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USN 06~E82

Eighth Semester B.E. Degree Examination, May/June 2010

.Hydraulics andP.neumatics

Note: Answer any FlVEfull questions, selecting

at least TWO questionsfrom eachpart...

a. What are the important con~iderations when selecting a pump for a particular application?Explain. (06Marks)

b. A displacement type cylinder has a rod of 65 rn.mdiameter and is powered by hand pumpwith a displacement of 5 ml per double stroke. The maximum operating pressure of the

systemis to be limited to 350 bar. Calculate:i) Thenumber of double pumping strokes needed to extend cylinder rod by 50rom.ii) Themaximum load which could beraised, using this system. (06Marks)

c. A hydraulic motor has a displacement of 130 cm3, operates with a pressure of 105 bar andhas a speed of2000 rpm. If the actual flow rate consumed by the motor is 0.005 m3/s andtheactual torquedelivered by themotor is 200,N-tn., fm4 .:: .i) Volumetric efficiencyii) Mechanical ~fficiency

iii) Overall efficiencyiv) Power delivered by motor.in kW. (08Marks)

a. Explain with aneat sketch, the working of abalanced vane motor. (06Marks)b. Findthe flow rate in Lpmthat an axis piston pump delivers at 1200 rpm. Thepump has 12,

15romdiameter pistons arranged onan 120rompiston circle diameter. The offset is set 10,and volumetric efficiency is 94%. (06Marks)

c. A pump is operating at 75.7 Lpm and 12400 kPa. It has an overall efficiency of 0.83. Itisdriven by an electric motor with an efficiency of 0.87. How much power in kW is the

l t i t d i ?

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iij No pressureiii) Actuator failureiv) Overheatingof hydraulic fluid.

c. Explainthefour different types of fireresistant fluidsin common use.

(08Marks)

(08Marks)

6 a. Givecompleteclassification of pneumatic actuators.b. Namethreereasons for consideringtheuse of pneumatics instead of hydraulics.c. Explain endcushionarrangement in double actingcylinder, with aneat sketch.

(06Marks)

(06Marks)

(08Marks)

7 a. How followingfunctions aregeneratedin pneumatic systems? Explain withasketch.i) AND

ii) ORiii) NOT. (15Marks)

b. Explain withasuitable circuit diagram, applicationof thememory valve. (05Marks)

8 a. Explain thefollowing as appliedto electro-pneumatic controls.i) Normally closed relay switch.ii) Normallyopen relay switch. (04Marks)

b. Sketch acircuit to control two pneumatic cylindersusing limit switch for sequential motion.(10Marks)c. Explain air filter for pneumatic system, with aneat sketch. (06Marks)