British Standards System

The British Standard (BS 4500) hole-based system of fits (refer to Fig. 2), also uses the basic terminology for holes and shafts. The terminologies are similar to those used in the Newall system. The holes and shafts are identified by a more extensive alpha/numeric identifier.

FIGURE

However it can be seen that, in an Interference Fit, the upper and lower limits of the shaft are greater than the corresponding limits of the hole and thus, force is necessary to achieve the fit.

In the Transition Fit, the differences in the upper and lower limits of both items are negligible so that only light effort is required to insert the shaft into the hole.

The upper and lower limits of the shaft in a Clearance Fit are always less than those of the hole, so that the shaft moves easily within the hole.