O’zbekistоn respublikasi оliy va o’rta maxsus ta`lim vazirligi

Figure 10.2 Scheme of the crystal lattice of graphite
They are divided into animals (beeswax, spermaceti, lanolin, etc.), vegetable (carnauba wax), mineral (ozocerite). Fats are substances of vegetable (so-called fatty oils) or animal origin, mainly esters of glycerol and monobasic fatty acids (triglycerides).
Polymers are classified as solid lubricants on the basis that the mechanism of their lubricating action consists in the formation and continuous renewal of transfer films on friction surfaces, which are formed from the products of mechanical destruction of macromolecules. From the point of view of tribology, the most interesting are fluoroplasts - polymers and copolymers of halogen derivatives (F, Cl) of ethylene and propylene. The coefficients of friction of fluoroplastics during sliding and dynamic friction are equally small, which ensures the smoothness of slow movements of movable mates. A feature of fluoroplastics is their exceptionally high chemical inertness in most working environments.
10.3 Lubrication
During the operation of friction units, lubricants undergo physical and chemical transformations and pass into sludge , decrease due to leaks, evaporate, burn out, etc. These losses are compensated by continuous or periodic lubrication of the friction surfaces.
Pressure lubrication is the most common type of lubrication in mechanical engineering, when a liquid or plastic lubricant is injected into the gap of a friction pair. If oil is pumped through the gap between the shaft and the bearing at a pressure greater than the load on the bearing, hydrostatic lubrication is realized and the shaft "floats" above the support, reducing friction. With a grease, only the layer near the friction surface becomes clogged. Injection of fresh material moves the spent layer, forcing it out of the gap. This type of lubrication is mainly used at low friction speeds.
Splash lubrication is carried out with lubrication with liquid lubricants, using the energy of the moving parts of the friction unit.
Oil mist lubrication is a type of lubrication in which a gas flow mixed with dispersed oil is directed onto the friction surface. This is how the cylinder walls in compressors and internal combustion engines are lubricated.
Immersion lubrication occurs when the friction surface is partially or completely, permanently or intermittently immersed in a bath of lubricating fluid.
Packing lubrication is performed using a capillary-porous part impregnated with lubricant, which is in contact with the friction surface. An example is the axle box lubrication system for wagon axles.
Rotaprint lubrication - the formation of a lubricating layer on the friction surface using a briquette of solid lubricant in contact with the abraded part (Fig. 10.3). The lubricating film is formed by a transfer mechanism and is renewed by friction.