Electric start on Stuart-Turner genny

It seems a bit quiet on the forums, so I thought I would pitch this one in.
I have a bad shoulder so cranking my ST genny can hurt or be
impossible - and I would like to put it in a shed where space is limited anyway, but in there I can plumb in the exhaust and keep it comfy. So I wondered about setting up an electric start using an old car starter motor to get it going.
Anyone done anything like this ? The cranking pulley is only about 4 inches and round section, the flywheel is between the engine and generator so hard to modify. I am not looking for an automatic start, just a chance to tease the choke while an electric motor does the hard work. I am wondering if I can set something up with belts and a layshaft, but I am not sure on what gearing ratio I would need. I have a big washing machine pulley lying around.
Steve
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I would be thinking in terms of a hinged motor with a rubber tyre with a lever to press it against a pully or flywheel.
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Two minds etc - I've rescued a hefty 12 volt motor with just this in mind. Bolted to its own cheap Chinese sack truck, the motor is fitted with a rubber tyred wheel. Solid would be best. Apply the tyre to the flywheel rim & push, thumbing the switch as you do so.
Brrrm!
regards,
Kim Siddorn
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On Sat, 23 Feb 2008 16:03:15 -0800 (PST), Steve
chips and mushy peas. Wiping their mouths, they swiggged the last of their cup of tea, paid the bill and wrote::

Of course, the alternative is to do what Stuart Turner themselves did and acquire (if that's still possible) a dynastart unit - starter and dynamo in one casing. S-T belted this up to the flywheel, so no modifications to the engine apart from bracketry - all you'd need to do then is to remember to switch the unit from "START" to "RUN" to charge your starter battery up again once the engine had started. If you could find a genuine S-T switch panel to do this with, so much the better!
Brian L Dominic
Web Site: http://www.brianscanalpages.co.uk
Newsgroup readers should note that the reply-to address is NOT read: To email me, please send to brian(dot)dominic(at)tiscali(dot)co(dot)uk
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Many of the low voltage Stuart lighting sets have a self start facility.If yours is a genuine Stuart set look on the control box for a large black knob with the word "start "underneath.When correctly wired up this motors the dynamo over to start engine. If you go the Dynasart route Wiring diagram on link below http://www.hodgm.pwp.blueyonder.co.uk/3c.html
Mike.H.

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Thanks for your input guys.
The Stuart (P5) has a 1.5 KVA main generator - so I don't think the generator can be used as a self-starter (though I am no expert on electrical gubbins).
As for the idea of using a rubber wheel friction drive against the flywheel, that had not occurred to me, excellent idea. I have a couple of Land Rover starter motors, so plenty of grunt.
Any ideas what ratio I should be looking for between wheel and flywheel diameter ? Presumably not the same as when cranking a 4- cylinder diesel ?
Steve
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I would go for exactly the same or possibly rotate the engine a little faster since the motor should cope easily. The trick is to design the tyre to flywheel contact so they are pulled together when the motor's in use but get pushed apart when the engine fires. It's difficult to describe but don't aim for the wheel to swing straight onto the flywheel but to meet it at a narrow angle. Hope you understand what I mean cos my description is terrible.
John
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John,
You appear to be describing that it comes in at a tangent to the flywheel so that the wheel is between the fixed point and the lever.
Martin P

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Think I understand you John, the action of the starter motor must drive the wheel in to firmer contact. Once the engine fires and it is no longer driven the action is reversed, I suppose a mechanical lever can bring it into and out of contact in the first place.
Is the speed of a starter motor determined by the voltage, or do they go faster and faster the less load they have ? I bought a book on re- using electrical motors in the workshop and for reasons I don't understand the author completely overlooked car starter motors - this is quite annoying as I have several and was wondering what use they might be.
Steve
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You seem to have got what I mean. Martin also put it quite well. A car starter moter is only rated for short use so isn't much use elsewhere. The speed is more or less fixed though they do rattle over quicker if you increase the voltage. They also go faster if there's less load but they seem to be capable of that in my experience. Almost any car starter motor should do for what you're proposing if it's geared right. Even that's not too critical.
John
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Starter motors do have a short rating but are powerful beasts. I had a B16 Volvo once & when I uprated it to 12 Volts, the old 6 Volt starter used to really fly round! I had a 12 volt version ready to fit, but never needed to in the next 18 months of ownership & its easy starting was a definite plus.
They will take a lot of abuse & whilst I've seen both solenoids and ring gears fail, I've never actually seen a knackered starter motor.
I'd not worry too much about the ratio, it'll spin round a lot faster than you could crank it by hand even at 1:1.
--

regards,

Kim Siddorn
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