This is a Hydraulic Rudder Propeller, which is for well mounting.
The hydraulic motor is inside the lower bulb housing, and is directly connected to the propeller shaft.
These are made of steel, and are fairly simple build, no driving gears sets and only a few bearings inside, for easy repair and very little maintenance.
All pipes etc. are inside the thruster and are not in contact with the water.
The bulb is the heart of the thruster and is simple to dismantle from the thruster.
Steering is 180 degrees, done by a hydraulic cylinder inside the top of the frame.
Because the propeller is hydraulic powered, we also have forward and reverse, so also covering the 360 degrees steering.