Full definition
The tension cord, also known as the tensile cord, is a critical component in power transmission belts, providing the structural integrity necessary to withstand the operational loads experienced during normal functioning. Located along the length of the belt at the neutral pitch line, the tension cord is the backbone of the belt, ensuring that it can effectively transmit power without excessive elongation or deformation. Various materials are utilized for tension cords, each offering distinct advantages based on the application's requirements. Polyester is commonly used due to its cost-effectiveness and moderate elongation characteristics, typically ranging from 2% to 4%. For applications demanding higher strength and lower elongation, aramid fibers, such as Kevlar, are preferable, exhibiting elongation rates of less than 1%. Fiberglass is another excellent option for timing belts, providing low stretch and superior fatigue resistance, while steel cables deliver the highest tensile strength for heavy-duty applications, such as in conveyor belts.
The material selection for the tension cord has significant implications on the performance of the belt, influencing factors like elongation under load, fatigue life, temperature tolerance, and the overall power capacity of the belt system. For instance, a tension cord made of aramid can withstand higher loads compared to polyester but comes at a premium cost. According to ISO 4184, the location of the tension cord at the pitch diameter is crucial since this serves as the reference point for accurate length measurements and alignment in pulley systems. Additionally, achieving proper adhesion between the cord and the rubber matrix is vital for maintaining performance and durability. This is typically done through a resorcinol-formaldehyde-latex (RFL) treatment, which enhances the bonding strength and ensures that the belt can effectively transmit power without cord slippage or failure over time. Consequently, understanding the specifications and behaviors of different tension cords is essential for engineers and maintenance managers when selecting and implementing power transmission solutions.