Mid PTO use
hardwood
Join Date: Dec 2002 Posts: 3583 iowa |
2004-03-19 80371
I'd like to mount a 30 GPM hydraulic pump under my 4410 driven by the mid PTO to power a 42 inch light duty rotary mower on an offset frame mounted on the 3pt. to be able to drive in the bottom of the road ditch and mow the steep incline while keeping the tractor level, kind of a mini version of the big units the county uses. My question is, does the smaller 2100 RPM mid PTO have the ability to handle the full power of the engine like the rear PTO, or was it meant only for light to medium duty use. I've tried to figure ways of using the rear PTO thru a 90 degree gearbox but that gets pretty complicaed, so for the sake of simplicity I'd like to use a hydraulic drive. Thanks, Frank.
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Mid PTO use
harvey
Join Date: Sep 2000 Posts: 1550 Moravia, NY Pics |
2004-03-19 80373
Frank I have looked at that idea many times, only for another purpose.
I can not see any problem with power. If it were me, I'd try to size the pump input shaft close to the pto size.
I think, (WAG) (wild ass guess) the pump would be expensive.
A 72" mid mount mower has gotta be using all avaiable power.
I need to get with the local guy at the hyd shop and prusue that idea. ....
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Mid PTO use
blizzard
Join Date: Jul 2003 Posts: 282 Central Maine Pics |
2004-03-19 80374
The mid PTO must be able to handle the full engine power, otherwise it would break if you ever plugged the mower with heavy grass. Torque would be a lot less than the 540 RPM rear PTO, and some mfgs. use a special shaft spline.
Here's the formula: HP = (Torque * RPM) / 5252
or, Torque = (Horsepower * 5252) / RPM
Hope this helps,
bliz
'$#&%!?' curses! Leading spaces reformatted again! I Hate Java! ....
Link: Torque_horsepower
 
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Mid PTO use
Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada Pics |
2004-03-19 80385
Frank, it will handle the load...however, you have to be careful.
Many PTO's are suseptable to bearing problems if you load them up at less than rated PTO speed. Same applies to transmissions, they are designed to run ground-engaging implements (plows, etc.) at about 5 mph.
I remember reading a study done by one of the big Ag. universities in conjunction with I believe Case. They found that the tx would only last half as long if you worked it hard at the wrong speed.
I also remember seeing a CUT in pieces at the dealers a few years back, the owner had been cutting a lot of grass with it, but instead of using the right speed and 540rpm setting, he was running much slower and using the 1,000rpm setting. Every bearing in the PTO line was shot and a few in the tx itself.
Usually the mid-PTO runs hat a higher speed than a pump wants to run. It's probably easier (and safer) to just buy a Prince PTO pump at TSC, they're only a few hundred bucks and will run ANYTHING.
And don't forget, you will need a BIG reservoir to keep all that work from making more heat than the system can handle.
Best of luck. ....
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Mid PTO use
Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada Pics |
2004-03-19 80397
The other problem will be weight.
Even a light duty Howse (42") cutter will weigh about 500 lbs. and if it is offset to run on the outside of the rear tires then the mid-point of the weight will be, half the width of the tractor, 30" ?, plus half the width of the cutter as hitched, 21", 51" beyond the centerline of the tractor. This will require some serious counter-balance weights a LONG way out the other side in order to be able to safely pick it up.
I would think an old sickle-bar mower would be a whole lot easier and safer.
Best of luck. ....
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Mid PTO use
beagle
Join Date: Jan 2004 Posts: 1333 Michigan Pics |
2004-03-19 80421
I like blizzards line of thought. The mid pto will develop 1/4 the torque of the rear pto. This will work the engine hard. I swore to never use a mid mount mower deck again for just that reason. It loads the engine harder than most anything off the rear. Use the rear pto to run the hydraulic pump for good torque at the proper rpm.
Thse sickle mowers look a little dangerous to me, but that is probably because I lopped the ends off two fingers a couple years ago with hedge trimmers. They look like big hedge trimmers to me. ....
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Mid PTO use
hardwood
Join Date: Dec 2002 Posts: 3583 iowa |
2004-03-20 80456
Thanks to everyone for all your input. The rear mounted offset rotary mower was one of those 2 o'clock in the morning strokes of genius that we all seem to have now and then. I allready have the pump, universal joint shaft, some of the mounting brackets built to put the pump under the 4410. The original idea of the pump unit was to power orbit motors on grain augers during harvest. We did kind of the same thing to an "M" Farmall a couple years ago, by mounting a pump under the tractor and powering it from a double v pulley mounted on the original belt pulley hub of the "M" and using the rear end housing as a sump. After some fine tuning it has worked out real well. The pump unit for the 4410 will be totaly independent of the tractor, separate sump, it's own valve unit, and possibly a radiator unit if heat becomes a problem. I normaly order pumps, valve units, orbit motors, etc. from The Surplus Center. They have a good tech. dept. that will help you size pumps, motors, valve units, or whatever you need to match what you want to acomplish. You've answered my question of the ability of the PTO to handle the load, and brought up a lot of good points on the problems I would run into with weight being off centered, etc. After doing some calculating it looked like even with a light duty mower, (the one I checked on weighed 440 lbs.), the 3pt. frame to mount all this to, quite a bit of counterballance weight I was going to end up in the 1500 lb. range, that seems pretty heavy. I called around checking the price of a light mower and with the most recent 9% price rise, things got out of hand pretty fast. I do have a couple sickle mowers out in my "Reserve Inventory Yard", my wife has another name for it something like "that blankety blank junk yard" so the old sickle mowere are starting to look better right along. Thanks again, Frank. ....
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Mid PTO use
TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley |
2004-03-20 80461
For a pump the shaft, direction of rotation, max pressure, displacement and rpm range are important. I think max rpm's may run up to 4000 rpm but typical operation is under 2000 rpm. Might be that a pump could be found that wouldn't require gearing. The flow/pressure requirements of the load would determine the pump displacement and pressure rating and also the pto output hp required. Well, payment for losses has to be thrown in.
I'll do a take on some concepts, or at least my understanding of how they apply. Good chance I'll learn something too.
A given source of power (engine output can be expressed in BTU's) produces combination of speed and torque that can be expressed as HP. Max engine HP and losses produces a set max output HP. A designer makes a choice between speed and torque to drive an output device but the HP remains the same--more rpm equals less torque for the same HP. However, an engine only produces output power sufficient to move a load at a demanded speed and how hard an engine works depends on the load.
If a MMM does work an engine harder than an rear mower of the same blade diameter then it may be because the blade speeds are higher. May be that MMM make a better cut because they have higher blade speeds and that's what requires more hp. Irrespective of the pto rpm it's the blades against the grass that produces the load. If the blade speeds are the same and the pto rpm's are different than the mowers have different gearing, and gearing in the mowers box has to be considered in the final torque applied to a load. Under-drives are sometimes called torque multipliers. ....
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Mid PTO use
hardwood
Join Date: Dec 2002 Posts: 3583 iowa |
2004-03-20 80463
TomG; Thanks again for your intrest in my project. I can't tell you the model number of the pump without going to the shop to look at the pump, but I do remember that it is designed to operate up to 3000 RPM and is also to operate in the correct direction. One of my goals is to elimenate any complex drives to the pump and have a direct hookup thru a universal joint PTO shaft. Any other ideas will be more than welcome, as I'm sorta in uncharted waters. Frank. ....
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Mid PTO use
beagle
Join Date: Jan 2004 Posts: 1333 Michigan Pics |
2004-03-20 80467
Tom good points, the Power curve of the engine tells you what Power is available at an operating rpm. A good unit to think of power in would be ft-lbs/sec. "Power" is the rate at which Work can be done, "Work" is Force applied x Distance. One Horsepower equals 550 ft-lbs/sec. A one hp engine can do the same Work as a 10 hp engine, but would theoretically take 10 times as long to get it done. An engine, due to mechanical and thermodynamic efficiencies, will reach maximum torque at a lower rpm than it will reach maximum hp.
After some digression, back to the original question. My feeling on the rear pto is based on the available torque at the shaft. Although the Power available at both shafts is roughly the same, the rear pto has about 4 times the available torque (about 1/4 the rpm). The mechanical advantage gained at the pto shaft would theoretically be lost if the mower is geared back up to the same blade speed. I'm not sure they are, which may explain why mid-mount mowers generally give a smoother cut, while rear mount mowers don't load the engine as heavily. I need to think about the angular momentum stored in the decks from the spinning blades, and what effect a heavy load at the blade has at the pto shaft. Because the rear is geared down, there may be an anvantage to the tractor there.
Thanks for the thoughts. Saturday morning, need another cup of joe to think this through.
....
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Mid PTO use
CraigC
Join Date: Jul 2003 Posts: 83 Hebron, IN |
2004-03-20 80538
A big draw back to a sickle mower would be that they are very fragile, any rock or good size tree, branch etc. and you have parts. ....
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Mid PTO use
hardwood
Join Date: Dec 2002 Posts: 3583 iowa |
2004-03-21 80550
CraigC; That's the reason I've been trying to think of some way to mow the steep banks without using a sickle mower. It got to the point I was spending more time fixing than mowing. There is surely someone on the board who can figure out some sort of a lazer beam, light beam, high pressure water jet system of some sort that will cut the grass and make mechanical mowers obsolite. He can keep the patent rights, just sell me one of them. Enjoy the day, Frank. ....
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Mid PTO use
TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley |
2004-03-21 80555
A contractor working for a nearby township has a thing for brushing road right of ways. It's a fairly small cutter head mounted on articulated arms like a BH. The head and arms are hydraulically operated and it will take out limbs and saplings. The trouble is that the one I saw was mounted on a 5-ton truck bed and still had a bunch of counter-weight hanging over the opposite side of the truck. It also took a driver and an operator to run. Sure did some spectacular work but I'm not sure how feasible the idea would be for a CUT.
For continuing to play with hydraulics ideas, a fairly recent thread on saw mills has some pretty good ideas. The problem there was high torque/low speed motors while the problems here may be high torque/high speed motors. Never the less, the discussions about matching pumps to motors are relevant. High torque motors tend to have max speeds around 700 rpm so the idea likely is feasible although it would take a specialist to actually design a system. ....
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Mid PTO use
CraigC
Join Date: Jul 2003 Posts: 83 Hebron, IN |
2004-03-21 80574
Hey Hardwood you forgot fire! I'm waiting for the right condition this spring so I can burn my fence rows down. I have alot of hedge and medaflora-rose (I think taht's what they call it, red thorns tear your ass up). ....
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Mid PTO use
hardwood
Join Date: Dec 2002 Posts: 3583 iowa |
2004-03-21 80582
CraigC; you hit the nail on the head, fire is the cheapest, lowest labor, automatic fencerow mower ever invented. but now the county health dept. gets really cranked over any open burning of anything, I guess it's better to truck the trash a couple states away and polute their environment than our ours acording to them, don't get me started on that subject or I'd be banned from the board for life. Frank. ....
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Mid PTO use
CraigC
Join Date: Jul 2003 Posts: 83 Hebron, IN |
2004-03-21 80609
I've got it Frank, a belly mounted flame thrower! We'll mount a 100 pond LP bottle on the 3pt and a weed burner under the tractor pointing out the side. You'll be able to burn as you drive (hopefully not literally!). What do you think, should we patent the idea? ....
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Mid PTO use
hardwood
Join Date: Dec 2002 Posts: 3583 iowa |
2004-03-21 80648
CraigC; I'm afraid someone beat us to the punch on the flame thrower idea. When I was a kid somebody came up with a weed flamer to cultivate corn with. I remember my Dad and I went to watch a demo of this thing. it looked pretty good till the next day when corn, weeds and all were dead. But then their patent probably has ran out by now, so why not we might end up richer than Oprah. Gotta laugh once in a while, Frank. ....
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Mid PTO use
Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada Pics |
2004-03-22 80714
Frank, the trick is to make it using the same theory as a trailer is based on, it's easier to pull than carry a load.
Hydraulically drive a mower which rides on dolly wheels. If you mounted it on an arm you could give it hydraulically adjustable offset, like the swing of a BH. Then you just go back & forth, each pass moving it further out till you have the desired width cut parallel to your path.
In fact for that sort of work a hydralically driven Mott mower might just be the ticket, and probably a lot sturdier too.
Although you could also make a tool bar with multiple string-trimmer heads along it's length and do the same thing.
Best of luck. ....
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Mid PTO use
itsgottobegreen
Join Date: Oct 2003 Posts: 329 Mt. Airy, MD Pics |
2004-03-22 80752
You guys might want to check ebay. number 2388309331 this guy took the mid pto and hooked up a pump to run the hydraulics on the loader mounted snow blower. I got to have one of thoses. its really neat. ....
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Mid PTO use
Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada Pics |
2004-03-22 80759
I have seen many FEL-mounted blowers, however they are normally powered by a 24hp. gas engine through a chain reduction unit.
In fact a lot of people north of here mount them on a pickup using a regular snowplow mount.
Best of luck. ....
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Mid PTO use
hardwood
Join Date: Dec 2002 Posts: 3583 iowa |
2004-03-22 80781
WOW, I never dreamed how many responses I'd get to my rotaty mower question, I really apreciated each and every one, and did learn a lot from you guys and the suggested web sites. For right now I'm going to build the pump unit for the farm use and someday go on from there with other ideas. I've never been happy without a challange of some kind. Just now got to thinking, why not buy a milk cow, have the wife milk her twice a day and just move the cow to the next fencpost down the road after every milking. Frank. ....
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