Influence of Contamination of Gear Oils in Relation to Time of Operation on Their Lubricity

The quality and reliability of consumables, including gear oils, results in the failure-free operation of the transmission components in heavy trucks. It is known that oil viscosity is essential for all lubricated tribopairs for wear and friction reduction in all vehicles with a gearbox. Viscosity may be influenced by the contamination that wear products can impart on the oil. Oil contamination can also affect lubrication efficiency in the boundary friction conditions in gearboxes where slips occur (including bevel and hypoid gearboxes). The present research focused on this issue. An obvious hypothesis was adopted, where it was theorized that exploiting the contaminants that are present in gear oil may affect how the lubricating properties of gear oils deteriorate. Laboratory tests were performed on contaminants that are commonly found in gear oil using the Parker Laser CM20. The study was designed to identify a number of different solid particles that are present in oil. At the second stage, friction tests were conducted for a friction couple “ball-on-disc” in an oil bath at 90 °C on a CSM microtribometer. The quantitative contamination of the gear oils that contained solid particles and the curves representing the friction coefficients of fresh oils with a history of exploitation were compared. The test results were statistically analysed. Exploitation was shown to have a significant impact on the contamination of gear oils. It was revealed that the contamination and the mileage had no effect on the tested oils.

Abrasive Wear, Scuffing and Rolling Contact Fatigue of DLC-Coated 18CrNiMo7-6 Steel Lubricated by a Pure and Contaminated Gear Oil

Due to extreme working conditions of mining conveyors, which contaminate gear oil with solid particles, their transmissions are exposed to intensive abrasion, scuffing, and even rolling contact fatigue (pitting). These effects shorten gear life. To prevent their occurrence, a wear-resistant coating can be deposited on gear teeth. The resistance to abrasive wear, scuffing, and pitting was investigated and reported in the article. Simple, model specimens were used. Abrasive wear and scuffing were tested using a pin-and-vee-block tribosystem in sliding contact. A cone–three-ball rolling tribosystem was employed to test pitting. The material of the test specimens (pins, vee blocks, cones) was 18CrNiMo7-6 case-hardened steel. Two types of DLC (Diamond-like Coatings) coatings were tested, W-DLC and W-DLC/CrN. The vee blocks and cones were coated. Two industrial gear oils were selected to lubricate the specimens: one with a mineral and one with a synthetic PAO (polyalphaolephine) base, as pure oil or contaminated with solid particles from a coal mine. The results show that, to minimize the tendency to abrasion, scuffing, and pitting of specimens made of 18CrNiMo7-6 steel, the W-DLC/CrN coating should be deposited. This coating also gives very good protection when the lubricating oil is contaminated.

Einfluss von Gruppe I Grundölen auf die Elastomerverträglichkeit von Radialwellendichtringen

Gear oils on the basis of Group I base oils are the most widely used lubricant in industrial drive systems. With dynamic friction torque tests, the influence of Group I base oils from different regions/refineries on elastomer compatibility of radial shaft seals is investigated by dynamic friction torque tests. The results show a significant influence of base oil on the development of frictional torque in the sealing gap and the elastomer compatibility.

Car Engine Oil: Investigation of Function and Related Challenges, and Provision of Environmental Solutions

In this paper, in order to solve challenges in the field of energy and fuel using a fully practical approach, types of engine oils and advantages of each over the other are discussed. A suitable car engine oil and its reasons are addressed. The viscosity of the engine oil is studied. A suitable car engine oil for cold and tropical regions of Iran is introduced. The standard classification of engine and gear oils in terms of viscosity is another topic discussed in this paper. Burning oil of Iranian cars, its reasons, identification methods and reduction strategies in accordance with domestic standards are described. Finally, plant-based engine oils, their applications, advantages and disadvantages, native challenges in this field and its complementary topics of the environmental aspect are provided in the present study.

Lubricity, Tribological and Rheological Properties of Green Ester Oil Prepared from Bio-Based Azelaic Acid

Plant oil derived compounds have been used as the raw material for the synthesis of green biolubricant. Azelaic acid derived from oleic acid is one of the interesting compounds. The synthesis of azelate esters oil based synthetic green biolubricants was carried out. The esterification process of azelaic acid with variety type of alcohols was catalyzed by concentrated H2SO4. The yields percentages of azelate esters oil produced were varied depending their overall molecular structure. The azelate esters oil properties were evaluated for their suitability as a biolubricant. The results showed that the linear azelate esters oil showed high pour point values in a range of 15 to 5 ºC for di-decyl azelate, di-octyl azelate and di-hexyl azelate respectively. On the other hands, the branch azelate esters oil showed very low pour point of -70, -58 and -50 ºC for di-2-butyloctyl azelate, di-2-ethylhexanol azelate and di-2-ethylbutyl azelate, respectively. Moreover, the linear azelate esters oil gave high values of flash point, viscosity index and oxidative stability, and they were slightly affected by branching molecule structure. The tribological and rheological properties of high molecular azelate esters oil were also performed. Subsequently, most of them were classified as non-Newtonian fluids and having boundary lubrication properties with low friction coefficient. The branch azelate esters oil is plausible to be used as green biolubricants in many applications including automotive, marine engine oils, compressor oils, hydraulic fluids, gear oils and industrial biolubricants.

Friction and temperature mapping of environmentally acceptable gear oils

In recent years, environmental issues have raised the demand to protect the environment against the pollution caused by the uncontrolled spillage of lubricating oils. One solution is using Environmentally Acceptable Lubricants (EALs), however, these oils are more expensive than the common mineral oils. The consumers require to test the oil performance using test machines but testing in real machines is costly and time-consuming. Small test machines like ball-on-disc have been previously used for friction mapping and ranking gear oils. In this paper, the friction maps are measured from 0.65 GPa to 1.25 GPa, and temperature maps are devised to experimentally simulate the gear contact along the line of action. Results illustrate that EALs can provide up to 60 % better frictional efficiency that leads to 20 oC cooler oil temperature in high-pressure contacts operating under elastohydrodynamic lubrication (EHL) regime.