Re: RE>Garage Door Openers

[Pat Donahue <pdonahue@xxxxxxxxx>]

Harvey gives us this tip:
> 
> If you are contemplating the chain drive design - check the following:
> 
> With the door closed, try and pull it open by hand as if you were trying to
> break in.
> 
> Last time I check this out, I was able to lift the door some amount and in
> so doing, the chain linkage transmitted the movement to the motor and sense
> switches.  The Sense switches "said" the door is supposed to be closed, but
> it isn't, so the motor turned on to drive the door closed.  Problem is, by
> holding on to the door with the motor trying to drive it closed, the sense
> switches then said  " door closing - oops, hit an obstruction, enable safety
> override and (depending upon design) stop motor in place or reverse and open
> door to release/reverse obstruction from being pinned by closing door.
> 
> As you can see, that then enables someone access to your garage (and house?)
> simply by pulling up on the door.

Wow.  Who made _that_ piece of shit?  I've always had the old Sears
garage door openers.  They're chain driven too.  Once they've stopped
the power to the sensors is shut down so even if your chain is poorly
adjusted and you manage to lift the door all 8 feet it won't try to
close it.

While we're on the topic of garage door openers I've seen a really nice
one that starts normal, accelerates through the middle of the travel,
and then decelerates smoothly at the end to get the door moved in half
the normal time.  I just wish I could remember who made it.
- -- 
Pat Donahue  CCA 125031
Vienna, VA
'91 M5 4GTFUL
need '87 or '88 325is 5 sp.!

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