4-6 Bearing Monitoring
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Retrofitting of Bearing Monitoring Systems
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Transcript of 4-6 Bearing Monitoring
Retrofittingof Bearing Monitoring Systems
2 Four-Stroke Licensee Family
MAN B&W Diesel3Four-Stroke Licensee Family
MAN Diesel PrimeServ can now offer its customers a full retrofit solution for bearing
monitoring systems. Currently, there are four different solutions with each having par-
ticular advantages in pricing or integrability into existing systems aboard marine ves-
sels. Three of the systems (BWM, WIOM and the shaftline earthing device) can, if used
together, reduce or even omit open-up inspections of main bearings.
Retrofitting of Bearing Monitoring Systems
Bearing Wear Monitoring (BWM)
The BWM system measures wear on crank-train (main,
crankpin and crosshead) bearings and was originally
patented in 1964 by Näsholm. Back then, this was
a mechanical system that measured the crosshead
BDC. Today, bearing linings are never thicker than 1
to 1.5 mm compared to the 5 mm thickness typical
then and, accordingly, the old Näsholm patent is now
unsuitable. The new system works by measuring the
distance deviation from each unit (cylinder) in BDC-
position. This is done by mounting a proximity sensor
on each side of the crosshead. The main benefit of this
system is that it provides an early warning of bearing
wear and can therefore reduce or eliminate the cost of
bearing breakdown by acting when bearing wear is in
its early stages.
Water in Oil Monitoring (WIOM)
The WIOM system measures water content directly at
the lube-oil inlet on the engine, giving an early warn-
ing of any corrosive bearing wear. Even a low level of
contamination, such as 0.2 % of water in oil, weak-
ens the bearings’ composite materials (HMO7 and
AISn40). Accordingly, if levels were to exceed 0.5 %,
the bearings would wear out rapidly. The advantage of
the WIOM system is that water contamination can be
cleaned out by purifiers, meaning that contamination of
the lubricating oil is automatically treated.
Shaftline Earthing Device (Spark Erosion)
Spark erosion is another risk element for bearings,
which over the years has been recognised as a major
issue for main bearings (see MAN Diesel service letters
SL83-193 and SL86-213). A recent, documented case
involved a defective shaftline earthing device that led
to extreme and relatively quick main-bearing wear that
eventually resulted in failure of the bearings. In the event
of spark erosion, affected bearings must be replaced
and polishing the journals may also be necessary.
Main Bearing Temperature Monitoring (MBTM)
The MBTM system has proved highly successful in
warning of problems before severe damage is caused
to main journals: an MBTM system will typically sound
an alarm several minutes before an oil-mist detector.
This reduces potential damage to both journals and
bedplates, while its lower price recommends it for use
on cylinders with a bore size of less than 46 cm.
The BWM, WIOM, earthing-device and MBTM systems
are available with new MAN Diesel engines but can
also be retrofitted to vessels in service.
For engines retrofitted with approved BWM, WIOM,
earthing-device and MBTM systems and connected to
a vessel’s alarm and slow-down system, MAN Diesel
will accept a change in the maintenance programme.
For further information on the retrofitting of bearing-
monitoring systems, please contact MAN Diesel
PrimeServ at [email protected].
MAN Diesel
Teglholmsgade 41
2450 Copenhagen SV, Denmark
Phone +45 33 85 11 00
Fax +45 33 85 10 30
www.mandiesel.com
Copyright ©
MA
N D
iesel · Subject to m
odification in the interest of technical progress. · 1510-0121-00ppr May 2009 P
rinted in Denm
ark
