EP additives

Because EP additives ate effective only by chemical action, their general use should be avoided to minimize possible corrosion difficulties and shortened lubricant life in any appHcation where they ate not necessary. For long-time operation of machines, conversion from boundary to hill-film operation is desirable through changes such as higher oil viscosity, lowered loading, or improved surface finish. 

Siace surface reactions iavolved with antiwear and EP additives depend not only on the type of mbbiag materials but also oa operatiag temperature, surface speed, and corrosion questions, selection should be carefully iategrated with the oil type, machine design, and operatiag coaditioas. 

Therefore, wear ean be eonsiderably redueed by providing good lubrieation eonditions (viseosity ratio x > 2 if possible) and a good degree of eleanliness in the rolling bearing. Where x < 0.4 wear will dominate in the bearing if it is not prevented by suitable additives (EP additives). 

Obviously the selection of an EP additive requires great care if it is too active it may give rise to excessive metal removal under normal operating conditions (see the section on corrosion by sulphur additives). Also, if a component is prone to fatigue pitting in service the presence of an overactive EP agent may result in corrosion fatigue. ... 

Gear lubricants In addition to the usual oxidation and corrosion inhibitors, lubricants for heavily loaded gears almost always contain EP additives containing sulphur, chlorine or phosphorus. In order to function, these additives must react locally with the metal surfaces, and yet the extent of the reaction should not be such that it could be described as corrosive, or promote fatigue pitting . These EP additives may be quite safe with ferrous metal surfaces, but may cause severe corrosion on copper alloys, e.g. on bronze worm wheels if for any reason excessive temperatures arise. 

Some turbine lubricants have to lubricate the turbine gears as well as the turbine in these circumstances any EP additives employed should not be corrosive in the presence of moisture... 

Active EP additives, 75 224 Active mass, 3 409 Active-matrix components, in fluid cracking catalysts, 77 680 Active matrix liquid-crystal displays (AMLCDs)... 

Antiwear (AW) and extreme pressure (EP) additives AW and EP additives can be chemisorbed to metal surfaces and help to avoid direct contact of the metal. 

EP oil—lubricating oil formulated to withstand extreme pressure (EP) operating conditions. See EP additive. 

Table 5.9. The correlation between load capacity and chemical reactivity for extreme pressure EP additives...

Organic sulfide Extreme pressure (EP) additives, eg., dibenzyl disulfide, diphenyl sulfide. 

The best performance found in the Climax Molybdenum Company test programme was for a lithium hydroxystearate soap-thickened grease with a conventional EP additive and 10% by weight of molybdenum disulphide with a nominal particle size of 7.0 jum. This grease had a Timken OK Load of 23 lbs (10.5 kg), Falex load capacity of 1450 lbs (658 kg). Mean Hertz Load of 90.5 and Weld Load of 630 kg. 

Emulsions contain oil, such as mineral or compounded oil, usually in proportions of 3-10%, in the form of suspended droplets dispersed with the aid of emulsifiers. They are used where rapid heat removal is a major requirement. The additives used are usually rust inhibitors and EP additives. Water-based products, also known as water-soluble fluids, chemical fluids or synthetic fluids, do not contain oil, but only water-soluble chemicals. Water-based lubricants comprise, for example [88] the following ... 

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