any propulsion shafting system, the load carried by each bearing is an
important factor contributing to the overall succesful operation of the
and offset as well as optical methods are used on new constructions to
align ship’s main propulsion shafting, and when careful procedures are
followed, will provide good alignment, however, they are indirect
methods of obtaining bearing reactions and subject to considerable error
in some cases.
HYDRAULIC JACKING METHOD, as developped by H.C. Andersen of MASS.,
U.S.A. is a direct method of propulsion shaft alignment, wherein the
bearing reactions are determined by jacking the shaft out of its bearing,
with a calibrated electronic load cell in between.
repair work, it expedites an alignment check, since it is not necessary
to unbolt the intermediate shafts, and quick answers are obtained on
what needs to be done to establish a good propulsion shaft alignment, in
other words, satisfactory bearing reactions.
the jacking method is used to obtain bearing reactions existing on a
lineshaft system, certain procedures must be followed, characteristics
of the shafting system understood and correct interpretations of the
hysteresis loop made, so correct results are obtained.
qualified engineer, assisted by one or two fitters, should carry out
this kind of shaft alignment operations.
There is no need for external engineering assistance, such as by
computer, all decisions are made on board and remedial actions are taken
immediately, so that in a shortest possible timeframe the propulsion
shafting finally will have satisfactory bearing reactions and bearings
will have optimum orientations for long-life, troublefree operation.
above-described method has approval from Regulatory Bodies.