Maintien de la pression CG

Selon l’engin moteur, il existe deux manières de maintenir la pression de la conduite générale : avec l'auto-maintien et l'ancienne, sans l’auto-maintien.

Self-Lapping

Sur les systèmes à auto-maintien, le maintien à une valeur précise de la pression de la conduite générale est gérée automatiquement. Le conducteur peut régler le levier du FCA sur n'importe quelle position de la plage “serrage”. Plus il est positionné dans le sens "serrage", plus la force de freinage est forte, et vice versa. La valve gère automatiquement la vidange ou le remplissage de la conduite de frein en fonction de la position du levier.

Non-Self-Lapping

Non-self-lapping control valves are older. With them, the control lever manipulates the brake pipe pressure directly, and 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”, releases pressure at the fastest possible rate.

By control the brake pipe pressure, you indirectly set the cylinder pressure to the required amount.

Auxiliary reservoirs are partially drained whenever brakes are applied. When brakes are then released, it takes some time for the reservoirs to be recharged. The lap position, however, functions only if the auxiliary reservoirs are full. So, to stay in full control over the brakes it is recommended to not release non-self-lapping brakes when knowing that moments later braking may be needed again. Calculated, infrequent moves are preferable when operating non-self-lapping brakes.

Monitoring

With both control valve types it is crucial to monitor the brake pipe and cylinder gauges to fully understand the current brake state.

Conflicts

In case a train contains multiple motorized vehicles their control valves will conflict each other. The conflicts will be even more severe if there are mixed self-lapping and non-self-lapping types. To ensure safe operation it is necessary to cutout all excess control valves, other than the one intended to be used.