Counterweights are used to counterbalance an opposing mass in a linear or rotary motion system, allowing movement with lower driving forces. In linear-motion systems, such as conveyors, for example, inertial loads and vibration are imparted to the drive mechanism. By using counterweights that move at the same speed but in the opposite direction of the trays, these problems may be reduced or eliminated. Counterweights can also be used to reduce vibrations in rotating systems such as automobile tires. The vibration is measured without any weights and the heavy spot is determined. A counterweight is then placed opposite this heavy spot to balance the load and reduce or eliminate the vibration.
Types of Counterweights
Counterweights are made out of metals such as:
- and various alloys.
Iron counterweights and cast iron counterweights are often used in elevators. Steel counterweights are suitable for scaffolding and may weigh as much as 7,000 lbs. Tungsten counterweights are designed for aircraft control surfaces, aircraft rotor blades, guidance platforms, and vibration-dampening governors. They are also used to balance fly wheels and turbines. Stainless steel and titanium counterweights are available from both manufacturers and distributors. Stainless steel counterweights resist corrosion and may feature a threaded shaft so that the weights can be positioned precisely for balancing adjustments. Titanium counterweights are used in audio systems such as stereos. Alloying materials may be used to reduce the overall product cost without degrading performance.
Applications for counterweights include:
- crank shafts (rotating shafts)
- grinding wheels
Lifts are platforms that are used to raise and lower material, personnel, vehicles, and workpieces for loading and positioning. Similarly, elevators are used to raise or move people or goods from one location to another within a building. Rotary shafts are elongated, rod-shaped devices that rotate about a longitudinal axis and transmit torque. They are similar in shape to linear shafts, but designed to withstand torsional forces. Cranes are used to raise, shift, and lower loads with a projected, swinging arm or a hoisting apparatus supported on an overhead track. Counterweights are also used with grinding wheels for metal removal, dimensioning, and finishing.
Theresa knott / CC BY-SA 3.0