1. The viscosity index,
a) is a measure of oil viscosity that ranges between 0 and 100;
b) is higher for lubricants exhibiting greater change of viscosity with changing temperature;
c) is negative for engine oils exhibiting increasing viscosity with increasing temperature;
d) is higher for oils exhibiting less change of viscosity with changing temperature.
2. A base oil
a) is the minor component of an oil-based lubricant;
b) is an oil additive that counteracts oil acidity arising from oil degradation;
c) can be mineral, synthetic or biological in origin and constitutes the major component of a lubricant;
d) is a reference oil used for baseline comparisons.
3. Which one of the following is classed as a metal detergent typically used in engine oils?
a) Zinc dialkyldithiophosphate;
b) Calcium salicyclate;
c) Molybdenum disulfide;
d) Lauric acid.
4. Viscosity increase of engine oils during service is most likely to be caused by,
a) fuel contamination;
b) additive reaction;
c) oil oxidation;
d) dust contamination.
5. Which NLGI class grease would be considered most suitable for lubricating the components of a conveyor station using an automatic centralised lubrication system,
a) 000;
b) 1;
c) 5;
d) 10.
6. Hydrodynamic lubrication requires
a) a converging film profile;
b) an inviscid fluid;
c) a negative entraining velocity;
d) all of the above.
7. For a narrow journal bearing, an eccentricity ratio of about 0.7,
a) gives maximum bearing load carrying capacity;
b) gives minimum bearing friction;
c) gives minimum bearing vibration;
d) gives minimum bearing temperature rise.
8. The film thickness in EHL is
a) directly proportional to the entraining velocity;
b) decreases as the reduced radius is increased;
c) is theoretically zero if the surfaces are travelling at the same speed but in opposite directions;
d) increases as the elastic moduli of the contacting surfaces increases.
9. The major mechanism of friction reduction in boundary lubrication involves,
a) increasing the hardness of the surface oxide;
b) weakening of the surface material;
c) increasing the yield strength of the surface material;
d) suppressing adhesion between contact interfaces.
10. An elastomer seal slides against the steel shaft of a hydraulic linear actuator. What coating would be preferred to reduce both friction and wear in an environment contaminated by hard sand and dust particles?
a) Titanium nitride on the seal;
b) Titanium nitride on the shaft;
c) Teflon on the seal;
d) Teflon on the shaft.