Obstacle links

This article deals with devices that can be used to establish a translational or rotational connection between two parts using obstacles. The shapes and dimensions of these obstacles vary according to the degrees of freedom allowed and the load transmitted. A distinction is therefore made between translational and rotational links, and between links that can slide and those that are fixed.

The article begins with a theoretical presentation of wedge devices, to which we can practically reduce the study of most of the types of obstacle links proposed.

It then goes on to describe the mechanical means that can be used to make a translational connection: pins and bolts, followed by those for rotational connections with inserts: keys, or by direct machining of the parts to be assembled: splines and serrations.

In practice, all these devices are standardized, and the article usually provides, in addition to the standard references, a summary of the main useful dimensional characteristics. For further information, particularly on spline control and the application of geometry formulas, the user can refer directly to the corresponding standard.

The article also provides information on how to calculate the dimensions of keys and splines, depending on the materials used and the forces transmitted. This calculation is not standardized, and the method indicated is derived from industrial experience, based on the use of simple, easy-to-apply empirical formulas.