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. The deformation of a rolling
element to carry a load is
known as what?
A)
B)
C)
D)
E)
Boundary lubrication
Hydrodynamic lubrication
Elastohydrodynamic lubrication
Deformative film lubrication
Mixed film lubrication
2. Which additive is responsible for giving a multi-grade lubricant suitable
viscosity over wide-ranging temperature?
A)
B)
C)
D)
E)
Viscosity index improver
Over-base detergent
ZDDP
Dispersant
Antioxidant
3. A common sampling frequency for an industrial oil would be:
A)
B)
C)
D)
E)
Every two weeks
Monthly (500 to 1,000 hours)
Quarterly
Six months
Yearly
Answers:
1. C
It is known as elastohydrodynamic lubrication, which is a form of hydrodynamic lubrication (full-film separation). However, it is called elastohydrodynamic because the mating surfaces deform elastically (slightly) to
enlarge the contact area in order to carry the load.
2. A
The viscosity index (VI) of oils represents how the viscosity changes with respect to temperature. VI
improvers, which are made from long-chain polymers, are added to the base oil at concentrations as high as
10 percent for better viscosity/temperature performance.
3. B
A common sampling frequency for industrial oil would be monthly. Two weeks is not considered cost-effective, while a sampling frequency of three, six or 12 months would not be practical, since detecting problems
and rectifying them early are essential to avoid major repairs and in some cases production loss.
30 |
January - February 2013
| www.machinerylubrication.com
