Which viscosity is typically used in splash lubrication systems for gears?

The viscosity typically used in splash lubrication systems for gears is SAE 80-90. This range provides adequate film strength and lubrication at the operating temperatures and pressures commonly found in gear systems. It strikes a balance between not being too thick, which could cause excessive resistance and drag, and not being too thin, which could lead to inadequate lubrication and increased wear.

In splash lubrication systems, the oil is circulated by the motion of the gears themselves, thus necessitating a viscosity that ensures proper coverage and prevents breakdown under shear forces. The SAE 80-90 range is designed to perform well in a variety of operational conditions, making it suitable for many gear applications, particularly those that experience moderate to high loads and variable speeds.

Other viscosity options, such as SAE 100-110 or SAE 120, might be too thick for efficient operation under typical splash lubrication conditions, potentially leading to poor circulation and inadequate coverage, especially at lower temperatures. Conversely, options like SAE 90-100 may also be on the higher side, potentially offering similar concerns regarding excessive thickness. Therefore, SAE 80-90 is widely accepted as the ideal choice for gear applications requiring splash lubrication.