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161.

The secondary critical speed of a shaft occurs at

A.	Half the primary critical speed	B.	Twice the primary critical speed
C.	Four times the primary critical speed	D.	Occurs only when there are more than 2 rotors on a shaft
E.	If the externam exciting system has a frequency other than the primary critical speed

162.

An axial flow fan balanced at one speed often exhibits substantial vibrational effects when operated at other speeds, mainly due to

A.	Secondary critical speed effect	B.	Primary critical speed effect
C.	Unbalanced parts of fan	D.	Aerodynamic unbalance
E.	Vibration in air

163.

In a balancing machine, the units for unbalance measurement are

164.

A 0.5 kg weight attached to a light spring elongates it 0.981 mm. The natural frequency of the system would be approximately

165.

In a Hartnell governor if the stiffness of spring is increased the governor will

A.	Become more sensitive	B.	Become less sensitive
C.	Remain unaffected as far sensitivity is concerned	D.	Start hunting (E) Become isochronous

166.

The abbreviation P.I.V. drive system stands for

A.	Polar Inertia Vee belt	B.	Purely Integral Variance
C.	Perfectly Induced Velocities	D.	Positive Infinitely Variable
E.	Periodic Ideal Vibrationless

167.

Identify incorrect statement regarding the flywheel, if any

A.	It is provided to minimise vibration of engine	B.	It is provided to control engine speed
C.	It takes care of output fluctuations and controls input accordingly	D.	In help in starting engine
E.	All above

168.

A beater machine in a pulp mill is driven by a 50 H.P. motor using 6 vee belts of D section. If one of the belt breaks after a month

A.	All the belts have to be replaced	B.	Broken belt may be replaced by the similar etc
C.	Broken belt and at least one adjacent belt should be replaced	D.	Broken belt and at least two adjacent belt should be replaced
E.	None of the above

169.

If a machine uses four V belts, while purchasing care should be taken to ensure that

A.	All belts are same section	B.	All belts are of same size
C.	All belts are of same manufacturers	D.	All belts are of same batch number
E.	All above

170.

For fluctuating loads, the appropriate bearing would be