If the casters were spaced more than 8 ft inside to inside, then they could straddle the truck bed, and a cross- beam could rest on the bed and support the a-frame. That, however, would constitute a 'wide load', and you'd need to make special arrangements to move the truck, etc.
That idea could work if you were exclusively using trucks with skeletal payload areas, e.g. timber haulers, instead of flatbeds, or if the flatbeds had big holes for the casters to drop into. E.g., you'd need control of the trailer fleet, which you probably don't have.
Let's assume that whatever mechanism you use to fold the casters will drop into a vertical position when the a-frame is supported by a crane. That in itself requires careful attention to working clearances and friction in a hostile environment, but let's assume it can be made to happen.
From there, I can imagine a set of small 'pilot casters' that hang below the big ones, and as the assembly is dropped onto a platform, run out laterally beyond a trailer's width and somehow cause the big casters to be engaged in rigid fashion under the a-frame. If lowered onto a trailer bed, said pilot casters would fall of the edges, and somehow cause the big casters to swing into a non- supporting position. Then, as the load is lowered onto the static stops, the pilot casters are somehow swung back inboard, so they don't project beyond the edges of the trailer.
Now, I have a problem; an eidetic mind. I can envision things that never were, and things that can't possibly work anyway, so you'd have to screw around with mechanisms for a while to _maybe_ come up with something that could meet that spec.
But I wouldn't bother, because I'm assuming that this mechanism has to be trusted by, and therefore understood at a glance by, stonecutters. I'm sure there are many fine mechanism designers hidden within the stonecutter community, but I can't imagine it being a job prerequisite, so it's a skill that's likely unexercised there.
I.e., if your assembly has moving parts, they have to be, pardon the expression, as simple as a stone.
So I'm thinking the casters could be attached to 'elephant feet', short pieces of fat square steel tube, that slide easily over some slightly longer, smaller, pieces of tube projecting vertically downward from the a-frame. Put some vertical slots in the elephant feet, and a sturdy cross- pin to keep them from falling off entirely.
Got the picture? As the assembly hangs from the crane, the feet with casters hang straight down below it. To make it suitable for ground transport, four laborers guide the smaller tubes into the larger tubes as the assembly descends, until the tubes are fully engaged with each other.
To put the assembly on the trailer, four laborers simply push the casters aside, so the elephant feet fold inward as the assembly is lowered to rest on the end of the shorter tubes. Of course, the unslotted sides of the big tubes have to be cut away near the top so the tubes can swivel and the small tube can travel right through the upper end of the big tube. The slotted faces of the big tubes just rotate around the upper end of the slot.
I'll think of something simpler after you've committed it to production. ;-)
Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA
