This section is available on request - MAN Diesel & Turbo
This section is available on request - MAN Diesel & Turbo
This section is available on request - MAN Diesel & Turbo
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<strong>MAN</strong> B&W 5.13<br />
The mechanical top bracing <str<strong>on</strong>g>is</str<strong>on</strong>g> to be made by the<br />
shipyard in accordance with <strong>MAN</strong> <strong>Diesel</strong> instructi<strong>on</strong>s.<br />
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Fig. 5.13.01: Mechanical top bracing stiffener.<br />
Opti<strong>on</strong>: 4 83 112<br />
Hydraulic top bracing<br />
178 23 61-6.1<br />
The hydraulic top bracing <str<strong>on</strong>g>is</str<strong>on</strong>g> an alternative to the<br />
mechanical top bracing used mainly <strong>on</strong> engines<br />
with a cylinder bore of 50 or more. The installati<strong>on</strong><br />
normally features two, four or six independently<br />
working top bracing units.<br />
The top bracing unit c<strong>on</strong>s<str<strong>on</strong>g>is</str<strong>on</strong>g>ts of a single-acting hydraulic<br />
cylinder with a hydraulic c<strong>on</strong>trol unit and an<br />
accumulator mounted directly <strong>on</strong> the cylinder unit.<br />
The top bracing <str<strong>on</strong>g>is</str<strong>on</strong>g> c<strong>on</strong>trolled by an automatic<br />
switch in a c<strong>on</strong>trol panel, which activates the top<br />
bracing when the engine <str<strong>on</strong>g>is</str<strong>on</strong>g> running. It <str<strong>on</strong>g>is</str<strong>on</strong>g> possible<br />
to programme the switch to choose a certain<br />
rpm range, at which the top bracing <str<strong>on</strong>g>is</str<strong>on</strong>g> active. For<br />
service purposes, manual c<strong>on</strong>trol from the c<strong>on</strong>trol<br />
panel <str<strong>on</strong>g>is</str<strong>on</strong>g> also possible.<br />
When active, the hydraulic cylinder provides a<br />
pressure <strong>on</strong> the engine in proporti<strong>on</strong> to the vibrati<strong>on</strong><br />
level. When the d<str<strong>on</strong>g>is</str<strong>on</strong>g>tance between the hull and<br />
engine increases, oil flows into the cylinder under<br />
pressure from the accumulator. When the d<str<strong>on</strong>g>is</str<strong>on</strong>g>tance<br />
decreases, a n<strong>on</strong>-return valve prevents the<br />
oil from flowing back to the accumulator, and the<br />
pressure r<str<strong>on</strong>g>is</str<strong>on</strong>g>es. If the pressure reaches a preset<br />
maximum value, a relief valve allows the oil to flow<br />
back to the accumulator, hereby maintaining the<br />
force <strong>on</strong> the engine below the specified value.<br />
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<strong>MAN</strong> <strong>Diesel</strong><br />
Page 2 of 2<br />
By a different pre-setting of the relief valve, the<br />
top bracing <str<strong>on</strong>g>is</str<strong>on</strong>g> delivered in a low-pressure versi<strong>on</strong><br />
(26 bar) or a high-pressure versi<strong>on</strong> (40 bar).<br />
The top bracing unit <str<strong>on</strong>g>is</str<strong>on</strong>g> designed to allow d<str<strong>on</strong>g>is</str<strong>on</strong>g>placements<br />
between the hull and engine caused<br />
by thermal expansi<strong>on</strong> of the engine or different<br />
loading c<strong>on</strong>diti<strong>on</strong>s of the vessel.<br />
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178 57 48-8.0<br />
Fig. 5.13.02: Outline of a hydraulic top bracing unit.<br />
The unit <str<strong>on</strong>g>is</str<strong>on</strong>g> installed with the oil accumulator pointing<br />
either up or down. Opti<strong>on</strong>: 4 83 123<br />
<strong>MAN</strong> B&W MC/MC�C, ME/ME-B/ME�C/ME�GI engines 198 46 72�5.7<br />
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