For detailed assembly instructions see Remotion drawing nr.: 123337 

The Center Assembly module serves as a bulkhead between the gear & output shaft and the motor & brake compartments, dividing the lubricated mechanical parts from the dry running electronics.  
 
On the gear side the wave generator of the strain wave gear is mounted onto the split shaft. 

On the electronics side the subsea connector is mounted on with the internal wirings routed towards the motor, the brake and the water sensor functions.