Ellensúly

Ellensúly, or counterweight, is a weight used to counterbalance another weight or force in a mechanical system. Its main purpose is to provide balance, reduce the energy required to move a load, and improve control, stability, and safety in operation.

In static conditions, the counterweight supplies a torque opposite to the load around a pivot, drum, or pulley. The mass and its position determine the balance, and the system is designed so that the sum of moments is close to zero. In dynamic use, a counterweight can move with the load to keep forces within acceptable ranges, reducing peak stresses on ropes, cables, and structures and smoothing motion.

Common applications include elevators, where a counterweight travels on a dedicated guide while the car moves in the opposite direction; cranes and hoists, where a weight balances the load to minimize the required lifting force and to stabilize the structure; and certain machinery that uses ballast weights to reduce vibration or maintain symmetry in moving assemblies.

Design considerations involve selecting a weight mass that matches the expected load profile, accounting for pulley geometry, friction, and dynamic factors; ensuring safety margins and incorporating locks or brakes to prevent uncontrolled movement in case of system failure; and performing regular inspection for wear, corrosion, or misalignment. In lifting equipment, standards often govern tolerances and testing to ensure reliable, safe operation.