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Most engines are fitted with one or two viscous shear type torsional
vibration dampers attached to the crankshaft at the opposite end
to the flywheel.
Why are Dampers fitted?
The crankshaft damper is fitted to minimise the influence of torsional
vibrations developing in the crankshaft. This keeps material stresses
arising from these vibrations within permissible design limits.
The damper, by reducing oscillations in the crankshaft to a low
amplitude, prevents premature failures of the driven equipment.
How does the Holset Viscous Damper work?
The damper absorbs torsional vibration energy by the shearing effect
of a highly viscous silicone fluid trapped between an inertia ring
and the damper casing. The shearing of the fluid generates heat
which is dissipated through the external surfaces of the damper.
Condition Monitoring
Condition monitoring of the damper is an essential preventative
maintenance practice. This ensures the torsional vibration system
of the vessel, generator or pump continues to function as per the
design calculations, thus preventing early life failures. The internal
condition and operating efficiency of the Holset viscous damper
should be monitored by extracting small samples (1cc.) of silicone
fluid for laboratory analysis removal of a silicone fluid sample
is a simple process which should be initially carried out after
15,000 hours of engine operation or at the first major engine service.
Metaldyne will advise subsequent sampling intervals via the analysis
report. Special sampling kits complete with instructions are available
from Metaldyne Int UK Ltd or an appointed service representative
Metaldyne reports satisfy Survey Societies requirements
The Metaldyne laboratory report meets all the requirements of major
survey classification societies like Lloyds, ABS, DNV BV for marine
propulsion and auxiliary power installations at the 5 year survey.
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