COST 334

Chapter 4tandem axleTCFtfthermal cracking,total widthtowed axletractora configuration of two axles, with less than 1.8 m spacing betweenthe axles. (Often the suspension of a tandem axle is such that theload on the tandem axle is shared rather equally between theconstituent axles.) The maximum load is dependent on axle spacingand suspension, and is different for motor vehicles or for trailers andsemitrailers. (The EC also distinguishes a ‘bogie’, being two axleswith shared suspension and less than 1.3 m spacing. In this report‘tandem axles’ will be used loosely to include ‘bogies’, but not‘double axles’.)Tyre Configuration Factortonne-force = 1000 kgf ≈ 9.81 kN. Often (as in this report), a tf isloosely taken to equal 10 kN.cracking in the bituminous material due to tensile stresses caused bytemperature changesin the regression formulae for the TCF, the ‘total width’ for singletyres equals the footprint width; the ‘total width’ for dual tyreassemblies equals the sum of the footprint widths of both tyres plusthe width of the gap inbetween. (NB The ‘total width’ should not beconfused with ‘tyre section width’).axle on which the wheels are neither driven, nor steeredleading, powered, part of a tractor-semitrailer combination (seeFigure 4.74). A tractor is connected to the semitrailer by the fifthwheel and kingpin. (In this report, tractor is not used in its commonmeaning of vehicle for pulling agricultural machinery.)Figure 4.74 Types of heavy goods vehicles (Vos 1996)version 29 November 2001163