250 LbsRe: How Big Is The Disc

"Bob La Londe"  wrote in message news:101vgi6$2f05q$1@dont-email.me...
I might still want a jib crane in the shop...
Anyway, what diameter is the disc on a fifth wheel trailer?  Not the
horseshoe int he back of the truck.  The disc that slides into it.  The
fifth wheel I'll need to move a few times yet is 60 miles away, so I
can't just walk outside and measure it.
Bob La Londe
------------------------------------
The welding and fab shop I use for jobs beyond my equipment's capacity has their jib crane outdoors, beside the overhead door where it can load trucks.
If I had much heavy lifting and moving to do on a hard level surface I'd pick a height-adjustable rolling gantry, low for indoors and high to load trucks. The tripod-supported gantry I built for offroad can be adapted to rolling on asphalt with temporary inverted T wood uprights and diagonal braces. It can have wheeled trailer jacks mounted at their proper height up on the diagonals as retractable casters.
Tripod end supports have some advantages like being free standing so the beam ends can be winched up. I don't think they would be stable enough on wheels, unless braced to the beam which changes the leg loading from axial to cantilevered and increases their necessary weight.
I have an electric hoist but prefer the fine height control of a manual chainfall. It can support enough of a 2000 Lb load to push it into position by hand. An engine load leveler can be used as a sling spreader.
https://www.harborfreight.com/2-ton-capacity-load-leveler-60659.html?
As I understand it, this is erected by assembling it flat and then pulling the feet in with the hoist to raise one end at a time.
https://us.reidlifting.com/porta-gantry
When I had to set up my gantry in an awkward cramped space I lifted the beam onto sawhorses with the platform stacker, then to stepladder height on cribbing etc on the platform. Another way is to place a folding A frame ladder crosswise at the beam center and set short planks across the first rungs down, them slide and balance the beam onto the planks. After connecting the ends, remove the planks and lift the ladder over the beam. Since mine is made from back to back channels I have to lift only 1/2 the weight for 8' or 1/4 for 16' beam length. A one-piece beam would be better structurally  if you can handle and store it. The channels nest together and take up very little floor space standing on end in a corner of a shed.