Many years ago there was/maybe a trial in the US using 4 xH34 to lift aN " X" shaped rig which carried a load slung from the centre.Don`t know how successful it was ,but on the basis that no-one does it ,probably in the "too difficult/dangerous" category, especially for single-engined helos.
CH-47 can probably lift about 28000 lbs if the crew leave all the flak jackets and lunch-boxes behind!
It is also possible to lift a greater weight than from a hover by having your load on a flat-bed moving along at 20-30 mph,ie above trans.lift speed, if you were going to load it on a ship steaming along,otherwise you have to have another flat-bed at your destination-could be tricky!!
