What is slack action and why does it matter for safety?

What is slack action and why does it matter for safety?

• A. Slack action is the movement between cars; it can cause unexpected jostling and miscommunication if not anticipated
• B. Slack action is the rate of air pressure loss in the brakes
• C. Slack action is the time delay between signal aspects
• D. Slack action is the propulsive force in the locomotive

Answer: (A)

Slack action is the movement that occurs between railcars because of the slack in the couplings and the springiness of the cars. When a train starts moving or brakes are applied, that stored play has to be taken up before all the cars move as a single unit, so you can feel a jolt as the cars engage. This matters for safety because unexpected shifting can injure workers who are nearby, cause loads to shift or fall, and lead to miscommunication about how quickly or in what sequence the train is moving. Crews manage slack action by applying brakes smoothly and starting movements in a controlled way so the cars take up slack gradually, and by staying clear of the train during the take-up period.

Slack action is the movement that occurs between railcars because of the slack in the couplings and the springiness of the cars. When a train starts moving or brakes are applied, that stored play has to be taken up before all the cars move as a single unit, so you can feel a jolt as the cars engage. This matters for safety because unexpected shifting can injure workers who are nearby, cause loads to shift or fall, and lead to miscommunication about how quickly or in what sequence the train is moving. Crews manage slack action by applying brakes smoothly and starting movements in a controlled way so the cars take up slack gradually, and by staying clear of the train during the take-up period.