I agree with Lou that dyeing might be a use for it. However, if it was used for that, wouldn’t there be more color on the bottom of the object? The skein winder in the back of the truck might be a clue, but do we know if the two objects are related?
From the look of the frame, it appears to me that the entire object was meant to be set in a tub or vat of some kind. There are two processes besides dyeing that come to mind:
One: it could hold a basket of raw olives between the platforms, and the unit could then be lowered into a lye bath. Table olives are processed in lye to remove the bitterness. And the crank mechanism could raise and lower the olives without the operator getting their hands in the caustic lye bath. Also, the crossed wooden beams could act as a gentle weight to hold the top platform against the basket to keep the olives from floating out. There might be other agricultural products that need processing in a bath, but olives are the ones I know about. Did this object come from an area where table olives were grown? You could also do a simple pH test on the residue on the bottom of the frame–Lye reads as 13 on the scale.
Two: From the pictures, it looks as if the entire frame mechanism is made of wood. There are half a dozen parts on the frame that could easily be made of metal and that would work better than the wood parts. Is this a choice of the carpenter who made the frame, or is there a reason metal could not be used? My other idea is that this frame was used to dip metal pieces in an electrolyte bath so that they could be electroplated. In this process, an electrical current is run through a conductive bath containing metals like nickel in the solution, and that anything metal in the bath would be plated in an electric-chemical process. Consequently, any of the equipment would have to be made of something other than metal. You could run a pH test on the sediment on the frame to see if it was acidic– readings lower than 7.
In searching last night, I could not find any images of objects that match what you have. So we might be working with a unique object here, and need to check all sorts of possibilities. Be aware of any smells or surface coatings on the object–those might give you some clues–they might also be poisonous, so I would encourage anyone handling the object to be cautious until you know for sure.
This is a great mystery–thank you for sharing.