tractor to small engine with gear reduction

Question

I want to run an implement requiring a minimum of 35 hp at 540 rpm with a small engine running 3600 rpm with a 6:1 gear reduction. What horsepower engine would be required to get the min hp to run the implement?

Answer 1

You'll need about 40 HP @ 3600 rpm at a minimum in order to run it. Here is my math (please correct me if I'm wrong):

• 35 HP @ 540 rpm = 340.41 ft lbs (convert HP to Torque)
• 340.41 / 6 = 56.735 ft lbs (6:1 gear reduction)
• 56.735 @ 3600 rpm = 38.89 HP (minimum size of engine if actually running at 3600rpm)

You'll need to look at the spec of any engine to ensure the speed and hp actually mate up. Some small engines may product 40 HP, but will do it at say 5000 rpm, which would mean @ 3600 rpm the HP output may be much lower. 40 HP is going to be the minimum number to shoot for, I'd think.