Carts of different uses have different body structures. Most general purpose four-wheeled trolleys have a cargo platform. For example: Folding trolley, with wire mesh board trolley, three-storey trolley, ascending car, trolley, flat trolley, mute trolley, etc., they all have different functions. According to the material classification, but also can be divided into: Stainless steel trolley, steel trolley, plastic trolley, aluminum trolley and so on.