Friday, August 7, 2015

GOVERNOR OBJECTIVE QUESTIONS

1. The ratio of height of porter governor (when length of arms and links are equal) to the height of watt governor is (Where m is the mass of the ball and M is the mass of sleeve)
a. (m+M)/m                   b. M/(m+M)
c. m/(m+M)                   d. None of the above

2. A governor is said to be isochronous when equilibrium speed of all radii of rotation of the balls with in the working range
a. Is constant                b. Varies uniformly
c. Is not constant          c. None of the above


3. A Hartnell governor is a governor of the
a. inertia type                         
b. pendulum type
c. spring controlled type                
d. dead weight type


4. Which one of the following is a Dead weight type governor?
a. Porter Governor         
 b. Hartnell Governor                            c. Wilson-Hartnell Governor            d. Hartung Governor


5. Height of a Governor is distance measured from
a. the centre of two balls mass
b. the centre of balls mass to the point of intersection of upper arms
c. the centre of balls mass to the point of intersection of  lower links
d. the point of intersection of upper arms to the point of intersection of  lower links


6. Which of the following is pendulum type of Governor?
a. Watt Governor             
b. Proell Governor           
c. Porter Governor                            
d. Hartnell Governor


7. Which of the following Governor is not suitable for High speeds
a. Watt Governor             
b. Hartnell Governor      
c. Wilson-Hartnell Governor       The ratio of height of porter governor (when length of arms and links are equal) to the height of watt governor is (Where m is the mass of the ball and M is the mass of sleeve)
a. (m+M)/m                   b. M/(m+M)
c. m/(m+M)                   d. None of the above

2. A governor is said to be isochronous when equilibrium speed of all radii of rotation of the balls with in the working range
a. Is constant                b. Varies uniformly
c. Is not constant          c. None of the above


3. A Hartnell governor is a governor of the
a. inertia type                            b. pendulum type
c. spring controlled type                d. dead weight type


4. Which one of the following is a Dead weight type governor?
a. Porter Governor          b. Hartnell Governor      c. Wilson-Hartnell Governor        d. Hartung Governor


5. Height of a Governor is distance measured from
a. the centre of two balls mass
b. the centre of balls mass to the point of intersection of upper arms
c. the centre of balls mass to the point of intersection of  lower links
d. the point of intersection of upper arms to the point of intersection of  lower links


6. Which of the following is pendulum type of Governor?
a. Watt Governor             b. Proell Governor           c. Porter Governor          d. Hartnell Governor


7. Which of the following Governor is not suitable for High speeds
a. Watt Governor             b. Hartnell Governor      c. Wilson-Hartnell Governor        d. Hartung Governor




9. Which of the following Governor can never be isochronous?
a.  Watt Governor            
b. Proell Governor           
c. Porter Governor          
d. Hartnell Governor



8. The sensitiveness of a Governor is
a. (N2+N1)/N                     
 b. (N2-N1)/N                       
c. (N2+N1) x N                    
d. N/(N2-N1)
Where N1=Minimum equilibrium speed
N2=Maximum equilibrium speed
N=Mean speed


9. Which of the following Governor can never be isochronous?
a.  Watt Governor            
b. Proell Governor           
c. Porter Governor          
d. Hartnell Governor

Sunday, August 2, 2015

GEOMETRY OF VARIOUS GEARS

GEOMETRY OF DIFFERENT TYPES OF GEARS



HELICAL GEAR



DOUBLE HELICAL GEAR



HYPIOD GEAR



MITRE GEAR



RACK AND PINION




SPIRAL BEVEL GEAR



SPUR GEAR



STRAIGHT BEVEL GEAR   




WORM AND WORM WHEEL





GEAR TERMINOLOGY





The following are the important dimensions and geometries concerned with toothed gear:


Pitch Circle :

Pitch circle is the apparent circle that two gears can be taken like smooth cylinders rolling without friction.

Addendum Circle :

Addendum circle is the outer most profile circle of a gear. Addendum is the radial distance between the pitch circle and the addendum circle.

Dedendum Circle :

Dedendum circle is the inner most profile circle. Dedendum is the radial distance between the pitch circle and the dedendum circle.

Clearance :

Clearance is the radial distance from top of the tooth to the bottom of the tooth space in the mating gear.

Gear Terminology

Backlash :

Backlash is the tangential space between teeth of mating gears at pitch circles.

Full Depth :

Full depth is sum of the addendum and the dedendum.

Face Width :

Face width is length of tooth parallel to axes.

Diametral Pitch :

Diametral pitch (p) is the number of teeth per unit volume.
p =  (Number of Teeth) / (Diameter of Pitch circle)

Module :

Module (m) is the inverse of diametral pitch.

m = 1/p

Circular Pitch :

Circular pitch is the space in pitch circle used by each teeth.

Gear Ratio :

Gear ratio is numbers of teeth of larger gear to smaller gear.

Pressure Line :

Pressure line is the common normal at the point of contact of mating gears along which the driving tooth exerts force on the driven tooth.

Pressure Angle :

Pressure angle is the angle between the pressure line and common tangent to pitch circles. It is also called angle of obliquity. high pressure angle requires wider base and stronger teeth.

Pitch Angle :

Pitch angle is the angle captured by a tooth.
Pitch angle = 360/T

Contact Ratio :

Contact ratio is angle of angle of action and pitch angle.

Path of Approach :

Path of approach is the distance along the pressure line traveled by the contact point from the point of engagement to the pitch point.

Path of Recess :

Path of recess is the distance traveled along the pressure line by the contact point from the pitch point to the path of disengagement.

Path of Contact :

Patch of contact is the sum of path of approach and path of recess.

Arc of Approach :

Arc of approach is the distance traveled by a point on either pitch circle of the two wheels from the point of engagement to the pitch.

Arc of Recess :

Arc of recess is the distance traveled by a point on either pitch circle of the two wheels from the point to the point of disengagement.

Arc of Contact :

Arc of contact is the distance traveled by a point on either pitch circle of the two wheels during the period of contact of a pair of teeth.

Angle of Action :

Angle of action is the angle turned by a gear during arc of contact.

SINGLE POINT CUTTING TOOL GEOMETRY



Friday, July 31, 2015

REFRIGERATION OBJECTIVE QUESTIONS

REFRIGERATION OBJECTIVE QUESTIONS

1. A REFRIGERATION SYSTEM

A. REMOVES HEAT FROM A LOW TEMPERATURE BODY AND DELIVERS IT TO HIGH TEMPERATURE BODY
B. REMOVES HEAT FROM A HIGH TEMPERATURE BODY AND DELIVERS IT TO LOW TEMPERATURE BODY
C. REJECTS ENERGY TO A LOW TEMPERATURE BODY
D. NONE OF THE ABOVE

2. RELATIVE COEFFICIENT OF PERFORMANCE IS

A. THEORETICAL COP/ACTUAL COP
B. ACTUAL COP/THEORETICAL COP
C. ACTUAL COP*THEORETICAL COP
D. NONE OF THESE

3. THE CAPACITY OF A DOMESTIC REFRIGERATOR IS IN THE RANGE OF

A. 0. TO 0.3 TR
B. 1 TO 3 TR
C. 3 TO 5 TR
D. 5 TO 7 TR

4. WHEN THE LOWER TEMPERATURE OF A REFRIGERATING MACHINE IS FIXED THEN COP CAN BE IMPROVED BY

A. OPERATING  MACHINE AT HIGHER SPEEDS
B. OPERATING MACHINE AT LOWER SPEEDS
C. RAISING THE HIGHER TEMPERATURE
D. LOWERING THE HIGHER TEMPERATURE

5. AIR REFRIGERATION  WORKS ON

A. REVERSED CARNOT CYCLE
B. BELL COLEMAN CYCLE
C. BOTH A & B
D. STIRLING CYCLE

6. AIR REFRIGERATION IS USED IN

A. COMMERCIAL REFRIGERATORS
B. DOMESTIC REFRIGERATION
C. AIR CONDITIONING
D. GAS LIQUEFICATION

7. DURING REFRIGERATION HEAT IS REJECTED BY REFRIGERANT IN A

A. COMPRESSOR
B. CONDENSER
C. EVAPORATOR
D. EXPANSION VALVE

8. IN A VAPOUR COMPRESSOION SYSTEM THE CONDITION OF THE REFRIGERANT BEFORE PASSING THROUGH THE CONDENSER IS

A. HIGH PRESSURE SATURATED LIQUID
B. WET VAPOUR
C. DRY SATURATED VAPOUR
D. SUPERHEATED VAPOUR

9. THE FORMATION OF FROST ON COOLING COIL IN A REFRIGERATOR

A. INCREASES HEAT TRANSFER
B. IMPROVES COP OF THE SYSTEM
C. INCREASES POWER CONSUMPTION
D. REDUCES POWER CONSUMPTION

10. IN A PRESSURE ENTHALPY CHART THE SPACE TO THE LEFT OF THE SATURATED LIQUID LINE REPRESENTS

A. WET VAPOUR REGION
B. SUPERHEATED VAPOUR REGION
C. SUB COOLED REGION
D. DEGREE OF SUPERHEAT

Wednesday, July 29, 2015

THEORY OF MACHINES OBJECTIVE QUESTIONS

THEORY OF MACHINES OBJECTIVE QUESTIONS

1. THE CAM AND FOLLOWER USED IN AUTOMOBILE ENGINES IS

A. KNIFE EDGE FOLLOWER
B. FLAT FACED FOLLOWER
C. SPHERICAL FACED FOLLOWER
D. ROLLER FOLLOWER

2. THE CAM FOLLOWER GENERALLY USED IN AIR CRAFT ENGINES IS

A. KNIFE EDGE FOLLOWER
B. FLAT FACED FOLLOWER
C. SPHERICAL FOLLOWER
D. ROLLER FOLLOWER

3. IN A RADIAL CAM THE FOLLOWER MOVES

A. IN A DIREECTION PERPENDICULAR TO CAM AXIS
B. IN A DIRECTION PARALLEL TO CAM AXIS
C. IN ANY DIRECTION IRRESPECTIVE OF THE CAM AXIS
D. ALONG THE CAM AXIS

4. FOR LOW AND MODERATE SPEED ENGINES CAM AND FOLLOWER SHOULD MOVE WITH

A. UNIFORM VELOCITY
B. SIMPLE HARMONIC MOTION
C. UNIFORM ACCELERATION AND RETARDATION
D. CYCLOIDAL MOTION

5. A SPRING CONTROLLED GOVERNOR WILL BE SAID TO BE ISOCHRONOUS WHEN THE CONTROLLING FORCE

A. INCREASES AS RADIUS OF ROTATION DECREASES
B. DECREASES AS RADIUS OF ROTATION INCREASES
C. INCREASES AS RADIUS OF ROTATION INCREASES
D. REMAINS CONSTANT FOR ALL RADII OF ROTATION

6. POWER OF A GOVERNOR IS THE

A. MEAN FORCE EXERTED AT THE SLEEVE FOR A GIVEN PERCENTAGE CHANGE IN SPEED
B. WORKDONE AT THE SLEEVE FOR MAXIMUM EQUILIBRIUM SPEED
C. MEAN FORCE EXERTED AT THE SLEEVE FOR MAXIMUM EQUILIBRIUM SPEED
D. NONE OF THE ABOVE

7. THE EFFORT OF A PORTER GOVERNOR IS EQUAL TO

A. C(m-M)g
B. C(M+m)g
C. C/(M+m)g
D. C/(m-M)g

8. WHICH OF THE GOVERNOR IS USED TO DRIVE A GRAMOPHONE

A. WATT GOVERNOR
B. PORTER GOVERNOR
C. PICKERING GOVERNOR
D. INERTIA GOVERNOR

9. IN A GEAR HAVING INVOLUTE TEETH THE NORMAL TO THE INVOLUTE IS  A TANGENT TO

A. ADDENDUM CIRCLE
B. DEDENDUM CIRCLE
C. PITCH CIRCLE
D. BASE CIRCLE

10. THE SIZE OF A GEAR IS USUALLY SPECIFIED BY

A. PRESSURE ANGLE
B. CIRCULAR PITCH
C. DIAMETRAL PITCH
D. PITCH CIRCLE DIAMETER