In a set-out operation, what is the purpose of closing angle cocks on the sections involved?

In a set-out operation, what is the purpose of closing angle cocks on the sections involved?

• A. To vent air to the atmosphere.
• B. To isolate the portions before separation by closing angle cocks on both ends, then separate.
• C. To lock the couplers to prevent motion.
• D. To reset the brake pipe flow.

Answer: (B)

Angle cocks are shut‑off valves in the brake pipe lines that let you control air flow between sections of a train. In a set‑out, you want to detach a portion without letting brake pressure move between that portion and the rest of the train. Closing angle cocks on both ends of the sections involved isolates that portion, so when you separate, the brake system on each side stays in its current state and won’t be disturbed by pressure changes from the other part. This keeps the set‑out portion and the remaining train stable and safe to move. Venting air to atmosphere would waste air and undermine brake control, and locking couplers or resetting brake pipe flow aren’t achieved by these valves.

Angle cocks are shut‑off valves in the brake pipe lines that let you control air flow between sections of a train. In a set‑out, you want to detach a portion without letting brake pressure move between that portion and the rest of the train. Closing angle cocks on both ends of the sections involved isolates that portion, so when you separate, the brake system on each side stays in its current state and won’t be disturbed by pressure changes from the other part. This keeps the set‑out portion and the remaining train stable and safe to move. Venting air to atmosphere would waste air and undermine brake control, and locking couplers or resetting brake pipe flow aren’t achieved by these valves.