The formula to calculate the horsepower capacity at lower speed is:

\[ HP = 0.004 \cdot T_1^{1.08} \cdot N_1^{0.9} \cdot P^3 - 0.007 \cdot P \]

Where:

• \(HP\) is the horsepower capacity in horsepower (hp).
• \(T_1\) is the number of teeth on the smaller sprocket.
• \(N_1\) is the speed of the smaller sprocket in revolutions per minute (rpm).
• \(P\) is the chain pitch in inches.