The European Regulation on Braking of two, three and four
wheelers specifies a friction coefficient of 0.8 μ for which the
determination of the coefficient of adhesion utilization by actual
test was sufficient. The Global Technical Regulations on motorcycle
and passenger car braking, Federal Motor Safety Standards on Brakes
and ESC now require the friction coefficient of the test track to
be greater than 0.9. This friction coefficient is evaluated by
(ASTM) E1136 standard reference test tire, in accordance with ASTM
Method E1337-90, at a speed of 64 km/h (40 mph) without water
delivery. Very few test centers in Europe use this equipment for
calculating the friction although it is a standard method followed
in USA.
A road friction dynamometer has been designed and developed by
Mahindra in India to determine the peak braking coefficient under
dry conditions on different surfaces. The paper describes the
salient features of the road friction dynamometer, its functioning,
operation and process of acquiring the data for determination of
the peak braking coefficient.