Important Questions and Answers: Actuation System

1.Name the control components in a hydraulic actuation system.

1.Hydraulic pumpsunit

2.control values

3.reciprocating or rotary unit

2. Write short notes on the working of a Ratchet and pawl mechanism.

A wheel provided with suitable shaped teeth, receiving an intermittent circular motion from an oscillating member is called a Ratchet wheel. In a ratchet and pawl mechanism , the ratchet is based on a wheel that has teeth cut out it and a pawl that follows as the wheel turns

3.List any four solid state switches.

Diodes, Transistors,(BJT,FET)and thyristors

4.Highlight the properties of a stepper motor.

1.Motor construction is simple and rugged

2.It has excellent position accuracy

3.  It have high holding torque and they have property of being "self locking" when the rotor is stationary.

4.It having high torque at small angular velocities

5.What is a servo motor?

A servo motor is a rotary actuator that allows for precise control of angular position . It consists of a motor coupled to a sensor for position feed back , through reduction gear box

6.compare hydraulic systems with pneumatic systems

s.no   Hydraulic system

1.       It is used to controlling , transmitting and harnessing power using pressured fluids

2.       It is used in the concepts of dams, rivers

3.       It using incompressible fluid medium

4.       Pressure range is 80-100 psi

Pneumatic system

1.       It is used in pressurized gases to influence mechanical movement

2.       It is used inmining ,and general construction

3.       It used compressible fluid medium

4.       Pressure ranges 1000-5000psi

7.state the function of a control valve control valve is to direct , regulate the flow of fluid and regulate the pressure in various loading devices. It is used for sensing , processing , controlling .

8. Define Actuator.

An actuator is an output device which performs useful works

9.Classify actuator based on motion.

1.Linear motion

Single acting cylinder Double acting cylinder

2.Rotary Motion

Air motors

Rotary actuators

3.Flow Control valve

10. When is cascade control Needed?

The need for cascade control will occur when a final control element experiences signal overlap i.e. when a trip valve mechanism is still held down , but the output signal has to been used and requires removal

11.            Write down the principles of cascade control.

A simple design procedure to determine the minimum number of groups in the circuit Evolve separate supply bus for each group

Arrange selector valves to divert the supply to whichever is the active group

12.            Mention the various components of a hydraulic system.

Motor Filter Pump

Pressure Regulator Control Valve

Piston and cylinder

13.            What is called a pneumatic system?

System using gas for power transmission are called pneumatic systems and industrial system are usually based on air.

14.            List down the components of pneumatic system.

Motor driven compressor Air receiver

Directional control Pneumatic cylinder

15.            What is the purpose of using filters in the hydraulic systems?

Filters are used to prevent dirt or dust entering important elements of hydraulic system like valves, seals, etc. Filters are used to remove very finer particles.

16. What are the types of pumps used as energy source in a hydraulic system?

Centrifugal Pump(Hydrodynamic Pumps) Positive displacement pump

a.     Gear Pumps

b.    Vane Pumps

c.     iston pumps

17.            What are the factors to be considered for selecting compressors?

The type of air compressor is selected dependent on quality of air, pressure and cleanliness

18.            List the features of synchronous motor.

It operates at a current speed from no load to full load Power factor of the motor can be controlled easily

19.            What is a stepper motor?

A stepper motor is a rotating machine which converts a DC voltage pulse into a series of discrete rotational steps. Each step position is an equilibrium position without further excitation, this makes it ideally suitable for the use with digital control

20.          What are the factors to be considered for selecting solenoids?

a. The size of the mechanical load. b. The movement distance of plunger. c. The type of electrical connections. d. The type of value of current and voltage.