Modern gear systems are characterized by enhanced power and torque transfer with smaller and lighter gears. The power to weight ratio ( Kg/ Kw) has been considerably reduced over the past decades, which has resulted in increased power density.  To accommodate this factor, there have been many mechanical changes made in terms of gear materials, hardening process resulting in wear reduction, improvement in machining methods and tooth geometry. However, the conventional, mineral based lubricating gear oil which was comfortably meeting the demands earlier, becomes severely stressed with increasing power density.

The stress on the gear oil is mainly with respect to its anti-scuffing, anti-wear and temperature resistance property. Due to smaller surface area available in the housing to dissipate the internally generated heat, the oxidation resistance of the lubricating oil becomes critical.

The way to reduce internally generated heat is to reduce frictional losses and ensuring a gear cooling arrangement. Frictional losses can be considerably reduced with synthetic base oils which results in reduced operating temperatures. In many cases, external cooling may not be necessary. Synthetic base oils have uniform molecular structure and are more stable than conventional mineral oils. Due to the inherent oxidation resistance of synthetic gear oils, substantial improvement in life time (typically 3 times that of mineral oils)  can be achieved. Enhanced life time ensures that frequent disposal of used gear oils is avoided and machine availability is enhanced.

Reduced frictional losses, means reduction in input energy required to deliver the required output torque. Hence power saving is achieved with specially formulated synthetic gear oils.

The gear movements are classified as primarily sliding, primarily rolling and combination of sliding and rolling gears. As the sliding percentage increases (for example sliding percentage starts from 10 to 30 % for helical gears extending up to 90 % for worm gears), the shear forces on the gear oil increases. Hence synthetic oils are a product of choice for most of the gear types in industrial gear boxes.

Analysing performance of food grade synthetic gear oil in agitator gear box on slurry line of food processing unit.

Condition of the oil prior to restarting a gearbox after a prolonged or unplanned stoppage would make the difference between smooth operation and unwanted wear as well as surge in temperature.  Here is a list of possible scenarios that can adversely affect performance output of the gear box due to lubricant starvation and remedies to ideally prep the gearbox before restart. Condition of the oil is an indicator of the long-term reliability of the gear box.

Synthetic oils offer three to five times better resistance to oxidation. Hence check oil for residue / sludge formation / drastic colour change (darkening). If none of the above exists you can continue using the existing oil