The length of a belt at the location of the tension members is represented by which term?

• A. Belt Length
• B. Pitch Line
• C. Pitch Circle
• D. Tension Length

Answer: (C)

In belt drives, the length of belt that wraps around a pulley is measured along the pulley’s pitch circle. The pitch circle is the imaginary circle on each pulley where the belt’s pitch points ride, and the belt length around that pulley is determined by the arc on that circle. Since the belt’s tension members move with the belt, the portion of the belt length at that location is represented by the pitch circle. So the term used for that belt length is pitch circle. The other terms don’t specifically describe the length around the pulley interaction: belt length is the total loop length, the pitch line is the belt’s centerline, and tension length isn’t a standard term.