they must be located at the after end of the engine
they can only be used with one engine at a time
they eliminate the need for controllable pitch propellers
they are connected to the engine with a flexible coupling
第1题：
Propeller pitch speed minus ship speed divided by the propeller pitch speed is termed ___.
A.apparent slip
B.true slip
C.pitch
D.propulsive efficiency
第2题：
Lubrication for the main reduction gears used with diesel engines is usually supplied by
A.oil from the main engine sump
B.an independent lube oil system
C.the stern bearing head tank
D.the stem bearing sump tank
第3题：
A.The automatic control system
B.The speed regularly system
C.The transmission system
D.The compression air system
第4题：
Prevents lateral movement of the slow speed gear
Transmits propeller thrust to the hull
Keeps spring bearings in line
Prevents main reduction gear axial movement
第5题：
the extra weight required for the diesel reduction gearing
a minimum speed for the engines that limits the minimum speed of the vessel
the higher fuel consumption per SHP
the low efficiency of the system when a controllable pitch propeller is used
第6题：
A controllable pitch propeller on a diesel driven vessel eliminates the need for
A.friction clutches
B.disconnect clutches
C.reversing gears
D.reduction gears
第7题：
In reducing engine speed to an efficient propeller speed by the use of reduction gears, _______.
A.speed and torque are both reduced
B.speed is reduced and torque remains unchanged
C.speed is reduced and torque is increased
D.speed is sometimes unchanged while torque is increased
第8题：
When transmitted by a reduction gear, diesel engine speed is reduced and the torque available for work
A.remains the same
B.is reduced
C.is increased
D.is eliminated
第9题：
030 to 1
300 to 1
333 to 1
330 to 1
第10题：
forward perpendicular
amidships
longitudinal center of floatation
after perpendicular