A Rachet drive uses a reciprocating action to accumulate movement.
Uses a sawtooth like profile to wind up a spring or rotate a drum.
Easier to picture than decribe!

Similar to an hand winch or fence wire strainer where you use a rachet
to hold the winch in position while you move the handle for the next
pull.

Also used in large circuit breakers to wind up a spring so that the
disconnect can be remotely operated by a low power device, or in
sequencing relays to save the cost of a motor.

Richard P

On 15/07/05, Gerhard Fiedler <lists@connectionbrazil.com> wrote:
> R. I. Nelson wrote:
> 
> > do You have any other energy sources available to use? compressed air for
> > example.
> 
> Not really available. I've thought about hydraulics or pneumatics, but I'd
> need to generate the pressure. May be viable; I don't know how much this
> would add to the overall cost and system complexity. Has anybody any good
> pointers to pumps (and cylinders, and ...) for such an application? I tend
> more towards hydraulics; seems smaller, quieter and easier to deal with.
> 
> 
> Richard Prosser wrote:
> 
> > Do You need this amount of speed (30 degrees 100ms) in both directions?
> 
> Yes, from a center position in both directions.
> 
> > You could use a motor or rachet drive to pull against a spring to cock
> > the system and a small solenoid to release it.
> 
> Something like that could work. It would buy me approx. a ratio of 1:4 (it
> needs to be ready to fire again after 500 ms). I'd like to avoid that
> though and be able to fire as quickly as somebody can push a button. And
> I'm shying a bit away from the mechanical complexity ... :)
> 
> What's a "rachet drive"?
> 
> Thanks,
> Gerhard
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