A Mechanical Weighing Scale is a type of weighing instrument that operates without the need for electrical or digital components. It uses mechanical mechanisms such as springs or levers to measure the weight of an object. Here's a more in-depth look at how a Mechanical Weighing Scale works. A spring is the central component in many mechanical scales. When you place an object on the scale, the weight of the object stretches the spring. The more weight on the scale, the more the spring stretches.