Counterweight

A counterweight is an equivalent counterbalancing weight that balances a load.

A counterweight is often used in traction lifts (elevators), cranes and funfair rides. In these applications, the expected load multiplied by the distance that load will be spaced from the central support (called the "tipping point") must be equal to the counterweight's mass times its distance from the tipping point in order to prevent over-balancing either side. This distance times mass is called the load moment.

Read more about Counterweight:  Counterweights in Action