Protiváha

Protiváha, in engineering and mechanics, is a weight used to balance another force or load within a system. The goal of a counterweight is to offset the gravitational force of a moving part, providing stability, reducing required drive torque, and improving energy efficiency and control.

Principle and function: In pulley- and rope-based hoisting systems, a counterweight is connected to the opposite side of the rope so that the weight of the car or load is balanced. If the counterweight closely matches the load, the motor or brake only needs to control motion rather than constantly support the full weight. This balance reduces peak forces, wear, and energy consumption, and helps stabilize movement under dynamic conditions.

Applications: The most common uses are in elevators and lifting cranes. Elevators typically employ a counterweight that travels in the hoistway opposite the car. Cranes and hoists use counterweights to balance the load at varying radii and to maintain stability of the structure. Stage rigging, industrial machinery, and ballast systems in ships are other contexts where counterweights play a key balancing role.

Design considerations: The counterweight must be sized for the maximum expected load, plus dynamic effects from acceleration, deceleration, and friction. Safety factors, inspection intervals, and proper alignment with pulleys and guides are essential. Some systems use fixed counterweights, while others employ adjustable or active counterbalancing arrangements.

Related concepts: Counterweights are related to ballast, counterbalance systems, and balancing in mechanical design. They are distinct from purely inertial weights but share the same fundamental purpose: to maintain equilibrium and improve control of moving systems.