Purpose of lubrication. Lubrication (oiling) belongs to the basic maintenance procedures and should be performed systematically and rationally. The purpose of lubrication is to reduce friction between mating surfaces, which protects them against too fast abrasion and increases the efficiency of the machine, by reducing energy losses to overcome frictional forces. Moreover, lubrication (especially oiling, i.e.. lubrication with liquid lubricant) facilitates the dissipation of heat generated by friction.
The machine should be thoroughly cleaned before lubrication. The lubrication intervals must also be strictly adhered to and only the lubricant specified in the machine's manual should be used. Irrational lubrication contributes to the rapid wear of the mechanisms.
Types of lubricants. Liquid lubricants are used for lubrication (oils) or permanent (lubricants).
Oils include petroleum products and synthetic ester and polysilicon oils. The main criteria for judging oils are: density, viscosity, flash-point, temperature of solidification, acidity and ash content. There is a general rule when choosing an oil: the higher the sliding speed (the larger the diameter of the shaft and journal) or the lower the load on the sliding surfaces, the lower the viscosity of the oil should be. Lubricants are made of mineral oils and thickeners, which are generally soaps. Multi-purpose greases are made with calcium soaps. Mechanisms operating at high temperatures are lubricated with high-melting greases, containing sodium soaps as thickeners. Certain types of solid lubricants, intended for time maintenance of metals and metal products, do not contain soap, treat cresin and paraffin. These lubricants are called petroleum jelly.
Lubrication methods. Oil is mainly used to lubricate plain bearings. We distinguish between supply and circulating oil. The tributary oil is about this, that the oil from the appropriate reservoir - the lubricator - flows in a manner dosed into the pan.
Oil lubricators: a) orifice wick, b) siphon wick, c) needle, d) float, e) circulator with a lubricating ring
Circulating oil (circulating) is based on the use of the so-called. pump lubrication system or self-lubricating rings (drawing e). The grease ring hangs loosely on the pin. The lower part of the ring is immersed in the oil. The rotating spigot carries the ring with it, which in turn grabs the oil and transfers it to the plug. Lubricators can supply oil to a single point or through lines to multiple points (central lubrication).
Solid grease is used to lubricate slow-running plain bearings and roller bearings, joints, etc.. Grease guns can be self-acting or pressure-operated.
Self-acting grease nipples: a) high-melting grease tank, b) tank for low-melting grease, c) hooded (Stauffera), d) piston-spring.
In these lubricators due to spring pressure, Due to the centrifugal force or the pressure caused by the hand tightening of the cover, the grease is forced onto the pin. Some machines use circulation pumps for grease. Hood grease guns are often used in catering machines (Stauffera).