CMRT CMRT Lubrication and Tribology 3

Question 1

What is the purpose of an EP (Extreme Pressure) additive in a gear lubricant?

Accepted Answer

To chemically react with metal surfaces under high load to prevent welding and scuffing

Answer

EP additives chemically react with metal surfaces under extreme pressure and high temperatures to form protective films that prevent metal-to-metal welding (scuffing) in heavily loaded gears.

Question 2

In centralized lubrication systems, what is the role of a divider valve (or metering valve)?

Accepted Answer

To distribute measured, precise amounts of lubricant to multiple points simultaneously

Answer

Divider valves (metering valves) in centralized lubrication systems distribute precise, predetermined quantities of lubricant to each lubrication point with each pump cycle.

Question 3

What does 'NLGI grade' indicate for a grease product?

Accepted Answer

The consistency (hardness or softness) of the grease as classified by the NLGI

Answer

NLGI (National Lubricating Grease Institute) grades classify grease consistency on a scale from 000 (very fluid) to 6 (very stiff), with NLGI 2 being the most common for general industrial use.

Question 4

Which oil sampling method is most preferred for accurate oil analysis results?

Accepted Answer

Taking a sample from a live zone in the system using a vacuum pump through a dedicated sample port

Answer

Sampling from a live zone (circulating oil) through a dedicated sample port provides the most representative sample of the oil condition and suspended wear particles throughout the system.

Question 5

What is the primary purpose of rust and oxidation (R&O) inhibitors in turbine and circulating oils?

Accepted Answer

To protect metal surfaces from rust and slow the chemical degradation of the oil

Answer

R&O inhibitors protect metal components from rust and corrosion while also acting as antioxidants to slow oil degradation, extending both component and lubricant service life.

(CMRT) Certified Maintenance and Reliability Technician Practice Test

(CMRT) Certified Maintenance and Reliability Technician Practice Test

CMRT CMRT Lubrication and Tribology 3