bow thruster ervice


Giovanni TESTA
 

To all,
first thanks a lot to all for help and suggestions .
Short story :
After a terrible Screech, Screech noise I explored the bottom of the motor where there is the connection with the black plastic column of the feet.
So, with the support of Photo section " Bow thruster service " I discovered that the bearing was broken.
This my experience to fix it.
- Remove the motor from steel and electric cables.
It is very heavy, so it is better to work on a table.
- remove the 2 circular clips
- remove the 4 studs
- separate now the lower part of the motor.
With the old broken bearing in position it is not so easy.
You may lever up with a screwdriver. At the end it works but, opening motor box, the all shaft, that is the rotor, may slide out. The rotor has 2 bearing : one on the top, the second at the bottom , that one broken.
-now you have 2 parts, the cylindrical black box ( stator) and the shaft ( rotor). More a little and thin circular spring that is positioned between the top bearing and its housing.
- remove the steel ogive on the top motor ( that one with the cable steel connection) and the "golden" cover ( 4 screws)
-remove all the 8 brushes. NOTE : you must mark them about their location and position.
- remove the hold broken bearing, part from shaft and part from housing.
Without extractor it was possible with gentle hammer and screw driver. Five hours of tough work.
- The bearings have n.6204V . All the bearings with this number , made by different makers ( NSK, Skf, ecc) , have identical features.
http://cgi.ebay.com/ebaymotors/New-NSK-C-Series-Bearing-Part-Number-6204VV-/290540406001#ht_500wt_1107
To reassemble the motor :
- with a soft sand paper clean the rotor copper part from the carbon deposit. Take care of cleaning very well the thin ditches .
- insert the rotor with the stator upside-down. But before, remember, insert the thin circular spring. Push and knock gently with an hammer all around to help the bearing entering into its housing. This is very critical. The bearing must enter soft and completely, less ,may be, 1 or 2 mm, that is the spring thickness, more or less.
- the 8 brushes must return in their identical location and position.
- close the upper part with the golden cover ( 4 screws)
- insert the new bearing into the bottom housing and its large circular clip.
- close the motor fitting in the lower housing part with the 4 screws
- insert the narrow circular clip around the shaft
End of the story
I'll try to post photos of broken bearing, new bearing and circular clips, label with motor characteristic.
Sorry,I forgot to take others photo in the concern of the moment.
Any way I stay stand by for any request.
Gianni TESTA
EUTIKIA SM n 428

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