KEYS AND COUPLINGS

A transmission shaft subjected to pure bending moment should be designed on the basis of

• Maximum principal stress theory

• Maximum shear stress theory

• Distortion energy theory

• Goodman or Soderberg diagrams

A transmission shaft is subjected to bending moment (M_b) and torsional moment (M_t). The equivalent torsional moment is given by,

• √(M_b + M_t)

• √(M_b² + M_t²)

• M_b + M_t

• M_b +√(M_b² + M_t²)

The standard height for flat key in terms of shaft diameter (D) is,

• d

• d/2

• d/4

• d/6

Kennedy key is used in

• Light duty applications

• Heavy duty applications

• High speed applications

• Precision equipments

A bushed-pin type flange coupling is used

• For intersecting shafts

• When the shafts are not in exact alignment

• For small shafts rotating at slow speeds

• For parallel shafts

The standard length for square or flat key in terms of shaft diameter (D) is,

• d

• 2d

• 1.5d

• 2.5d

The key, which fits in the keyway of hub, only is called,

•  Saddle key

• Feather key

• Woodruff key

• Kennedy key

Splines are used if,

• The power to be transmitted is high

• The torque to be transmitted is high

• The speed is high

• here is relative motion between shaft and hub

Maximum principle stress theory is used for

• Cast iron shafts

• Steel shafts

• Aluminum shafts

• Plastic shafts

The keyway,

•  Reduces strength of shaft

• Reduces rigidity of shaft

• Increases stress concentration

• All of above