유지 작용

동력 차량에 따라 브레이크 파이프 압력을 제어하는 ​​두 가지 방법이 있습니다. 셀프 래핑과 이전의 비자립 래핑입니다.

Self-Lapping

셀프 랩핑 시스템에서 브레이크 파이프 압력은 자동으로 처리됩니다. 운전자는 열차 제동 레버를 범위 내 아무 위치로나 설정할 수 있습니다. "적용" 방향으로 멀리 설정할수록 제동력이 강해지며 반대의 경우도 마찬가지입니다. 밸브는 레버의 위치에 따라 브레이크 파이프의 덤핑 또는 가압을 자동으로 처리합니다.

Non-Self-Lapping

The 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 controlling the brake pipe pressure, you indirectly control the cylinder pressure, and thus, brake application.

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 non-self-lapping brakes it is recommended to not release when knowing that moments later braking may be needed again. Calculated, infrequent moves are advised instead.

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 are in conflict. The conflict can be even more severe if there are mixed self-lapping and non-self-lapping valves in the train. To ensure safe operation it is necessary to cutout all excess control valves, other than the one intended to be used.