Subtopic: Design and selection of machine elements – gears, pulleys, chains and sprockets and belts
Question Statement:
In roller chain drives used on agricultural seed drills and combines, 'chordal action' refers to:
Options:
(A) Cyclic variation in linear chain velocity as the chain links engage the polygonal sprocket teeth
(B) Lateral vibration caused by loose tensioners
(C) Centrifugal elongation of the pin bushings
(D) Fatigue fracture of the roller plates
Answer Key:
A
Step-by-Step Solution & Explanation
Because a sprocket is a polygon rather than a circle, as links seat, the effective pitch radius oscillates between $r$ and $r\cos(\pi/z)$, causing cyclical velocity pulsation (chordal action).