Iplayfarmer
Super Member
What is the gear ratio of a bush-hog gearbox? It could be 1:1, or 1;2, or maybe 1:3
It's probably about 1:2. Bush Hog pitches a blade tip speed of 14,800 fpm on the 48" mower. A 2 foot radius equals about a 12.5 foot circumfrence. This means that to hit 14,800 fpm the blade has to go about 1170 rpm. On a 540 PTO that's just about a 1:2 gear ratio.
Of course even if you only had a 6" diameter drive attached to the output of the gearbox for a trencher, that's still 1850 fpm for the trencher blade to be moving. How fast do most trenchers blades move?