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German to English: Schmieröl PDF General field: Tech/Engineering Detailed field: Petroleum Eng/Sci
Source text - German Schmieröl PDF.
Translation - English Y. Saheem/ Schmieröl/ translation D - E
07.07.2009
Gearboxes and mechanical transmission systems
Vehicles are fitted with manual, automatic, split and axle mounted gearboxes. In order to provide guaranteed faultless operation over the whole period of use, a special transmission oil is needed for each particular unit. For this reason, today’s transmission oils form an integral part of the design process. The following characteristics of a transmission oil have to be considered:
Transmission oils: reliable operation
Lubrication, shear stability, reliable wear protection of components and seals, anti-foaming, temperature control, corrosion protection, load bearing, prevention of pitting, contaminant dispersal, sensitivity to seals, sensitivity to metals, mixing with other lubricants.
Gear changes and synchronisation properties
Quick, smooth and easy gear changing at all engine speeds and temperatures.
Noise attenuation
Transverse and in-line gearboxes
Avoidance of noises during tick-over and normal operation, low noise at high and low temperatures, engine speeds and loads.
Efficiency and functionality
A lengthening of the oil change intervals means increasing demands on the oils, i.e. unvarying operation over the period of service, high thermal and oxidative stability during long periods of operation and the optimisation of friction characteristics to reduce energy losses.
Cold starting
wear-free starting characteristics at low temperatures
Environmental considerations
Emissions reduction by improving the overall efficiency
Problem-free disposal (free from chlorine and heavy metals)
Recycling ability (no special disposal requirements)
Specifications
Along with the rules and regulations impacting on the automobile and supplier industries, the guidelines of the American Petroleum Institute (API) for transmission oils are also applicable. However, the API classification can only offer a rough classification because the requirements of modern transmission oils are very complex.
API classification
A description of the service requirements for American automobile transmission oils follows. The GL grades do not indicate any quality features.
GL- 1 For bevel gears, worm gears, and manual change gears with low sliding speeds and minimum surface pressures on the teeth flanks. It fulfils the lubrication requirements without the need for wear protection additives.
GL- 2 Worm drive gears with requirements on load bearing properties, temperature levels and sliding speed which the GL -1 specification cannot fulfil.
GL- 3 For bevel gears and manual change gears under medium operating conditions with respect to load and engine speed. Oil with mild wear protection additives.
GL- 4 Inline and transverse gears, also with slight axis misalignment. Transmission oils to API GL-4 specification are used typically in modern transverse mounted transaxle transmissions.
GL- 5: Hypoid gears (offset shafts with large axis misalignment) in cars and other vehicles subject to shock loads at high engine speeds. Today, API GL-5 transmission oils are the preferred choice for rear axle differentials.
In practice, only API GL-3, GL-4 and GL-5 transmission oils are used today.
Torsen differentials require API GL-5 transmission oils
Limited slip differentials require GL-5 transmission oils with additional LS performance (LS = limited slip). Noise will occur when cornering without the additive.
Can API GL-3/GL-4 be used instead of GL-5 transmission oil?
A modern manual change gearbox transmission oil must on the one hand be synchromesh-friendly and on the other, resistant to high pressures and surface loading in order to avoid wear and pitting etc. therefore a balance must be found since with increasing anti-wear and extreme pressure (EP) performance, the synchromesh properties of a manual-change gearbox transmission oil deteriorate.
An API GL-4 lubricant therefore has an optimised additive ratio for a manual transmission, so
the use of such transmission oils in an API GL-5 application can cause higher wear.
Can API GL-5 transmission oils be used instead of API GL-3/GL-4?
Today’s modern manual gearbox transmissions almost always have synchromesh because the customer wants a comfortable and quick synchronisation without grating noises. This means that the friction on the synchronising cone must not be too high to avoid rough gear changes, however, it must not be too low either in order to avoid slippage of the synchro-ring, which would not make it possible to change gear.
Partly because too little friction can be observed when using API GL-5 lubricants in a synchromesh transmission, their use is expressly discouraged.
Test bench results
The advantages of fully synthetic rear axle transmission oils can be impressively demonstrated in a test. The breakaway torque of 700Nm can be reduced by up to 80% by using a synthetic rear axle transmission gear oil. It can be deduced from this that an increase in the life of the transmission, reduced maintenance costs and lower wear is possible.
Winter-time gear changes can be improved by using certain fully synthetic transmission gear oils
Automatic Transmission Fluid (ATF)
An ATF serves primarily to transfer force. By the use of a converter, flow energy is converted into torque. The planetary gear set, brake band and multi-plate clutch assembly are hydraulically controlled and braked according to the required gear ratio.
Leading manufacturers now offer a new generation of automatic transmissions whose aim is to reduce fuel consumption and exhaust emissions, and to optimise driving comfort and operational reliability. The main features are a 5-stage automatic system, controlled lockup clutches, and extensive use of microprocessors to electronically control gear changes.
Lockup of clutches saves fuel
Please click here for a complete description.
The most prominent worldwide manufacturers of automatic transmissions are General Motors and Ford.
Both manufacturers decided together on their requirements specifications for the ATF, which is known as MERCON by Ford and DEXRON by GM. By reason of the worldwide availability of ATF, other manufacturers have willingly adopted the same specifications and have refined and expanded them to meet their own requirements.
Advantages of synthetic ATFs
The advantages are:
Very high temperature and aging stability i.e. higher protection against deposits and carbonisation.
Noticeably better cold flow characteristics
Higher efficiency
Reduction in oil temperatures
Test bench results 2
An example of the high aging stability of synthetic ATFs is shown in the results of a DKA oxidisation test. The test demonstrated the viscosity behaviour.
DKA Oxidisation test (160oC, 500hr)
The early aging of mineral ATF oils had the following effects on the functioning of an automatic transmission:
Gear change clunking
Slipping out of gear
Influence on operational life
Poor efficiency
Please click here for full description
Application and useful tips
Here you can find some practical tips
Mixability of motor oils
Generally speaking, motor oils must be mixable, independent of whether they are synthetic or mineral oil based products. This requirement was also raised by the automobile companies. The mixing of motor oils of different brands or compositions should only be done when there is no other alternative.
It is not recommended to mix synthetic or part synthetic oils and mineral based engine oils because the high quality of the synthetic oils will be degraded. The resulting quality is only as good as the weakest link in the chain.
Oil consumption
1. Mechanical influencing factors (engine construction)
Piston ring design: piston ring clearance => piston ring gap, piston ring groove clearance, piston ring tension.
Valve guide clearance, valve stem seals
Crankcase ventilation
Running-in condition of the engine; running-in not completed (piston rings not yet lapped in)
Leakages
Defective cooling system (operating temperature too high)
Operational conditions
2. Physical/chemical influencing factors (engine oil formulation)
High vapourisation tendency at high temperatures
Thinning due to petrol => reduction in the viscosity (slippage and evaporation loss)
Heavy oxidisation
High tendency to foam
Overfilling of oil (oil splashing)
Decline in viscosity due to mechanical stress (viscosity loss through shearing)
Oil pressure decline
A decline in oil pressure can, in the main, be the result of two causes:
Mechanical condition or motor oil condition.
Constructional or mechanical causes of oil pressure decline
Possible mechanical causes are:
Capacity or a functional failure of the oil pump
Excessive engine wear (bearing clearance)
Rated capacity of the oil feed channels
Too low tick-over engine speed
Location, functioning and precision of the oil pressure sensor
Too high oil splashing in the engine e.g. construction of the oil sump
Defective cooling system (operating temperature too high)
Engine oil and external influences as causes of oil pressure decline
Possible lubrication-specific causes are:
Too high shearing stresses on the oil (viscosity decline)
Too high petrol dilution
High water content in oil => build-up of steam bubbles and foam
High foam build-up – a lot of air pockets
Over filling (oil)
Over heating of the engine oil, e.g. defective cooling system
Foam build-up
Possible causes of foam build-up are:
Overfilling the engine leads to greater mechanical loading on the oil => air pockets
Too much water in the oil (steam bubble build-up at high temperatures)
Oil with poor air segregation properties
Heavy contamination of the oil
High fuel dilution (influence of fuel additives)
Heavy foaming development in the oil leads to increased wear, resulting in overheating. The oil supply can be interrupted if the oil pump runs dry. Hydraulic tappet trains are very sensitive to heavy foam build-up.
Air pockets in the oil feed channels can lead to functional breakdowns, which endangers the pressure equalisation (noise build-up) Air bubbles in the oil can also cause damage to materials, e.g. big-end bearings. Another aspect is cavitation (air bubbles implode under high pressure and cause severe damage to materials.
Changing from mineral oil to synthetic oil
In general, changing from a mineral oil based engine oil to a synthetic product does not cause any problems. Over time, engines with a high mileage (60,000 – 100,000 km or more), which have used a mineral oil could have built up considerable oil carbon deposits (e.g. around the piston rings and valve guides) or heavy surface sludge because mineral oil is not as thermally stable as synthetic oil. Due to the cleansing and rinsing effect of some synthetic oils the carbonisation and deposits will eventually be removed. Because this cleaning process does not occur simultaneously or evenly at every point, e.g. around the piston rings, it can lead to a slight increase in oil consumption during the settling-in period, which will normalise once the rings have been rinsed clean or are freed up.
It is recommended that for heavily contaminated engines the first oil change interval should be reduced by a half or one third. There is no danger of large amounts of released contamination blocking up oil ways.
Storage of motor oils
Lubricants should be stored above 0oC in a dry, closed room preferably at constant temperature. Unsuitable storage locations (wide temperature variations, High humidity) can lead to moisture absorption through the container. All containers are sealed against liquid loss, but are not impervious to gas (air) ingress.
Water can lead to clouding, and not least to precipitation in the product. Oil can age if stored in plastic containers in direct sunlight (UV light).
The date stamp on the neck of the container shows the date of manufacture. We recommend a maximum of three years storage when stored under correct conditions.
Oil Sludge
Sludge or nitrate sludge is a non-flowing, tar-like mass, which is neither petrol nor oil soluble. Engines affected with this condition cannot normally be cleaned with the use of synthetic oils or commercially available oil sludge removers.
Factors affecting the build up of oil sludge:
Quality of petrol
Nitrous oxides (NOX)
Engine construction
Oil level
Oil change intervals
Engine oil quality
Temperature
The process of oil sludge build-up:
During the combustion process nitrogen reacts at high temperatures with oxygen and fuel constituents, leading to organic nitrate or acidic organic compounding, which prematurely ages the engine oil. Water can accelerate the reaction process.
The use of a sludge limiting, free running motor oil is recommended.
Fundamentals of motor oil technology
Motor oil
Modern motor oils are based, according to each one’s design and performance, on various kinds of base oils or mixtures of base oils. Additionally, additives can be used which perform various functions. Only a balanced formulation (base oils and additive components) results in a highly efficient motor oil.
Constituents of a typical multi-purpose motor oil
78% base oil
10% viscosity-index improver
3% detergent
5% dispersant
1% wear protection and
3% miscellaneous constituents
Base oils
The base oils used endow the lubricant with its specific, fundamental characteristics, which are the most noticeable features in the performance of the finished product.
Mineral oils: hydrocarbon compounds in various forms, structure, design and size (VI: 80-95).
Hydro-crack oils: processed mineral oils with a high purity level and improved molecular structure (VI: 130-140).
Poly-alpha –olefin (POAs): synthesised petro-chemicals – chemically constructed, straight forward hydrocarbon compounds (VI: 130-145).
Synthetic esters: chemically manufactured compounds from organic acids with alcohols, consisting of molecules with a defined shape, structure, design and size (VI: 140-180).
Mineral oil based base oils
Below is a schematic diagram of the production process of mineral oil based base oil – the refining process – as well as a molecular model of the constituents of the resulting mineral oil.
First the raw oil is treated in an atmospheric distillation, from which ethylene is produced, which is the basic component in the manufacture of poly-alpha-olefins (PAO).
The next stage is a vacuum distillation, which follows the refining process. In the next stage unwanted paraffins are removed. In special cases a hydrogen treatment process is carried out before the mineral oil reaches its completed product stage.
Please click on the graphic to enlarge it.
Hydro-cracking oils
The diagram shows the individual steps in the manufacture of hydro-cracking oils. The starting products are the long-chain (fixed) normal paraffins from the deparaffining stage of the reffinates. The paraffin molecules are broken down in a special cracking plant in a hydrogen atmosphere in the presence of special catalysts and are broken into shorter lubricant molecules (cracked). Herewith arise process particular predominantly isoparaffin (ramified/branched hydrocarbon chains).
In an ensuing vacuum distillation they will be separated according to their viscosities and the remaining normal paraffins (unramified hydrocarbon chains) will be removed in a downstream deparaffining stage. The oils produced in this way are high in isoparaffins and show clear homogenous molecular structures.
Poly-alpha-olefins (PAOs)
Poly-alpha-olefins or PAOs for short are synthesised from ethylene in a chemical process. The hydrocarbon compounds resulting from this process exhibit a well-defined molecular structure.
Clicking on the graphic will show a production schematic for the manufacture of synthetic poly-alpha-olefins in detail.
Synthetic Esters
Synthetic esters are chemically manufactured compounds from organic acids and alcohols. Defined molecular structures can be synthesised according to the desired properties of the esters. See below the general chemical formula of the reaction of acids and alcohol to Ester and water, and the converse.
Clicking on the graphic will show all the details.
Additives
Additives are soluble supplements or agents which are added to the above mentioned base oils. They alter or improve the characteristics of the lubricant through chemical and/or physical action.
Physically acting additives
VI improvers
Anti-foam
Pour-point improvers
Friction modifier (friction force reducer)
Detergents
Detergents are cleansing substances which counteract the build-up of deposits on thermally stressed components. They keep the engine clean. Furthermore they build an alkali reserve in the motor oil, i.e. acidic by-products from the combustion process are neutralised.
The picture on the right shows a schematic of the neutralisation process.
Dispersants
The task of dispersants is to envelop solid and liquid contaminants which get into the oil during the operation of the engine, and to keep them in suspension and well dispersed thereby hindering deposits.
One thereby differentiates between the following processes:
Peptisation:
Is the enveloping and holding in suspension in the oil of solid contaminants e.g. dust, combustion by-products or aging products.
Solubilisation:
Is the enveloping and holding in suspension in the oil of liquid contaminants e.g. condensation water or acids resulting from the combustion process.
Antioxidants
Lubricants tend to oxidise under the influence of heat and oxygen (aging).This degradation process is accelerated by acidic combustion by-products and traces of metals, which have a catalytic effect (abrasive or corrosive wear). The addition of antioxidants results in a substantial improvement in aging protection. The aging process cannot be stopped, but it can be slowed down.
Oxidisation
The aging of oil builds up acids, as well as lacquer, resins and sludge deposits, which are largely oil-insoluble, such as oil carbon.
Aging protection substances work in three ways:
• Radical scavengers/antioxidants (primary anti-aging substances): radicals are hydrocarbon chains in which free valences come into being due to a break in the chain or a pulling out of hydrogen atoms. Oxygen immediately accumulates at this point (oxidisation). Radical scavengers/antioxidants fill (repair) the “gap” by transferring hydrogen from the additive onto the free valences.
• Peroxide decomposers: (secondary aging protection substances): These work first when aging substances (oxygen compounds) have built up. They strip out the oxygen and form harmless compounds.
• Passivators / metal-ion deactivators: They passivate the iron and copper particles and thereby terminate or weaken their catalysing effect on the aging process. They encase the metallic ions in the oil so that in practice, they no longer possess any catalytic properties.
Wear protection additives
By using suitable additives an extremely thin layer can be built onto the sliding surfaces whose sheer strength is considerably less than the metal itself. Under normal conditions it is solid, but under wear-developing conditions (pressure, temperature) it becomes a slippery. Thus an excess amount of wear (galling, welding) is prevented. If required (metal/metal contact) the layer can be continually renewed by a chemical reaction.
Extreme pressure and anti-wear (EP/AW) additives
The earliest EP additive was pure sulphur. EP/AW additives are boundary surface active substances and the polar groups can contain amongst other things, zinc, phosphor and sulphur in various combinations. The most well-know kind is zinc dithiophosphate – ZDDP – which in addition functions as an anti-aging and corrosion protection additive.
The functioning of anti-wear additives – ZDDP
In the first phase the surfaces are at the point were friction begins (transition from sliding to sticking friction). At this point when a metal to metal contact is about to occur, heat builds up. The zinc-phosphor compound reacts on the surface and produces a protective layer.
Corrosion protection additive
In general, corrosion is a chemical or electro-chemical attack on metal surfaces. For corrosion protection, boundary-surface-active additives are preferred, which can be either ash-free or ash-producing. The polar groups bind themselves onto the metal surface and the alkyl rest forms a thick, fur-like, hydrophobic (water repelling) barrier. Due to their polar structure the corrosion protection additives are in competition with EP/AW additives, i.e. they can affect their effectiveness.
Improvers
The inclusion of VI improvers (VI= viscosity index [/]) enables the production of multi-purpose motor oils. VI improvers increase or extend the viscosity range of the oil, thus improving the viscosity-temperature relationship. In appearance they are like very long, fibre shaped molecules, which bundle together when cold, and thus offer little resistance to the movement of the oil molecules. As the temperature increases they unbundled and increase in volume, building a mesh network which restricts the flow of the oil molecules, so delaying a too quick thinning of the oil.
VI improvers: Shearing under load can shear the VI improvers, i.e. the long molecules can easily be torn. This gives a loss in viscosity. The loss of viscosity is irreversible, which is then described as permanent shearing. The torn molecules reduce in volume and therefore have a reduced thickening effect. The shear stability of a lubricant is generally classified according to the quality of the VI improver. High shear loading occurs e.g. in the piston ring area (high engine speeds, sliding surface speeds, pressures and temperatures)
Anti-foaming additives
Polysilicones (Silicon polymerisate), polyetheleneglycoether and other components minimise the tendency of an oil to foam primarily because there are fewer gases (air, combustion gases) trapped in the oil. Another reason is that the trapped gases can escape more quickly. Foaming considerably affects the lubricant characteristics (oxidisation, pressure properties).
A lubricant with poor foaming characteristics produces noticeably higher temperatures, wear and hydraulic tappet train noise.
Pour-point improvers
The pour-point is the temperature in degrees Celsius at which oil just begins to flow. This is defined as the “coagulation” point at which the paraffin wax in the oil crystallises as the temperature decreases. With the addition of pour-point reducers the crystallisation of the paraffin wax is delayed and the low temperature performance of the oil is improved.
Friction modifier (friction reducers)
Friction reducing additives, so-called friction modifiers, can only work in proper friction areas. These substances build fur-like films on the surfaces (a physical process) which can separate metal surfaces from each other. FMs are highly polar i.e. there is a high affinity to surfaces combined with friction-reducing characteristics.
Motor oil classification
Motor oil classification/specification
At the beginning of the 19th century it was normal for motor vehicle engine oils not to have any additives or classification. At the beginning of the 1940s the American military required oils with additives. These were designated as HD-motor oil (HD= heavy duty) in the American MIL-specification. Today this abbreviation has no meaning.
At about the same time the American Petroleum Institute (API) developed a classification system for motor oils which is still valid today. The API classification system distinguishes between the S-class for petrol engines and the C-class for diesel engines. The second letter or number gives the corresponding performance standard of the oil. An alphabetically higher letter indicates that it includes the preceding performance standards.
At the beginning of the 1990s the European organisation CCMC developed a motor oil classification system on the basis of European engines, fuel and operating conditions. The CCMC D, CCMC PD (petrol engines) and CCMC G (diesel engines) specifications were replaced by the ACEA classification A (petrol engines) B,C, and E (diesel engines). The important European motor manufacturers’ own-stipulated specifications based on the ACEA classification are having increasing importance. In recent years in the Asian region the API classification for cars known as ILSAC was introduced. Furthermore, there are different classifications for two-stroke engines in various vehicles.
In motor oil classifications and specifications the engine requirements are primarily described as well as the chemical/physical ones. For some criteria, critical engine tests provide the foundations for the current European, US and Japanese classifications. The respective national requirements in respect to engine type, exhaust gas emission laws, fuel type and operating conditions form the basis of the classification. The classifications are continually adapted to accommodate ever-tightening limits.
Along with the oil characteristics, other engine properties are evaluated during the test phases e.g. wear on various components, surface residues and deposit build-ups, and fuel and oil consumption. Pre-production petrol and diesel engines with a wide array of fuel delivery systems (e.g. common rail, petrol direct injection, pump-jet) and turbo/super chargers are needed for testing in accredited laboratories or in-house test facilities. Type approvals will be released as and when they are granted.
The following are the most significant current worldwide classifications and specifications:
ACEA Motor oil classification (Europe)
The Association des Constructeurs Européens d’Automobiles is the organisation of vehicle and mineral oil manufacturers which compile, among other things, the requirement profiles of motor oils. The ACEA organisation is the successor of the CCMC, whose classifications CCMC D ... and CCMC G have been replaced by the ACEA classifications.
To date these are the ACEA classifications for motor oils:
Class A – motor oil for petrol engines in cars A1, A2, A3, A4 and A5 with different chemical/physical requirements and various minor motor requirements for petrol engines – also with direct injection – with various oil change intervals, light loading and fuel economy potential. The letter/number combination is often expanded with a year number advising the classification issue date.
Class B – motor oil for diesel motors in cars and light commercial vehicles B1, B2, B3, B4 and B5 with different chemical/physical and motor requirements for diesel engines with various oil change intervals, of a light loading and fuel economy potential. The letter/number combination is often expanded with a year number advising the classification issue date.
Class E – Motor oil for diesel engines in commercial vehicles and trucks E1, (in the meantime withdrawn), E2, E3, E4 and E5 with different minor chemical/physical characteristics and widely varying motor requirements for diesel engines with various oil change intervals, US performance and light loading. The letter/number combination is often expanded with a year number advising the classification issue date.
In 2005, in the framework of the continual upgrading of the ACEA classifications, some fundamental new details and alterations were issued: For motor oils used in diesel engines with particle filters, classification class C was issued for the use of these oils in cars and light commercial vehicles.
Class C – Motor oil for use in diesel engines with particle filters, C1, C2 and C3 with different chemical/physical characteristics and various minor motor requirements, classification for motor oils with new additive technologies, longer, flexible oil change intervals, light loading and fuel economy potential.
The classifications A and B will be combined. This means a reduction in the number of classifications from the current nine to four:
ACEA A1/B1 □ ACEA A3/B3 □ ACEA A3/B4 □ ACEA A5/B5
The chemical/physical data including the basic motor requirements remain unchanged for the time being. The combination ACEA A2/B2 classification will be adapted to the market data by 2006; eventually it will be referred to as Global DLD1.
The classification E will be extended to E6 – for commercial vehicle oils in engines with particle filters, E3 will be deleted without substitution and E5 will be replaced by E7. In every classification some new engine tests will be applied.
API motor oil classifications (USA)
The American petroleum Institute has compiled the following nomenclature:
API – S.. for petrol engines in cars, API – C.. for diesel engines in commercial vehicles and trucks.
The number of cars with diesel engines in the US is small, meaning that there is no relevant classification available. In addition to the letters S or C a letter of number will follow. The current classifications are API SL and API C1-4. These classifications substantially overlap earlier letter/number combinations. New engines, increasing requirements for exhaust emissions and further tightening of limits for engine tests will eventually lead to the need for the API SM classification in the near future.
ILSAC Motor oil classification (USA)
The International Lubricant Standardization and approval Committee, together with another American institute and the JAMA (Japan Automobile Manufacturers Association) use the API classification for their own ILSAC standard. The current one is ILSAC GF 3 (API SL), classification ALSAC GF 2 corresponded to API SJ, ILSAC GF 1 was API SH. ILSAC GF 4 will be assigned the classification API SM.
Motor vehicle manufacturer Specifications
Vehicle manufacturers have published their own standards based on the ACEA or API classifications.
They have tightened their testing requirements with respect to the ACEA or API tests in regard to the chemical/physical requirements data and other special tests through to road testing.
VW, Ford, Opel, Mercedes-Benz, Porsche and BMW have released their own standards.
Global motor oil classifications
ACEA, Alliance, EMA and JAMA have produced the Global DLD and DHD specifications. Global DLD describes the requirements for motor oils used in high speed four-stroke diesel engines used in light commercial vehicles with reference to the worldwide exhaust emissions laws (at 2000). As well as tests for chemical/physical values, tests are required on European engines and a Japanese engine. The requirements are divided into three classification classes: Global DLD 1, Global DLD 2 and DLD 3.
Global DLD 1 describes the requirements for a motor oil in high speed four-stroke diesel engines used in heavy commercial vehicles with reference to the worldwide exhaust emissions laws (at 1998). As well as chemical/physical values, tests are required on American, European and Japanese engines.
Alliance = Members of the Alliance of Automobile Manufacturers EMA = Engine Manufacturers Association.
Specifications for two-wheeled vehicles
Two-wheeled motor vehicles are manufactured with both four-stroke and two-stroke engines.
In some of these vehicles there is an oil circulation system which includes the four-stroke engine, the transmission and the clutch. In motor oil classification and specifications for two-wheeled vehicles tests have to be performed on the clutch as well as tests for the engine’s chemical/physical requirements and other engine requirements. As two-stroke engines work on a different principle, other oil requirements are needed. There are requirements to provide adequate lubrication – even with a low fuel/oil mixture ratio, for engine cleanliness, deposit build-ups and environmentally clean combustion.
The oils specified for use in two-wheeled, four-stroke engines are primarily to the API standard for cars (e.g. API SG) – see 2.2 - or the ACEA classification A .. (see 2.1). Classifications for two-stroke engines were released by API, ISO and JASO.
API motor oil classification for two-stroke engines
The classifications:
API-TA (TSC-1) for light motor cycles (mopeds) API-TB (TSC-2) for motor bikes/scooters API-TC (TSC-3) for high performance engines API-TG (TSC-4) for outboard engines to NMMA TC-WII are no longer valid. The engines for these tests are no longer available.
JASO motor oil classification for two-stroke engines
The Japanese Automotive Standards Organisation has published the classifications for Asian motor vehicles:
JASO FA for light loads JASO FB for medium loads JASO FC for medium loads/ especially low smoke.
The motor performance properties of the JASO classification are however not adequate for European two-stroke engines. New classifications from the ISO were released.
ISO motor oil classification for two-stroke engines
The International Organisation for Standardisation has released tighter requirements than those in the JASO classifications:
ISO-L-EGB (Global GB) comparable with JASO FB ISO-L-EGC (Global GC) comparable with JASO FC ISO –L-EGD (Global GD) especially low smoke.
ASO motor oil classification for motor oils in clutches
JASO has released the classification T 903 based on the car standards of API, ILSAC and ACEA. Clutch tests will be carried out besides the chemical/physical requirements. Friction values will be determined as rated and permitted in JASO MA or JASO MB.
The rating in JASO MA indicates that clutch-slip or sticking, as far as is possible, should not occur.
Motor oil classification for two-stroke engines used in outboard engines
The NMMA (National Marine Manufactors Association) and the BIA (Boating Industries Association) have released the following classification for water-cooled outboard engines:
BIA TC-W (no longer valid) NMMA TC-W II (no longer valid) NMMA TC-W III
Viscosities
In 1911 viscosity formed the foundation for the first motor oil classification and was defined in the SAE classification system (Society of Automobile Engineers). Even today, viscosity is one of the most important characteristics of oil. The development of test procedures which could better predict engine behaviour led to viscosity measurement (DIN 51511) at various temperatures and speeds.
Viscosity is that characteristic of a fluid which is based on the internal friction which resists the flow of adjacent particles in the fluid. Viscosity can be described as the resistance to the flow of a liquid.
Below is a schematic description of viscosity
If two surfaces separated by a fluid layer of a specific thickness are moved at various speeds relative to each other, then the following physical values can be defined:
Sheer stress [Tau] = shear force acting on each surface horizontal to the Y-coordinate (Pa)
Velocity gradient [D] = speed difference per unit of film thickness (s-1)
When considering viscosity there are two measurement parameters:
Dynamic viscosity
In Newtonian fluids shear stress is proportional to velocity gradient. The proportionality factor is known as “Dynamic viscosity”, measurement unit: milli-pascal second [mPas], formerly centi-Poise [cP].
Shear stress = dyn. viscosity x velocity gradient
Click her to see how the rotation viscosimeter functions
Measuring method:
The cold-cranking simulator (rotation viscosimeter) is a specially developed visicometer for measuring oil viscosities at low temperatures. A constant torque electric motor drives a rotor whose speed corresponds to the viscosimetric characteristics of the measured fluid. With the help of a calibration curve (which was developed from standard oils) the dynamic viscosity will be determined.
Oils are divided into the following winter viscosity classes: 0W, 5W, 10W, 5W, 20W, 25W. The smaller the number before the W, the thinner it flows when it is cold.
The cold viscosity has an influence on the starter motor speed.
Kinematic viscosity
Kinematic viscosity is the ratio of the dynamic viscosity to the density at a specific temperature. Measurement unit: [mm3/s], formerly centi-Stoke [cSt].
Kinematic viscosity = dynamic viscosity / density
Click here to see how a capillary viscosimeter works
Measurement method:
A capillary viscosimeter is used to determine kinematic viscosity. The physical construction of a viscosimeter can vary but the measurement principle is identical. A specific amount of oil at a specified temperature flows by means of gravity along a defined distance of the capillary. The kinematic viscosity in cubic millimetres per second is determined from flow rate time. The summer viscosity classes are divided into 20, 30, 40, 50, 60, determined at a test temperature of 100oC. The larger the number after the W, the more thick-flowing the oil will be at 100 degrees celcius.
HTHS
Along with the described viscosity classes (winter, summer) there is the so-called HTHS viscosity. HTHS stands for High Temperature High Shear and describes the dynamic viscosity measured at 1500C and a shear gradient of 10 per second. By indicating the HTHS limits for its category, the engine oil shall possess adequate lubrication safety margin, ever for bearings (high sheer/stress gradient, high oil temperatures).
The limit values of motor oils with the specification ACEA A2/A3 and ACEA B2/B3 are 3.50 mPas. Motor oil quality in the category ACEA A1/B1 have a reduced HTHS of 2.9mPas. The reason for the lowering is anticipated fuel economy measures. Experiments are taking place at the moment to determine how far the dynamic viscosity can be lowered without increasing wear.
SAE viscosity classes SAE J300 – motor oils
Click here for a full overview
The table below once again shows the difference between single grade and multi-grade motor oils. Single grade motor oils fulfil only one SAE class and are today normally only tested at 1000C. Multgrade motor oils must fulfil at least two SAE classes for cold and high temperatures at 100oC. The pumping temperature limit is also a test requirement of the SAE classification system. The oil must pass through the oil pump at the specified temperature for the viscosity class. If these specifications are not met air pockets can form leading to defective lubrication. The result could be major damage to the engine.
Characteristics of a multigrade oil
Below is a diagram of the various performances of lubricants with various viscosities at designated temperatures:
SAE classes for motor vehicle transmission oils to the DIN 51512 standard
Please click for a complete description
The reference temperature for cold conditions lies between -55oC and -12oC depending on the SAE class. At this point the dynamic viscosity must not have reached 150,000 mPas. The cold viscosity will be measured in a Brookfield rotations viscosimeter. The SAE classes with a defined cold performance have also the addition of “W”, like the other motor oils. The minimum viscosity measurement at high temperatures is made as before at 100oC
ISO – VG classes – hydraulic oils
Please click for a complete description
“The International Organisation for Standardisation” – ISO – hs devised a viscosity class structure (viscosity Grade – VG), which covers 18 viscosity classes from 2mm3/s to 1500 mm3/s at 40oC. In contrast to automobile lubricants the viscosity ranges are more narrowly limited. Only a viscosity at a reference temperature of 40oC will be provided with a tolerance of ±10%. A viscosity index will not be provided. In the same ISO-VG there will possibly also be viscosity differences between oils at high and low temperatures. In practice, the variations are quite minor and will be compensated for by the ±10% tolerance. The numerical ISO-VG divisions and a rough correlation of the SAE classes are shown in the following table.
The viscosity index (VI)
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In 1929 Dean and Davis had already developed a viscosity index as a handy measure on the basis of two base oil components from processing mineral oil. The change in viscosity with temperature change can vary from oil to oil. Therefore the VI is readily used today to characterise the VT-behaviour (viscosity-temperature-characteristics) of lubricants in a particular temperature range. The dimensionless VI is calculated using the kinematic viscosity at 40oC and 100oC. A high viscosity index indicates that only a relatively small alteration of the viscosity will occur as the temperature increases, and the converse.
Please click for a complete description
Normally the VT behaviour for lubricants is described using an Ubbelohde diagram.
With such a diagram the advantages of synthetic products are clearly evident. Although both products are 40-grade, at 150oC the synthetic 5W-40 product shows a higher viscosity. Synthetic products do not thin out as much as mineral oil products with increasing temperature.
German to English: AGB PDF Detailed field: Business/Commerce (general)
Source text - German PDF.
Translation - English Terms and Conditions of Omed Exchange GmbH for the transfer of money to and from a foreign country
1. Application
The terms and conditions apply to all transactions between the transferring customers (hereinafter the “customer”) and Omed Exchange GmbH (hereinafter Omed Exchange GmbH), in which Omed Exchange GmbH facilitates the money transfers with its foreign agents which function on behalf of and in the name of Omed Exchange GmbH.
2. General contractual terms
With the completion and signing of the Omed Exchange GmbH order form, the customer agrees to the paid in money being paid out at the demand of the recipient.
Due to the contractual terms between the customer and Omed Exchange GmbH, the recipient should be aware that he accrues no independent right to demand payment, and in particular, he has no independent right to payment from Omed Exchange GmbH, its foreign agents or any businesses with which Omed Exchange GmbH is associated.
3. Money transfer service
On completion of the order and paying in of the money, payment in the destination country can be made to the recipient.
It is the duty of the customer to advise the recipient that the money is available for payment.
In certain countries the amount of money transferred may be subject to limitations.
4. Payment of the money transfer order
The payment of the transferred money is made in cash. Alternatively, payment can be made by cheque (US: check), or a combination of cash and cheque by the foreign agent. Payment is subject to availability of the payment means, and also according to the terms of the paying out agent.
Payment is made in the currency of the country to which the money is transferred. In some countries payment can be made in US dollars or another currency.
The exchange rate for money transfers from non-European Union currency member states which require currency conversion is made at the prevailing rate from the exchange rates provided by Omed Exchange GmbH on the day of payment.
On the instruction of the customer, the exchange rate can be set on the basis of that on the day the order is placed.
.The exchange rate set by Omed Exchange GmbH is based on the current rate at the stock exchange with a fixed premium added, which is determined by Omed Exchange GmbH, which is retained by Omed Exchange GmbH, its associated businesses or foreign agents. The current exchange rates are available from Omed Exchange GmbH.
5. Payment terms and alterations
Payment is normally made on presentation of suitable identification papers at the designated paying out location. Should the recipient not have any valid identification papers, a customer card with photo can be obtained from Omed Exchange GmbH. A customer card will only be issued after an identity check has been carried out at a security bureau using the data provided or by the presentation of valid identification papers.
The transfer Nr. is purely for control purposes. It cannot be used by the recipient in place of the standard identification methods.
The order can be changed by the customer at the Omed Exchange GmbH place of business where the order was placed up to the moment of payment to the recipient on presentation of proof of identity in the form of an ID card or passport, or the order form.
When making the transfer order the customer is not permitted to make an alteration to the transaction which would name someone else as recipient other than the original recipient in order to fulfil another payment obligation (e.g. a purchase contract). Omed Exchange GmbH cannot be held responsible for any damages which may occur due to breach of its obligations. Omed Exchange is entitled to charge a fee for carrying out the order changes, which the customer will be advised of at the time of his request.
6. Participation and due diligence of the customers
The customer is duty-bound to ensure the correctness, completeness and legibility of his part in a transaction. Furthermore, the customer has to ensure that unauthorised persons will not have access to any relevant payment data.
7. Repayment of non-collected money
When transferred money is not collected, repayment can be made to the customer in person at the place of business of Omed Exchange GmbH where the transaction was made on production of a valid personal ID card or passport, or the order form. Omed Exchange is entitled to charge a fixed compensation fee, which the customer will be advised of at the time of the repayment. The customer is entitled to be presented with the costs incurred in returning the money in order to see they equate to the fee charged.
8. Costs
The price tariff shows the fees at the time the order is made, providing no other arrangements are in force at this time. Furthermore, the current exchange rates of Omed Exchange GmbH are available to the customer. The customer accepts that the exchange rate may change, as shown in point 4 paragraph 3, if the transferred money is not collected on the day it is sent.
9. Liability
Omed Exchange accepts liability during the completion of its contractual obligations pursuant to the provisions of German law for all failures of its employees and any other parties involved in the completion of its obligations.
In the case of minor negligence no liability is accepted by Omed Exchange GmbH, its associated businesses or foreign agents. This rule shall not be applicable in the case of death, personal injury or damage to health, or to breach of significant contractual obligations. In the latter case, liability is limited to that which is typically applicable is such cases, to a maximum of 500.00 (Euros) plus the transmitted order sums and fees charged.
.
Omed Exchange GmbH accepts no liability for damages caused by force majeure, telecommunication breakdowns, riots, war and natural catastrophes or other events not directly under Omed Exchange GmbH’s control (e.g. strikes, lock-outs, orders by national and foreign state authorities).
If the customer’s transfer order is to fulfil an obligation to the recipient (e.g. a purchase or service contract), Omed Exchange GmbH will not be held responsible for any aspect of the responsibilities of the recipient for this contract.
If the money to be transferred is paid in any form other than cash (e.g. cheque, credit card, EC card, direct debit), Omed Exchange GmbH will only accept liability for damage after the money is paid into the Omed Exchange GmbH bank account.
10. Data protection
The customer agrees to the data given overleaf being used by Omed Exchange GmbH, its associated businesses and foreign agents in order to carry out the transfer order.
The data provided will only be used and passed on to others in order to process the transfer order, and only in accordance with the data protection laws.
The customer is also advised, and that he is in agreement with, that the provided data used by Omed Exchange GmbH, its associated businesses and foreign agents for the money transfer could be stored in order to fulfil their legal obligations.
The customer is also advised, and that he is in agreement with, that the provided data used by Omed Exchange GmbH, its associated businesses and foreign agents for the money transfer could be transmitted and stored in a location outside the European Economic area.
The customer is also advised that he has a legal right to see the data stored on him. The customer can have errors corrected and can see any data not available at the moment.
11. Agreement to the rights of collateral to the benefit of Omed Exchange GmbH
The customer affords the right to Omed Exchange GmbH to use any money paid to Omed Exchange GmbH, including a transfer order, as collateral. Omed Exchange GmbH has the right to exercise the right to collateral when it has a claim against the customer.
12. Final clause – governing law
The terms of business between Omed Exchange GmbH and the customer are subject to the laws of the Federal Republic of Germany.
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As a former electronics and telecommunications engineer, with several other in-depth knowlege areas, I am able to offer my technical skills to provide technically and grammatically accurate translations in my fields of expertise, which I have been doing since 1987 when I first came to Hamburg, Germany. Incidentally, I prefer to liaise directly with the originator of a text whenever possible to ensure absolute accuracy.
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