Tony Tissot wrote on Fri, 22 June 2007 22:10 |
Any suggestions for a lighter duty, semipermanent set of hoists for a load of no more than 300 lbs (I'll probably spec 1/2 ton).?
I am well familiar with the "real stuff" (CM lodestars) - and counterweight fly systems. Wonder if there are any other budget strategies for a 2-point load, 20 feet (cheap tri truss - or batten) that does not cost so much, or require installation of a real line set.
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Hi Tony;
Let's try this again.
You began by speaking of two points.
I was envisioning two sheaves, one at the top of each pick point.
Possibly these would be suspended from welded link chain, or aircraft cable, wrapped over your overhead beams.
You could run aircraft cable from an attachment point on your truss or pipe, up, through one of your overhead sheaves, across to a sidewall, through another sheave serving as a head block, turn 180 degrees with a thimble and Crosby, back up through a second headblock sheave, across to your second overhead sheave and back down to an attachment point on your truss or pipe.
One piece of aircraft cable with both ends terminating at your truss or pipe and a 180 degree turnaround near it's mid point.
When the truss is in, the 180 degree turnaround is just below your headblock.
When the truss is out, the 180 degree turnaround is approximately head height and secured to a point on the wall.
A padlock could be added to keep helpful fingers from grunting the turnaround off of it's point.
When you arrive, you could use either a small CM Lodestar, or a set of chain falls anchored to a lower point to pull the 180 degree point down off it's head height tie-off point and then to raise the point and lower your truss.
The CM or chain falls would remain near floor level paying out chain upwards as your truss comes in.
When your truss is back up to trim, you'd secure the 180 degree point back to the wall and take your CM / chain falls away with you.
This would mean working with your truss at the same high trim all the time and having two points on a wall; one to secure your truss when out and a second, lower, to anchor your CM / chainfalls. On the wall, you could add a safety from your upper load bearing point to your lower rigging point as additional security when you're not on site.
Just an economical thought bearing in mind that I can't see your space from here and have no idea if you have a suitable wall, or vertical steel column, anywhere near convenient.
Toodleoo!
Ron Hebbard