Transmission of power by propshafts
33
Arrangement of the drive line
The drive line consists of the engine and the free standing (not flange mounted) gearbox. This allows the
engine and gearbox to be installed at different positions (usually in V−Drive design), so that the power
transmission from the engine to the gear box is made through a propeller shaft. For this type
of setup MAN
has developed solutions for the selection of the coupling and guidelines for the alignment of the drive line.
The goal here was to:
D Avoid damage caused by vibrations at the engine, gearbox, resilient coupling and propeller shaft
D Avoid the transfer of vibrations into the engine foundation and thus
avoid vibrations of the ship and
therefore increase the comfort on board
There are two ways to connect a propeller shaft to the engine:
1. Engine power is transferred through a highly resilient coupling (figure at top left).
The highly resilient coupling connected to the engine’s flywheel allows working angles of max. 3°.
À Engine
Á Resilient engine mounts
 Highly resilient coupling, see page 34
à Free−standing gearbox
Ä Propeller shaft, see page 35
2. Engine power is transferred through a resilient coupling with a flange bearing (figure at bottom left).
This concept requires more construction space due to the flange bearing, but allows a working angle of
up to 9°.
À Engine
Á Resilient engine mounts
 Resilient coupling with flanged bearing, see page 34
à Free−standing gearbox
Ä Propeller shaft, see page 35
Torsional−vibration analysis
The forces of gas and inertia from the engine can cause vibration of the entire drive line. In order to
determine the resonance in terms of position and strength and to avoid overstressing, a torsional−vibration
analysis is required.
This can be carried out by MAN for a fee. The requisite data are to be collected during the project phase in
the form of a questionnaire − "Questionnaire on torsional vibration calculation for ship’s drive line".
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