Why are clevises called out by a number?
Clevises are a component of tie rod assemblies that rods thread into. Unlike most other female threaded components such as nuts or turnbuckles, calling out a clevis size by the diameter of rod being threaded into it is not the correct way to reference it. Clevises are called out by a number, ranging from a #2 up to a #8.
The numbers on clevises are determined by the eye diameter. As shown below, the ‘D’ dimension on the clevis corresponds to the clevis number, with the exception of #2 clevises, which have an eye diameter of 1-7/16”.
Another reason clevises can’t be called out simply by providing the rod diameter is that particular rod diameters can be used with several different clevis sizes. While each clevis size does have a maximum diameter of rod that can be used with it, a particular rod diameter can be used with several different clevis sizes. For instance, a ⅞” diameter rod can’t be used with a #2 clevis, which has a maximum diameter of ⅝”, but it can be used with a #2½ or #3 clevis.
Please refer to our dimensional chart on the clevis page of our website to see the allowable diameters for each size of clevis.