Influence of Tread Width of the Brake Pedal Pads on the Friction Coefficient Generated by Bare Foot and Footwear Soles

The present work discusses the effect of the treads width of the rubber brake pedal pads on the friction coefficient. Measurement of friction coefficient generated by bare foot and rubber footwear soles sliding against the brake pedal pads of different treads width in dry, sand contaminated, water and oil lubricated conditions is discussed. Experiments of the sliding of bare foot against the rubber pedal pad showed that friction coefficient of dry sliding significantly decreased with increasing tread width. The sliding direction has no effect on the friction coefficient for the tested pads. In the presence of sand particles separating the two contact surfaces, load had no influence on friction coefficient. Friction coefficient slightly decreased with increasing tread width. For water wetted pedal pad, friction coefficient displayed higher values than that observed for the condition of presence of sand particles. Friction values showed consistent trend with increasing the tread width. Friction displayed by oil lubricated pedal pads was the lowest and the sliding condition could be considered as unsafe. When rubber shoes slide against the tested rubber pads friction coefficient displayed relatively lower values than bare foot. Sliding in the transverse direction displayed higher friction values than longitudinal one at dry sliding. In the presence of sand particles on the sliding surfaces, the shortest tread width displayed the highest friction. Sliding against water wetted pedal pad, the highest values of friction coefficient were displayed by 2 mm tread width due to the water leakage from the contact area. The friction values displayed in the transverse direction were relatively lower than that observed in the longitudinal one. Besides, sliding against oil lubricated pedal pad showed relatively low friction values which were considered as unsafesliding.