Aa	surface area of the nominal contact region (m2)
Ar	total area of the real contact regions (m2)
b 0	parameter of the reference-surface curve
c	temperature-dependent specific heat capacity (J kg−1 K−1)
c 0	specific heat capacity at the initial temperature (J kg−1 K−1)
dr	diameter of an average spot of real contact (m)
f	coefficient of friction
h	heat transfer coefficient (W m−2 K−1)
h max	maximum roughness height of the friction surface (m)
HB	temperature-dependent Brinell hardness (MPa)
HB 0	Brinell hardness at the initial temperature (MPa)
I 0	initial moment of inertia (kg m2)
K	temperature-dependent thermal conductivity (W m−1 K−1)
K 0	thermal conductivity at the initial temperature (W m−1 K−1)
M	braking torque (N m)
p	contact pressure (MPa)
p 0	nominal contact pressure (MPa)
q	friction power density (W m−2)
r	radial coordinate (m)
rav	average rounding radius of roughness (m)
req	equivalent radius of the contact region (m)
t	time (s)
tm	rise time (s)
ts	braking time (s)
T	temperature (°C)
Ta	ambient temperature (°C)
T 0	initial temperature (°C)
Tf	flash temperature on the real contact region (°C)
Tm	average temperature of the nominal contact region (°C)
Tmax	maximum friction surface temperature (°C)
Veq	translational velocity on the equivalent radius (m s−1)
W	work done during braking (J)
W 0	initial rotational kinetic energy (J)
z	axial coordinate (m)