counterweight

A heavy mass of often iron or concrete, mechanically linked in opposition to a load which is to be raised and lowered, with the intent of reducing the amount of work which must be done to effect the raising and lowering. Counterweights are used, for example, in cable-hauled elevators and some kinds

• Four 110-ton counterweights, one in each tower, make this feat possible by reducing the effective weight to be lifted to some 25 tons; but an additional 20 tons (a very heavy snow load) can be lifted if necessary.
• Like other supertall towers, 432 Park relies on the counterweight system to address the forces of wind and reduce the feeling of swaying for residents.

A counterbalance.figuratively

• A counterweight to the anti-immigrant fear mongering of the former leader of the right-wing U.K. Independence Party, Nigel Farage, Lexiteers^([sic]) argued a left-wing, democratic and internationalist case for Brexit.

To fit with a counterweight.transitive

• The lifting span, which rises vertically between the towers, weighs 465 tons and is counterweighted by four 110-ton weights.
• Everything on the grid – all the backdrops and curtains, anything that has to move up and down from the fly-tower – has to be counterweighted.