Samoregulujúce ventily (lapping)

V závislosti od motorového vozidla existujú dva spôsoby regulácie tlaku v brzdovom potrubí: samoregulovacie (ang. self-lapping) a staršie, nesamoregulujúce (ang. non-self-lapping).

Pri samoregulujúcich systémoch sa tlak v brzdovom potrubí riadi automaticky. Rušňovodič môže nastaviť páku brzdy vlaku do ľubovoľnej polohy v rozsahu. Čím ďalej je nastavený v smere „aplikovať“, tým je brzdná sila silnejšia a naopak. Ventil automaticky zvládne vyprázdnenie alebo natlakovanie brzdového potrubia v závislosti od polohy páky.

On non-self-lapping systems, the process is more hands-on. The lever has a few fixed positions. Two of the positions, called “release” and “service” can be thought of as adding and releasing the brake pipe pressure, respectively. The position in between them, called “lap”, is used to maintain whatever pressure is in the brake pipe. The furthest position, called “emergency”, will release pressure at the fastest possible rate.

Auxiliary reservoirs are being drained when braking. When the brakes are released, it takes some time for auxiliary reservoirs to fill up again. The lap position, however, functions only if the auxiliary reservoirs are full. To stay in full control over braking it is recommended to not release non-self-lapping brakes when knowing that moments later braking may be needed again. Calculated, slow moves are preferable when releasing the non-self-lapping brakes.

With both brake types, the driver can see exactly how much braking force they are applying by looking at the brake pipe and brake cylinder gauge needles.

Obidva systémy sú pomerne jednoduché na používanie, aj keď samoregulovacie môže byť pre začiatočníkov intuitívnejšie. Zjednodušene povedané, pri samolapovaní ovládacie zariadenie nastavuje požadovanú brzdnú silu, pričom prácu prenecháva automatickému ventilu, zatiaľ čo pri nesamoregulovaní nastavuje brzdnú silu priamo ovládacie zariadenie.

In case a train contains motorized vehicles with both self-lapping and non-self-lapping brake valve types, only the self-lapping ones will be functional when operating the brake. For that purpose, vehicles are also equipped with brake cutout valves, which can be used to isolate certain vehicles from the brake system and resolve this conflict.