal conical, i) cross-needle.

Depending on the direction of the transferred forces, rolling bearings are divided into transverse ones, longitudinal and oblique.

The rolling bearing consists of two rings – internal and external (figure a), in which the raceways for the rolling elements are made (balls, rollers) enclosed in the baskets that guide them. The inner ring of the bearing sits firmly on the shaft journal, and the outer ring, also still, in a suitable housing. This way, the journal is not rubbed when the shaft rotates, as is the case with plain bearings, but the intermediary elements (rolling) and their treadmills.

Self-aligning bearings allow slight deflections of the shaft embedded in them.

Shaft bearing in self-aligning bearing.

Rolling bearings are standardized and produced in a very wide range. The basic dimensions of the bearings are: d, D and B standardized worldwide. Rolling bearing catalogs contain a set of bearings marked with appropriate symbols, which define unequivocally; type, typ, variety, the form and size of the placenta.

The advantages of rolling bearings are: low friction, possibility of carrying heavy loads, easy replacement during repair. However, their disadvantage is that they work noisily than with plain bearings.

Rolling bearings are used in numerous catering machines (wilk, cutter, cake mixer etc.).