The idea behind tolerance rings is very straightforward – they’re simply radially sprung steel rings that are designed to be press fitted between two mating components, such as a motor shaft and a take-off pulley. They are, in other words, a special form of frictional fastener.

Typically manufactured from high quality spring steel, stainless steel or specialist spring materials, tolerance rings are invariably custom designed to suit a particular application. All types, however, have one essential characteristic in common – a series of protrusions or ‘waves’ around their circumference. Each of these waves acts as an individual radial spring which, when the tolerance ring is in situ, transfers forces between the mating components.

This arrangement means that tolerance rings are capable of handling

direct torque transfer, torque slip, axial retention,controlled collapse and radial loading between the mating components.

Providing exactly the right combination of properties needed for a particular application involves deciding on the number of waves on the ring, the optimum wave design, and the best combination of material from which to manufacture the ring. The design work is, however, undertaken entirely by Rencol; all users need to do is to supply basic information about their application and then, when the rings are supplied, fit them!

Now let’s take a look at some practical examples of where tolerance rings are solving problems in the automotive industry, and at the important benefits they are providing for their users.