單項選擇題The main advantage of improved Simplex tailshaft seal are（）

A.the good sealing performance and the simple structure
B.the good sealing performance and the short life expectancy
C.the good sealing performance but the short life expectancy
D.the good sealing performance and the lower cost


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1.單項選擇題Simplex tailshaft seal equipment’s working condition is terribleThe main cause is （）

A.the shafting’s vertical vibration
B.violent friction and sea water corrosive
C.friction and high temperature
D.violent friction and high temperature

2.單項選擇題The center line condition of the transmission shaft can be checked by（）

A.the border flange’s excursion and flection
B.the both end shafts line’s accordance
C.the border flange’s flection and the both end shafts line’s accordance
D.the border flange’s accordance and both end shafts flection degree

3.單項選擇題In the navigation（） cause the shafting over load easily.

A.the stopping engine suddenly
B.the sailing astern and changing direction suddenly
C.the sailing from the shallow water area to the deep water area
D.the ship’s trim too much

4.單項選擇題When the vessel on the full speed ahead, if full astern immediately （） the main engine start astern and fuel injection.

A.after the thrust power is zero
B.after the torsion is zero
C.surpass the critical point on the water turbo phase
D.after the speed is zero

5.單項選擇題According to the Robinson Graph, suddenly astern maneuvering of main engine during navigating will cause（）

A.rapid reduction of ship’s friction force
B.shaft system over mechanical load
C.sharp growth of the torque of diesel engine
D.propeller torque change along J=0 curve