單項選擇題

Critical speed in diesel engines occurs when engine torque pulsations become （）

A.opposed to the crankshaft rocking couple
B.resonant with the crankshaft natural frequency
C.critical fore and aft crankshaft vibrations
D.horizontal whipping motions of the crankshaft

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單項選擇題

Air receivers installed in starting air systems are to be （）.

A.cylindrical in shape with service connections located at the top and bottom
B.opened and made available for inspection during biannual inspections provided
C.with automatic drain traps for the removal of moisture
D.so installed as to make the drain connections effective under extreme conditions of trim

單項選擇題

Which of the conditions listed may occur in an operating diesel engine if air pockets form within the cylinder head circulating water passages? （）

A.Hydraulic stress and distortion will develop
B.Hot spots will develop
C.Fuel oil viscosity will increased
D.An increase in trapped deposits of scale and dirt