Go BottomJohn Deere JD 2520 with 72 inch mid mower
 | nosteiner4me
Join Date: Mar 2007 Posts: 113 ohio 
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2007-07-02 143365
Just left a dealer that hesitated for a minute with me wanting to put a 72 inch mid mower on a 2520 machine. He said that i may want to jump to the 3120 with the extra 3 hp, but the machine just looks too big for my 4 acres of just mowing, not brush hogging. He said it would "probably" be fine with the 20pto hp for the 2520 as long as not too tall of grass. Would i be putting too much strain on the 26.5 hp engine to run a 72 inch deck or would it be ok. My acreage is a weed grass mix, but looks great when mowed. Also could not find anywhere on the 2520 as to ground speed it can travel in high, any ideas? 10mph or so?
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 | earthwrks
Join Date: Dec 2003 Posts: 3853 Home Office in Flat Rock, Michigan 
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2007-07-02 143367
You should be fine. I have a New Holland TC33D 33 hp (brake) 27 hp (PTO) and can brushhog 6' tall, fine grass and weeds---even 3" trees with no problem. A finish mower will see even much less "abuse" than that. My ground speed in high range is 17 mph---but trust me---unless your yard is smooth as glass you won't be flying around your yard unless you have a good chiropractor. ....
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Add PhotoJohn Deere JD 2520 with 72 inch mid mower
 | kthompson
Join Date: Oct 2005 Posts: 5275 South Carolina
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2007-07-02 143370
EW, height and width are not the same for normal people. :)
I have about the same size Kubota in a B series and just happen to cut grass with it Saturday with a 72" RFM. Boy did it have it's hands full. The grass was thick due to a lot of recent rain and the temp ran toward he upper end of the normal range even at 5 MPH (max speed in mid range). Now when I got to the normal not thick grass I could have cut it in high range and been fine. kt ....
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| nosteiner4me
Join Date: Mar 2007 Posts: 113 ohio
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2007-07-02 143373
kthompson/earthwrks...The dealer did not have a 72 inch mid mount mower and would have to order one. He said i could demo the loader and tractor....... but maybe i need to demo the 72inch mid mount mower to be sure it can handle 4 acres. Now you used a rearmount 72 inch deck? Isn't the rpm of the rear pto different (slower) than the mid pto and that could be the poor performance in wet grass or the b series kubota you were using was 24hp or less?. I think i need to demo the 2520 with the 72 inch mower and want it to mow faster than 5mph for sure, it is nice and flat, It should handle it but at $20,000 plus or so with loader it better. ....
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Add PhotoJohn Deere JD 2520 with 72 inch mid mower
 | Chief
Join Date: Jul 2003 Posts: 4297 Southwest MiddleTennessee
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2007-07-02 143375
A 72" MMM is too much mower for a 2520 in my opinion. Can the 2520 cut grass with a 72" MMM? Yes, but the engine will be taxed much more than with a 60" or smaller MMM. The mid pto turns at a MUCH higher speed than the rear pto. 2100 rpm mid vs. 540 rpm rear. The engine actually works harder to turn the mid pto under most circumstances due to the much higher gear ratio. In moderate to heavy turf the load on the engine will only get worse. Not a good idea to match components on your tractor that run the engine at its max or near max power on a regular basis. Deere lists the 72" MMM deck as being compatible with the 2520 and it should cut OK provided you are not trying to mower over grown, thick, or heavy turf vegetation. The 72" MMM will be more prone to scalping as well as being a little more difficult to install and remove than the 62D On Ramp MMM, not to mention manueverability with respect to trimming in close around obstacles on the lawn. Be advised that the 72" MMM that Deere lists as being compatible is NOT the 72" 7 Iron MMM but a MUCH lighter duty MMM that I think you will be disappointed with. I would go with the 62D On Ramp MMM. I don't think the 62D is 7 gauge construction either but it is the MMM designed for this series machines and a much better fit in my opinion.
I have the 72" 7 Iron MMM on my Deere 4410 and it takes ALL of the 29 pto hp to run this mower in heavy turf when finish mowing my fields and pond area. It is a great mower but I think MMM this width would be a bit much in some circumstances for your 2520. ....
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 | JasonR
Join Date: Jan 2006 Posts: 142 Northern Indiana
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2007-07-02 143376
Slightly off topic (or at least the initial question)...
I don't own a 3PH rear mower, but I am curious if they have a gearbox on them such that the blade speed (at 540RPM) is the same of a MMM (at 2100RPM). When I set up my MMM to run off the back, my drivetrain added a 1:4 ratio, so the blade speed was close to the MMM speed.
- Jason ....
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| earthwrks
Join Date: Dec 2003 Posts: 3853 Home Office in Flat Rock, Michigan
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2007-07-02 143379
Jason can you elaborate on the MMM mounted on the rear as far as RPM's. On the face of it, it would seem that your RM MMM had a speed reduction of 1/4 if you directly connected the MMM PTO shaft to the 540 PTO. ....
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Add PhotoJohn Deere JD 2520 with 72 inch mid mower
 | candoarms
Join Date: Mar 2007 Posts: 1932 North Dakota 
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2007-07-02 143380
JasonR,
The gearbox on the rear mounted bush mower is likely a 1:1 ratio. It is not geared up.
The rear mount mower uses a single blade, with a very large diameter, which increases the blade tip speed tremendously.
The mid-mount mower uses three (or more) smaller blades, which doesn't provide much blade tip speed. The only way to increase blade tip speed on the MMM is to increase the PTO shaft's RPM. Doing this, however, decreases the amount of torque supplied by the tractor, by a factor of about 4.
The difference between the mowers in the length of the blade on the Brush Mower. At five feet in length, or more, and spinning at 540 RPM, the blade's tip speed is incredible.
Joel ....
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| JasonR
Join Date: Jan 2006 Posts: 142 Northern Indiana
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2007-07-02 143384
earthwrks - the rear pto turns a shaft with a large dia. pulley, which in turn drives a smaller dia. pulley (this pully is the pivot point for the ditch mower) and the pivot pully turns a slightly smaller pulley mounted to the original gearbox on the MMM (where the MM PTO used to hook up)
candoarms - thanks, I never checked one out ....
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Add PhotoJohn Deere JD 2520 with 72 inch mid mower
 | DRankin
Join Date: Jan 2000 Posts: 5116 Northern Nevada
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2007-07-02 143386
Not all rear mount mowers are "brush hogs". My RMM has three overlapping blades just like a MMM. ....
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| candoarms
Join Date: Mar 2007 Posts: 1932 North Dakota
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2007-07-03 143388
DRankin,
You're absolutely correct.
You are referring to a Three-Point finish mower, which incorporates several smaller blades. Those shorter blades don't cut well at 540 RPM, which is why there are usually several pulleys used on the 3-point finish mowers, which are sized to speed up the blade tip speed.
A tractor with a 20 Horsepower PTO rating is essentially reduced to 4 Horse, when the 3-point finishing mower is geared up by a factor of 5 to 1. (2500 RPM) This is why it is so important to keep a finishing mower's blades sharp at all times.
Joel
....
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Add PhotoJohn Deere JD 2520 with 72 inch mid mower
 | hardwood
Join Date: Dec 2002 Posts: 3583 iowa
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2007-07-03 143391
What ever year the 4300's came out I bought one with the idea of having a mid mount mower. My dealer did me a favor by changing my mind to a three point finish mower. His reasoning was for the ease of mounting a RFM compared to the MMM, he was right. Just pulling the deck from under the wife's 345 ranks right up there with a root canal experience. I've still got the same mower for the 4310, it is a Land Pride 72 inch Air Tunnel model. This time of year I probably mount and dismount it at least twice a week, it takes all of five minutes either direction and all from a standing position, a quick coupler on the three point helps a lot too by not having to line up and push the three point arms over the pins on the mower. Frank. ....
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| kthompson
Join Date: Oct 2005 Posts: 5275 South Carolina
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2007-07-03 143393
Jason, many if not all mowers give their tip speed in sales brochures and possible manuals. It will vary within a brand from model to model. ....
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| nosteiner4me
Join Date: Mar 2007 Posts: 113 ohio
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2007-07-03 143394
Ok back to my main concern on the JD 2520 and 72 inch mmm.
I got rid of steiner tractor 28hp Kubota deisel with a 72 inch front mower due to serious problems with hydraulics and lack of lifting power and they discontinued the line. Anyway the steiner had no problem whatsoever with a 72inch front mounted deck which was belt driven from the pto. I find it hard to believe the JD 2520 would have any trouble at all with the 72" mmm in normal cutting conditions. I used to mow at 7-10mph and would like the tractor to do the same. My land is fairly flat but does have a long hill in the front. I take everyones advice on here to the bank because you are the experts with the experience... ....
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| DRankin
Join Date: Jan 2000 Posts: 5116 Northern Nevada
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2007-07-03 143395
I think you just said it...."normal cutting conditions". If you mow frequently you should be ok.
As far as the ground speed, the 2520 is very similar to my 4115 and my top speed with 33 inch tires is 11-12 mph. Low range is more like 5 mph. ....
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| hardwood
Join Date: Dec 2002 Posts: 3583 iowa
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2007-07-03 143406
NoSteiner; I just re read your questions, and have to ask why you would want to mow at the speeds you mention. At anything above 3-4 MPH the blades of any mower no matter how sharp just aren't above a given spot long enought to give it a decent cut, at speeds of 10MPH, no mower can be expected to do a decent job no matter how much horsepower the tractor may have. My top speed for the RMF is about 2.5-3 MPH. Frank. ....
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| nosteiner4me
Join Date: Mar 2007 Posts: 113 ohio
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2007-07-03 143410
Hardwood....Have never had an issue with the speeding while i mow. The cut looks fine and i want to get done and not mow all day long( now i do have a grass and weed mix, not a real manicured all grass Scotts commercial lawn). I guess at 7 mph plus i cut probably 97% plus of the grass under the deck at any given time and i really don't need to cut 100% of it per week for the 4 plus acres. Guess i have always mowed fast and 2-3mph on 4 acres forget it. I've tried to mow once with a 72" deck with a 25hp gas kubota and it would loose rpms and i had to slow down quite a bit but not with the deisel engine. ....
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Add PhotoJohn Deere JD 2520 with 72 inch mid mower
 | Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada
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2007-07-03 143413
As has been pointed out, the blade speed of a PTO-driven mower is fixed, as a multiple of the 540 rpm PTO driving it.
It is only on larger commercial mowers where they run very high blade speeds (compared to PTO-driven mower) that you can cut at speeds much above about 5 mph.
Unfortunately if you are looking for cutting speeds in the 10 mph range on a CUT you're just plain out of luck.
Best of luck. ....
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| kthompson
Join Date: Oct 2005 Posts: 5275 South Carolina
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2007-07-03 143417
nost..
Missed your reply to my first reply. My Kubota is 27 hp. The grass was not wet, but thicker than normal due to above normal rain. Think I pointed out for normal situation my 27 hp handles the 72 RFM fine. Yes in high range and yes running as fast as I want to...maybe 7 or 8 mph. As to how the tip speed compares between MMM and RFM, I have no idea. Never wanted a MMM, like the RFM for reasons someone else posted. The type of grass you have of course will affect it. ....
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Add PhotoJohn Deere JD 2520 with 72 inch mid mower
| hardwood
Join Date: Dec 2002 Posts: 3583 iowa
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2007-07-03 143420
NoSteiner; Not trying to give you a hard time on mowing speed but here goes anyway. I did a bit of math, First let's assume that a 72 inch mower is actually cutting 65 inches per swath moving at 3 miles per hour, that comes out to be 1.96 acres per hour or 2.04 hours to mow 4 acres. Now we add 20% to that time for turning, breif stops for what ever reason, that works out to roughly a short two and one half hous to mow the 4 acres at 3 MPH. Now lets use your ten MPH mowing speed. Same thing we'll use 65 inches as the average cutting width of the 72 inch mower. using the same formula it comes out to aproximately 48 minutes to mow your four acres, it could have been slightly less but I added 20% to the time for turns and a another 10% to your mowing time to allow you to slow down enough to make a turn without rolling the tractor on a sharp turn. Nuff from me. Frank. ....
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| nosteiner4me
Join Date: Mar 2007 Posts: 113 ohio
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2007-07-03 143422
Math is good frank....I buy and sell diamonds all day long calculating things like estimated weights, table and depth % and so on. Your math is very correct...It takes me 1 hr 10 minutes to mow my 4 plus acres with 72 inch deck with normal weekly mowing..nothing overgrown.. without trimming of course. I appreciate all the response from the experts here...you guys know your stuff and thats why i needed your advise before spending 20,000 on another toy. Didn't think i was opening a can of worms on rpms,pto hp,blade tip speed,and mowing speed. Again thank you all for your valuable time. ....
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Add PhotoJohn Deere JD 2520 with 72 inch mid mower
| whiteturbo
Join Date: May 2005 Posts: 77 Shelby NC
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2007-07-05 143452
Have you considered buying a cab tractor? If you don't mind about 5,000 more dollars it is well worth the cost. I have a 3520 cab and love it. ....
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| nosteiner4me
Join Date: Mar 2007 Posts: 113 ohio
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2007-07-05 143453
Those cabs are sweet...but wouldn't past muster with the
CEO. If i got one it would cost me the cost of the cab plus a diamond bracelet or ring, and besides i don't think it would fit in my garage because of height. ....
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| hardwood
Join Date: Dec 2002 Posts: 3583 iowa
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2007-07-05 143455
Whiteturbo; I am assuming the cab has AC. How does it affect the power when the compressor kicks in? I'm not ready to trade yet, but when I do a cab might be in the pictire if I can mount the 48 hoe on it. Frank. ....
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| Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada
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2007-07-06 143467
Frank, I don't know about the JD machines, but being an engineer with a yard full of Kubotas I've done the power calculations on the A/C system in our machines.
A typical small A/C compressor has a power consumption of about 2,000 watts or 2.6 horsepower while running under full load. Bear in mind however, the compressor cycles on and off as demand dictates.
On a personal level, I can tell you I haven't yet found a time when I could detect the power drop when the A/C compressor kicked in. I sure do notice the sudden drop in temperature and humidity though! ;)
Best of luck. ....
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| hardwood
Join Date: Dec 2002 Posts: 3583 iowa
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2007-07-06 143472
Thanks Murf; 95% of the time I'm never running under max load, so likely woudn't notice the slight losd of the little compressor. I think today would be a good day to test drive one. Weather person said 95 here today. Frank. ....
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| kthompson
Join Date: Oct 2005 Posts: 5275 South Carolina
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2007-07-06 143477
nost...does that tractor have a folding roll bar? Or have you checked to be sure it clears the garage also? ....
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Add PhotoJohn Deere JD 2520 with 72 inch mid mower
| nosteiner4me
Join Date: Mar 2007 Posts: 113 ohio
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2007-07-06 143478
Yes the 2520 has folding rops 68.9 inches. It will fit folded just fine. The 3120 folds down to 72 inches and will also fit just fine. Just can't make up my mind on which one to get. The 3120 is 2900 lbs and 2520 1900 lbs. Big difference in weight without any attachments. 3000 lbs for a tractor for 5 acres seems overkill to me with really just mowing and the occasional moving firewood and rocks. ....
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| whiteturbo
Join Date: May 2005 Posts: 77 Shelby NC
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2007-07-06 143479
I have 37 hp and I mostly use mine to cut grass so it does not seem to affect my hp at all. The only time I even know the compressor is cycling is when I am outside the cab at a idle and I can hear it click in and I don't hear the engine die down any when it does. The compressor is a very small one anyway. As far as using a hoe JD says you can't install a hoe with the small can tractor. I guess because the back window there is not enough room.
As far as going inside a garage i don't think the cab tractor is as tall as a non cab. Mine goes in a 8' doorway and has about 6" left. I have R 3 turf tires on mine. ....
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