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.

The best way to mount something like this would be to put a heavy steel channel
strongback on top of the joists above the track to spread out the load. Secure
the hoist track to the strongback with long bolts through the thickness of the
ceiling to avoid weakening the joists by drilling holes in the highly stressed
lower edges. With the load spread over several joists overloading should not be
a problem. What is the total span of the joists and are they the bottom chords
of a truss roof?.