If you need replacement roller bearings for the output shaft of the
Autohelm 3000 belt drive unit which I believe same drive unit on several other models, here is a source:
Nordex Inc.
426 Federal Road
Brookfieldk, CT 06804
203-775-4877
Welcome to Nordex.com
info@nordex.com
item is EPSM6004 (stainless dowel pin)$1.16 each plus
shipping
The motor/drive unit uses 10 of these
Discussion:
I bought a
Dufour 31 this summer and it came with a very used
Autohelm 3000 autopilot that had never been installed on this
boat. I took it home and bench testing the unit I found the drive was frozen and would not rotate. I unscrewed the tapered back shell of the drive unit exposing the
motor and separatling it fropm the planetary drive unit. With the
motor disengaged from the planetary drive the motor responded fine to commands in both directions. I very carefully placed a drop of
oil on each motor bearing using a fine point needle oiler and I checked the motor
brushes which were fine, then set this aside for re-installation later.
I pressed out the retaining pin that holds the plastic belt drive
gear to the planetary drive output shaft and quickly found the bearing inside the belt drive
gear to be completely corroded and rusted. There are 10 short
steel roller bearings held in a plastic cage. These roller bearings run in a space inside the plastic belt gear and on a
bronze bushing that is part of the case and surrounds the planetary unit's output shaft. This bearing is the one that actually carries loads imposed on the motor/drive shaft when the drive belt is tightened to perform
steering and is very important. These roller bearings were completely rusted beyond
repair, and frozen in place.
Salt water corrosion was obvious. The plastic cage and the
bronze bushing around the planetary gear output shaft both cleaned up effortlessly, so I concluded that if I could locate replacement roller bearings I could
repair the unit. I decided to look for stainless roller pins instead of hardened
steel for better
corrosion resistance, and I eventually found these at Nordex, per the above. They fit perfectly.
After removing the plastice belt drive gear and its internal roller bearings, I opened up the planetary drive itself and carefully removed the three layers of planetary gears and spacers, laying them out in such a way that
cleaning and re-assembly would be logical and obvious. I found some minor corrosion and that the gear lube had hardened. I cleaned the housing and each part with a gentle solvent and then used a very fine emory cloth to touch up each metal shaft where there was any sign of rust or debris. The worst corrosion was found all the way at the bottom where the main output drive shaft exits the housing towards the plastic gear drive.
{Most people might want to skip the following step in which I performed a little "improvement surgery" that is likely not needed. For the adventurous, I'll describe this separately below, but it is an
experiment and I would not recommend it unless you have the experience and the right tools to do machining. I highly recommend you skip this step unless it is only way
salvage your unit, which was the case for me due to the extent of the corrosion on the case itself allowing
water to penetrate inside.}
For re-assembly, I lubed each shaft and gear and re-assembled in reverse order of my dissassembly. Once completely assembled, I lubed and installed the new roller bearings into the original plastic cage, and lubed the bronze bushing, then re-installed the plastic belt drive gear, aligned the retaining holes in the plastic gear drive and the shaft, and carefully pressed the retainer pin back into place. I re-installed the motor and screwed the tapered back of the case onto the plantetary gear unit. With this minor
overhaul the unit now responds properly in both directions to commands from the control unit.
Next I need to install the
autopilot in Dauphine for the first time. We'll see how that goes.
I hope this is helpful to anyone out there struggling with an
Autohelm motor/gear drive unit.
-----------
Ok: For those interested in the {"surgery"} mentioned above. I noticed that
water had entered the planetary gear case from the output shaft. The case around the output shaft was badly corroded, and looked like an easy source for future water with no obvious way to seal it. I could not determine any means of keeping water from entering along the shaft without modification. So I used a drill press and precision centering vice to keep everything perfectly true, and in a two step process I bored out the shaft hole in the case just enough to press fit a new bronze bushing I bought and create a larger partial
depth recess to accomodate the flange on the exterior face of the housing. I bored the smaller center hole first, all the way through, and the larger partial
depth recess from the outside. I was careful to ensure that both ends of the press fit bronze bushing sit flush with the face of the case on both the inside and outside faces. This busing is not intended to carry the shaft loads, but rather to put a small o-ring onto the output shaft between the plastic gear drive and the bronze bushing flange. There is very slight pressure on the o-ring and I expect this to prevent future water intrusion. Be very careful to ensure the end of the bushing inside the case does not extend further in than the original housing or it will pinch the planetary drive gear assemblies. The preceding will prove to have either improved the original design, or destroyed the case. Time will tell.
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