Abstract: A double reverse revolution propeller apparatus includes front and rear propeller wherein the rear propeller is rotated at higher speeds than the front propeller. When seizure occurs, an inner shaft is disconnected from an engine at an inner shaft connection unit and is connected to an outer shaft at an inner and outer shaft connection unit to be driven in the same direction as the outer shaft. The ratio of absorption horsepower of the front propeller to the rear propeller can to be substantially equal to the ratio of rotational speed of the front propeller to that of the rear propeller. One or both of the front and rear propeller can include a variable pitch propeller. The front propeller can have more blades than the rear propeller.

Abstract: A stern tube bearing system of contra-rotating propeller includes an inner shaft having a rear propeller and an outer shaft having a front propeller, both shafts being rotated in opposite directions. A shaft center portion of the inner shaft is made hollow, a plurality of oil supply holes are bores radially in the inner shaft so as to pass therethrough perpendicularly to the outer peripheral surface thereof, and a plurality of rows of these oil supply holes are arranged in the longitudinal direction of the inner shaft, whereby seizing of the bearing owing to offset contact at its rear end caused by the propeller being overhung can be prevented.

Abstract: An axial plunger pump or motor of the type such that a valve plate having a suction port and a discharge port drilled therein is fixed to a casing in which a rotary shaft is mounted. A cylinder block having one end surface opposed to the valve plate is coupled to the rotary shaft. A plurality of bores whose one ends can be communicated with the suction port and the discharge port are drilled in the cylinder block in parallel to the rotary shaft. A plurality of plungers, which can reciprocate within the respective bores in accordance with rotation of the rotary shaft are slidably fitted in the bores on the side of the other ends. A seal plate positioned between the valve plate and the cylinder block and making slide contact with the valve plate is coupled to the rotary shaft.