I have had to move some heavy things that were in an awkward place. I had built some big shelf units to hold 36 banker’s boxes of paper each, to store 72 boxes in an outbuilding. Each weighed well over 1000 pounds. I put 2-inch (50mm)-wide aluminum extrusions on the floor to make smooth tracks, and teflon pads on the bottom of the shelves, thinking I’d be able to move them out of the way so I could get to other things in the building. But the scheme didn’t work. The floor didn’t stay quite flat, and after sitting in one place for a long time the pads didn’t slide on the aluminum, so I couldn’t move the shelves. I tried to lift the shelves to put some rollers under them, but the limited space around them made it very difficult to use levers and wedges, and there was only a quarter inch (6mm) gap under them, at most. I tried clamping a wooden bar to the side of the shelves and lifting that with a hydraulic jack, but the huge weight just caused the clamps to slip and tear into the plywood of the shelf units while I pumped the jack.
So I was stuck for a while. But then I got an idea.
I took a large ziplock plastic baggie, which is thin enough to slip under the shelves into the gap between the bottom plywood sheet and the floor. I stuck a thin plastic tube into it, by pushing a sharp pointed awl from the inside of the open bag out through one far corner, sticking the plastic tube onto the awl, and withdrawing the awl and tube so that the tube ended up entering the baggie through a tight stretched inverted hole in the corner. I added some ordinary tape to hold the tube in place, and zipped the baggie shut. I slid the baggie completely under the shelf unit, inside the small gap, and inflated it with compressed air. Because of the large area of the bag, it does not take much pressure to generate a lot of force, and the shelf unit lifted easily. I had to experiment with how high to go, because the bag will come unzipped or burst if you go too far, and everything drops suddenly. But it was easy to slip wedges and blocks under the shelf, carefully keeping fingers away from the danger area, and lift the shelves bit by bit, inserting spacers like magazines to keep the baggie thin as needed.
There are enormous baggies available, intended for storing blankets etc.
Once I had a little working space, like 10 or 20mm, I tried another scheme, using beach balls. I connected four beach balls to thin tubes using ball inflator tips, and put little valves on the tubes so I could control them separately. With one ball underneath near each corner, it was easy to raise the shelf unit far enough to get big blocks underneath in one step, but there is a new problem–the shelf unit is free to move from side to side when on the balls, so everything is unstable. It works better to just lift one side at a time, blocking up the sides alternately, so the heavy shelf can’t roll around.
It’s tempting to use the beachballs instead of rollers for the normal moving of the shelves, but I’d need some good way to control the motion. Also, the tubes get in the way–if a ball rolls over the inflation needle and tube, something is likely to break.
Another time, I needed to bend a heavy board away from the wall (in a corner of a room) briefly while I passed a Cat-5 network wire through the gap, and I used the baggie-with-air trick again.