welding c channel for gantry type engine crane

huangyhg

welding c channel for gantry type engine crane
greetings,
i wish to construct a "gantry" (if that is the proper word) type of engine hoist system with beam trolleys. i wish to have the two main "beams" span the width of the garage 17 ft. the center beam that will travel will be 8 ft long.
question is, due to several factors, "i" beam for the 17 ft spans is probably not possible. i have access to some c channel of various sizes, but not 17 feet. i wish to weld two pieces on each side to make up the i beam. joints will be staggered at least 4 feet apart. maximum load will be 1000# but realistically 600 - 700# and load will never be suspended for more than 30 minutes. i have seen several engine shops with similar systems , but wish to ask the ones in the know.
regards,
fireguy

you don't give the depth of the channel, so it might or might not work without excessive deflection.  if channel is greater than about 6 inches deep, will probably work but you should run the numbers on it to limit the deflections under load to something reasonable.  welding is not the big issue here.  try to get as close to a complete penetration butt weld as you can for your splices.  offsetting the splice locations must be done.
thanks for the reply ron,
i didnt mention the size, as i wasnt sure exactly what was the smallest i could use and still be safe re deflection etc.
i was planning on the 6" though. headroom is at a premium and every inch is important. are there differences in shape of the flange for c channel? most of the c channel i have seen has a fairly pronounced bevel when compared to "i" beams. curious if there will be any issues with a beam trolley.
regards for all your help,
my field is thermal validation, but my passion is the old brit cars.
ken
some trolleys can accomodate both uniform thickness flanges and tapered flanges and some are specificly designed for one or the other.  dayton and cm both make good beam trolleys.
to save head room you can get the wheel diameter of the trolleys you're going to use and put the upper portion of the channels inside the ceiling.  depending on how you support the beams from the trolleys you can cope (remove) the top flange of your channels for a couple of inches at the end of the beam, drill a hole with a min of ~3/4" edge clearance, and suspend the beam from that hole to save a couple of inches.