During a service reduction, if the rear pressure decreases but abnormally slowly due to a partially closed angle cock, which air brake test is required before proceeding?

During a service reduction, if the rear pressure decreases but abnormally slowly due to a partially closed angle cock, which air brake test is required before proceeding?

• A. An Application and Release test
• B. A Full Service Brake test
• C. An Emergency Brake test
• D. No test required

Answer: (A)

When you see an abnormal and slow pressure drop on part of the train, you need to verify that the basic brake function responds correctly to the control input. The Application and Release test directly checks that applying the brakes causes the brake cylinders to energize and then releasing the brakes allows them to de-energize. This confirms there isn’t a sticking brake or a leakage issue masking under the slow pressure decline, and that the system will respond properly as you propel the train again. A Full Service Brake test looks at overall braking performance across the train under full service application, which isn’t the immediate need when diagnosing a single car’s slow pressure drop. An Emergency Brake test is about emergency application behavior, not the normal service response highlighted here. And skipping a test isn’t appropriate given the abnormal condition.

When you see an abnormal and slow pressure drop on part of the train, you need to verify that the basic brake function responds correctly to the control input. The Application and Release test directly checks that applying the brakes causes the brake cylinders to energize and then releasing the brakes allows them to de-energize. This confirms there isn’t a sticking brake or a leakage issue masking under the slow pressure decline, and that the system will respond properly as you propel the train again.

A Full Service Brake test looks at overall braking performance across the train under full service application, which isn’t the immediate need when diagnosing a single car’s slow pressure drop. An Emergency Brake test is about emergency application behavior, not the normal service response highlighted here. And skipping a test isn’t appropriate given the abnormal condition.