carl mciver wrote:

I had another one of my ideas today and it concerns needing to lift
things in my garage around my workbench and the area I usually devote to
working on engines and such. There's never enough room to set up my engine
hoist, so I have to roll everything outside or hump it by hand. I'm getting
too beat up to do all that stupid heavy lifting by myself anymore, so ideas
are welcome.
What I had in mind was to install three or so fifteen foot long barn
door tracks in the area I usually work. Suspend from them on rollers a
track (or two) that work like a bridge. Since my work area is partially
under the garage door in the up position, I need the upper tracks to be in
and out of the area, and parallel to the door track. The bridge has to be
lower than the door and track, simply because the frame that holds up the
end of the track is in the way. I'd have to have a rigid drop frame with
the upper rollers to allow the bridge to clear the garage door track.
The door tracks are available in several load ratings. The highest I
can ever see lifting is about five hundred pounds, but most likely in the
order of three fifty or so. The engines I usually work on are about that
much. If I had a double track bridge would I be able to safely double the
load rating of a single rail? I have in mind a foot or so spread between
the bridge tracks that would allow me to raise the hoist point above them to
keep the working height to a maximum. I figure the rails will be spreading
out the load between multiple beams to keep local stresses down.

The other thing to consider is the load carrying ability of my garage
ceiling. It's 2x6's on 24" centers, with 5/8" sheet rock below and
strandboard above for creating floor storage space. I could put some
plywood webs between the roof joists and the ceiling beams to give me a
little more beef, but I'm having a hard time guesstimating what will be safe
and what will be asking for trouble. My work area is one corner of the
garage, so I won't be picking things up out in the middle of the span. That
space is currently occupied by the garage door opener and screw track, which
is a point I can't cross with a device like this anyway.

Do not under any circumstances try to hang any significant load from the
bottom chord of a truss roof. Truss roofs can only support loads on the
top chords, the bottoms are limited to sheetrock and light fixtures.

If you have a truss roof an independently supported beam will be
required. This beam can be located above the bottom chord of the
trusses as long as there is sufficient clearance given so that no load
can be exerted on the truss due to beam deflection. This will allow the
crane track to be flush against the ceiling and supported by the beam
above. The truss can be used to provide lateral support for the beam as
long as the connections used insure that no vertical loads are placed on
the truss.

If it is not a truss roof and they are "real" 2x6 joists at 24" centers
then you *may* be able to get away with distributing the load across
multiple joists by placing a suitably sized beam across the joists and
anchoring your door track to that beam.

Consult an appropriate architectural engineering reference for the beam
sizing and load limits for a 2x6 24" oc structure.

You also can not place multiples of the 500# door hangers close
together, the door track is not designed for that loading. If you can
lift what you need from a single 500# hanger then it can work.

A company called Spanco (http://www.spanco.com/) produces a gantry
system that is very similar to the barn door tracks. If you need to lift
more than the 500# that the door system is rated for I recommend using
the Spanco products. If a 500# limitation is ok I don't see any reason
why you couldn't use the door tracks within the parameters they are
engineered for.

Pete C.