ceiling truss loading

[Robert Bownes <rbownes@neworks.net>]

Anyone know anything about loading formulas & trusses? I'm thinking
about an I beam all the way across the shop ceiling with a hoist and
roller for moving large stuff across the shop. I'd either have to build
all new supports for it or support it from the existing truss system
(pretty standard types of ceiling trusses built of 2x4's every 16").
Clearly the latter is *much* easier, but I'm wondering how much load I
can actually carry up there...

iii