ML
TEST your
KNOWLEDGE
This month, Machinery Lubrication continues its "Test Your Knowledge" section in
which we focus on a group of questions from Noria's Practice 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 practice test with
expanded answers is available at store.noria.com.
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
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.
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 flash point.
1. D
Group IV is a PAO synthetic and has high oxidation stability.
Answers:
22 |
July - August 2013
| www.machinerylubrication.com
