What does an engineer do to the brake pipe pressure to release the train brakes?

What does an engineer do to the brake pipe pressure to release the train brakes?

• A. Lowers the brake pipe pressure
• B. Raises the brake pipe pressure
• C. Maintains the brake pipe pressure
• D. Fluctuates

Answer: (B)

In an air brake system, the brake pipe pressure is the signal that controls both application and release of the brakes. When brake pipe pressure is lowered, the triple valves on each car respond by applying the brakes (air from the reservoirs goes to the brake cylinders to push the pistons). To release the brakes, the engineer returns the brake pipe pressure to the normal, charged level. This increase causes the valves to vent the brake cylinders and allow the brakes to release. So raising the brake pipe pressure is how the brakes are released.

In an air brake system, the brake pipe pressure is the signal that controls both application and release of the brakes. When brake pipe pressure is lowered, the triple valves on each car respond by applying the brakes (air from the reservoirs goes to the brake cylinders to push the pistons). To release the brakes, the engineer returns the brake pipe pressure to the normal, charged level. This increase causes the valves to vent the brake cylinders and allow the brakes to release. So raising the brake pipe pressure is how the brakes are released.