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Seventh Semester B.E. Degree Examination, Dec. 07 / Jan. 08
Hydraulics and Pneumatics
Time: 3 hrs.
1
Max. Marks: 100
Note : 1 .
nswer any FIVE full questions.
2.
Draw neat sketches wherever necessary:
a. Stale Pascal's law. Kxplain with neat sketch the basic hydraulic power system. (06 Marks)
b. Explain briefly various factors that influence the selection of pump for hydraulic system.
(09 Marks)
2
c. A vane pump is to have a volumetric displacement of 82 cm . It has a rotor diameter of
5.0 cm. a cam ring diameter of 7,5 cm and a vane width of 4.0 cm. What must be the
eccentricity?
(05 Marks)
a. With a neal sketch explain second class lever system used wilh hydraulic cylinders to drive
load.
(06 Marks)
b. Explain with neat sketch the operation of swash plate piston motor in hvdraulie system.
(06 Marks)
c. A hydraulic motor has a displacement of 165 cm /rev and operates wilh a pressure of 70
bars and a speed of 2000 rpm. If the actual flow rate consumed by the rotor is 6.0 Ips and
the actual torque delivered by the motor is 170 N-m. Find,
i) Volumetric efficiency ii) Mechanical efficiency and iii) Overall efficiency (08 Marks)
3
a. Classify live control component? used in hydraulics systems and name any six valve
actuation symbols used in Iwdraulie *;> stern with simple sketch.
(Lift Marks)
b. Explain briefly with neat sketch tne construction and operation ot simple pressure renei
valve.
(07 Marks)
c. Explain briefly with neat sketch the working of pressure compensated flow control valve
used in hydraulic system.
(07 Marks)
4
a.
With the help of neat circuit diagram explain briefly the 4-way control system for double
acting cylinder.
(08 Marks)
b. Explain briefly with neat sketch the cylinder synchronizing circuit operated together'with a
pair of cylinders in scries in a synchronized manner to lift the load.
(OK Marks)
c. What are hydraulic accumulators? Classify the different accumulators used in hydraulic
System.
5
a.
(04 Marks)
What ate the desirable properties of hydraulic fluids? Explain briefly an> five of them.
(JO Marks)
b.
6
7
8
What are the functions of reservoir system? Explain briefly with neat sketch construction
features of a hydraulic reservoir.
(10 Marks)
a. For continuous rotation with neat sketch explain briefly turbine type air motor which is
used as a pneumatic actuator.
(05 Marks)
b. Discuss advantages of air motors compared to electric and hydraulic motors.
(08 Marks)
c. Explain briefly with neat sketch V2 way spool type directional control valve to control the
flow of air in pneumatic system.
(07 Marks)
a. Explain briefly with neat sketch, construction and principle of operation of a typical quick
exhaust valve, to increase the actuation speed of a cylinder in pneumatic system. (07 Marks)
b.' Discuss advantages of pneumatic logic devices over electrical logic devices.
(06 Marks)
c. Explain a typical pneumatic circuit based on AND logic function using a two-pressure
valve, with a neat circuit.
(07 Marks)
a. Draw and explain briefly a typical two-cylinder pneumatic circuit to control its motion in a
pneumatic system.
0>7 Marks)
b . Define and explain vac opeial\on o^ •=,o\e\io\d'a WA<;& m pnewmaUc system wVxVi t\ca\ ^eicYv.
(06 Marks)
c. Classify compressors of pneumatic system. Explain briefly the diaphragm compressor.
(07 Marks)
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USN I
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ME73
Seventh Semester B.E. Degree Examination, Dec.08/,Tan.09
Hydraulics and Pneumatics
M a x . Marks: 1 0 0 .
N o t e : Answer any FIVE full questions.
(08 Marks)
Explain the working of a hydraulic jack using Pascal's law.
(06 Marks)
Explain the role of a pump in a hydraulic system.
A vane pump has a rotor diameter of 60mm. a cam ring diameter of 90mm and a vane width
of 50mm. If the eccentricity is 10mm, determine the volumetric displacement.
(06 Marks)
Discuss with a neat sketch, the working of a swash plate type axial piston pump. (08 Marks)
Explain the "End cushion" provided in hydraulic cylinder with a neat sketch.
(06 Marks)
A single-vane rotary actuator has the following data:
Outside radius of rotor = 12 mm; Outer radius of vane ~ 38mm, width of vane = 25mm,
Hydraulic pressure developed = 70 bar. Find
(i)
The hydraulic force acting on the vane.
(ii)
The torque generating capacity of the rotary actuator.
(06 Marks)
Differentiate between:
(08 Marks)
(i)
Poppet type DCV and sliding spool type DCV.
(ii)
Check valve and pilot operated check valve.
Explain the working principles of the following along with their symbols:
(08 Marks)
(i)
Sequence valves.
(ii)
Counter balance valves
"A lite a note on needie lluw coniroi vatve.
(04 Marks)
Explain with suitable circuits, how the single acting and double acting hydraulic cylinders
are controlled.
(10 Marks)
Design and explain the hydraulic power circuit for sequencing of the following operations in
a drilling machine.
(10 Marks)
(i)
Clamping the work piece.
(ii)
Drilling the work piece.
(iii)
Unelamping the work piece.
Explain with the help of a hydraulic circuit, how the cylinder speed can be controlled by
metering out oil from the cylinder.
(08 Marks)
Compare a dead weight type accumulator with a spring loaded type accumulator. Explain
•their merits and demerits.
(OS Marks)
Derive an equation for Beta efficiency.
(04 Marks)
Differentiate between the following:
(08Marks)
(i) Single acting and Double acting pneumatic cylinder, (ii) Air motor and Air cylinder.
Explain with a neat sketch, the working of valve scat type four way. two position direction
control valve.
(08 Marks)
Write a note on cylinder mountings.
(04 Marks)
What do you mean by Quick exhaust valve? Explain its working principle with a sketch.
{10 Marks)
Explain with a pneumatic circuit, the control of extension of a double acting cylinder using
OR and AND logic gates.
(10 Marks)
Write short notes on any FOUR of following:
(20 Marks)
Accumulator as an emergency power source.
Pump characteristic curves.
Filters and Strainers
Electro-pneumatic control
Pneumatic pressure regulator.
Time: 3 hrs.
1
a.
b.
c.
a.
b.
c.
a.
b.
c.
a.
h.
a.
b.
c.
a.
b.
c.
a.
0
a.
b.
c.
d.
e.
*****
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USN
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ME73
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Seventh Semester B.E. Degree Examination, May / June. 08
Hydraulics and Pneumatics
Time: 3 brs.
Max. Marks: 100
Note : Answer any FIVE full questions.
(05 Marks)
a, List live applications of fluid power in the automotive industry.
Sketch
and
explain
the
working
of
a
balanced
vane
pump.
(07
Marks)
b.
A
gear
pump
has
a
75mm
outer
diameter
50mm
intenial
diameter
and
25mm
width.
If the
c.
volumetric efficiency is 90% at rated pressure, what is the corresponding actual flow rate
in lilies per minute given pump speed is 1000 r.p.m.
(08 Marks)
a. With a neat sketch, explain the construction of a double acting hydraulic cylinder. Explain
how cylinder cushioning is achieved.
(it) Mark?)
b. A hydraulic motor has a displacement of 130cm3 and operates with a pressure of 105 bar
and a speed of 2000 r.p.m. if the actual flow rate consumed by the motor is 0.005nvVs and
the actual torque delivered by the motor is 200Nm. find i) Volumetric efficiencv
ii) overall efficiency and iii) kW power delivered by motor.
(10 Marks)
a. Explain a pilot operated pressure relief valve with a neat sketch. (07 Marks)
b. Assuming that the two double rodded cylinders of fig.3(b) are identical, what unique
features does this possess?
(05 Marks)
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I'ig.3(b)
c. Sketch and explain working of a locked cylinder hydraulic circuit using pilot check
valves.
(08 Marks)
a. Show that in a regenerative circuit the extending and retracting speeds of the cylinder can
be made equal when the piston area equals two times the rod area.
(08 Marks)
b. Tn what circumstances meter - out flow control valve system is preferred to meter - in
system. What are the disadvantages of meter - out system? (05 Marks)
For
a meter - in system the following data are given. Valve capacity coefficient 1.8
c.
Ipm/VkPa ; cylinder piston diameter 5cm ; cylinder load 17.8 kN ; specific gravity of oil
0.90 ; Pressure relief valve setting 96 bar. Determine the cylinder speed. (07 Marks)
a. What are the most common causes of hydraulic system break down.
b. Classify filters. What is meant by Beta ratio? Define Beta efficiency.
c. What are the problems caused by gases in hvdraulie fluids?
1 of 2
(07 Marks)
(07 Marks)
(06 Marks)
- ME73
Sketch and explain Diaphragm type of air cylinder. Give its applications. (06 Marks)
With a sketch, explain the actuation of a double acting cylinder using air pilot control.
(08 Marks)
Explain the construction and working of a quick exhaust valve with suitable sketches.
(06 Marks)
Using 2/2 Direction control valves show the following logic functions.
»
i) AND ii) OR iii) NOR and iv) NAND.
(08 Marks)
Sketch a circuit to control two pneumatic cylinders using limit switches for sequential
motion.
(12 Marks)
Sketch a two - handed safety control circuit for actuation of a pneumatic cylinder.
(08 Marks)
What happens to the cylinder of fig.8(b) when the push button is momentarily depressed.
(06 Marks)
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Fig.8(b)
Sketch neatly an air lubricator and briefly explain its working.
*****
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®
(06 Maries)
2 0 0 2 SCHEME
USN
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Seventh Semester B.E. Degree Examination, June-July 2009
Hydraulics and Pneumatics
Time: 3 hrs.
Max. Marks:100
Note
: Answer any
FIVE full questions.
1
a. State Pascal's Law.
(02 Marks)
b. With a neat sketch, explain the working of a lobe pump.
{08 Marks)
c. Find the flow rate in units of m /min for an axial piston pump running at 1000 rpm. The
pump has 9 number of 15mm diameter pistons arranged on a 125mm diameter piston circle.
The offset angle is set at 10° and the volumetric efficiency is 94%.
(05 Marks)
d. Explain the factors considered for the selection of pumps
<os Marks)
2
a.
b.
Explain the working of balanced vane motor with a neat sketch.
(!0 Marks)
A hydraulic motor has 82cm [0.082LJ volumetric displacement. It has a pressure rating of
70 bar and it receives oil from a pump having 0.0006 m J /s theoretical flow rate. Find
i) Motor speed ii) Theoretical torque and iii) Theoretical power.
(id Marks)
3
a.
With a neat sketch, explain spool type DC valve used to control double acting cylinder.
b.
Explain the working of a simple pressure relief valve with a neat sketch.
(11) Marks)
(10 Marks)
4
a.
Explain regenerative circuit with a neat sketch. Derive an expression to calculate the ratio
of velocities of extension to that of retraction.
(10 Marks)
b. With a neat sketch, explain the circuit for double pump hydraulic system.
(10 Marks)
5
Write notes on :
a. Desirable properties of hydraulic oils.
b. Sealing Devices.
c. Filters and Strainers.
d. Problems caused by gases in hydraulic fluids.
(05 Marks)
(05 Marks)
(05 Marks)
(05 Marks)
6
a. Write a note on characteristics of compressed air.
b. Sketch and explain the w-orking of a shuttle valve.
c. What are air dryers'? Explain in detail.
(05 Marks)
(08 Marks)
(07 Marks)
7
a. Sketch and explain circuit for Air - pilot control of double - acting cylinder.
b. With sketches, explain logic of i) AND
ii) OR
gates.
(12 Marks)
(OS Marks)
8
a. Sketch the circuit for cylinder cycle timing.
b. Write a circuit for control of hydraulic cylinder, using a limit switch.
(10 Marks}
(10 Marks)
* * * * i :