I can't say I know much about automated shifting systems, but the specs you
give make me think about automotive starter solenoids. Take a look at
smallblock Chevy starters. The starter engagement solenoid should produce
what you need and I'd expect to be able to pick them up from a junk yard for
a reasonably price. Though you might need to cut up the starter housing to
build some sort of mounting.

-Denny

----- Original Message ----- 
From: "Martin K" <martin-distlists@nnytech.net>
To: <piclist@mit.edu>
Sent: Friday, February 18, 2005 10:20 PM
Subject: [EE] large force solenoid


> Hi there everyone
> I'm working on an electronic shifting system for a Formula SAE car
> (motorcycle engine/tranny)
> We want to implement shifting utilizing solenoids and (of course) we're
> trying to do it on the cheap. What I need are solenoids that can travel
> about an inch and provide a force of around 10 pounds for a duty cycle
> of about 10%. I don't know where to look for such a thing, so I'm
> wondering if anyone has any ideas as far as that goes. Our electrical
> system is 12v.
>
> The other idea I was looking into was using a solenoid originally
> designed for a lower force, but feeding it a much higher initial current
> to get it moving faster, giving it more momentum for the portion of the
> stroke that would require a stronger force. This is what I'm thinking so
> far:
>
> 12v ------->D1>------------o X1 o-----))))solenoid coil))))-- GND
>      |
>                       |--|C1|---GND
>      |
> 12v->n*12v converter--
>
> X1 is a contactor, C1 is a capacitor bank (20mF or so)
>
> Part 3 is a question as to what would be required to design and build a
> solenoid that could do everything we need. I sold my physics book so I
> haven't had a chance to refresh myself on the physics of solenoids yet.
>
> Thanks for any ideas everyone.
>
>
> -- 
> Martin K
> http://wwia.org/sgroup/biofuel/
> -- 
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