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TEST YOUR KNOWLEDGE
This month, Machiner y Lubrication continues it s " Test Your Knowledge" sec tion in which we focus on a group of questions from Noria's
Prac tice Exam for Level I Machine Lubrication Technician and Machine Lubricant Analyst. The answers are located at the bottom of this
page. The complete 126-question prac tice test with expanded answers is available at store.noria.com.
ANSWERS
1. D
Group IV is a PAO synthetic and has high oxidation stability.
2. E
Thermal degradation (breakdown) typically occurs at very high temperatures due to
heat alone with or without oxygen present. Acid number and other oxidation stability
tests will not help in monitoring the thermal breakdown of oil. Thermal breakdown
may result in thermal cracking of the base oil, thus leading to a critical drop in
viscosity and sometimes fl ash point.
3. A
This is because overgreasing creates high viscous friction, which leads to high
temperature. The high temperature causes the oil within the grease to rapidly oxidize
and in some cases leads to premature failure.
1. Oxidation stability is highest for which of the
following groups?
A) Group I
B) Group II
C) Group III
D) Group IV
E) Fuel oil
2. Thermal breakdown of lubricants typically:
A) Occurs at very high temperatures due to heat alone with an
absence of oxygen
B) Is monitored with acid number
C) May result in thermal cracking of the base oil and
a decrease in viscosity
D) All of the above
E) Answers A and C
3. Overgreasing is a common problem with higher
speed rolling bearings because:
A) It causes the temperature to rise
B) It causes the grease to mechanically shear down
C) It causes the grease to change color
D) It causes the temperature to decrease
E) It causes the bearings to elastically deform in shape