Gear Wear, Adhesion and Guidelines

Abrasion. Abrasive wear is caused by particle contaminants in the lubricant. Particles may originate internally due to poor quality control during the manufacturing process. Particles also may be introduced from the outside during servicing or through inadequate filters, breathers, or seals. Internally generated particles are particularly destructive because they may become work-hardened during compression between the gear teeth. The following guidelines should be observed to prevent abrasive wear in gear units:

• Remove internal contamination from new gearboxes. Drain and flush the lubricant before initial start-up and again after 50 hours of operation. Refill with the manufacturer’s recommended lubricant. Install new filters or breathers.

• Use surface-hardened gear teeth, smooth tooth surfaces, and high-viscosity lubricants. Maintain oil-tight seals and use filtered breather vents, preferably located in clean, nonpressurized areas.

• Use good housekeeping procedures.

• Use fine filtration for circulating-oil systems. Filtration to 3 µm (120 µ-in.) has proven effective in prolonging gear life.

• Unless otherwise recommended by the gear manufacturer, change the lubricant in oil-bath systems at least every 2500 hours or every 6 months. 

When warranted by the nature of the application, conduct laboratory analysis of lubricants. Analysis may include spectrographic, ferrographic, acid number, viscosity, and water content.