ME 2305 - APPLIED HYDRAULICS AND PNEUMATICS

TWO MARK QUESTION AND ANSWER

UNIT - II

1.Define Hydraulic pump?

In a hydraulic system, liquid is drawn from the tank by a pump, which converts

mechanical energy into hydraulic energy.

2. How gear pumps are classified?

1. External gear pump

2. Internal gear pump

3. Lobe pump

4. Screw pump

5. Gerotor pump

3. How Vane pumps are classified? Anna, Nov-2004

1. Unbalance vane pump

2. Balanced vane pump

3.Variable displacement vane pump

4. How piston pumps are classified? Anna, Nov-2004

1. Radial piston pump

2. Piston pump with stationary cam and rotating block

3. Axial pump with swash plate

4. Bent axis pump

5. Define Axial Piston pump & Radial Piston pump

A pump having multiple pistons disposed with their axes parallel to shaft axis.

A pump having multiple pistons disposed radially to the shaft axis, actuated by an eccentric element.

6. Define Gear pump & Vane pump.

A pump having two or more intermeshing gears or lobed members enclosed in housing.

A pump having multiple radial vanes within a supporting rotor.

7. Define Motor Anna, Nov-2005

A device that converts fluid power into mechanical power. It usually delivers Torque and rotary

motion to a shaft.

8. How pumps are classified?

1. Positive displacement pumps

2.Hydrodynamic (or) Non-positive displacement pumps.

9. Write about positive displacement pumps?

Positive displacement pumps have the internal working elements, which make a very, close fit

together so that there is very little leakage (or) slippage between them. This type of pumps ejects a fixed

quantity of liquid into the hydraulic system per revolution of the' pump shaft.

10. What is the function of hydraulic actuator?

Hydraulic actuators convert the pressure energy of fluid into mechanical output to

Perform useful work.

11. How the displacement of the gear pump is determined? '

The displacement of the gear pump is determined by

1. Volume of fluid between each pair of teeth

2. Number of teeth

3. Speed of rotation

12 Define Motor Anna, Nov-2005

A device that converts fluid power into mechanical power. It usually delivers Torque and rotary

motion to a shaft.

13. What are the factors to be considered for pump selection?

1. Discharge 4. . Performance 2. Operating speed 5. Reliability

3. Pressure rating 6. Maintenance 7. Cost 8. Noise

14. What is cylinder cushion?

Cylinder cushions at ends of the cylinder to slow the piston down near the ends of the stroke.

This prevents excessive impact when the piston is stopped by the end caps.

15. What are the main advantages of gear motors?

The main advantages of gear motor are its simple design and subsequent low cost.

16. What is telescoping- rod cylinder?

Telescoping cylinder contains multiple cylinders that slide inside each other. They are used where

long work stroke are required but the full retraction length must be minimized. One application of

telescoping cylinder is the high-lift fork truck.

17. Why does a hydraulic motor deliver less torque than it should be in theoretically.

Due to frictional losses, a hydraulic motor delivers less torque then it should theoretically.

18 what are the important components of a power pack

The important components are

1 electric motor

2 pump

3 reservoir

4 valves

19 How is pressure created in the hydraulic system?

The pressure is created only when the flow is resisted,by putting a load on a cylinder.

If there is no resistance to flow, threre is no pressure

20 what is pump cavitations

Pump cavitations is the formation of air bubbles in the hydraulics fluids, its occurs when the pump

suction lift is excessive and the pump inlet pressure falls below the vapor pressure of the fluid

21 what is pump slippage

The small clearance (.0254mm) between the teeth tip and the pump housing allows some of the oil

at the discharge port to leak directly back towards the suction port. This internal leakage

Is called pump slippage

22 what are the parameter affect the noice level of a positive displacement pump

o pump speed

o pressures

o pump size

23 what are the basic element of the hydraulic element system

o Hydraulic pumping unit

o Control valve

o Fluid power line

o Reciprocating cylinder or Rotary motor

24 Define volumetric efficiency?

It is indicate the amount of leakage that take place within the pump.This includes the

manufacturing tolerance and flexing of the pump casing under design pressure operating condition

25 Define Mechanical efficiency?

It is indicate the amount of energy losses that occurs for the reason other than leakages.