Review Questions

REVIEW QUESTIONS

1. Briefly describe the construction of various types of accumulators.

[A.U., Nov/Dec 2005; Nov/Dec 2012; May/June 2013; Nov/Dec 2013; Apr/May 2017; Apr/May 2018; Nov/Dec 2018]

[Ans. Refer Sections 9.2 to 9.9]

2. With neat sketch explain the weight-loaded accumulator. 

[A.U., Nov/Dec 2006]

[Ans. Refer Section 9.2]

3. List the advantages and limitations of a spring loaded accumulator.

[A.U., May/June 2012] 

[Ans. Refer Sections 9.3.3 & 9.3.4] 

4. With the help of circuit diagrams, illustrate the applications of accumulators. 

[A.U., May/June 2006; May/June 2009; Nov/Dec 2010; Nov/Dec 2013; Nov/Dec 2018] 

[Ans. Refer Section 9.10]

5. An hydraulic cylinder is used for an industrial application. It has been decided to use an accumulator as leakage compensator. Design a circuit to fulfill these requirements. 

[A.U., Nov/Dec 2007; Nov/Dec 2011; Apr/May 2017] 

[Ans. Refer Section 9.10.1] 

6. With a neat sketch explain the use of accumulator as an emergency power source. (or) Draw the circuit employing accumulator for supplying emergency hydraulic power. 

[A.U., Apr/May 2010; Nov/Dec 2010; Nov/Dec 2011] 

[Ans. Refer Section 9.10.2] 

7. Make a circuit sketch, showing the use of an accumulator, as hydraulic shock absorber. 

[A.U., Nov/Dec 2008] 

[Ans. Refer Section 9.10.4] 

8. Consider the charging and discharging of a hydro pneumatic accumulator to be isothermal and explain the procedure to arrive at the size of accumulator.

[A.U., Apr/May 2010] 

[Ans. Refer Section 9.11]

On Intensifiers

9. (a) What is the function of a hydraulic intensifier?

(b) Make a list of applications where intensifiers are employed?

10. Write and explain the working principle of pressure intensifier, with neat diagram. 

[A.U., Nov/Dec 2008; Apr/May 2011] 

[Ans. Refer Section 9.12.2]

11. Explain air-over-oil intensifier system with suitable example. 

[A.U., Nov/Dec 2006] 

[Ans. Refer Section 9.13.2]

12. Make a circuit, showing an intensifier in a punching press application. (or) Draw and explain a basic hydraulic circuit employing an intensifier for using in a punching press. 

[A.U., Apr/May 2008; Nov/Dec 2010] 

[Ans. Refer Section 9.13.1] 

PROBLEMS FOR PRACTICE

On Accumulators

1. An accumulator has a ram of 150 mm diameter and a lift of 5 m. If the oil is supplied at 50 bar, find the necessary load on the ram, and capacity of the accumulator.

[Ans. 88.36 kN ; 441.79 kN-m]

2. What is the size of accumulator necessary to supply 2000 cm3 of oil with an allowable pressure drop from 22 MPa to 16 MPa. The precharge pressure is 13 Mpa. Take charging and discharging processes as isothermal. 

[Ans.  9025.64 cm3 or 9.02 L]

3. The car crushing system is to be designed. The crushing force requirement is such that a 0.20 m diameter hydraulic cylinder is required at a working pressure of 1.3 × 107 N/m2. Time for crushing is about 10 seconds and the stroke required to flatten the car is 2.5 m. Compare the power requirement of a circuit without accumulator and with accumulator. Accumulator details:

Time taken for charging of accumulator = 5 min; 

Initial pressure of charging (uncharged), P1 = 0.8 × 107 N/m2;

Charge pressure of accumulator, P2 = 2.4 × 107 N/m2;

Minimum pressure for crushing, P3 = 1.3 × 107 N/m2.

[Ans. (kW pump) with accumulator = 12.56 kW, and

(kW pump) without accumulator = 102.1 kW]

On Intensifiers

4. If an intensifier has an input pressure of 105 bar and the area of the input piston is 65 cm2, what would be the output pressure if the output ram has an area of 10 cm2 ? 

[Ans. 682.5 bar]

5. A hydraulic intensifier gets the low pressure liquid at a pressure of 40 bar and delivers it to a machine at a pressure of 160 bar. If the intensifier has a capacity of 0.021 m3 and stroke 1.2 m, determine the diameters of the fixed ram and the sliding cylinder to be used for this intensifier.