Abstract:
Open gear drives, or girth gears are a common method of power transmission since the beginning of the Industrial Revolution. Open gear drives are the economical alternative for use in applications having the high load-carrying capacity and long service life under severe shock load conditions.
Characteristics like flexibility in the machine’s design have made open gear drives the most common type of drive used for ball mills and grinding mills, kilns, dryers, draglines and shovels. Broadly, there are two types of open gear drives:
Type 1 - utilizes a rack
Type 2 - utilizes a series of gears.
OPEN GEAR LUBRICANT REQUIREMENTS AND INDUSTRIAL LUBRICANTS STANDARDS
Open gear applications associated with ball mill and finishing mill applications are some of the most difficult applications for the lubricant. Generally, these types of open gears operate at low pitch line velocities and under heavy loads.
Recent designs of equipment require open gears to transmit increasingly higher loads. Due to these considerations, an open gear lubricant possesses the following characteristics and properties:
Retention of lubricant on the surface of gear
Resistance to wet environment.
Protection against wear & corrosion
Load carrying capacity
Vibration damping capability
Sprayability and dispensability
TYPES OF OPEN GEAR LUBRICANTS
Currently, the lubricants used by both type open gears consist of the following:
1 Asphaltic lubricant & Cutbacks
2. Semi Fluid Greases
3. Polymer-thickened types
4. High-viscosity synthetics
Each of these OG lubricants possesses performance and compositional characteristics that define their capabilities.
ASPHALTIC TYPE & CUTBACKS
Asphaltic-type open gear lubricants are also known as black oils. This type of open gear lubricant is most commonly used in older equipment and has been used for years. They are formulated from high-viscosity cutbacks of the refining process of mineral oils. It contains a high level of asphalt and a volatile solvent diluent, which is used in the application of the product. The residual black oils used in the formulation have viscosity of 643 cSt or higher at 100ºC. eg. mobil 375 LC.
Operating on the principle of an oil film separating the mating surfaces of the pinion and the gear, The Asphaltic type lubricants are applied by an automatic spray system. Once applied, the solvent diluent evaporates, leaving behind a viscous coating of lubricant. Also retains the wear debris and dust from the environment
SEMI FLUID GREASES
These open gear lubricants contain medium- to high-viscosity petroleum or synthetic base oil. They contain a thickener system such as an aluminum complex. solid lubricants and EP additives such as molybdenum disulfide and graphite and rust inhibitors.
These types of open gear lubricants can be used in the lubrication of both unidirectional as well as reversible type open gears. The following has been observed when these type open gear lubricants have been used:
They are more fluid than the asphaltic type.
Used through an intermittent centralized lubrication system in open gears, resulting in simplified lubrication, a reduction in consumption.
Formation of a tacky lubricant film which is easier to clean off for maintenance inspections, repairs and welding.
POLYMER THICKENED TYPE
These types of lubricants contain medium- to high-viscosity mineral or synthetic base oils that are thickened with a polymeric thickener, EP agents, and solid lubricants to enhance their thin film and boundary film performance.
Products that fall in the classification contain volatile solvents for ease of application. These types of open gear lubricants are typically NLGI # 00 to # 0 consistency.
Polymer-thickened open gear lubricants are thixotropic in nature. The thixotropic property allows better lubrication in the loaded zone and aids in their ability to be applied by standard intermittent spray systems or be used in splash or idler immersion systems.
Once applied to the surface of the open gearing, polymer-thickened open gear lubricants form a thick, tenacious, opaque to transparent film coating on the gears that can be observed during inspections.
HIGH VISCOSITY SYNTHETIC OILS
These are formulated from medium- to very high-synthetic base fluids, such as polyalphaolefin (PAO) and polyol esters, or a combination of both, and contain EP additive.
Some products may also contain solid lubricants such as molybdenum disulfide that is dispersed into the lubricant in a colloidal suspension, or contain viscosity index improvers to enhance the viscometric properties of the synthetic base fluids. Also, the use of viscosity index improvers has traditionally been considered unacceptable by gear manufacturers.
INSTALLATION OF OPEN GEAR IN AN EQUIPMENT
1st Stage - Priming
Priming Lubricant cleans the tooth flanks and protects from damage during the initial installation of the gear and 1000cSt Viscosity base oil ensures thick oil film which helps in cleaning the wear debris.
2nd Stage - Running In
Running-in Lubricants are applied to a new or repaired gear to increase the contact surface of the gear tooth. The Lubricants of 460 cSt are applied on the No load to 25 % load condition of the open gear mechanism.
3rd Stage - Operational
Operational lubricants provide excellent gear protection with low consumption rates. Here 16000 cSt base oil viscosity lubricant is sprayed on the tooth flank as per the lubrication schedule in full load conditions.
4th Stage - Repair
Repair Lubricants recondition the tooth flank to quicken the increase of load-bearing area surface to extend the life of your gears.
Expertise is required for carrying out such repair jobs.
SCOPE FOR MOSIL
When we are looking for the optimum lubrication solution, there’s always a space for a trustworthy lubrication partner. Here a Lubricant supplier or Manufacturer plays a key role in providing the required solution and handling and solving the pain points of the customer. Mosil Lubricant is a leading Manufacturer of Industrial lubricants. Mosil with its understanding of gear drive mechanisms tries to resolve the industrial lubricants-related issues build a trust-based relationship with its satisfied customers and remain a Partner In Progress.
Know more about MOSIL at www.mosil.com or write at enquiry@mosil.com.
![Gear Drive Lubricant Selection [Gearbox Lubricants]](https://mosil.com/assets/uploads/blog/blog_1782972100_6a45fec4dbc03.webp)
![The Ultimate Guide To Grease Thickeners [Thickening Agents]](https://mosil.com/assets/uploads/blog/blog_1754991852_689b0cec60a8a.jpg)
