Mechanical Design Handbook

Let's take a look at the formulas related to chain design. The pitch diameter of a sprocket with N teeth for a chain with a pitch of p is determined by Note: the angle of sine function must be degree (not radian) The center distance, C, is the distance between the center of the driver and the driven sprockets. It's the distance between the two shafts coupled by the chain drive. In typical applications, the center distance should be in the following range: The chain length, L , is the total length of the chain. Because the chain is comprised of interconnected links, the chain length must be an integral multiple of the pitch . "It's preferable to have and odd number of teeth on the driving sprocket and an even number of pitches (links) in the chain to avoid a special link" The chain length is expressed in number of links, or pitches (not in mm or inches!) , can be computed as The center distance for a given chain length can be computed as Please no

GENERAL CHAIN DESIGN CONSIDERATIONS Nominal Tensile Load The main consideration for all types of chain is the nominal tensile load that is required to perform the basic function. The nominal tensile load generally fluctuates in a regular cycle. For example, the chain tension from the nominal load in a chain drive increases as the chain moves around the driven sprocket. The tension remains basically constant at a high level as the chain runs through the tight strand. Tension then decreases as the chain moves around the driver sprocket. It then remains basically constant at a low level as it runs through the slack strand. This cycle then repeats again and again. Shock Load Shock loads are caused by the characteristics of the power source and the driven machinery. They occur repeatedly in a regular cycle, usually one or more times in each shaft revolution. They usually must be added to the nominal tensile load. Service factors are used to account for commonly known shock loads i