If the drive sheave has more teeth than the driven sprocket, the belt drive ratio is less than 1.

• A. Less than 1
• B. Greater than 1
• C. Equal to 1
• D. Undefined

Answer: (A)

In belt drive systems, the ratio used here is the driven pulley’s teeth divided by the drive pulley’s teeth. If the drive has more teeth, that means the numerator (driven teeth) is smaller than the denominator (drive teeth), so the ratio falls below one. For example, a drive with 60 teeth and a driven with 40 teeth gives 40/60 = 0.667, which is less than 1. It’s helpful to note that the speed relationship goes the other way: driven speed relative to drive speed is driven teeth over drive teeth, which would be 60/40 = 1.5 in this example. The key point is the ratio as driven over drive teeth, which is less than 1 when the drive is larger.