CLS Grease Technology & Application

Question 1

What is the primary function of a thickener in lubricating grease?

Accepted Answer

To act as a sponge-like structure that holds the base oil

Answer

The thickener forms a three-dimensional matrix or sponge-like structure that holds the base oil in place and releases it under shear during lubrication.

Question 2

Which NLGI grade is most commonly used for general-purpose bearing lubrication in most industrial applications?

Accepted Answer

NLGI 2

Answer

NLGI Grade 2 is the most widely used grade for general-purpose bearing lubrication due to its balance of consistency and pumpability under typical operating conditions.

Question 3

What does the dropping point of a grease indicate?

Accepted Answer

The temperature at which the grease loses its structure and becomes liquid

Answer

The dropping point is the temperature at which the grease transitions from a semi-solid to a liquid state, indicating its upper operating temperature limit.

Question 4

Which thickener type is generally considered incompatible with most other thickener types?

Accepted Answer

Polyurea

Answer

Polyurea-thickened greases are generally incompatible with most other grease thickener types, including lithium and calcium-based greases, and mixing can cause significant degradation.

Question 5

What is the purpose of EP (Extreme Pressure) additives in grease?

Accepted Answer

To form a protective film on metal surfaces under high load and shock conditions

Answer

EP additives chemically react with metal surfaces under high pressure and temperature to form a sacrificial film that prevents metal-to-metal contact and welding.

(CLS) Certified Lubrication Specialist Practice Test

(CLS) Certified Lubrication Specialist Practice Test

CLS Grease Technology & Application