How may it be determined that the brakes in the rear car apply and release?

How may it be determined that the brakes in the rear car apply and release?

• A. A decrease of at least 5 psi followed by a 5 psi increase in brake pipe pressure at the rear of the train
• B. A continuous decrease in brake pipe pressure at the rear with no subsequent increase
• C. An increase of 3 psi at the rear with no decrease
• D. No change in brake pipe pressure at the rear

Answer: (C)

In this braking system, you determine rear-car action by looking at brake pipe pressure. Brakes on the rear car apply when the brake pipe pressure drops, and they release when the pressure rises back toward normal. To confirm that both apply and release occurred, you’d observe a sequence: first a decrease in brake pipe pressure (indicating application), then a subsequent increase (indicating release). The typical threshold is a drop of at least a small amount (commonly around 5 psi) followed by an increase of a similar amount to show the brakes were applied and then released. An observation of only an increase means release without a prior application, while only a continuous decrease means sustained application with no release, and no change means neither action. So the telltale sign of the rear brakes both applying and releasing is a decrease in brake pipe pressure followed by a rise.

In this braking system, you determine rear-car action by looking at brake pipe pressure. Brakes on the rear car apply when the brake pipe pressure drops, and they release when the pressure rises back toward normal. To confirm that both apply and release occurred, you’d observe a sequence: first a decrease in brake pipe pressure (indicating application), then a subsequent increase (indicating release). The typical threshold is a drop of at least a small amount (commonly around 5 psi) followed by an increase of a similar amount to show the brakes were applied and then released. An observation of only an increase means release without a prior application, while only a continuous decrease means sustained application with no release, and no change means neither action. So the telltale sign of the rear brakes both applying and releasing is a decrease in brake pipe pressure followed by a rise.