Question

Grease is applied to parts of a motor vehicle for smooth movement. Greases are, essentially, lubrication oils made into a jelly by:

• A. soaps of fatty acids
• B. blowing air under pressure
• C. adding wax
• D. churning of starch

Answer 1

Answer: (A)

soaps of fatty acids

Grease is a semisolid lubricant. Grease generally consists of a soap emulsified with mineral or vegetable oil.

The characteristics feature of greases is that they possess a high initial viscosity, which upon the application of shear, drops to give the effect of an oil-lubricated bearing of approximately the same viscosity as the base oil used in the grease. This change in viscosity is called shear thinning. A true grease consists of an oil and/or other fluid lubricants that is mixed with a thickener, typically a soap, to form a solid or semisolid. Soaps are the most common emulsified agent used, and the selection of the type of soap is determined by the application.