2nd Section: Ocean navigation: Communications, Volumes 1-36
Another reversing gear by means of the screw has been applied on a large scale to explosive engines built by the Société des Propulseurs Amovibles, systhme Ducasson (Neuilly-sur-Seine). These are small removable engines which are placed at the stern of boats used in river navigation, and are arranged in the following manner:
The driving shaft transmits the movement to a vertical shaft which transmits it by means of conical gearing to the horizontal propeller shaft, as shown on the accompanying figure.
The case E which encloses the propeller shaft can turn around the vertical axis gg, so that the screw not only propels but also steers.
As the propeller shaft can make a complete revolution in its own horizontal plane, a turn of 180° will make the vessel go astern and a turn of 90°, that is when the propeller shaft is perpendicular to the axis of the vessel, will cause the latter to turn upon itself. The direction of the vessel can be altered or reversed without reversing the engines.
This is a very neat and simple device which, naturally, can only be applied to low powers and to navigation in tranquil waters. For this reason it is very suitable for tugs or cargo boats in river navigation. The aforesaid firm also builds removable engines of this type up to 50 H. P. These engines, placed astern, leave the vessel perfectly free for loading and manoeuvering. The engines can be easily and rapidly set up or removed.
The engines are fairly light ; they weigh, everything included, about 25 kilos per horse-power. In instance a 12 H. P. engine weighs 260 kilos and consumes 4.60 litres of spirit per hour.