What are buff and draft forces in coupling?

What are buff and draft forces in coupling?

• A. The horizontal and vertical forces generated during acceleration, braking, and coupling that act on a train.
• B. The friction forces on wheels due to track irregularities.
• C. The passenger load distribution.
• D. The longitudinal friction of wheels.

Answer: (A)

Buff and draft forces are the longitudinal forces that travel through the train’s couplings between cars as the train changes speed. Because each car has inertia, the trailing cars tend to resist acceleration and the leading cars pull on them, creating a pulling force (draft). Conversely, during braking or when a car pushes against the one in front, the coupling experiences a pushing force (buff). These forces act along the length of the train, primarily in the horizontal direction along the track, and are generated during acceleration, braking, and coupling operations. Understanding this helps explain how forces are transmitted through the train and why couplers and buffers are designed to absorb or accommodate these pushing and pulling loads. The other options describe different phenomena (friction with the track, passenger load distribution, wheel friction) that aren’t what buff and draft refer to.

Buff and draft forces are the longitudinal forces that travel through the train’s couplings between cars as the train changes speed. Because each car has inertia, the trailing cars tend to resist acceleration and the leading cars pull on them, creating a pulling force (draft). Conversely, during braking or when a car pushes against the one in front, the coupling experiences a pushing force (buff). These forces act along the length of the train, primarily in the horizontal direction along the track, and are generated during acceleration, braking, and coupling operations. Understanding this helps explain how forces are transmitted through the train and why couplers and buffers are designed to absorb or accommodate these pushing and pulling loads. The other options describe different phenomena (friction with the track, passenger load distribution, wheel friction) that aren’t what buff and draft refer to.