Shredder Sizing Question

[schmellba99]

I have an L3800 - a smidge over 30hp on the PTO (hydrostatic). Right now I run a Land Pride 48" shredder/rotary cutter because that is what I had for my smaller tractor before I upsized.

While it is extremely nice to be able to drive at virtually any speed in the L3800 and cut with almost not even noticing the shredder is there, it's only a 48" cut and ideally I would get something wider.

The general rule of thumb I have read has always been 5hp/ft, which would be 6ft. I generally am of the opinion that going one size down so you have reserve power for heavier cutting when you need it is a good thing, you can make up for the loss in width with speed most of the time if you have the extra power available.

That being said - still seems like 5' is kind of small for a 38hp tractor. I read about folks using much smaller rigs with bigger cutters. Most of what I use it for is cutting my ROW's at deer camp - combination of goat weed, johnson grass, bermuda and some bahia here and there. Light brush clearing on occasion, but nothing more than maybe 1"-1.5" thick.

Opinions/experience from those with a lot more knowledge? Am I overthinking this? Is a 6' cutter really right at the edge or is it something that I could handle easily with my tractor?

 

[Elliott in GA]

You will be fine with a 6 foot cutter; look at the Land pride spec sheets.

I am at the bottom of the recommended PTO power for my 5 foot cutter, and it does a great job in the field and eating up brush. In the field, I mow in M at regular speed - I am not mowing waist high grass. I clear brush slowly, carefully to maintain 540 RPMs and most importantly to avoid hitting things that I did not see - despite a walk through.

 

[SDT]

I have an L3800 - a smidge over 30hp on the PTO (hydrostatic). Right now I run a Land Pride 48" shredder/rotary cutter because that is what I had for my smaller tractor before I upsized.

While it is extremely nice to be able to drive at virtually any speed in the L3800 and cut with almost not even noticing the shredder is there, it's only a 48" cut and ideally I would get something wider.

The general rule of thumb I have read has always been 5hp/ft, which would be 6ft. I generally am of the opinion that going one size down so you have reserve power for heavier cutting when you need it is a good thing, you can make up for the loss in width with speed most of the time if you have the extra power available.

That being said - still seems like 5' is kind of small for a 38hp tractor. I read about folks using much smaller rigs with bigger cutters. Most of what I use it for is cutting my ROW's at deer camp - combination of goat weed, johnson grass, bermuda and some bahia here and there. Light brush clearing on occasion, but nothing more than maybe 1"-1.5" thick.

Opinions/experience from those with a lot more knowledge? Am I overthinking this? Is a 6' cutter really right at the edge or is it something that I could handle easily with my tractor?

Sizing a mounted rotary cutter depends depends mostly upon tractor PTO HP (ignore engine HP), size and weight, what one intends to cut, how close one intends to cut it, how fast one intends to travel when mowing, and mower weight. Steepness of ground comes into play if one is marginal on HP or tractor weight and/or heavy on mower weight.

Yes the 5 PTO HP per foot of mower cut is a good rule of thumb but is not foolproof. I often mow in conditions where 5 PTO HP per foot of mower weight is not nearly adequate but not everyone does this. Heavy grass requires much more HP than does tall weeds/brush.

You should be OK with a 6' rotary cutter if cover is not too heavy, you are not in too big of a hurry and the ground is not too steep.

SDT

 

[mcfarmall]

I run a 5 footer on the old Farmall C which has less than 20 hp at the PTO...no problems.

 

[NCL4701]

I have bush hogged with both gear drive and HST. With the gear you can put it in the lowest gear but to maintain PTO speed your ground speed is determined solely by the gear you’re in because your engine RPM is constant to maintain 540 on the PTO. Speeding up and slowing down to match changing conditions requires gear change. If the area is consistent, that’s swell. If it isn’t, you end up either changing gears a good bit or mowing the whole thing in the gear required for the worst of it. Even worse, if your pushing the HP limits of the tractor the lowest gear at engine RPM required for 540 PTO is the slowest you can go.

One of the advantages you have is the HST. If you get in really heavy stuff that’s bogging it down you can proceed as slowly as necessary and quickly speed back up when you get to lighter stuff. And with HST “the slowest you can go” at 540 PTO speed is pretty dang slow.

Point being I wouldn’t be quite as concerned pushing the size a bit on a mower with a HST tractor as I would with a gear drive.

 

[PaulL]

I generally am of the opinion that going one size down so you have reserve power for heavier cutting when you need it is a good thing, you can make up for the loss in width with speed most of the time if you have the extra power available.

My counter proposition is that with a larger cutter you can always slow down if things get too heavy going, but often it's not possible or practical to speed up, particularly on bumpy terrain. So I would go the other way - too big rather than too small.

I think 6 foot is pretty safe on that tractor. If you have lots of money you could look at a batwing, Tractor Time with Tim is excited about one of those at the moment.....but I think it's 9 foot or thereabouts. Claims that it runs fine on a smaller tractor - and has a few videos of him doing it.

 

[schmellba99]

My counter proposition is that with a larger cutter you can always slow down if things get too heavy going, but often it's not possible or practical to speed up, particularly on bumpy terrain. So I would go the other way - too big rather than too small.

I think 6 foot is pretty safe on that tractor. If you have lots of money you could look at a batwing, Tractor Time with Tim is excited about one of those at the moment.....but I think it's 9 foot or thereabouts. Claims that it runs fine on a smaller tractor - and has a few videos of him doing it.

I watched those videos with him using the 10' batwing on the 3038r JD - but it was all during winter time when everything was dry and dead. Looks like it worked great, but I'd like to see that combo during the spring when conditions are a bit more challenging.

 

[NCL4701]

I watched those videos with him using the 10' batwing on the 3038r JD - but it was all during winter time when everything was dry and dead. Looks like it worked great, but I'd like to see that combo during the spring when conditions are a bit more challenging.

Agree.

I would really like to see that as well. I’d really like to see that 3038r with a 9’ or 10’ mower slogging through the 4’, thick as hair on a cat’s back mix of whatever happened to grow there that I bush hog once or twice a year. Maybe it would get it done, I’d really just like to see it.

I actually do have a good bit of respect for TTWT experience and knowledge but I also understand he’s pushing small CUTS and SCUTS to their limits to both find what their limits are and to make interesting content. Some stupid redneck bush hogging 4’ mare’s tail, 6’ Johnson grass, 4’ sawgrass, 1/2” sweet gum saplings thicker than the grass in my yard, and a bunch of Japanese stilt grass with a 5’ old as dirt bush hog behind a L4701 that’s clearly more tractor than required for a 5’ rotary cutter isn’t very interesting YouTube content (which is one of many reasons I’m not a content creator on YouTube).

 

[PaulL]

My watching of TTWT and that batwing says he's pasture mowing, with a little bit of sticks and saplings. It's more than you'd want to do with a finish mower, but it's not heavy going. If you're doing real brush hog work I think you'd want a 6' single spindle machine. Depends what OP is intending to do. I see a lot of people who are really keeping the fields near their home semi-mowed. For that sort of work you're mowing frequently, and it's mainly grass not small trees. A batwing might be a good investment if you're mowing a large field often.