INDUSTRIAL GREASES

Detail Description

Coefficient of Lubricant Friction or Duty Parameter is proportional to Viscosity x Speed/Load

• λ=H/S, where λ = Specific Film Thickness, H = Minimum Film Thickness,

S = Composite average surface roughness
Full Film Lubrication λ > 3
Mixed Film Lubrication 1< λ < 3
Boundary Lubrication λ < 1

• Approximately SUS = Kinematic Viscosity @ 40 ºC / 5
• Viscosity (cSt) = Dynamic Viscosity (cP) / Density (g/cc)
• Arrhenius law: Oxidation rate doubles for every 10 ºC rise in temperature.

SIMPLIFIED VISCOSITY SELECTION FOR WORM AND HYPOID GEARS

GEAR OILS

• Erichello Method:

Viscosity @ 40 ºC = 7000÷√V1
V1 = Pitch line velocity of the lowest speed gear in feet per minute (fpm) = 0.262 x speed (pinion RPM) X pinion diameter (inches)

• If ambient at 95 ºF increase jump ISO Grade by one step.
• If ambient at 122 ºF increase ISO Grade by two.