17.
Power Transmission
17.1
Flexible coupling
The engine is connected to the reduction gear or generator with a flexible coupling. The type
of flexible coupling is determined separately for each installation based on the torsional vibration
calculations.
17.2
Clutch
Hydraulically operated multi-plate clutches in the reduction gear are recommended.
A clutch is not absolutely required in single main engine installations, provided that the friction
torque of the shaft line does not exceed the torque capacity of the turning gear, or there is a
tooth coupling so that the engine can be separated from the propeller shaft. A combined
flexible coupling and clutch mounted on the flywheel is usually possible without intermediate
bearings, because the engine is equipped with an additional bearing at the flywheel end.
Clutches are required when two or more engines are connected to the same reduction gear.
To permit maintenance of a stopped engine, either clutches or tooth couplings are required
in twin screw vessels, if the vessel can operate with only one propeller.
17.3
Shaft locking device
Twin screw vessels are to be equipped with shaft locking devices to prevent propeller
windmilling, if the vessel can operate with only one propeller. Locking devices should be
installed as safety equipment for maintenance operations also when the ship can operate with
one propeller trailing (requires continuous lubrication of gear and shaft).
The shaft locking device can be either a disc brake with calipers, or a bracket and key
arrangement.
Fig 17-1
Shaft locking device and brake disc with calipers
17.4
Power-take-off from the free end
Full output is available also from the free end of the engine. The weight of the coupling
determines whether a support bearing is needed, and for this reason each installation must
Wärtsilä 46F Product Guide - a19 - 1 December 2017
17-1
17. Power Transmission
Wärtsilä 46F Product Guide
Summary of Contents for 12V46F
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