Power Transmission Interview Questions & Answers

Question 1. What Is Meant By A Belt Drive?

Answer :

When power is driven from driver pulley to driven pulley by means of belt , it is known as belt drive. In open belt drive both the pulleys run in the same direction and in cross belt drive both the pulleys run in opposite direction to each other.

Question 2. What Is The Material Of Belts?

Answer :

Belts are generally made by canvas ,rubber, leather and steel.

Question 3. What Are The Reasons For Slipping Of Belt?

Answer :

• The belt is loosely fitted.
• Overloading on belt drive.
• Misalignment of pulleys.

Question 4. What Are The Points To Be Noted When Selecting A Belt?

Answer :

• Load of the machine.
• Speed of the machine.
• Capacity of machine.
• Atmosphere of the climate.

Question 5. What Are The Uses Of Jockey Pulley?

Answer :

Jockey pulley is used to increase the contacting area in between the belt and pulley and also used to press the belt for giving tension.

Question 6. Define Crowning In Belt Drive?

Answer :

The outer surface or face of rim of the pulley is made in convex form to keep the belt in center when it is in movement, it is called crowning.

Question 7. What Is Dressing In Belt Drive?

Answer :

To avoid slip or creep, the resin powder or paste is poured in between the outer surface of pulley and belt for increasing the tension is called dressing.

Question 8. Write Short Notes On Creep And Slip In Belt Drive?

Answer :

• The movement of belt upon the face of rim or outer surface of driver and driven pulleys within the area of arc of contact is called creep in belt drive.
• If the belt is loosely fitted on pulleys, it slips down which is called slip in belt drive.

Question 9. What Are The Rules For Belt Drives?

Answer :

• The distance between two pulleys should not be less than three times the diameter of the larger pulley. 
• The slack side should be uppermost which may increase the arc of contact.
• The ratio of diameter of both the pulleys should not exceed 6:1. 
• If necessary ,a jockey pulley should be used to minimize the slip.

Question 10. What Are The Advantages And Disadvantages Of V Belt?

Answer :

• The main advantages of V belt are it has more gripping power, long life and it occupies less space.
• Disadvantages are it is not fit for long distances and cross belt drive.

Question 11. What Are The Functions Of Gears?

Answer :

• To change the direction of rotation
• To change the speed.
• To change the plane directions.
• To transmit power.
• To give positive drive.

Question 12. What Do You Mean A Worm Drive?

Answer :

Worm drive consists of a worm and worm wheel and the worm wheel is always driven by the worm. It is suitable for heavy loads and also for speed reduction.

Question 13. What Is Spur Gear?

Answer :

It is a common type of gear having teeth in straight. It is used to transmit the motion on parallel shafts and used for all general purpose for transmitting motion.

Question 14. What Is The Difference Between Addendum And Dedendum?

Answer :

• Addendum is the distance from the top of tooth to the pitch circle.
• Dedendum is the distance from the root to the pitch circle of gear tooth.

Question 15. Define Chordal Thickness?

Answer :

It is distance in straight line from tooth to tooth along the pitch circle.

Question 16. What Is Module?

Answer :

It is the ratio between the pitch diameter and the number of teeth in the gear.

Question 17. Define Diameteral Pitch?

Answer :

Diameteral pitch is the ratio between the number of teeth of a gear and the pitch circle diameter.

Question 18. Which Gears Are Used To Connect The Shafts Lying In The Same Plane?

Answer :

Spur gears, Helical gears, Internal gears and Herringbone gears

Question 19. Differentiate Between Herringbone Gears And Helical Gears?

Answer :

• Herringbone Gears . Double helical gears are known as Herringbone gears. These gears have teeth in series on both sides from the centre in the inclined position to the axis. These type of gears are used to transmit motion at high speed with heavy load without producing noise. 
• Helical Gears. These type of gears have teeth in series of single way in an inclined position. Helical gears are used to transmit the motion at high speed without producing noise.

Question 20. Which Gears Are Used To Connect The Shafts Which Intersect At Same Angle?

Answer :

Bevel gears and angle gears.

Question 21. Which Gears Are Used To Connect The Shafts At An Angle But Lying In The Same Plane?

Answer :

• Spiral gears
• Worm and worm wheel

Question 22. What Do You Mean By Bevel Gear?

Answer :

These gears have intersecting axis. Bevel gears are used to connect shafts which are not parallel and when their axis meet at an angle and found with straight, helical and spiral teeth.

Question 23. Explain Rack And Pinion ?

Answer :

Rack is a flat bar having straight teeth in series .It is meshed with a pinion having straight teeth like spur gear. These type gears used in carriage of lathe and milling machine table.

Question 24. Explain Briefly About Friction And Anti-friction Bearings?

Answer :

• Friction bearings. This type of bearings contact that shaft directly such as bush bearing ,journal bearing etc. These bearings generally made of cast iron ,brass and gun metal.
• Anti-friction bearings. These type of bearings have rolling elements such as balls, rollers etc.

Question 25. Why Is The Bearing Tinned Before Refilling?

Answer :

While removing the damaged lining it helps to melt the lining at low temperature and it helps to spread over the molten metal on the bearing surface.

Question 26. What Are The Functions Of A Bearing?

Answer :

• To guide the shaft.
• To support the shaft.
• To give free rotation to the shaft.

Question 27. Where Are The Following Bearings Used?

Answer :

• Ball bearing is generally used on high speed with light load because it has point contact.
• Roller bearing is generally used on high speed with heavy load because it has line contact.

Question 28. What Is The Use Of Taper Roller Bearing?

Answer :

A taper roller bearing is used to carry heavy loads because it has taper rollers instead of plain cylindrical rollers.

Question 29. What Is The Application Of White Metal Bearing?

Answer :

It is generally used on high speed with light load because its bearing metal controls the heat.

Question 30. What Are The Reasons Of Over Heating On Anti-friction Bearings?

Answer :

The main reasons are, inadequate lubrication ,overloading ,miss-alignment and bearing in defective condition.

Question 31. What Are The Various Types Of Bearings?

Answer :

• Bush Bearing. It is a plain cylindrical bearing made of brass , gun metal ,cast iron etc. Its inner bore is finished and made running fit to the shaft. It is generally used on low speed shafts carrying light load.
• Ball bearing. It consists of outer race, inner race, steel balls and cage. The balls are rolling themselves in the tracks between the outer and inner races ,bearing is fitted on shaft while its outer portion is fixed in housing .Balls have point contact and are free in the races,friction makes balls to rotate.

Question 32. What Is Journal Bearing And Mention Its Use?

Answer :

It is a split bearing having two halves which are made of brass, gun metal, etc. Its outer ends have collar on both sides. IT is fitted in the housing generally made of cast iron. It is used where the supporting pressure of the bearing is at right angle to the shaft axis.

Question 33. What Are The Advantages Of Anti-friction Bearing Over A Friction Bearing?

Answer :

• For reducing wear and tear.
• For saving the power consumption.
• For easy setup.
• For smooth running of machine.
• For running at slow and high speed carrying light and heavy loads.

Question 34. What Is A Cam?

Answer :

A cam is a cylinder, plate or other solid with curved outline which is designed to convert rotary motion into timed irregular motion on the follower which is in contact with it.ie,cams rotary motion can be changed to reciprocating motion.

Question 35. What Are The Main Types Of Cams?

Answer :

There are two main types of cams used in industries,

• Radial cam. On this cam the follower operates in a plane perpendicular the axis of the camshaft which is raised and lowered as the cam revolves.
• Cylindrical Cam. On this cam the follower oscillates in a plane parallel with the axis of the camshaft .

Question 36. Name Different Types Of Shafts Used In Industry?

Answer :

Commonly four types of shafts are used in industry:

• Main shaft
• Counter shaft
• Crank shaft
• Splined shaft.

Question 37. What Are The Different Types Of Cam Motions?

Answer :

Uniform or constant motion,Harmonic motion, Uniform accelerate and retarded motion.

Question 38. Name Different Types Of Cam Followers?

Answer :

Commonly used followers are, Pointed , Flat faced, Roller and Spherical faced.

Question 39. Explain About A Screw Jack?

Answer :

A Screw jack consists of a body and a square threaded screw rod. Its screw rod has a head and a revolving pad. This screw rod acts on both directions according to the action of the lever attached with ratchet arrangement with the handle. It is used to lift the loads therefore it is mostly used by motor mechanics.

Question 40. Explain Briefly The Use Of Clutch?

Answer :

Clutch is used to connect and disconnect the driving and driven units of a machine. It does the function when machine speed is changed after stopping the driving unit.

Question 41. What Do You Mean A Coupling?

Answer :

It is a device used to connect two shafts. These are generally used to increase the length of shafts.

Question 42. What Is A Flange Coupling?

Answer :

It is very common type of coupling used to connect the shafts by means of two flanges. Two cast iron flanges are fitted with key to the ends of the two shafts to be connected and fastened together by means of bolts and nuts.

Question 43. Explain About Universal Coupling?

Answer :

It is used to connect two shafts whose axis are not in line with each one center block, two pins and two pins and two collars with lock pins. The forks are fitted with key on the ends of two shafts and then joined to a center block having two arms at 90 degree to each other. This coupling does the function on the action of its two pins. It does not work well if the angle between the two shafts is more than 45 degree.

Question 44. What Is A Flexible Coupling?

Answer :

It connects the shafts with soft materials such as rubber, leather, canvas etc. It adjusts the little misalignment and controls the vibrations also. It is generally used electric pumps.

Question 45. Explain About Pulley Block?

Answer :

Pulley block is a block in which two or three group of pulleys are used with a rope to lift and heavy loads. The load is tied in the hook of the movable block and the effort is applied at the end of the rope which comes through the fixed pulley block.

Question 46. Write About Muff Coupling?

Answer :

It is a hollow piece which is used with key to connect the shafts. It may be found in cylindrical muff,half lap muff or split muff type. A gib head key or a saddle key is inserted between the coupling and shafts through out for connecting the shafts.

Question 47. Explain About Hydraulic Jack?

Answer :

It consists of a cylinder and ram. The oil is forced into the cylinder. The load is lifted by this jack according to the pressure of the oil. In its working system the oil is filled through the oil plug in the oil reservoir. It has a tube at the lower en d and a non return valve. When the lever is operated up and down, plunger moves up in the tube supplying the oil and it down the non return valve which allow the oil into the cylinder which causes the ram raises. The ram raises according to the pressure of the oil which lift the load accordingly.

Question 48. What Is A Chain Block?

Answer :

It consists of two grooved pulleys which are fixed side on the same spindle having chain also. While another pulley is fitted with clamp in which a lifting hook is provided. One chain connects the hanging pulley. When a chain is pulled by hand then all the pulleys start functioning and the hook carries the load. In this way the load is lifted to a required height.

Question 49. What Is The Formula To Find Out The Length Of A Belt In An Open Belt Drive?

Answer :

L = 2C + 1.57 (D + d) + (D-d)2 /4C

Question 50. What Is The Formula To Find Out The Length Of A Belt In A Closed Belt Drive?

Answer :

L = 2C + 1.57 (D +d ) + (D+d)2/ 4C

Question 51. How To Calculate The Number Of Teeth In A Gear If Given The Module And Pitch Circle Diameter?

Answer :

• Pitch = Module* 3.14 (pie value)
• Number of teeth = Pitch circle diameter/ pitch

Question 52. What Are Standard Pipe Threads?

Answer :

Pipe threads are grouped in certain ranges such as 1/4” to 3/8” pipe threads have 19 T.P.I , ½ “ to 7/ 8” pipe threads have 14 T.P.I, 1” and above size pipe threads have 11 T.P.I . Pipe threads may be either straight or tapered.

Question 53. Name Different Pipe Fitting Accessories?

Answer :

Commonly used pipe fitting accessories are : Socket, Reducing socket, Cross, Union, Stop valve, Elbow, Union, Plug, Flange, Tee.

Question 54. What Is The Use Of Chain Wrench In Pipe Fitting?

Answer :

It is used to hold the pipe firmly and it is fit for rotation on both ways.

Question 55. Explain About Common Types Of Pipe Materials And How Are Pipes Specified?

Answer :

Pipes are commonly made of cast iron , steel, copper, lead, zinc, galvanized iron(G.I) wrought iron , aluminium and also cement and plastic pipes are used. Generally pipes are specified by the length, material, bore size.

Question 56. Describe The Methods Of Protecting Leakage At The Pipe Joint?

Answer :

• Threads joints should be fixed applying red lead, white lead, dry point etc. in the threads, bound the pipe threads using twine and tightened them fully with a suitable wrench. 
• Flanged joint should be fixed using a washer of rubber, leather, card board or soft metal in metal in between the inner sides of both the flanges. 

Question 57. What Are The Different Types Of Tools Used In Pipe Fittings?

Answer :

Generally tools used in pipe fittings are Pipe vice, Pipe wrench, Pipe die, Pipe tap, Chain wrench, Chisel, Hammer, Reamer and Pipe cutter.

Question 58. Explain Briefly The Uses Of Pipe Vice And Pipe Wrench ?

Answer :

• Pipe vice. It is used to hold the pipe firmly while cutting, threading etc.
• Pipe wrench. It is used fir tightening and loosening the pipes.

Question 59. Explain About Spigot And Socket Joint?

Answer :

This joint is generally used to connect cast iron pipes which are buried in ground .This is also suitable for straight pipe line carrying water and this joint has less rigidity.

Question 60. What Do You Meant By Expansion Joint?

Answer :

This joint is used to carry the piping system at high pressure. This joint is provided with gland and stuffing box which make the joint perfectly steam tight. To prevent leakage asbestos packing is provided.