Marine Surveyors Lexicon

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Cycloidal Drive (VSP)


About 75 years ago this ship's propulsion system, the only one of its kind in the world, was developed by Voith from an idea by the Austrian engineer Ernst Schneider. It allows thrust of any magnitude to be generated in any direction quickly, precisely and in a continuously variable manner. It combines propulsion and steering in a single unit.

This solution is as convincing as it is straightforward: on the Voith-Schneider propeller, a rotor casing which ends flush with the ship's bottom is fitted with a number of axially parallel blades and rotates about a vertical axis.

To generate thrust, each of the propeller blades performs an oscillating motion about its own axis (similar to the motion of the tail fin of a fish). This is superimposed on the uniform rotary motion. Blade excursion determines the amount of thrust, while the phase angle of between 0° and 360° determines its direction. As a result, the same amount of thrust can be generated in any direction, making this the ideal variable-pitch propeller. Both variables - the magnitude and the direction of thrust - are controlled by a mechanical kinematic transmission.

More detail here.