That is an interesting point I had not considered. You want the
pneumatic system not to begin operating until the latch has released,
otherwise it will put strain on the latch and frame, possibly preventing
the latch from opening smoothly. That shouldn't be too difficult to
arrange. A simple microswitch attached to the latch wired in parallel
with a microswitch on the door frame should do the trick. That way the
latch can be allowed to power down while the door opens, avoiding
battery drain; currently it stays on throughout the raising cycle. Then
the pneumatic system won't begin operating until the latch has released
and would continue to operate when the latch was off but the door was
open as sensed by a door frame switch. I'll have to give some thought
to this, because it could be wired so the door opens with a momentary
contact. A second momtary contact could be arranged to stop the door
before it is fully open and then a third to begin its closure unless it
has already reached its highest point at which time only a second
momentary contact would be needed to initiate closure. Just like a
garage door. The reverse sequence would occur on the down stroke with
the latch opening just before the door closes and the latch closing
after the odor is closed or the D-ring is in place. The latter option
would permit not only a "door ajar" warning, but also a "latch ajar"
warning. This could be done with simple relays or with a little
off-the-shelf microcontroller.
George Schiro
Michael Mitchell wrote:
>
> I assume that since you need the solenoid that you are running air doors
> (if you are still using hydraulics, you can remove the latch -- the
> pressures involved with the hydraulic system will keep the door shut. Be
> careful that you don't remove both screws at the same time, though, and
> accidentally lose the bottom plate the latch attaches to into the
> frame). Although I am not using them, I understand that Terry Tanner has
> been working on or has available air actuated door locks. They don't put
> a burden on the electrical system, and are designed to release before
> enough pressure has built up to raise the door. This eliminates the
> bending of the door that occurs when the lock gets stuck and pressure is
> applied to the door.
>
|