Level 1 MLT & MLA Practice Exam
The primary reason that machinery is replaced is due to:
a) Erosion
b) Accidents
c) Obsolescence
d) Surface degradation of the metal
e) Corrosion - ANS-Answer: "d"
Wear is the primary cause of machinery replacement Surface degradation of the metal
includes all types of wear such as abrasion, adhesion, erosion, corrosion, etc.
Which of the following is not a lubrication regime (mode / type)?
a) Boundary
b) Elastohydrodynamic
c) Boundarydynamic
d) Hydrodynamic
e) Mixed film - ANS-Answer: "c"
• Boundary lubrication is defined as that regime of lubrication in which the load is carried
by the surface asperities rather than by the lubricant
• Elastohydrodynamic lubrication is a form of hydrodynamic lubrication (full film
separation). It is called elastohydrodynamic because the lubricated components deform
elastically due to high pressure as in antifriction bearings, gears and cams.
• Hydrodynamic lubrication is also called full film lubrication in which the load is carried
totally by the lubricant. The hydrodynamic film is a result of the relative movement of
surfaces and the viscous resistance of the lubricant
• Mixed film lubrication is a combination of full film and boundary lubrication. In this type,
the lubricant is insufficient to carry the load and provide full film separation. Some points
of contact still occur between surfaces.
Which maintenance strategy is based strictly on tasks performed at specific time
intervals?
a) Proactive
b) Predictive
c) Preventive
d) Percussive
e) Reactive - ANS-Answer: "c"
,Preventive maintenance is time-based. Generally, this type of maintenance is not
cost-effective because parts are changed prematurely and failures occur due to late or
improper maintenance.
Condition-based maintenance:
a) is based on the condition of the equipment and the early detection of faults
b) is based on regular time-based overhauls
c) Is based on run to failure
d) is based on the condition of the oil and other root causes
e) Answers a and d - ANS-Answer: "e"
Condition-based maintenance is often referred to as predictive maintenance (PdM)
where the ultimate goal is to perform maintenance activity based on early detection of
problems using periodic or continuous monitoring, Obviously, (e) is the correct answer,
while (b) and (c) represent preventive and reactive maintenance, respectively,
The Pareto Principle (80/20 Rule) states:
a) The largest beneficial effect is obtained from a critical few maintenance tasks
b) The largest beneficial effect is obtained from the (random) many maintenance tasks
c) All machines die sometime
d) All bearings live forever
e) 80 percent of the people do 20 percent of the work - ANS-Answer: "a"
In general, the Pareto Principle states that, for many events, roughly 80 percent of the
effects come from 20 percent of the causes, so the correct answer is (a).
Which of the following is not a function of the lubricant?
a) Cool surfaces
b) Separate surfaces
c) Prevent corrosion
d) Repair surfaces
e) Provide some scaling - ANS-Answer: "d"
The functions of a lubricant include controlling friction and wear by separating surfaces
in addition to cooling, corrosion prevention, sealing and transmitting power in some
applications such as hydraulic systems. The correct answer is (d), as surface repair
cannot be achieved using lubricants.
Which type or form of lubrication is considered to provide a full fluid (oil) film?
a) Elastohydrodynamic
,b) Solid Film
c) Boundary
d) Mixed - ANS-Answer: "a"
Elastohydrodynamic lubrication is a form of hydrodynamic lubrication (full film
separation). It is called elastohydrodynamic because the lubricated components deform
clastically due to high pressure.
Elastohydrodynamic lubrication (EHL) is considered to occur primarily in:
a) Piston rings and liners
b) Journal bearings
c) Rolling bearings, gears and cams
d) Slow-moving pins and bushings
c) Worm gears - ANS-Answer: "c"
EHL occurs in systems where the contact area is small and the pressure is high, such
as rolling clement bearings. gears (at the pitch line) and cams. The mating surfaces
deform elastically to enlarge the contact area, which is why it is called
clastohydrodynamic lubrication.
The oil film thickness (or dynamic operating clearance) in operating bearings:
a) Cannot be determined
b) Is about 10 microns for journal bearings (although can vary considerably)
c) Is about a micron for rolling bearings
d) Is not measurable
e) Answers b&c - ANS-Answer: "e"
Generally, the film thickness in a journal bearing is approximately 10 microns, while in a
rolling element bearing it is about 1 micron. This is why rolling element bearings are
more sensitive to contaminants.
Which is not a type of base oil (base stock)?
a) Mineral
b) Synthetic
c) Antioxidant
d) Vegetable
e) Group III synthetic - ANS-Answer: "c"
, All of these options are base oil types except antioxidant, which is an additive that is
added to the base oil to improve oxidation stability.
Benefits generally associated with the use of synthetics include:
a) Better oxidation resistance
b) Better compatibility with clastomers (seals)
c) Less toxicity
d) Higher cost
e) Better paint compatibility - ANS-Answer: "a"
In general, synthetic base oils have better oxidation stability. However, most synthetics
are incompatible with clastomers (seals), as they cause the scals to swell or shrink.
Some synthetics can also be toxic. High cost and incompatibility with paints are other
shortcomings of synthetics, so the correct answer is (a).
PAO synthetic base oils:
a) Offer the best additive solubility
b) Are the prime choice for fire resistance
c) Have better oxidation stability than mineral oils
d) Are incompatible with mineral oils
e) Offer the very best high-temperature stability - ANS-Answer: "c"
PAO base oils have high oxidation stability compared to mineral oils. The additive
solubility is limited because of the high degree of purity (the more refined the base oil,
the less solubility of the additives). Furthermore, PAO base oils are compatible with
mineral oils but are not fire-resistant fluids, so the correct answer is (c).
Polyglycol (PAG) synthetic oils:
a) Offer the best additive solubility
b) Are the prime choice for fire-resistant fluids
c) Are a copy of the best structure found in mineral oils
d) Are incompatible with mineral oils
e) Offer the very best high-temperature stability - ANS-Answer: "d"
PAG oil offers marginal additive solubility. While it is fire resistant when combined with
water (water-glycol), it is not the prime choice for fire-resistant fluids. (Phosphate ester
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