12v DC motor question

[jdc]

Thanks for the suggestion, a good idea except that there are no markings at all on the motor and the SHOWA corporation do not seem to sell spares for these. New motors come in around £400 but may take several months to land.

DC electric motors are one of the relatively few industrial products made in numbers counted in tens of billions per year, and typical costs are a few $, less than $10, unless you are after special magnets etc, so £400 is an utter rip-off. Some questions it might be worth getting answers to:

1. is it a motor only or motor + gearbox assembly?
2. what is the unloaded shaft speed (rpm)?
3. Roughly how many amps does it draw when running in the application?

With this information and with a dimensioned drawing you can very probably find a new one for more like ~£10. Mechanical designers look in standard catalogues for motors so in all probability your one is quite commonplace, if only you could find it! Maybe worth a quick look on ebay (search for '12V DC electric motor').

 

[C08]

Thanks for all the ideas and suggestions. In all I feel I now have a better understanding about how Dc motors work and things to look into.

This was the outcome. The problem turned out to be an over crimped ring connector on one of the motor leads where it bolted to the solenoid. When I first had the problem I checked for continuity from the ring connector down to the brushes and that was ok. Having checked out brushes, armature resistance, any insulation breakdown to earth etc I still could see nothing wrong so I started wiggling things about whilst checking continuity which is when I discovered there was a problem within the wire. The outer plastic cover of the wire (looks like 15A wire) was fine but the copper inside was burnt and corroded. I suppose the three quarter severed wire got over heated and burnt out helped by a bit of corrosion. It was clear that some wires had been cut at the crimping stage and the few remaining strands had burnt out.
Having had the tilt unit apart and re-assembled it several times I feel happy that I now know how to get the thing off quickly if I need to, I have repainted some flaking paint with etch primer and spray (at about £1k for a new unit it is worth looking after) , I have become familiar with the manual/auto bypass screw that needs to be released to manually operate the leg. All in all pleased that I now understand part of the boat which previously was pretty much unknown to me.
The motor I spent so long fiddling about with is pretty small for almost £400 for a new one. There are lots of pattern motors for sale mainly in the US but it is very hard to match my motor up with what is easily obtainable. I will keep looking and try and pick up a cheap spare motor-looking at user and group forums Tilt and Trim units are clearly less reliable than the rest of outboard motors.
Thanks again.