B.E./B.Tech. DEGREE EXAMINATION, NOVEMBER/DECEMBER 2010

B.E./B.Tech. DEGREE EXAMINATION, NOVEMBER/DECEMBER 2010

Fifth Semester - Mechanical Engineering – Regulation 2008

ME 2305 - APPLIED HYDRAULICS AND PNEUMATICS

Time: Three hours

Answer all questions. 

Maximum: 100 marks

Part - A (10 × 2 = 20 Marks)

1. Why are hydraulic systems preferred for heavy work than the pneumatic systems? 

Ans. Refer Chapter 1, Q. No. 12, Two Marks Q&A, Page No. 1.24.

2. What is neutralization number of hydraulic fluid? Give its significance. 

Ans. Refer Chapter 2, Q. No. 2, Two Marks Q&A, Page No. 2.23.

3. Why are double acting cylinders known as differential cylinders? 

Ans. Refer Chapter 5, Q. No. 10, Two Marks Q&A, Page No. 5.31.

4. Draw the ANSI symbols for (a) a pilot-operated check valve, and (b) a shuttle valve. 

Ans. Refer Chapter 6, Q. Nos. 16 & 17, Two Marks Q&A, Page No. 6.49.

5. Mention few applications where piston motors are employed.

Ans. Refer Chapter 5, Q. No. 23, Two Marks Q&A, Page No. 5.23.

6. What are the functions of accumulators?

Ans. Refer Chapter 9, Q. No. 1, Two Marks Q&A, Page No. 9.33.

7. What do you mean by bleed-off circuit control?

Ans. Refer Chapter 8, Q. No. 14, Two Marks Q&A, Page No. 8.38.

8. Distinguish between meter-in and meter-out circuits with respect to speed control circuits.

Ans. Refer Chapter 8, Q. No. 11, Two Marks Q&A, Page No. 8.37.

9. What is a bistable flip-flop?

Ans. Refer Chapter 15, Q. No. 7, Two Marks Q&A, Page No. 15.28.

10. If an air cylinder produces erratic cylinder action, identify the probable causes and also give remedies for them.

Ans. Refer Chapter 17, Q. No. 13, Two Marks Q&A, Page No. 17.26.

PART B - (5 × 16 = 80 Marks)

11. (a) (i) Compare and contrast between hydraulic, pneumatic and electro-mechanical power systems.

Ans. Refer Chapter 1, Section 1.9, Page No. 1.19.

 (ii) List out the applications of fluid power employed in different industries/fields.

Ans. Refer Chapter 1, Section 1.6, Page No. 1.7.

[OR]

(b) (i) Fluid is flowing through a tapering pipe having diameters 50 mm and 25 mm at sections 1 and 2 respectively. The discharge through the pipe is 7.5 Lps (i.e., liters per second). The section 1 is 3 m above datum and section 2 is 1.25 m above datum. If the pressure at section 1 is 200 kPa, find the pressure section 2. The specific gravity of the fluid is 0.9.

Ans. Refer Chapter 3, Example 3.11, Page No. 3.22.

(ii) Write Pascal's law. Explain any one applications of Pascal's law with neat diagram.

Ans. Refer Chapter 3, Section 3.5, Page No. 3.5.

12. (a) (i) Enumerate the working principle of balanced vane pump with neat sketch.  Also write the advantages and disadvantages.

Ans. Refer Chapter 4, Section 4.15, Page No. 4.19.

(b) (i) Explain with neat sketch the working of semi-automatic control of a double- acting pneumatic cylinder.

Ans. Refer Chapter 13, Section 13.5, Page No. 13.8.

(ii) Explain the working of a hydraulic circuit used in drilling machine

Ans. Refer Chapter 16, Section 16.2, Page No. 16.1.

15. (a) (i) What are electrohydraulic servo systems? Write the advantages of the electro hydraulic servo systems over hydro mechanical servo system.

Ans. Refer Chapter 6, Section 6.25, Page No. 6.32.

 (ii) Draw and explain the construction and operation of proportional pressure relief valve.

Ans. Refer Chapter 6, Section 6.26.3, Page No. 6.38.

[OR]

 (b) (i) Draw the block diagram of a PLC and explain the working of major elements.

Ans. Refer Chapter 15, Section 15,9, Page No. 15.21.

 (ii) List out any five types of faults that can be found in compressors. Also write the remedial actions for the faults.

Ans. Refer Chapter 17, Section 17.7, Page No. 17.16.