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# Important Answers: Design of Shafts and Couplings

Mechanical - Design of Machine Elements - Design of Shafts and Couplings

1.What are various types of stresses induced in the shafts?

Shear stresses due to transmission of torque.

Bending stresses.

Stresses due to combined torsional and bending loads.

2.What is a flange coupling?

It is a coupling having two separate cast iron flanges. Each flange is mounted on the shaft end and keyed to it. The faces are turned up at right angle to the axis of the shaft. One of the flanges has a projected portion and the other flange has a corresponding recess. This helps to bring the shafts into line and maintain alignment.

3.       What is the effect of keyway cut into the shaft?

The keyway cut into the shaft reduces the load carrying capacity of the shaft. This is due to the stress concentration near the corners of the keyway and reduction in the cross sectional area of the shaft. In other words the torsional strength of the shaft is reduced.

4.       What is the difference between coupling and a clutch?

A coupling is a device used to make permanent or semi permanent connection where as a clutch Permits rapid connection or disconnection at will of the operator.

5.       How hollow shaft are superior to solid shaft?

The weight of hollow shaft is 75% less then solid shaft for same torque transmission

6.       Define Preferred Numbers?

Preferred Numbers from a general basis for standardizing and grding a series of simulator dimension characteristics or articles

7.       Is what situation flexible coupling are used?

The flexible coupling is employed to tolerate lateral and angular misalignment of the shafts.

8.What are the various factors involved in good shaft coupling?

It should be easy to connect or disconnect

It transmit full power of the shaft

9.What types of stresses are developed in the key?

Shear stress

Crushing stress

Why a hallow shaft has great strength and stiffness then solid shaft of equal weight?

The weight of hollow shaft is 75% less then solid shaft for same torque transmission.

11. 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 or whirling speed.

12. . Factor is considered to design a shaft?

i. strength

ii. stiffness

13. What is key?

A key is device, which is used for connecting two machine parts for preventing relative motion of rotation with respect to each other.

14.What are the types of keys?

Tangent key

Sunk key

Round key and taper pins

15.What is the main use of woodruff keys?

A woodruff key is used to transmit small value of torque in automotive and machine tool industries. The keyway in the shaft is milled in a curved shape whereas the key way in the hub is usually straight.

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