Sheave Static balance

Static balance occurs when the centre of gravity of an object is on the axis of rotation.The object can therefore remain stationary, with the axis horizontal, without the application of any braking force. It has no tendency to rotate due to the force of gravity. This is seen in bike wheels where the reflective plate is placed opposite the valve to distribute the centre of mass to the centre of the wheel.For example :- Grindstones or Car Wheels，sheave

The balancing of rotating bodies is important to avoid vibration. In heavy industrial machines such vibration can cause catastrophic failure, as well as noise and discomfort. In the case of a narrow wheel, balancing simply involves moving the centre of gravity to the centre of rotation. For a system to be in complete balance both force and couple polygons should be closed.