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Choosing the Right Lubricant For Your Spur Gears

June 11, 2018

Choosing the Right Lubricant For Your Spur Gears

Spur gears are some of the most versatile gears, which also makes them one of the most widely used gears. Spur gears are the default gear for virtually many power transmission operations, in equipment big and small, and are used in enclosed and open configurations.


Choosing the right lubrication for spur gears will not affect their lifespan and performance, it may also mean you need to change the way you operate your machinery.


However, though spur gears are efficient at power transmission, their mode of operation means energy is lost through heat generation, and they create noise and vibration in their operation. Which is why lubrication is an essential part in the operation of spur gears.


What are some of the aspects that must be considered when deciding on lubrication for operations in involving spur gears? Load-carrying, vibration reduction, adhesion to gear, operating temperature range and more.


In open spur gears, the resistance to being washed off and resistance to contamination are particularly important since the spur gears are not enclosed from external contamination.


To encapsulate the various use cases spur gears are put through, several industry-wide lubricant specifications have been defined. These consider the pitchline velocity of the gear, operating temperatures and more. There are significant differences between lubricants that are chosen for open and enclosed gear drives. That discussion is beyond the scope of this article, instead we will look more generally lubrication for spur gears.


Viscosity is the most important part in the selection of lubricant for spur gears. A lubricant must be viscous enough to adhere to a gear, without coagulating. It must be able to transfer heat evenly around the gear, while keeping the mating surfaces of spur gears apart. Too low a viscosity and the lubricant will struggle to adhere to the gear, and metal to metal contact will cause excessive wear and tear. Conversely, too high a viscosity will mean heat build-up and loss in operating efficiency and drop in power transmission.


Operating temperatures also determine the specification of lubricant to be used for spur gears. This will influence not only the operating range of the lubricant chose, it will also affect the pour temperature of the lubricant. How equipment must be operated at start-up (for instance, start-up temperatures) will also be affected by the choice of lubricant, and must be considered when choosing the most appropriate lubricant for spur gears.


As a general note, it is with good reason that a gear manufacturer specifies a particular specification of lubricant for spur gears. And it is advisable to stick to these lubricant specifications, and check with your gear manufacturer before changing lubrication.