ME6503 Design of Machine Elements 2 marks

ANNA UNIVERSITY,CHENNAI

REGULATION 2013

DEPARTMENT OF MECHANICAL ENGINEERING

SUBJECT CODE:ME 6503

SUBJECT NAME:DESIGN OF MACHINE ELEMENTS

UNIT II SHAFTS AND COUPLINGS 

Design of solid and hollow shafts based on strength, rigidity and critical speed – Keys, key ways and splines - Rigid and flexible couplings.

PART-A ( Two Marks)

1.What is a shaft? List out the types of shafts.

A shaft is a rotating machine element,which transmits power from one point to another point.

Types of shafts:

i.Line shaft 

ii.Spindle 

iii. Stub shaft 

iv. Counter shaft

2.What is key?

Key is a device which is used for connecting tow machine parts for preventing relative motion of rotation with respect to each other.

Types of Keys:

 i. Saddle key 

ii.Tangent key 

iii.Sunk key 

iv.Round key and 

taper pins.

3.Define the term critical speed?

The speed at which the shaft runs so that the additional deflection of the shaft from the axis of rotation becomes infinite, is known as critical speed.

4.What are the types of Flexible coupling?

i.Universal coupling,

ii.Oldham’s coupling,

iii.Pushed pin type coupling.

5.What are the types of Rigid coupling?

i.Sleeve coupling, 

ii.Flange coupling, 

iii.Clamp coupling.

6.Under what circumstances flexible couplings are used?

They are used to join the abutting ends of shafts when they are not in exact alignment. They are used to permit an axial misalignment of the shafts without under absorption of the power, which the shafts are transmitting.  

7.How are sunk key designed?List the various failures occurred in sunk keys.

Sunk keys are designed to fit in a sunk key way. Whose bed is parallel to the axis of the shaft.

Various failures:

1.Shear failure 2.Crushing failure 

8.What is the function of a coupling between two shafts?

 Couplings are used to connect sections of long transmission shafts and to connect the shaft of a driving machine to the shaft of a driven machine.

9.What are the purposes in machinery for which couplings are used?

i.To provide the connection of shafts of units those are manufactured separately such as motor and generator and to provide for disconnection for repairs or alterations.

ii.To provide misalignment of the shafts or to introduce mechanical flexibility.

iii.To reduce the transmission of shock from one shaft to another. 

iv.To introduce protection against over load.

10.What are the different measures followed to control the lateral deflection?

i. Reducing the span length 

ii. Increasing the number of supports 

iii. Selecting the cross-section in which the area moment of inertia as in case of hollow shaft.

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