What must be closely observed to determine if any leakage occurs in the brake system?

To determine if any leakage occurs in the brake system, closely observing the equalizing reservoir pressure is crucial. The equalizing reservoir functions as a key component in the braking system, maintaining pressure balance and enabling effective brake operation. If there is a leakage, the pressure in the equalizing reservoir would show a decline, providing an immediate indication that something is amiss within the braking components.

Monitoring this pressure allows for the identification of issues that could affect the overall braking system reliability, leading to timely interventions before they escalate into more severe problems. While other pressures such as the brake pipe and main reservoir pressures are also important, they do not provide the same direct insight into potential leakage within the brake system compared to the equalizing reservoir. Thus, focusing on the equalizing reservoir pressure is essential for maintaining safe and effective train operations.