contragreuti

Contragreuti, or counterweights, are masses positioned in mechanical systems to balance forces and control motion. By providing a force equal to part of the load due to gravity, they reduce the motor torque required to lift or move a load, help stabilize movement, and improve safety and efficiency. The effectiveness depends on the weight, its placement relative to a pivot or guide, and the dynamic characteristics of the load.

Common applications include elevators, cranes, hoists, and other lifting devices where large loads must be moved smoothly. In a crane, a counterweight on the opposite side of the pivot offsets the weight of the load, allowing the crane's hoist motor to operate with lower peak demands. In elevators, counterweights balance the car, reducing energy consumption and wear.

Counterweights also appear in machines with rotating parts to balance inertia and reduce vibrations. In clocks and timing devices, weights can drive trains or serve a balancing function, depending on design. There are static counterweights, composed of fixed masses, and active or adjustable counterweights, using hydraulic, pneumatic, or motorized systems to change the balance as needed.

Design considerations include selecting appropriate mass, determining the leverage arm, ensuring the weight remains fixed or safely adjustable, and accounting for safety factors and maintenance access. Proper installation reduces stress on supports and prevents accidental displacement.