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Roller conveyors have a long history; the ancient Egyptians began using the principle of rotation to transport stones when building the pyramids. The prototype of the modern roller conveyor is said to have emerged in the 19th century as the U.S. automotive industry pursued automation. Today, roller conveyors are widely used in various industries. Such as automated production lines for mines, ports, and docks. With the construction of logistics centers as automated and labor-saving conveyor systems, a large number of roller conveyors have been put into use. Generally speaking, a roller conveyor is a conveying machine that can transport items continuously. A roller conveyor can be defined as a machine that uses the aforementioned components as a supporting surface to carry the goods that need to be transported. The definition of a roller conveyor in China’s roller conveyor industry is: a mechanical device that transports goods such as those in bulk packaging from a certain or arbitrary loading point to a unloading point, along a predetermined route, in a horizontal or vertical manner. Two key points are emphasized here: (1) from the loading point to the unloading point; (2) a machine that transports goods along a set route. The most notable feature of a roller conveyor is continuous transportation over a certain distance and the accuracy of the transportation time. Classification and types of roller conveyors There are many types of roller conveyors, and different classification methods exist. For example, based on the driving method, they can be divided into two main categories: gravity-driven and power-driven. It can also be distinguished by the construction of the transmission mechanism. A roller conveyor is also known as a roller table or roller conveyor system. The two ends of the shaft that passes through the center line of the rollers are fixed to brackets on the left and right sides; multiple such fixed rollers arranged at regular intervals constitute a roller conveyor. Rollers are also known as idler rollers or drum rollers. It is formed by installing bearings at both ends of the cut pipe. Rollers can be classified by shape into straight and conical types. The straight type is used in linear roller conveyors, while the conical type is used in curved corner roller conveyors. Depending on the application, rollers can be made from materials such as steel, aluminum, stainless steel, or resin. Conveyor belts can be classified into two main categories based on the method of drive: gravity (driven) conveyor belts and powered (driven) conveyor belts. Our company provides an introduction and explanation of the structural features and applications of roller conveyors. A gravity roller conveyor is a machine that uses its own weight to continuously transport items. Strictly speaking, when a conveyor is in an inclined position, it uses its own weight to transport items, whereas when the conveyor is horizontal, gravity is not used; instead, human power or some other external force is required to move the items. The advantages of gravity roller conveyors include the need for no power, simple structure, low maintenance costs, low price, and easy layout modification. But there are also the following problems. (1) Since the items are moved by their own weight on an inclined roller conveyor, the longer the conveyor, the faster the moving speed becomes due to acceleration ； (2) Heavy objects move quickly, while light objects move slowly or not at all. When light and heavy items are transported simultaneously and there is a significant difference in their weights, differences in movement speed can lead to collisions between the items, resulting in damage to those items or their detachment from the rollers of the conveyor belt ； (3) Since cardboard boxes absorb moisture easily, even if the inclination angle of the roller conveyor remains constant, changes in humidity during the rainy or dry seasons can cause the items to move intermittently. The design inclination angle of a gravity roller conveyor is expressed in terms of the self-propulsion slope, and its value can change slightly depending on the temperature and humidity of the items being transported, as well as the condition of the surface and the external temperature and humidity. Therefore, it is difficult to obtain an accurate value. Assuming the bottom surface of the item is flat, its self-shift slope value can be determined with reference to the specifications. Gravity roller conveyors come in various (material) series, with the rollers being made of different materials depending on the components used in them.