Spring Scales

Right hand side, you see a few pictures of Spring Scales.
Touch a picture, if you want to see some details.

This type of instrument used the springiness of metal to balance the load being weighed, and the weight is indicated according to the degree of distortion of the spring.
Coil spring are the most common type and they are usually arranged so that the spring is extended by the load, i.e. " in tension ". Sometimes the spring is " in compression " where the length is reduced by the load. A number of other spring shapes were also used, the " C " the " V ", the lyre, the ellipse, the flat spring etc., some of which are shown on my page.
Because the instrument finds its own point of equilibrium, the spring balance is called a self-indicating scale. There are many variations in design, some with a rotating pointer and graduations on a dial. The spring principle is used in shop scales, person scales, warehouse scales and general-purpose scales of all kinds.