Two marks questions and answers

TWO MARKS QUESTIONS AND ANSWERS

1. What are the four important factors that should be considered while designing a fluid power circuit?

1. Safety of operation,

2. Performance of desired function, 

3. Efficiency of operation, and

4. Cost.

2. What is the use of a regenerative circuit ?

A regenerative circuit is used to speed up the extending speed of the double-acting cylinder.

3. Why is the load-carrying capacity of a regenerative cylinder small when the piston rod area is small?

Regenerative cylinder extending load-carrying capacity = Fload = P.A,

Therefore when piston area (A,) is small, then the load-carrying capacity of the regenerative cylinder will also be small.

4. Why is extension stroke faster than retraction stroke in a regenerative circuit ? 

This is because oil flow from the rod end regenerates with the pump flow to provide a total flow rater, which is greater than the pump flow rate to the blank end of the cylinder. 

5. What do you mean by sequencing of cylinders ? (or) What is a sequencing circuit?

In many applications, the operation of two hydraulic cylinders is required to be performed in sequence one after another. This is known as sequencing of cylinders.

6. What is the advantage of using sequencing circuit?

Sequencing circuits automatically move actuators in a predetermined sequence.

7. State the need for synchronization of hydraulic cylinders.

There are many industrial applications which require nearly perfect synchronization of movement of two or more cylinders in order to complete some phase of operation. Synchronization is required where exact movement is required at both ends of a span, such as on rolling equipment, power shears, power brakes, large presses, etc. 

8. When synchronizing circuit is required?

Synchronizing circuit is needed to accomplish the identical task from the cylinders at the same rate.

9. What is the purpose of a fail-safe circuit ?

Fail safe circuit is designed to safeguard the operator, the machine, and the workpiece. It prevents any possible injury to the operator or damage to the machine and the workpiece. 

10. Where speed control circuits are required? 

Speed control circuits are required to reduce the speed of cylinder from maximum speed based on selected size of final control valve to the nominal speed depending on the applications.

11. Differentiate between meter-in and meter-out circuits with respect to speed control circuits. 

• In meter-in circuit, the flow control valve is located in between the pump and the actuator (piston side connection). Thereby, it controls the amount of fluid flowing into the cylinder.

• In meter-out circuit, the flow control valve is located in between the actuator (rod side connection) and the oil reservoir. Thereby, it controls the fluid flowing out of the actuator.

12. What is “meter-in” circuit? What is its limitation?

• The 'meter-in' circuit controls the amount of fluid flowing into the cylinder. 

• Limitation: There will be a drop in oil pressure fed to the cylinder due to throttling effect of the flow control valve. Hence for a low pressure system, meter-in circuit is not preferred.

13. What is "meter-out" circuit? What are its limitations?

• The 'meter-out' circuit controls the fluid flowing out of the actuator.

• Limitation: Even at no-load, the actuator is subjected to maximum pressure. Also, as the cylinder is fed with the entire pump pressure, pressure there is possibility of higher friction loss.

14. What is the function of bleed-off circuit ?

• Bleed-off circuit is used to control the flow of fluid by bleeding off the excess not needed by the actuator.

• In bleed-off circuit, the flow control valve is located in between the pressure line and return line (either before the DC valve or after the DC valve).

15. What are hydropneumatic circuits ?

In some applications, the hydraulic and pneumatic circuits are coupled to get best use of the advantages of both oil and air mediums. These combination circuits are known as hydropneumatic or pneumohydraulic circuits.

16. List any four advantages of employing pneumo-hydraulic circuits.

1. Using the combination circuit, the quick action of air and smooth, high pressure action of oil can be blended.

2. The hydropneumatic circuits will reduce space requirements.

3. These circuits increase the performance of the equipment.

4. These circuits will reduce initial and maintenance cost of original equipment.

17. What is meant by hydrostatic transmission system?

Hydrostatic transmission is special case of energy transmission system where the mechanical energy of the input drive shaft is converted into pressure energy in the nearly incompressible working fluid and then reconverted into mechanical energy at the output shaft.