I hear ya. I hate borrowing anything I can’t afford to replace if damaged. I didn’t ask to use it. It was offered up and I didn't want to make him feel like his was not enough unit for my tractor. I already told him it wasn’t a good match for my tractor. I’ll disc instead this year.What?! You want to borrow my tractor. No ******* way! You’d have better luck asking to swap….…something else for a couple days.
(IMO) If the tiller has a shear bolt or PTO slip clutch it will be fine.
The slip clutch or shear bolt limit the amount of torque the tiller gets and will be be sized to protect the tiller’s gear box. Make sure they are correctly sized and operational. (Note: At a reduced rpm, the bigger tractor may be putting less horsepower (and heat) into the tiller’s gearbox than the little tractor at 540 rpm).
(IMO) I think the real danger is having a small tractor on a big tiller where the shear bolt protects the tiller but not the tractor.