V zvezi z enosmernim (DC)sistemi je povprečna kontaktna sila Fm, ki jo tvorijo statične in aerodinamične komponente kontaktne sile z dinamičnim popravkom in se uporablja za DC 1,5 kV in DC 3,0 kV sisteme, prikazana na sliki 5.2 kot funkcija hitrosti vožnje.
Concerning DC systems, the mean contact force Fm formed by the static and aerodynamic components of the contact force with dynamic correction which shall be applied for DC 1, 5 kV and DC 3, 0 kV systems is shown in fig. 5. 2 as a function of running speed.