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Open Gear Lubrication- Are you using the right open gear lubricant?


Power transmission: Open gears

While visiting mines and similar sites, it’s common to see big excavators, wire rope shovels picking up high loads. One of the mechanisms used in this operation is OPEN GEAR  for power transmission.

When it comes to the lubrication of open gear, normal greases won’t work here. The specialty lubricating grease applied has to sustain impact or shock load, extreme operating conditions and many more severe requirements.

This blog is written with an aim, to get introduced to the basics of Open Gear Lubrication, its properties, Standards.

Wherever Open Gears are used usually they are directly exposed to atmosphere. As described above if we consider the equipments working in mining areas we can imagine the continuous presence of dust, dirt, high temperature conditions etc.

Before going into details of Open Gear lubrication, lets get introduce to some machines in which Open Gear Lubricants are used. This would give idea about what we actually going to see further.

Machine: Rope Shovel
Mechanism: Actuator Rack system


Machine: Kiln
Mechanism: Gears in series system


What properties are required in an Open Gear Lubricant?

Industrial Lubricants are used in various applications such as bearings, gearboxes, wire ropes etc. But the properties required in lubricant change as per the application. In some application low viscosity & less tacky lubricant is preferred while others may demand high viscosity and more tacky lubricant.

Lubricants should thus be selected based on operational parameters, surrounding atmospheric conditions, life expectancy etc.

Following are the properties that an open gear lubricant should possess.

  • Tackiness- The applied lubricant should adhere firmly to the Gears
  • Resistance to water washout and spray off.
  • Excellent load-carrying capacity- This should offer resistance against friction and wear.
  • Cushioning ability – Vibration should be reduced. Open gear lubrication grease should not build up in the roots of the gear tooth

Open Gear Lubricant Standards

Several Industry specifications and standards are developed for Open Gear lubricants by American Gear Manufacturing Association (AGMA) and Many OEM’s. The most widely used is AGMA 251.02 and US Steel 226 and 336.

Types of Open Gear Lubricants

Ashpaltic Type

They are formulated using high viscoisty residual compounds such as ashpalt , bitumen and a volatile solvent. Typically these residual compound has a viscosity of 643 cSt or higher @ 100 deg C.After application the solvent gets evaporised leaving behind a viscous coating of the lubricant. They are relatively cheaper , give excellent performance, have a adhesive film. But has environmental concerns.


  • Potential of cause ozone layer depletion and cancer.
  • At lower temperature they tend to harden peel off, whereas at high temperature they tend to be less viscous.`

Semi-Fluid Grease and Semi-Fluid Grease Cut Backs

They are formulated using medium-high base oil viscosity with some bitumen, asphalt. It also consists of Thickener, Additives and has NLGI 0 – 1. However, some products are manufactured using solvent, in order to improve their spray ability.


Due to its paste type tendency, the consumption rate is two to three times higher. as the ase oil separates from thickener due to high shock / impact loads.

Gel Polymer thickened type

It has a polymeric thickener along with solid lubricants, the film is thixotropic in nature, which allows friction to be reduced to minimum, and thus can be applied by standard intermittent spray system, splash, idler immersion systems.

These Open gear lubricants have excellent pumpability , hence pumps, metering devices are subjected to less stress. Also, they work well in dusty and dirty environments.

High Viscosity Synthetic Oils

Synthetic oils with medium to high base oil viscosity along with solid lubricants, additives such as viscosity index improvers, EP agents, Rust and corrosion inhibitors are added to the base oil to improve its performance. PAO has low traction properties, it results in low friction, and hence lower the operating temperature of the pinion.


Under high load, viscosity index improvers may get sheared off, this results in permanent loss of viscosity, so sometimes there are chances of Gear lubricant failure.


We have seen various types of lubricants for Open Gear application. However selection of lubricant depends on actual operating conditions of equipment, environmental factors.

Mosil Lubricants has 40 years of excellence in lubrication for various industries. Our Technical team recommends the best suitable product by studying the applications, and several factors.

We invite you to write to us to discuss your application and the most appropriate lubrication solution that MOSIL may offer.

MOSIL Best Selling Open Gear Lubricants


It is heavy duty semi-fluid adhesive type grease with EP additives to impart extremely high anti wear and load carrying capacity. It is blended with additives such as rust and corrosion inhibitors and anti-oxidants to provide rust protection and oxidation stability for high temperature and heavy duty applications. It is free of any solvents, lead, antimony, barium etc. substances.


It is heavy duty semi-fluid adhesive type grease with high quality lubricating solids to provide high anti-wear and load carrying capacity. It is blended with additives such as rust and corrosion inhibitors and anti-oxidants to provide rust protection and oxidation stability for high temperature and heavy duty applications.

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