Platform scales are mainly used in force measurement. The principle of the platform scale consists in supporting a platform upon a system of 4 horizontal levers, which are placed in a shallow portable box or in a pit in a ground. The levers hinge upon a fixed knife edge of steel in one of the corners of the box or pit. It transfers the load at the four corners of the platform to a single point, where a cable pulling down in a steelyard beam with a sliding poise, for example, could be used to measure the loads on the platform. The salient feature of the platform scale is that the reading on the scale is independent of the location of the weight on the platform. It eliminates the need for lifting heavy loads such as carts, locomotives off the ground in order to weigh them.