Proposals for the classification of brake noise - an equivalent noise dose rating

Proposals are presented which enable a brake to be graded as to its noise propensity over a range of conditions such as pressures, temperatures and also the audible frequency range. The brake may be given an equivalent noise dose rating based on an averaging of the noise level equivalent over a specified range of variables.

It is shown that the complex recorded noise may be reduced to an equivalent noise level and then averaged in three ways with the validity of each of these methods being discussed. The sensitivity of each method is compared against a set change in the variables and a final proposal is presented for the brake industry to consider.

A case study, which evaluates the effect of applying noise fix shims in a variety of ways to a sliding fist-type calliper, is used to demonstrate the value of the proposals. The analysis allowed the shim supplier to identify the most cost-effective way of applying the shims in addition to the most effective manner in order to reduce overall noise propensity.

Recommendations suggest further development of the "equivalent noise dose" proposal.