The rotational speed of high speed single axle electromotor must be reduced when driving the contra rotating propeller

and then a reducer which is suitable for underwater vehicles is designed.The construction principle and characteristics of the gear reducer is analyzed.Analysis results of motorial and dynamic characteristic of the gear reducer show that this kind of gear reducer can balance reaction torque itself

which can reduce the pressure of vehicle roll control system.Also through analysing the characteristics of electromotor and battery which has influence on the gear reducer

several key aspects in designing such kind of reducer is concluded.An example is given at last

ant provided strong evidence for the application in underwater vehicles of this kind of gear reducer.