Introduction to Hydraulic and Pneumatic Systems
1.Heavy lifting work is often accomplished by shifting fluids in big machines. The power system of such machines can be described as
a)Reciprocating
b)Pneumatic
c)Hydraulic
d)Hybrid
Ans: c) Hydraulic
2.The scientific principle that makes hydraulic systems possible is
a)Pascal’s principle
b)Boyle’s law
c)Bernoulli’s principle
d)The fluid flow principle
Ans: a) Pascal’s principle
3.Which of the following is not the application of hydraulics system?
a)Back hoe loader
b)Spray Painting
c)Dumper
d)Fork lift
Ans: b) Spray Painting
4.Which of the following reasons make water unsuitable to use as a fluid in hydraulic systems?
1.poor lubrication
2.high viscosity
3.more leakage
4.quickly evaporates
a.1 and 3
b.2 and 4
c.1, 3 and 4
d.all the above
ANSWER: c. 1, 3 and 4
5.Which of the following statements are true?
1.low viscosity fluids have higher leakage
2.high viscosity fluids have high pressure drop
3.low viscosity fluids consume more power
4.low viscosity leads to wear of components
a.1 and 2
b.1, 2 and 3
c.1, 2 and 4
d.2, 3 and 4
ANSWER: c. 1, 2 and 4
6.In industrial applications hydraulic fluids have viscosity grade ranging from
a.20 to 50
b.70 to 95
c.46 to 68
d.15 to 44
ANSWER: c. 46 to 68
7.High viscosity fluids have
a.low pressure drop
b.less power consumption
c.slow operation
d.all the above
ANSWER: c. slow operation
8.What is viscosity index?
a.effect of pressure on changes in viscosity
b.effect of temperature on changes in viscosity
c.effect of resistance between two surfaces
d.none of the above
ANSWER: b. effect of temperature on changes in viscosity
9.Highest temperature at which a fluid in hydraulic system flows is called its pour point.
a.True
b.False
ANSWER: b. False
10.Which property decides the behaviour of fluid when mixed with water?
a.pour point
b.demulsibility
c.viscosity
d.oxidation
ANSWER: b. demulsibility
11.For any operation in a hydraulic system the fluid should have pour point
a.20 0F below the lowest temperature
b.20 0F above the lowest temperature
c.20 0C below the lowest temperature
d.20 0C above the lowest temperature
ANSWER: a. 20 0F below the lowest temperature
12.What is the disadvantage of petroleum based fluids?
a.low flash point
b.low density
c.light weight
d.all the above
ANSWER: a. low flash point
13.How is the water content in High Water Fluids (HFA) compared to oil content?
a.more oil than water
b.oil and water are in same proportion
c.more water than oil
d.contains only water
ANSWER: c. more water than oil
14.A fluid used in hydraulic systems should have
a.low oxidation resistance
b.high oxidation resistance
c.high oxidation enhancing ability
d.none of these
ANSWER: b. high oxidation resistance
15.At which pressure, petroleum oil used in hydraulic systems gets compressed by 1/2 % ?
a.70 bar
b.40 bar
c.30 bar
d.95 bar
ANSWER: a. 70 bar
16.What is the relation between temperature and specific weight for water glycol?
a.as temperature increases specific weight decreases
b.as temperature increases specific weight increases
c.temperature and specific weight vary linearly
d.none of the above
ANSWER: a. as temperature increases specific weight decreases
17.What is the relation between temperature and viscosity for hydraulic oil?
a.temperature and viscosity vary linearly
b.as temperature decreases viscosity decreases at atmospheric pressure
c.as temperature increases viscosity decreases at atmospheric pressure
d.none of the above
ANSWER: c. as temperature increases viscosity decreases at atmospheric pressure
18.Match the following group 1 with group 2 and select the correct option: Group 1 Group 2
1.High water fluids A. water and synthetic chemical
2.water in oil B. fire-resistant fluid
3.water glycol C. oil in water
4.synthetics D. tiny droplets of water in oil
a.C – D – A – B
b.D – C – B – A
c.C – B – D – A
d.D – C – A – B
ANSWER: a. C – D – A – B
19.High Water Fluids contain
a.oil in water
b.water in oil
c.only water
d.none of the above
ANSWER: a. oil in water
20.Viscosity of High Water Fluids is
a.greater than water
b.less than water
c.nearby water
d.none of the above
ANSWER: c. nearby water
21.Adding an additive to water glycol fluids improves
a.flammability
b.viscosity
c.oxidation
d.all the above
ANSWER: b. viscosity
22.Can all hydraulic fluids be compressed when extremely large pressure is applied
a.Yes
b.No
ANSWER: a. Yes
23.The resistance offered to the flow of fluid inside a piston develops into
a.pressure
b.force
c.stress
d.all of the above
ANSWER: a. pressure
24.At low pressures, liquids are
a.compressible
b.non-compressible
c.unpredictable
ANSWER: b. non-compressible
25.Which of the following statements are false?
1.pressure is resistance to flow
2.friction creates pressure
3.load cannot create pressure on the system
4.the pressure developed decreases if load offers more resistance
a.1, 2 and 4
b.1 and 2
c.3 and 4
d.none of these
ANSWER: c. 3 and 4
26.If no load is attached to piston rod, the movement of piston assembly is possible when
a.oil overcomes its self weight
b.oil overcomes friction in the piston rod assembly
c.both a and b
d.none of these
ANSWER: c. both a and b
27.During any operation in hydraulic system, oil prefers the path of
a.least resistance
b.maximum resistance
c.both a and b
d.none of the above
ANSWER: a. least resistance
28.In a hydraulic circuit a pump is provided with two outlet paths, one where load is attached and other to the reservoir. Which path will the oil choose to flow first?
a.oil will flow to the path where load is attached
b.oil will flow back to the reservoir first
c.oil will flow through both the paths simultaneously
d.none of the above
ANSWER: b. oil will flow back to the reservoir first
29.Pressure applied on a fluid in a container is equally distributed in all directions and acts with
a.equal force on equal areas parallelly
b.equal force on different areas and at right angles
c.equal force on equal areas and at right angles
d.none of the above
ANSWER: c. equal force on equal areas and at right angles
30.Which law explains the behavior of hydraulic fluids under pressure?
a.Charles's law
b.Newtons law
c.Pascal's law
d.None of the above
ANSWER: c. Pascal's law
31.Flow of oil in a pipe takes place due to
a.balanced forces
b.unbalanced forces
c.both balanced and unbalanced forces
d.none of the above
ANSWER: b. unbalanced forces
