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Propeller shaft systems
Propeller shafts
When selecting a propeller shaft for a particular ap-
plication, there are many points to be taken into con-
sideration. Shaft material and shaft sizes must suit
the individual vessel designs and application.
The shaft material must have good strength and be
corrosion resistant. A stronger material is beneficial
in many sport cruiser applications, because a smaller
diameter results in less underwater resistance and
turbulence.
Depending on the length, the shaft may need to be
supported with bearings. The minimum distance
between the propeller shaft coupling to the first rigid
bearing should be 0-4 x the shaft diameter. The
distance should be sufficient to allow engine move-
ments without excessive stresses to the shaft system.
The maximum distance between bearings is deter-
mined by shaft critical speed. This can be calculated
based on the type of installation and shaft properties.
During installation of the shaft, it is of great impor-
tance to protect the precision straightness and fine
surface finish. When lifting shafts it is best to use
slings with spreaders to distribute weight more evenly
to avoid straightness problems.
Always check the straightness of the propeller shaft.
The run-out of the shaft from 00% straightness must
not exceed 0.3 mm per metre (0.0036" per foot).
Shafts that are tapered at both ends, double tapered
shafts, can be machined to be reversible. This effec-
tively doubles the life of the shaft as it can be turned
around when seals and bearings have made wearing
marks in the shaft. Before the shaft is installed, check
the fit of the coupling to the shaft taper.
Propeller shaft dimensions
and bearing distances
The propeller shaft will be subject to both bending
and torsional forces and must be dimensioned with
regard to this. Also a certain safety margin must also
be applied. The maximum bearing distance has a
major influence for the calculation of shaft dimension-
ing.
To determine the propeller shaft dimension and bear-
ing distance, use the Volvo Penta computer program
or consult the shaft supplier.
Single tapered shaft
Double tapered shaft
Summary of Contents for D11 series
Page 1: ...Marine Propulsion Diesel Engines Installation 1 1 D E D5 D16 series ...
Page 2: ......
Page 208: ...206 References to Service Bulletins Group No Date Concerns ...
Page 209: ...207 Notes ...
Page 210: ...208 Notes ...
Page 212: ...7748655 English 11 2007 ...