Exam Question
A controllable pitch propeller on a diesel driven vessel eliminates the need for: (16)
(a) Friction clutches
(b) Disconnect clutches
(c) Reversing gears
(d) Reduction gears
Justify your answer and explain the working of CPP in brief.
Class 4 (4th Engineer)
MEKG
📅 May 2024
Reference Answer
The correct option is **(c) Reversing gears**.
### Justification
A Controllable Pitch Propeller (CPP) system allows the direction of thrust to be changed from ahead to astern without altering the direction of rotation of the main engine and propeller shaft. This is achieved by mechanically changing the pitch angle of the propeller blades. Since the engine does not need to be stopped and restarted in the opposite direction, or have its rotational direction reversed by a gearbox, the need for reversing gears or a direct-reversing engine is eliminated.
#### Analysis of Other Options:
### Justification
A Controllable Pitch Propeller (CPP) system allows the direction of thrust to be changed from ahead to astern without altering the direction of rotation of the main engine and propeller shaft. This is achieved by mechanically changing the pitch angle of the propeller blades. Since the engine does not need to be stopped and restarted in the opposite direction, or have its rotational direction reversed by a gearbox, the need for reversing gears or a direct-reversing engine is eliminated.
#### Analysis of Other Options:
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