540 RPM rotary cutter run 1000 RPM

[rutwad]

I'm pretty confident my friend's cutter is 540, but he thinks 1000. He usually only runs around 740 RPM but I am waiting to see what happens. I wasn't sure if the seals and bearings would be damaged or not since there are 1000 RPM available. I used it one day and had the tractor down to 1200 RPM's doing light cutting. It was nice and quiet. I think the A/C fan blower was making the most noise.


We have a 50 HP Kubota and finishing mower. I went outside one day when my nephew was cutting and could tell it sounded "fast". I got on the tractor and found it will rev high enough to take the 540 RPM up to 680. I'm cheap and like to save fuel, so I run about 480 as long as it's cutting fine.

 

[GManBart]

I'm cheap and like to save fuel, so I run about 480 as long as it's cutting fine.

Since fuel consumption is primarily dictated by the load on diesel engines, you're probably not saving much at all, but it won't hurt anything.

 

[brown40]

You can find the same gearbox castings with multiple flavors from 0.83:1.00 to 1.93:1.00, with same input and output shafts, just changing the gear splines to get the speed you're looking for at the output.
The question would be the application, and with a cutter there's some huge shock & shear forces involved with the sudden stop, & higher tip speeds create higher forces.
That said, so long as you match your 1000 rpm machine's output speed, with the 540 rpm cutters input, and have the power to do it, and keep that speed within, it can't hurt a thing... turn it up and the steel will fail, somewhere in the line.

 

[buickanddeere]

Applied forces would be increased by 3.429 times . Do you feel lucky? Do you have liability insurance ? Actually it would be void now that you were warned.

 

[rutwad]

It's not mine and I don't run it 1000. But neighbor bought this thinking it was 1000 and I can't convince him otherwise. We'll see what happens.

 

[RickB]

It's not mine and I don't run it 1000. But neighbor bought this thinking it was 1000 and I can't convince him otherwise. We'll see what happens.

If it isn't your machine maybe all you should do is stand back and leave him alone.

 

[kf4uda]

If it isn't your machine maybe all you should do is stand back and leave him alone.

Sometimes people just insist on learning things the hard way. I agree with Rick, stand back and let him learn

 

[buickanddeere]

I would stand back behind a very robust tree.

 

[RickB]

Let's not discount the possibility that the owner of the machine actually knows what he has.

 

[Ken Pike]

I have a 1980 Kubota B7100 & a King Kutter 48" brush cutter. I have the knives sharpened & the height adjusted so it cuts grass as well as a Bush Hog brand finish mower I recently sold. This is part of a hayfield we mow & use as a small driving range after the hay is cut & is mowed like a lawn once a week. On light cutting like this I run in the 2nd PTO speed (780 RPM?) & 2nd gear, High Range & throttle back a bit. After 1 hour cutting the gearbox is only slightly warm to the touch. No way would I cut heavy stuff at that PTO & tractor speed but works great as a finish mower.