Pumps and Actuators
1.A single acting cylinder can be pressurized externally from one direction only.
a)True
b)False
Ans: a) True
2.The ......... converts the compressed air energy into mechanical energy in the form of linear movement in one direction only.
a)Piston cylinders
b)Double acting cylinders
c)Single acting cylinders
d)Hydraulic pumps
Ans: c) Single acting cylinders
3.Which of the following is a roto-dynamic pump?
a.vane pump
b.centrifugal pump
c.gear pump
d.piston pump
Ans: b. centrifugal pump
4.Variable displacement pumps used in hydraulic applications can
1.have variable flow rate
2.consume less energy
3.be operated with high accuracy for slow and rapid motion
4.generate more heat
a.1 and 2
b.3 and 4
c.1, 2 and 3
d.all the above
Ans: c. 1, 2 and 3
5.Which type of displacement is observed in gear pumps?
a.only variable displacement
b.only fixed displacement
c.both fixed and variable displacement
d.none of the above
Ans: b. only fixed displacement
6.What is the principle of operation used in gear pumps?
a.two gears rotate in same direction
b.two gears rotate in opposite direction
c.both a and b
d.none of the above
Ans: b. two gears rotate in opposite direction
7.What causes suction of fluid into the gear pump?
a.when pressure drops during disengagement of teeth at the suction side
b.when pressure increases during disengagement of teeth at the suction side
c.when pressure drops during engagement of teeth at the suction side
d.when pressure increases during engagement of teeth at the suction side
Ans: a. when pressure drops during disengagement of teeth at the suction side
8.How is the smooth and continuous discharge of fluid achieved in a gear pump?
a.increasing number of teeth
b.decreasing number of teeth
c.none of the above
Ans: a. increasing number of teeth
9.What cause discharge of fluid in an external gear pump?
1.the electric motor drives one gear which turns the other gear
2.the electric motor drives both the gears simultaneously
3.fluid passes between the gears to discharge side
4.fluid passes through interior of the casing between teeth and casing and not between the gears
a.1 and 3
b.2 and 3
c.1 and 4
d.2 and 4
Ans: c. 1 and 4
10.The rotation of gears in internal gear pump takes place in
a.Same direction
b.different direction
c.none of the above
Ans: a. same direction
11.How does the fluid flow in internal gear pump?
a.fluid enters the suction side between rotor, which is a large exterior gear and idler which is a small interior gear
b.fluid enters the suction side between rotor, which is a small exterior gear and idler which is a large interior gear
c.fluid enters the suction side between rotor and idler which rotate in different directions
d.none of the above
Ans: a. fluid enters the suction side between rotor, which is a large exterior gear and idler which is a small interior gear
12.What causes internal leakage in internal gear pump?
a.less tolerance level between the meshing surfaces
b.more tolerance level between the meshing surfaces
c.no tolerance between the meshing surfaces
d.none of the above
Ans: b. more tolerance level between the meshing surfaces
13.What is the relation between pressure and overall efficiency for a gear pump?
a.as pressure increases, overall efficiency decreases
b.as pressure increases, overall efficiency increases
c.overall efficiency is not affected by change in pressure
d.none of the above
Ans: a. as pressure increases, overall efficiency decreases
14.What is the advantage of internal gear pump?
a.moderate speed
b.medium pressure
c.high viscosity fluids can be used
d.all the above
Ans: c. high viscosity fluids can be used
15.Which force causes vanes to come out of the rotor slots?
a.centripetal force
b.centrifugal force
c.friction force
d.none of the above
Ans: b. centrifugal force
16.Which of the following statements is false for vane pumps?
a.wear in contact surfaces occurs due to continuous contact between vane tips and the cam ring
b.different sizes of cartridge kits can be replaced in same vane pump
c.elliptical cam ring is replaced by round cam ring to reduce unbalanced forces
d.none of the above
Ans: c. elliptical cam ring is replaced by round cam ring to reduce unbalanced forces
17.Balanced vane pumps are designed to have
a.fixed displacement
b.variable displacement
c.both fixed and variable displacement
d.none of the above
Ans: a. fixed displacement
18.Cam ring of unbalanced vane pump is
a.round
b.elliptical
c.both a and b
d.both of the above
Ans: a. round
19.In pressure compensated vane pump,
1.having variations in eccentricity between rotor and cam ring gives variable displacement
2.as eccentricity between rotor and cam decreases, flow of fluid decreases
3.as eccentricity between rotor and cam decreases, flow of fluid increases
4.having variations in eccentricity between rotor and cam ring gives fixed displacement
a.1 and 3
b.3 and 4
c.2 and 4
d.1 and 2
Ans: d. 1 and 2
20.What is the relation between speed and flow rate for fixed displacement vane pump?
a.flow rate increases with increase in speed of rotor
b.flow rate decreases with increase in speed of rotor
c.flow rate is constant and does not change with change in speed
d.none of the above
Ans: a. flow rate increases with increase in speed of rotor
21.In fixed displacement vane pump,
a.flow rate decreases with increase in working pressure
b.flow rate increases with increase in working pressure
c.flow rate is constant and does not change with working pressure
d.none of the above
Ans: a. flow rate decreases with increase in working pressure
22.What effect does working pressure have on input power for radial piston pumps?
a.as working pressure increases input power decreases
b.as working pressure increases input power increases
c.pressure remains constant for different input powers
d.none of the above
Ans: b. as working pressure increases input power increases
23.Radial piston pumps can have,
a.cylinder block rotating and cam stationary
b.cylinder block stationary and cam rotating
c.both a and b
d.none of the above
Ans: c. both a and b
24.What is the difference between vane pump and radial piston pump?
a.in radial piston pump, radial slots in vane pumps are replaced by radial bores which accommodate pistons
b.in radial piston pump, radial slots in vane pumps are replaced by radial bores which accommodate swash plate
c.in radial piston pump, radial slots in vane pumps are replaced by radial bores which accommodate both swash plate and pistons
d.none of the above
ANSWER: a. in radial piston pump, radial slots in vane pumps are replaced by radial bores which accommodate pistons
25.What is the advantage of multiple piston pump?
a.multiple piston pump do not have pulsating flow
b.multiple piston pump have pulsating flow which is required
ANSWER: a. multiple piston pump do not have pulsating flow
26.How many strokes does a single piston pump need to discharge oil?
a.one stroke
b.two strokes
c.three strokes
d.none of the above
ANSWER: b. two strokes
27.How is the arrangement of pistons in piston pumps?
a.axially
b.radially
c.both a and b
d.none of the above
ANSWER: c. both a and b
28.In which of these pumps, swash plate is used to translate the motion of rotating shaft into reciprocating motion?
a.radial piston pumps
b.axial piston pump
c.bent axis piston pump
d.all the above
ANSWER: b. axial piston pump
29.Which factors are considered while designing a axial piston pump?
a.use of swash plate
b.application in open loop or closed loop circuit
c.design of bent axis piston pump
d.all the above
ANSWER: d. all the above
30.Angle of swash plate in axial piston pump is adjusted by
a.compensator
b.yoke
c.both a and b
d.none of the above
ANSWER: c. both a and b
31.In axial piston pump, the yoke is pushed away from cylinder block due to which,
a.yoke angle increases
b.swash plate angle decreases
c.both a and b
d.none of the above
ANSWER: a. yoke angle increases
32.When the angle of swash plate decreases
a.flow rate increases
b.flow rate decreases
c.flow rate does not depend on swash plate angle
d.none of the above
ANSWER: b. flow rate decreases
33.What will be the discharge of oil in axial piston pump, when the angle of swash plate is zero?
a.discharge of oil is maximum
b.discharge of oil is minimum
c.there is no discharge of oil
d.none of the above
ANSWER: c. there is no discharge of oil
34.Which of the following statements are true?
1.piston pumps are self priming
2.piston pumps require high maintenance
3.piston pumps have low cost of production
4.piston pumps have low volumetric efficiency
a.1 and 2
b.3 and 4
c.1 and 3
d.all the above
ANSWER: a. 1 and 2
35.A bent axis piston pump has
a.pump axis bent
b.cylinder block which is inclined at an angle to the drive shaft
c.both a and b
d.none of the above
ANSWER: b. cylinder block which is inclined at an angle to the drive shaft
36.In which of these pumps, swash plate is replaced by cylinder block?
a.bent axis piston pump
b.radial piston pump
c.axial piston pump
d.none of these
ANSWER: a. bent axis piston pump
37.What happens when the distance between flange and cylinder block is varied?
a.piston displacement cannot be varied
b.variable flow rate of fluid can be achieved
c.fixed flow rate can be achieved
d.all the above
ANSWER: b. variable flow rate of fluid can be achieved
38.What is the maximum angle between cylinder block and shaft axis?
a.30o
b.50o
c.45o
d.all the above
ANSWER: a. 30o
39.When does holding piston keep the angle between yoke and cylinder block maximum?
a.when set pressure is greater than load pressure
b.when set pressure is less than load pressure
c.when set pressure and load pressure are same
d.all the above
ANSWER: a. when set pressure is greater than load pressure
40.Which type of motion is transmitted by hydraulic actuators?
a.linear motion
b.rotary motion
c.both a and b
d.none of the above
ANSWER: c. both a and b
41.What is the advantage of using a single acting cylinder?
a.high cost and reliable
b.honing inside the inner surface of pump is not required
c.piston seals are not required
d.all the above
ANSWER: c. piston seals are not required
42.Why are hydraulic cylinders cushioned?
a.cushioning decelerates the piston of a cylinder
b.stress and vibrations can be reduced
c.both a and b
d.none of the above
ANSWER: c. both a and b
43.Which of the following statements is true?
a.Tie-rod cylinders are used in applications having working pressure of 70 bar
b.Welded type cylinders are used in systems having working pressure more than 70 bar
c.Tie-rod cylinders can be used in systems having working pressure more than 70 bar
d.All the above
ANSWER: d. All the above
44.Which of these actions does a hydraulic cylinder perform?
a.pushing
b.lifting
c.both a and b
d.none of the above
ANSWER: c. both a and b
45.In single acting hydraulic cylinders, the piston comes back to its original position due to
a.spring force
b.self-weight
c.momentum of a flywheel
d.all the above
ANSWER: d. all the above
46.When does expansion of spring and retraction of cylinder take place in spring type single acting cylinder?
a.oil pressure exerted is less than spring compression pressure
b.oil pressure exerted is more than spring compression pressure
c.oil pressure exerted and spring compression pressure are same
d.none of the above
ANSWER: a. oil pressure exerted is less than spring compression pressure
47.Double acting cylinder can be used as a single acting cylinder
a.True
b.False
ANSWER: a. True
48.In a telescopic cylinder, as the number of stages increase
a.diameter of piston rod also increases
b.diameter of piston rod decreases
c.diameter of the piston rod remains the same
d.none of the above
ANSWER: b. diameter of piston rod decreases
49.Which of the following statements is true for standard hydraulic cylinder and a telescopic cylinder?
a.telescopic and standard cylinders give same stroke length
b.telescopic cylinders give lesser stroke length than standard cylinder
c.telescopic cylinders give greater stroke length than standard cylinder
d.none of the above
ANSWER: c. telescopic cylinders give greater stroke length than standard cylinder
50.Which of the following statements are true?
1.the length of two stage telescopic cylinder is more than a standard cylinder
2.the length of two stage telescopic cylinder is less than a standard cylinder
3.telescopic cylinder is single acting
4.telescopic cylinder is double acting
a.1 and 3
b.2 and 3
c.2, 3 and 4
d.1, 3 and 4
ANSWER: c. 2, 3 and 4
51.Telescopic cylinders have
a.only two stage units
b.only three stage units
c.two or three stage units
d.multistage units
ANSWER: d. multistage units
52.Which type of hydraulic cylinder has one piston connected to piston rod extended on both the sides of the cylinder?
a.telescopic cylinder
b.tandem cylinder
c.both a and b
d.none of the above
ANSWER: b. tandem cylinder
53.Which factor decides the working pressure of a hydraulic cylinder?
a.diameter of circular flange
b.bore diameter of cylinder
c.stroke length
d.all the above
ANSWER: b. bore diameter of cylinder
