Recent developments in coefficient of friction measurements at the rail/wheel interface

Contact Force Estimation in the Railway Vehicle Wheel-Rail Interface

“…Experimentation has shown that, contrary to expectation from theoretical models such as that of Kalker, Kalker (1967), the initial slope of the creep curve varies with different adhesion levels, Pearce and Rose (1985), Harrison and McCanney (2002). Four levels of adhesion are defined in this study as dry, wet, low and very low conditions.…”

Adhesion estimation at the wheel–rail interface using advanced model-based filtering

“…Experimentation has shown that, contrary to expectation from theoretical models such as that of Kalker [13], the initial slope of the creep curve varies with different adhesion levels, [7,15]. Four levels of adhesion are defined in this study as 'dry', 'wet', 'low' and 'very low' conditions, relating to 55%g, 30%, 6%g and 3%g potential deceleration rates.…”

“…This paper proposes a novel approach to the detection of areas of low adhesion in the wheel/rail interface that are created by such things as: leaf contaminant; dew formation; lubricant dispersal; ice; and many other reasons, [7]. These areas can create large cost and punctuality issues for train operators and users alike.…”

Tribology of the wheel–rail contact – aspects of wear, particle emission and adhesion

“…The adhesion between the wheel and rail cannot be measured directly although friction can be measured on the rail surface. Measuring techniques include a hand-pushed tribometer and a vehicle companion Tribo-Railer [44]. Both of them use small steel wheels rolling on the rail.…”

“…Moreover, the results of the measurement techniques may differ slightly even when measured under similar conditions. For example, a hand-push tribometer and a Tribo-Railer give different friction coefficient values when both measured on the dry railhead [44] because of the difference in measuring speed, length and measuring wheel. In the laboratory a pin-on-disc rig is often used to measure the friction coefficient based on a stationary loaded pin sliding on a rotating disc.…”