Ramsay Test Lubrication

Question 1

Which type of lubricant is most appropriate for a high-speed ball bearing operating at elevated temperatures?

Accepted Answer

High-temperature bearing grease (NLGI Grade 2 or 3)

Answer

High-temperature bearing grease provides the necessary consistency to stay in place at speed and thermal stability to resist breakdown. EP gear oil and hydraulic fluid are not formulated to stay in bearings, and penetrating oil has no film strength.

Question 2

NLGI grease consistency grades (000 through 6) measure which property?

Accepted Answer

The stiffness or consistency of the grease

Answer

NLGI grades classify grease from very fluid (000) to block-solid (6) based on worked penetration — essentially how stiff or soft the grease is. Base oil viscosity and dropping point are separate specifications.

Question 3

A pillow-block bearing housing feels unusually hot and grease is purging out of the seals. The most likely cause is:

Accepted Answer

Over-greasing causing churning and heat buildup

Answer

Over-greasing forces excess grease through seals and causes the rolling elements to churn through the surplus, generating friction and heat. A dry bearing would show noise and rapid wear before heat; water contamination produces a milky grease appearance.

Question 4

What is the primary function of Extreme Pressure (EP) additives in gear oil?

Accepted Answer

To form a protective chemical layer on gear teeth under high load and shock

Answer

Under high contact stress, EP additives chemically react with metal surfaces to form a sacrificial layer that prevents metal-to-metal welding and scoring. The other functions belong to viscosity index improvers, pour point depressants, and antioxidants respectively.

Question 5

A technician finds that grease in a bearing has turned black and smells burnt. The most likely cause is:

Accepted Answer

Thermal degradation from overheating beyond the grease's service temperature

Answer

Black discoloration combined with a burnt odor is the classic signature of thermal degradation — the grease has been exposed to temperatures beyond its rated range, carbonizing the thickener and base oil. Water contamination produces a milky or whitish appearance; mixing incompatible greases causes softening or hardening.

Ramsay Test Practice Test

Ramsay Test Practice Test

Ramsay Test Lubrication