review questions

REVIEW QUESTIONS

On Directional Control Valves

1. (a) Explain how poppet type DC valve and a sliding spool type BC valve differ in construction and operation.

(b) Which of these two types are mostly used in a hydraulic system? Why?

2. Explain the operational features of the check valve with neat diagram.

[A.U., Nov/Dec 2006; Nov/Dec 2011] 

[Ans. Refer Section 6.7] 

3. How does a pilot-operated direction control valve function? Explain with a diagram. [A.U., Nov/Dec 2007; May/Jun 2012] 

[Ans. Refer Section 6.7.4] 

4. Classify the direction control valves in terms of position and explain each with neat circuits. [A.U., Nov/Dec 2016] 

[Ans. Refer Sections 6.8.7 – 6.10.2] 

5. How 4/3 direction control valve is working in hydraulic power circuits? Explain the construction detail with neat sketch. Draw the graphical symbol of the valve.

[A.U., May/June 2009; Nov/Dec 2010 ] 

[Ans. Refer Section 6.10]

6. Sketch and explain commonly used 3-position 4-way direction control valves. Also state the applications for closed center, open center, and tandem center valves.

[A.U., Nov/Det 2013] 

[Ans. Refer Section 6.10]

7. Describe with the help of neat sketch the construction and operation of a shuttle valve. [A.U., Nov/Dec 2006] 

[Ans. Refer Section 6.11].

On Pressure Control Valves

8. Explain the construction of pressure relief valve with neat sketch.

[A.U., May/June 2012; Apr/May 2018]

[Ans. Refer Section 6.14]

9. Explain how the pressure relief valve and its variants could be used for unloading applications. [A.U., May/June 2006] 

[Ans. Refer Sections 6.14 – 6.15]

10. Explain the working of a pressure reducing valve with an example application.

[A.U., May/June 2011] 

[Ans. Refer Section 6.17]

11. Explain the working of a direct-acting pressure reducing valve. [A.U., May/Jun 2012]

[Ans. Refer Section 6.17]

12. Explain the working of a pilot-operated pressure relief valve with neat sketch.

[A.U., Nov/Dec 2012] 

[Ans. Refer Section 6.18]

13. With a neat sketch, describe the construction and operation of a pilot-operated sequence valve.

[A.U., Nov/Dec 2008; May/Jun 2012] 

[Ans. Refer Section 6.19.2]

On Flow Control Valves

14. Write short notes on the globe and needle flow control valves.

15. With a sketch describe the construction and operation of a pressure compensated flow control valve. 

[A.U., Nov/Dec 2005; Apr/May 2008; Nov/Dec 2010]

[Ans. Refer Section 6.22]

On Servo Valves

16. Explain the construction and working principle of hydromechanical servo valve with neat diagram. [A.U., Nov/Dec 2006; Nov/Dec 2008; May/June 2012]

[Ans. Refer Section 6.24]

17. What are electrohydraulic servo systems? Write the advantages of the electrohydraulic servo systems over hydromechanical servo system.

[A.U., Nov/Dec 2010] 

[Ans. Refer Section 6.25]

18. Explain with a neat sketch construction and operation of an electro-hydraulic servo valve. State at least two applications. [A.U., Nov/Dec 2006; May/June 2009; Apr/May 2010; Apr/May 2011; Nov/Dec 2012; Nov/Dec 2016] 

[Ans.Refer Section 6.25.4 & 6.25.5]

On Proportional Control Valves

19. What are proportional control valves? Write the types of proportional control valves? [A.U., Nov/Dec 2008] 

[Ans. Refer Sections 6.26.1 & 6.26.2]

20. Draw and explain the construction and operation of proportional pressure relief valve. [A.U., Nov/Dec 2010] 

[Ans. Refer Section 6.26.3]

21. Draw and explain the working of proportional pressure reducing valve.

[A.U., Apr/May 2008; Nov/Dec 2010] 

[Ans. Refer Section 6.28.4]

PROBLEMS FOR PRACTICE

1. A pressure control valve has a pressure setting of 125 bars. Compute the kw power loss across this valve if it returns all the flow back to the tank from a 1.5 Lps pump. 

[Ans. 18.75 kW]

2. A flow control valve experiences a pressure drop of 700 kPa for a flow rate of 1.6 Lps. - The specific gravity of the fluid is 0.90. Determine the capacity coefficient. 

[Ans. 3.44 Lpm/√kPa]