On Mon, 19 May 2008 13:29:47 -0500, Bill wrote:

The old man wants to put a 'dumbwaiter' into the barn so he can get
'stuff' up to the second story easier, he's getting old (79) and walking up
stairs is getting harder so I've been kicking plans around and want to see
if anyone could help with a detail I haven't worked out yet.

What, you have a barn with *stairs*? What kind of decadent luxury is
that? My barn has (very old, highly worn) 2x4s nailed to the studs,
serving as a ladder. When you get to the top, there really isn't much
to grab onto for the last step.

I'd like to
make it that the 'dumbwaiter' gets locked in place when on the second
floor, was thinking of something like pawls on the guide tracks that the
carriage would click by so if the 'dumbwaiters' hydraulics would fail then
there would be no way for it to fall. This way if you are loading a couple
of hundred pounds on it it can't suddenly drop taking your arms, legs or
feet with it, although since I'm planning on hydraulics it would take a
really big failure of the cylinder to get that fast a drop. What I'd like
to do is make it that the 'dumbwaiter' would have to be raised a few inches
before going down to disengage the pawls but I'm not sure how to go about
designing it to do this. I could do it with a solenoid but I think that
adds another failure point and would rather have it be all mechanical in
nature. I'm not worried about a failure while ascending or decending since
the failure mode would be a slow descent as the fluids bleed out, so I
don't need pawls all the way up the guide rails just at the 2nd floor.
Anyone ever seen something like this and could point me in the right
direction??

I'm planning a similar application to get items up to the upper story
of my garage (there's a deck there). I'm going to use a hoist, as
others suggested, and want the "carriage" to remain up top normally,
so as to fill the hole. I plan on manually inserting pins through the
deck's floor joists into matching holes in the lower carriage. It
won't be really convenient, but the dumbwaiter will see only
occasional use.

My bigger issue is what to use to guide the carriage, so it won't
swing or twist during its transit. One guy (whose name actually is
Guy) suggested rails & rollers for a garage door, but I found a linear
slide on a piece of scrapped equipment that has a rail long enough to
work, so that's what I'm contemplating using. It's pretty hefty,
though, and we wonder about its appearance. It also weighs a couple
hundred pounds or more.

[snip]

Joe