The belt body of the timing belt is composed of a strong layer, a toothed layer, a cloth layer and an adhesive layer. The strong layer is a core rope with high tensile strength, usually a surface-treated glass fiber, polyarylamide fiber or steel wire rope. This layer mainly bears the tensile force of the load. The tooth layer is the part of the synchronous belt in contact with the pulley, and its tooth root line is roughly at the position of the joint line, so as to ensure that there is no change in the circumference during bending. The tooth profile must be accurate and not easily deformed in order to accurately transmit movement. The cloth layer is wrapped around the entire toothed layer to protect and prevent cracking. The adhesive layer is also called the belt back, and its main function is to glue the tensile material of the strong layer to the position of the section of the belt and protect the tensile material.