OPEN GEAR LUBRICANTS Exploring the Depths of a Technology in a Constant Evolution By: Hocine Faci, Martin Maass, John Haspert, Soman Dhar Castrol Industrial
Abstract
Unlike underground mining operations, open pit mining is a surface mining technique that allows extraction of mineral ores or rocks from the ground of an open pit. This technique requires usage of heavy pieces of equipment, namely shovels and draglines. Shovels, usually electrically powered, are used for removing dirt from the earth with the help of a hydraulic bucket. Draglines are much larger in size and are commonly used in strip-mining operations. These machines are equipped with numerous rotating components, including open gears, and require lubrication under extremely harsh conditions. Load carrying capacity, wear protection, water resistance, adhesiveness, dust tolerance as well as mobility are the most critical characteristics for an open gear compound. The lubricant technology associated with this application has significantly evolved over the last decades. This paper will cover the journey of this technology as the OEM specifications evolved over time; from the first heavy open gear compounds and the solid highly fortified lubricants, to the solvent based and lately solvent free compounds …and onto the bio-based and environmentally friendly lubricants Introduction Open pit mining is a surface mining technique that allows extraction of mineral ores from the ground of an open pit. To mine the ore, it is generally necessary to excavate, remove and relocate immense quantities of “overburden” as waste rocks (or dirt). Mining economics are directly dependent of the handling and storing of these rock quantities, constrained
frequently by certain geologic and mining engineering challenges. Minerals and waste are removed in successive layers forming mine benches at different elevations. This technique requires the use of heavy pieces of equipment, namely shovels and draglines. Shovels, usually electrically powered, are used for removing the dirt from earth with the help of a hydraulic bucket. The large type of draglines which are typically built on site are commonly used in strip mining operations to remove dirt above minerals or coal and more recently for oil sands mining . Their weight can vary between 8,000 and 13,000 tons. These massive machines are equipped with numerous rotating components, including open gears and guide rails, and require lubrication under extremely harsh conditions. Load carrying capacity, wear protection, water resistance, adhesiveness, dust tolerance as well as mobility are the most critical characteristics for an open gear compound. The lubricant technology associated with this application has significantly evolved over the last decades.
Background
Dirt removal operations for the pyramid building during the ancient Egyptian era go back to the 17th Century BC. Based on archaeological discoveries, construction crews used to remove the stones from open caverns and move them to the construction site using wet sand, fine clay, gypsum. Olive oil was in use as lubricant in the same era (Figure 1). Since 50 A.D., various other oils obtained from palm oil, castor beans, rapeseed, etc. were used until the early period of the 19th century [1, 2, 3]. Three to four centuries later, beef and mutton fat (tallow), animal lard, wool grease, and sperm whale oil to name a few were used. Sometimes, vegetable oils and
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