The 30 series has a 10% overdrive. A 20 series has no overdrive. I think Del Ray is saying that if you are looking for pulling power, you don’t need the overdrive so a 20 series might be better than a 30 series.
Also the driven pulleys are usually 6” in diameter, but a 7” driven can be had which again would give a better ratio for pulling. A 7” can be added later but you would need a bigger belt.
Also the driven pulleys are usually 6” in diameter, but a 7” driven can be had which again would give a better ratio for pulling. A 7” can be added later but you would need a bigger belt.