Twin spindle 7' cutter on deere 3520?

compact · Jul 20, 2013

Thinking about a 7' twin spindle light duty shredder on a 30PTO deere 3520. Do these use less PTO than a single spindle 6'? The fields I mow are light brush and fairly thin grass - old pasture and cropland. The machine breezes along with a 5' mower at 5MPH on cruise set at min. height (2"), occasionally it'll load down to 3.5MPH under electronic load control, but not very often and if I raise up another inch it wouldn't slow down at all. I'm thinking the 750 lb twin spindle / twin tail wheel design should sit in closer to the machine and hopefully balance about like the 600lb 5' rc2060. I would actually be a little happier if I ran less than 5MPH - this gets a bit fatiguing on this little machine - about 4MPH is much nicer but I'm trying to get'er done as I have 45A 6 hours from home and would like to mow it 2x per year - the farm I grew up on. Any experiences with this type of mower / machine?

mikehaugen · Jul 20, 2013

how much would one of those cost? How much are you mowing? If you are only mowing a couple acres, it seems it would be a long ROI vs. just paying someone to mow it.

But I am interested to hear what people say as well, as I would like to get a twin spindle 8' for mine, but unless I find a decent used one, will probably never be able to justify the upfront cost. I have a woods 6' that I paid $165 for and only replaced seals on the gearbox and is working fine for me.

jenkinsph · Jul 21, 2013

If you wan't a wider cut in thin grass and are cutting it about 2 to 3 inch height I would consider a 3ph grooming mower. The Frontier GM2190 with 90" cut and the GM2109 with 108" cut come to mind. If you raise them up to the highest setting about 5"+ and mow more frequently the grass and pastures should improve. Scalping the pastures to 2 or 3 inches twice a year will lead to poor grass and more weeds. If the ground is smooth enough I would go for the 9' model which should allow you to run the 4mph while making good coverage/hr. Just a guess but about 4 acres/hour +, should be able to cut an acre for every mph of travel speed in light grass. If you currently use a 5' cutter at 5mph I would guess this 45 acres takes about 16 to 18 hours to cut, with the larger 9' mower I would guess 11 to 12 hours at 4mph, at 5mph about 9 or 10 hours.

Normally I would recommend a larger brush mower but some of these can be hard to get turning with a 30hp 3520 and are heavier and hard to handle. Whereas the 9' grooming mower with four casters wheels on the ground would be a lot easier to pull imo.

I would allow it to top out and go to seed each fall too which will help thicken your grass over time. After about three years of more frequent mowing I can guarantee your land will look much better with thicker grass and less weeds.

compact · Jul 22, 2013

Thanks Jenkinsph, that's an interesting idea - running a wider mower higher with a grooming mower. The fields aren't really rough but they aren't exactly smooth either, so the casters will be getting a pretty good workout, the bushes get up to a foot or so between mowings, and despite best efforts I still manage to find the occasional rock - will a grooming mower withstand that? I've never used one. It takes me about 25 hours to mow counting edges etc. so 12 hours at 4MPH sounds pretty attractive. The property has been on the once every 2 (3-4 sometimes) year schedule for a couple of decades, so some of the bushes are pretty well established and some of it would love to go to forest if left alone - it used to all be grass 40 years ago. Hoping 2x per year will cure some of that, I may be able to swing 3x but it's a 6 hour tow from home to get there.

8404 · Jul 22, 2013

if you are considering a double rotary mower like this one I want to warn you. If the blades rotate the same direction as this one does it wont cut tall thick grass with out clogging up and chocking down the engine of your tractor. and I don't mean just working the engine hard but actually piling up the grass on top of the left side stump jumper so tight that the grass was putting pressure on the stump jumper like a disc break does on a vehicle. it was so bad that I traded it back and lost 1000.00 on the trade in just to get rid of it on a single gear box 7 foot cutter. Now if the twin blades counter rotate then there is no problems.

jenkinsph · Jul 22, 2013

I would cut it close with a brush cutter and then maintain it at the higher level with the grooming mower afterwards. I would really stress that mowing three times a year would be very beneficial for the grass, that is a small investment for the benefits you will get. I would figure out a way to store the mower on the property so that all you have to tow is the tractor.

compact · Jul 29, 2013

Thanks for the advice 8404, it would not have occurred to me that anyone would spin both shafts in the same direction - not sure why they did that.

jimmysisson · Jul 30, 2013

You might also consider a flail, which I think requires no more power than a finish mower. The roller on a flail will probably last longer than the casters on a finish mower. You might have to hit it with a rotary first to get the big stems.
I have an old Mott 88" flail. It doesn't work my 39 PTO HP much unless its June grass (fine and dense) that's wet. Leaves a almost-lawn finish.
Jim