Why do gas-lubricated systems have lower load capacities than liquid-lubricated systems?

Gas-lubricated systems exhibit lower load capacities than liquid-lubricated systems primarily due to the fundamental physical properties of the lubricants involved. While both gases and liquids function under the principles of fluid-film lubrication, they differ significantly in two key areas:

• Viscosity: Gases possess much lower viscosity than liquids. Because viscosity is critical for building up a film thick enough to separate sliding surfaces and support a load, the lower viscosity of gases limits their ability to maintain the necessary pressure between surfaces.12
• Compressibility: Gases are far more compressible than liquids. This high compressibility makes it more difficult for a gas film to maintain the structural integrity required to support heavy loads compared to the relatively incompressible nature of liquid lubricants.1

Consequently, these differences result in thinner film thicknesses and reduced load-carrying capacities in gas-lubricated systems compared to those using liquids.1