Iveco Marine Diesel Engines, Installation Handbook

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Rigid suspension
It is not admitted for 3-cylinder engines and 4-cylinder engines without balancing masses.
It is often used on work boats where a lower dampening level of the vibrations and noise coming from
the engine and the reducer is usually accepted.
It is also recommended for applications on fast boats where structural solidity is favoured instead of
comfort, as these boats must bear substantial stresses at high speeds.
The engine brackets are directly fastened to the hull basement keelson, taking care to level out the rel-
evant supporting planes by placing the suitable steel shims, if needed, to distribute the support evenly
and to obtain the correct alignment of the engine-axis line.The brackets and the relevant fasteners must
be sufficiently rigid and resistant to bear the inverter thrust on the inverter thrust bearing when the
inverter is directly flanged on the engine.
The correlations needing the axis line installation are mentioned in Section 3, to which you should make
reference.The figure illustrates an example of rigid assembly on four points.
Flexible suspension
It is used when a higher soundproofing and vibration reduction are required; it is imposed for 3-cylin-
der engines and 4-cylinder engines without balancing masses.
It is installed by placing two flexible elements between the engine brackets and the engine support keel-
son.The flexible elements are chosen according to the weight resting on them and the level of required
dampening.
Take particular care in the choice of the suspensions for the applications on fast boats or their use on
fully developed sea. In some cases special supports are required. If the engine must bear the propeller
thrust, the flexible supports must be able to resist also to the alternate variations of the vertical load
(axial for the support) resulting from the reaction torque and the thrust actions in the two propeller
directions, operating them in radial direction.
Figure 2 illustrates an example of the flexible support adjustable in height, supplied upon request by
IVECO for some applications and figure 3 shows an example of installation.
The height adjustment shall be carried out according to the specific instructions provided by each sup-
port supplier. Generally, the installer is reminded that the height adjustment must be a final alignment
operation of the engine-axis line, for the correct load distribution on the supports, to be completed
after the preliminary positioning.
The engine bracket must be placed as close as possible to the flexible element and never to the thread-
ed stem top, to prevent dangerous bending caused by horizontal forces.
MARCH 2004 ENGINE INSTALLATION
4.54
MARINE ENGINES INSTALLATION
Figure 1