Tribologie S

SAE
Society of Automotive Engineers. International society of over 83,000 engineers from 97 countries, which exchange know-how in the fields of automotive engineering, aerospace, engines, commercial vehicles, production, fuels and materials.
More at www.sae.org/about/

SAE classes
Classification of viscosity classes for vehicle lubricants - see tables below.
 

Selective solvent refining
Refining using solvents (duo-sol, Edeleanu, furfurol processes, etc.); undesirable hydrocarbon compounds are released from the individual hydrocarbon types and separated.
 

Self-ignition point
Is the temperature at which a flammable substance will ignite without external ignition, depending on the conditions (temperature, pressure, etc.) and the oxygen content of the surrounding air.
 

Sewing machine oils
Very thin-bodied technical white oil, 7 to 12 mm2/s at 40°C, often contains solid additives.
 

Shear stability
Viscosity index improvers (polymers soluble in oil) are added to lubricating oils, hydraulic oils, etc. to improve the viscosity-temperature characteristics. Some of these polymer molecules, which have linear, lattice or net structures, have a huge molecular structure in the high-temperature range (macro molecules) and then change or break their molecular structure when exposed to shear forces, as occur in gears or hydraulic systems. Here there is a loss of viscosity to a greater or lesser extent. Checking.
 

Silicone
Silicone oxide compounds, which exist in forms that range from viscous to solid. The various viscous silicones are generally colourless oils with very good viscosity temperature properties. They are used as additives, synthetic oils, hydraulic oils, insulating agents, etc. in the mineral oil industry. Solid silcones are very resistant to temperature.
 

Sludge formation
Ageing of mineral oils. The influence of air and water may cause mineral products to form oxidation substances and polymerisation may occur; if this problem is pronounced, these oxidation products are no longer dispersed in oil so they solidify and form sludge.
 

Sodium complex soap lubricating grease
Has good lubricating characteristics, with good adhesion and especially low oil separation, thus making it particularly suitable for fast-running bearings. It is, however, very sensitive to water.
 

Sodium lubricating grease
Lubricating grease made of sodium soap and mineral oils; can be used up to operating temperatures of 120°C. Sodium lubricating greases are emulsfiable and must not be used at wet lubricating points. They are very suitable for lubricating gears and as fluid gear greases in NLGI classes 0,00,000.

SOLID LUBRICANTS
Is generally only used and required for lubricating tasks under extreme conditions (e.g. for operation in mixed friction areas). The best known are graphite, molybdenum disulphide and plastics such as polytetrafluoroethylene, etc. These are applied directly in powder form, in suspensions, pastes, metallic films, paints and plastics.
 

Solvates
Solvent-neutral oils, solvent raffinates, mineral oils refined with solvents.
 

Soot
Pure amorphous carbon, which is produced by incomplete combustion of fuels containing carbon.shear stability: DIN 51 382; CEC L-14-A-88; L-25-A-78; L-37-T-85; L-45-T-92.
 

SPARK-EROSION OILS
Are used as dielectric materials during spark-erosion machine operations on what are generally very hard metals. They must provide good insulation, cool the tool and workpiece and they should be readily ionisable. Some of the points that good products feature are: very little volatility, high flash point, oxidation stability, non-aggressive to the skin and seals, chemically neutral, highly refined, low in aromatics. Viscosity is approx. 2 to 4.5 mm2/s at 40°C.
 

Specification
Specifications for lubricants and fuels in which physical characteristics, chemical characteristics and test methods are specified.
 

Spectroscopy
Radiation energies of various wavelengths, e.g. infra red rays, cause hydrocarbon molecules to reflect radiation which varies according to the molecule and thus allow the structure of the molecule or additives or metal abrasives to be identified.
 

Spindle oils
Thin-bodied lubricating oil for lubricating spindles in textile machines; viscosity around 10 to 80 mm2/s at 20°C. Also lubricants to lubricate and cool electrically powered spindles in machine tools, etc.
 

SPRING GREASES
Lubricating greases to lubricate leaf springs, generally containing MoS2 or graphite.
 

Stabilisers
Active ingredients, inhibitors which protect the medium from ageing.
 

Stick-slip additives
Additives (friction-modifying active ingredients) added to gear oils and other lubricants in order to prevent stick-slip effects – e.g. for slideways on machine tools – at very low speeds.
1 St (Stokes) = 1 cm2/s = 100 cSt = 100 mm2/s
 

Stokes
Unit to measure cinematic viscosity
 

Super Tractor Oil Universal - STOU
Hydraulic oil for engines and gearboxes for universal application in as many engines, machines, devices and units as possible, in particular with wet brakes and clutches in agriculture and the construction industry. To streamline types and prevent different lubricants from mixing when different items of equipment are connected together.
 

Synthetic lubricants
These lubricants are developed for special technical applications and special requirements. Nowadays they are specified for high-performance engines and aggregates and also for special purposes, for instance requirements such as fire resistance, high-temperature stability, low-temperature performance, resistance to radioactive radiation, volatility loss, resistance to oxidation (complying with service life), high-pressure stability, viscosity temperature characteristics, etc.
The response of additives for the various synthetic lubricants is very different and results in the development of new additive combinations, which in some cases can only be used for certain synthetic lubricants. The following synthetic lubricants are used: Polyalkylene glycols, synthetic hydrocarbons
(e.g. polyalphaolefins, dialkylbenzole, polyisobutylene), dicarbon acid and polyalcohol ester, phosphoric acid ester, silicone, polyphenyl ether, fluorocarbons, etc.