## Nomenclature
  
angle (positive if counter-clockwise) between the abscissa/ordinate axis of the coordinate system of the support plane (\(x_{SP}\) or \(y_{SP}\)) and the abscissa/ordinate axis of the coordinate system of the vehicle (\(x_{t}\) or \(y_{t}\)) [\({}^{\circ}\)]  
\(\delta\) & pitch angle of a vehicle (in the vehicle frame of reference) [\({}^{\circ}\)]  
\(k_{\perp}\) & coefficient of elasticity in the direction perpendicular to the support plane for each of the two sides of the vehicle under test [N-mm\({}^{-1}\)]  
\(k_{//}\) & coefficient of elasticity in the direction parallel to the support plane and to the wheel rotational axis for each of the two sides of the vehicle under test [N-mm\({}^{-1}\)]  
\(k_{\perp,Fl}/k_{\perp,FR}/k_{\perp,RL}/k_{\perp,RR}\) & coefficient of elasticity in the direction perpendicular to the support plane for the front-left/front-right/near-left/rear-right type of the vehicle under test [N-mm\({}^{-1}\)]  
\(k_{FFL}/k_{\parallel,FR}/k_{\parallel,RL}/k_{\parallel,RR}\) & coefficient of elasticity in the direction parallel to the support plane and to the wheel rotational axis for the front-left/front-right/rear-left/rear-right type of the vehicle under test [N-mm\({}^{-1}\)]  
\(\varphi\) & roll angle of a vehicle (in the vehicle frame of reference) [\({}^{\circ}\)]  
\(\psi\) & yaw angle of a vehicle (in the vehicle frame of reference) [\({}^{\circ}\)]  
\((a,b)\) & coordinates of \(CoG^{\prime}\) in the reference frame of the vehicle placed on the turntable [m; m]  
\(\Delta\ell\) & distance of the \(CoG\) of a vehicle under test from its longitudinal axis/plane [m]; in other words, in a plane transverse to the longitudinal axis of the vehicle, offset from the centreline of the vertical line passing through the \(CoG\)  
\(\Delta y_{SP}(CoG^{\prime})\) & shift of \(CoG^{\prime}\) downstream the inclined support plane in the frame of reference fixed to the turntable as an effect of an increase in the support plane inclination [m]  
\(d_{1},d_{2}\) & dimensions of the quadrilateral linking the load cells under the quadrants (i.e., distance along \(x_{SP}\) and \(y_{SP}\) between the load cells under the quadrants) [m]  
\(d_{Fr},d_{Re}\) & distances of the \(CoG^{\prime}\) from the front and the rear axles of a vehicle under test [m]  
\(d_{FL},d_{FR},d_{RL},d_{RR}\) & respectively the distances of the line passing through \(CoG^{\prime}\) from the front/rear left/right wheels of the tractor  
\(FT\) & front track width of the vehicle under test (positioned on the support plane) [m]  
\(g\) & modulus of the gravitational acceleration [m-s\({}^{-2}\)]  
\(h=z_{t}\) & distance of the \(CoG\) from the vehicle support plane (height of the \(CoG\)) [m]  
\(\ell\) & half-track width of a vehicle under test (positioned on the support plane) or half-width of a vehicle under test (positioned on the support plane) in correspondence to the \(CoG\) [m]  
\(m\) & mass of the vehicle under test [kg]  
\(P\) & modulus of the weight force of a vehicle under test [N]  
\(r_{BR}\) & ratio between the components perpendicular to the support plane of the binding reaction in the points \(R\) and \(L\), i.e., in the center of the right and left rear wheel of a vehicle under test (positioned on the support plane) [-]  
\(r_{dist}\) & ratio of the distances of \(CoG^{\prime}\) from \(L\) and from \(R\), i.e., from the centers of the right and left rear wheels of a vehicle under test (positioned on the support plane) [-]  
\(r_{ms}\) & maximum slope direction of the support plane of the test system  
\(r_{p}\) & direction perpendicular to the support plane, on which the vehicle under test is placed  
\(r_{p}\) & (absolute) vertical direction, perpendicular to the horizontal plane on which the test  
\(R_{R\perp},R_{L\perp}\) & modulus of the component perpendicular to the support plane of the binding reaction in the points \(R\) (\(L\)), i.e., in the center of the right (left) rear wheel of a vehicle under test, i.e., positioned on the support plane [N]  
\(R_{R},R_{L}\) & modulus of the binding reaction in the points \(R\) (\(L\)), i.e., in the center of the right (left) rear wheel of a vehicle under test (positioned on the support plane) [N]  
\(RT\) & rear track width of the vehicle under test (positioned on the support plane) [m]  
\(W_{1},\ldots\) & weights measured by the load cell placed under each quadrant [N]  
\(W_{1},\ldots\) & \(W_{4}\)% & percentage distribution of weights on each quadrant [%]  
\(WB\) & wheelbase of the vehicle under test (positioned on the support plane) [m]  
\(W_{F},W_{R}\) & weight supported by the front (rear) axles of the vehicle under test (positioned on the support plane) [N]  
\(W_{FR},W_{FL}\) & weight supported by the front right (left) wheel of the vehicle under test (positioned on the support plane) [N]weight supported by the rear right (left) wheel of the vehicle under test (positioned on the support plane) [N]  
total weight supported by the wheels of the vehicle under test (positioned on the support plane); NB if the support plane inclination is not null, it is different from the weight force P of the same vehicle under test [N]  
Cartesian frame of reference of the support plane fixed to the turntable (i.e., rotating with it)  
Cartesian frame of reference of a vehicle under test (positioned on the support plane, NB variously inclined with respect to the horizontal plane)