Which one of the following frictions occurs in an un-lubricated journal bearing ?

Sliding friction

Rolling friction

Fluid friction

Dry friction

Tool steel

Grey cast iron

Copper

Aluminium

Cutting oil

Grease

Lard oil

Kerosene oil

Carry away the heat produced in bearing

Prevent metal-to-metal contact and reduce friction

Prevent entry of foreign material i.e dust, dirt etc. in the bearing

Provide a cushion to a load and shocks

No change in viscosity due to variation in temperature

Reduces friction between machine parts

Takes up the surface pressure between sliding parts

Becomes thicker after prolonged use