According to American Weighing Scales, different types of platform scales are composed of different parts and use different terminology. However, there are two main types: spring scales and balance beam scales. The main function of both mechanisms is to provide an accurate weight measurement of an object.
American Weighing Scales describes spring scales as containing a spring mechanism that stretches in direct proportion to the weight of an object placed on the bottom end, commonly called the "load receiving end." These types of scales are also known as "strain gauge scales." Modern versions use electronics to replace the actual spring or gauge, and are most likely found in laboratories because of their greater accuracy.
Balance beam scales are traditional, more widely recognized scales. A balance beam scale uses a fulcrum and lever. The lever balances across the fulcrum with the object to be weighed at one end and a counterweight at the other. Alternatively, the lever can be suspended from the fulcrum with the pans or plates for the object and counterweight suspended from each end. Once the lever is horizontal to the fulcrum, the unknown weight and the counterweight are equal, and the weight of an object can be determined.