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Stromag Vector® Couplings & Composite Shaft for Ferry Propulsion System
A coupling solution was needed for a new catamaran ferry propulsion system that was
powered by twin diesel engines connected to a speed reducing gearbox which drives a remote-mounted
waterjet or thruster pod. The coupling/shaft connects the gearbox to the water jet with
a flange-to-flange span length of more than 9 feet. The gearbox is close-coupled to the engine,
with both bouncing on resilient engine mounts, so the gearbox output flange has several
millimeters of radial and axial movement under normal operation from vibration and sway of
the engines when the hull moves on the waves.
Due to the span length and weight considerations, the use of a TB Wood’s carbon fiber
composite shaft mounted between high-misalignment-capacity Stromag Vector® couplings on
both ends is an ideal choice for this application.
This solution eliminates multiple sections of heavy steel shafting and pedestal bearing
supports. Lighter-weight, spherical bearings positioned at both ends of the shaft provide
stabilization, eliminating shaft “whirl” that can occur when a shaft orbits off-axis if unsupported,
especially at long lengths. The dual Vector couplings, one mounted on the gearbox output
flange and the other connecting the waterjet input shaft, feature lower reaction forces and very
low overall torsional stiffness.
The Vector coupling represents the next logical step in the evolution of Stromag’s proven
GE rubber-fabric coupling that has become successfully established in diverse applications
worldwide. The Vector coupling provides zero backlash for shaft-to-shaft and flywheel-to-shaft
connections. The coupling’s rubber-fabric element radial arrangement within a compact design
facilitates installation and removal without the need to displace the drive units.
Highlights
- Compact flexible
coupling design
- Special rubber-fabric
elements enhance
service life
- Lightweight and easy to
install
- Accommodates large
shaft displacements in all
directions
- Carbon fiber composite
shaft