Re: Furler motor to gearbox sm2000


Matt & Michelle Day, SM#208 SV Talia
 

When I pulled the outhaul motor and gearbox off of Talia back in Feb (before I pitched myself from the mizzen mast), the shaft was sheared before the first shaft step behind the keyway.  You can see the stress rings on the shear plane of the shaft.  They start at a single point.  I could not tell if it was corrosion, or an inclusion without polishing.  However, an inclusion on the surface of the shaft would be very odd.  I still have the motor and shaft, and will pass along a few pictures when I can get back to the boat in June.  I will see if I can polish the shear surface as well for fun.

Not sure I buy the wear on the gear teeth and side loading with a bonze tooth gearbox.  I fully expected to see wear on the teeth, following BWs book.  There was little to no wear presence and the tooth convolutes were clean and mirror like when washed down. 

I also can't reason AMEL designing a drivetrain where the gearbox is the failure mechanism .  No self respecting Mech Eng would do that.  Your coupling/keyway should fail first, followed by your easily changed electric motor.  I think AMEL has done a fine job designing this geartrain, and Gary did a great maintaining the boat prior to my owning it.  But, on this specific boat the motor shaft red herring failed.   

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