Hamilton Jet HJ212, Installation And Service Manual

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Design Basics
Installation and Service Manual
Drive Lines
Loads on jet unit thrust bearing
The thrust bearing accepts thrust loads from the jet unit to propel the craft. It should not be
subjected to excessive loads from other sources as described below:

The thrust bearing will not stand excessive radial loads caused by adapters and belt
pulleys overhanging the jet coupling flange.

The thrust bearing will not withstand excessive loads produced by rigid drivelines which
do not accommodate misalignment resulting from engine movement.

There is a limit to the driveshaft weight that can be supported at the jet unit.
Requirements of the Driveline
The driveline:

Must allow for parallel and angular misalignment plus axial movement.

Must transmit the torque to the jet unit with an acceptable life expectancy.

Does not have to transmit thrust loads as these are absorbed by the jet unit.

Must allow for torsional flexibility. A torsional vibration analysis must always be done on the jet unit. The
resultant torque must always be in the same direction and should be carefully checked at engine idle
speed.
H-Bar Drive Lines
In vessels designed for higher operational hours and severe use e.g. tourist boats operating in
narrow, shallow rivers, the H-bar type drive shaft or companion flange plus Cardan shaft must
be used.
This is to isolate the jet unit from possible high engine inertia forces associated with extreme
manoeuvres or groundings.
Due to certain engine components fouling on the jet unit intake, the 454 Chev Mercruiser engine cannot be
mated to the HJ212 jet unit using a Centaflex coupling.
C.W.F Hamilton & Co Ltd recommend the use of a H-bar type coupling in preference to the Centa coupling
arrangement for the 454 Chev Mercruiser engine. Refer to drawing: HJ21202004 H-Bar Drive Coupling.
The HJ 212 jet is offered with a torsionally flexible close coupling arrangement combined with an engine
mount. This option is designed to make it easy to install the driveline and engine as it avoids the need for
careful arrangement of drivelines. Refer to drawing: HJ21202005 Close Coupling Kit.
If an H-bar or longer driveline is to be used the following sections are relevant.
If a longer driveline is to be used the jet can be fitted with a companion flange, which allows a driveline to be
mounted on to the jet. Refer to drawing: HJ21202003 Couplings.
When a companion flange is used it is important to use a fixed length driveshaft with no axial plunge. Any
axial float can then be taken up on the jet mainshaft spline, which should be suitably lubricated.
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