$a$	Effective depth of heat penetration ($\mathrm{m}$)
$A_a$	Nominal contact area (m2)
$c$	Specific heat of materials ($\mathrm{J}\hspace{0.17em}{\mathrm{kg}}^{-1}{\mathrm{K}}^{-1}$)
$D_d$	External diameter of the disc (m)
$d_d$	Internal diameter of the disc (m)
$F$	Contact force (N)
$F_0$	Nominal contact force (N)
$F_t$	Tangential force (N)
$f$	Mean coefficient of friction
$H(\cdot )$	Heaviside step function
$k$	Thermal diffusivity of materials (${\mathrm{m}}^2{\mathrm{s}}^{-1}$)
$K$	Thermal conductivity of materials ($\mathrm{W}\hspace{0.17em}{\mathrm{m}}^{-1}{\mathrm{K}}^{-1}$)
$p$	Contact pressure (Pa)
$p_0$	Nominal contact pressure (Pa)
$r$	Radial coordinate ($\mathrm{m}$)
$R_p$	External radius of the pad (m)
$r_p$	Internal radius of the pad (m)
$r_{eq}$	Equivalent radius of friction (m)
$R_W$	External radius of the wheel (m)
$q$	Intensity of heat flux ($\mathrm{W}\hspace{0.17em}{\mathrm{m}}^{-2}$)
$q_0$	Nominal specific power of friction ($\mathrm{W}\hspace{0.17em}{\mathrm{m}}^{-2}$)
$t$	Time ($\mathrm{s}$)
$t_i$	Time of pressure increase ($\mathrm{s}$)
$t_s^0$	Time of braking with constant deceleration ($\mathrm{s}$)
$t_s$	Stop time ($\mathrm{s}$)
$T$	Temperature (${}^{\circ }\mathrm{C}$)
$T_0$	Initial temperature (${}^{\circ }\mathrm{C}$)
$W_0$	Initial kinetic energy (J)
$V$	Sliding velocity (${\mathrm{ms}}^{-1}$)
$V_0$	Initial sliding velocity (${\mathrm{ms}}^{-1}$)
$z$	Spatial coordinate in axial direction ($\mathrm{m}$)
$\gamma$	Heat partition ratio
${\delta }_d$	Thickness of the disc (m)
${\theta }_p$	Cover angle of the pad (rad)
$\mathsf{\Theta }{\hspace{0.17em}}_0$	Scaling factor of temperature rise (${}^{\circ }\mathrm{C}$)
$\eta$	Coverage factor of the disc rubbing surface
$\rho$	Density of materials ($\mathrm{kg}\hspace{0.17em}{\mathrm{m}}^{-3}$)
$\tau$	Dimensionless time
${\tau }_i$	Dimensionless time of pressure increase
${\tau }_s^0$	Dimensionless time of braking with constant deceleration
${\tau }_s$	Dimensionless stop time
$\mu$	Instantaneous coefficient of friction
$\omega$	Angular speed of the brake disc (rad s−1)
${\omega }_0$	Initial angular speed of the brake disc (rad s−1)
$\zeta$	Dimensionless spatial coordinate in the axial direction