It is patented, so I am not sure of the legalities, but a piston with freon 
in it that is heated by a PTC generates great force.

----- Original Message ----- 
From: "Roland" <jemelectric@mweb.co.za>
To: "Microcontroller discussion list - Public." <piclist@mit.edu>
Sent: Thursday, February 17, 2005 3:20 AM
Subject: Re: [EE] large force solenoid


> At 08:30 PM 19/02/05 +1300, you wrote:
>>> 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.
>>
>
> cheap solenoids with some omph and decent travel can be found on most
> starter motors, used to pull the bendix in.
>
> Otherwise scrounge for a truck auto-selector/shifter. I got a few from the
> scrapyard the other day;
> - Eaton Fuller
> - both axis driven by servo motors with a 50mm travel ball-screw drive
> - both axis linked to rotary pots for position feedback (travel is an arc)
> - 24V but still powerful at 12V
>
>
> Regards
> Roland Jollivet
>
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