Brush cutter size for a given horsepower

[aczlan]

The blades will only be turning at 54% of their designed speed.
It will be like running a 540 rpm mower at 291 rpm.
Will it still cut? Depends on what your cutting and how fast you're going.

I believe (someone check my math) if you drive at 54% of your normal speed, the torque required will be equal to a 540 rpm mower, but you'll only need 54% of the horsepower.
and if you drive at normal speed, the horsepower required will be equal to a 540 rpm mower, but you'll need (1/.54=) 185% more torque (assuming the blades are going fast enough to cut).

I think the OP is talking about running a 1000RPM mower on a tractor that has a 1000RPM PTO, not running a 1000RPM mower on a 540RPM PTO.

Aaron Z

 

[jrsavoie]

I think the OP is talking about running a 1000RPM mower on a tractor that has a 1000RPM PTO, not running a 1000RPM mower on a 540RPM PTO.

Aaron Z

Correct. Check the 4010 link from the earlier post

 

[LD1]

There is not appreciable difference in 540 pto on a 540 mower and 1000 pto on a 1000 tractor.

Torque is what breaks things. Changing speed and gearing doesnt change HP but it certainly does change the torque.

Pushing 80HP through a 540RPM shaft takes almost twice the torque as it does to push that 80HP through a 1000 shaft.

Since things can only be built so strong within a reasonable weight to be able to handle hooking up and unhooking....onces tractors started pushing 100 HP and beyoned....the need to increase the PTO speed to transmit that torque through a reasonable sized shaft became a necessity.

Newer stuff of even higher HP maintained the 1000rpm, but upped the shaft size to 1-3/4

 

[jrsavoie]

There is not appreciable difference in 540 pto on a 540 mower and 1000 pto on a 1000 tractor.

Torque is what breaks things. Changing speed and gearing doesnt change HP but it certainly does change the torque.

Pushing 80HP through a 540RPM shaft takes almost twice the torque as it does to push that 80HP through a 1000 shaft.

Since things can only be built so strong within a reasonable weight to be able to handle hooking up and unhooking....onces tractors started pushing 100 HP and beyoned....the need to increase the PTO speed to transmit that torque through a reasonable sized shaft became a necessity.

Newer stuff of even higher HP maintained the 1000rpm, but upped the shaft size to 1-3/4

Thank you much.