What is the friction loss in a journal bearing directly proportional to?

Friction loss in a journal bearing is directly proportional to bearing oil viscosity. This is due to the fact that viscosity represents the internal resistance of the oil to flow. As the viscosity of the oil increases, it creates greater resistance to movement between the bearing surfaces, which in turn increases friction loss. A thicker oil will not flow as easily, leading to higher friction forces at play.

While other factors can influence friction loss, such as the load on the bearing, oil temperature, and the radius of the bearing, those do not have a direct proportional relationship to friction loss as viscosity does. For instance, although an increase in load can also contribute to friction loss by increasing the contact pressure between surfaces, it is the viscosity that fundamentally dictates how easily the oil can lubricate and manage those forces. Thus, the direct relationship between friction loss and oil viscosity is a key concept in understanding how journal bearings function.