When roto-tilling how much engine RPM drop?

[North Dakota]

I have a ford 1710 with a 60 inch KK II tiller attachment the tractor has a 3 cyl diesel with a 24 hp PTO. Tiller manual says not to lug the tractor when tilling. KK web site says 25 to 40 HP recommended PTO HP.

OK onto my question. I set the RPM to 2400 which is the 540 PTO speed. Put the tiller in the ground and start tilling. The RPM will drop some 100 - 200 rpms and to get it back to 540 PTO speed I give the tractor a little more throttle. To me this would seem normal for a tractor doing work.

When is to much RPM drop a problem? What is considered lugging? To me a lugged engine would blow black smoke from the exhaust and have quit a bit of RPM loss.

 

[NewToy]

Sounds like you're doing fine. Depending on soil conditions you'll experience some RPM drop when you fully engage the tiller in the soil. You can feel the lugging factor, it's like trying to take too steep a hill in hi gear in your truck. It doesn't sound like you are having a problem, keep on grinding up that dirt.

John

 

[jbrumberg]

North Dakota:

"To me a lugged engine would blow black smoke from the exhaust and have quit a bit of RPM loss." I think you answered your own question. My "29" is comparable to your 1710 as is my tiller to yours. If I sense the tractor starting to strain (usually on the first pass on new sod) I increase throttle and/or raise the tiller slightly. I believe that the "specs" on the KKII tiller are very conservative as to PTO HP recommendations. Jay

 

[dqdave1]

I beleive some get "working" an engine and "lugging" an engine. A working engine will show black smoke , but holds RPM's near where you start. A lugging engine will drop many RPM's. Am I wrong in this accessment?

 

[JC-jetro]

A 'lugging" engine will not respond to increase of the throttle as if it can not cope with excess demand put on it. Reducing the throttle bring a lugging engine closer to normal condition, the same can also be archived by gearing down a lugged engine. As far as tilling RPM, I personally do not look at engine rpm, based on the soil type I set the throttle as low as I can to achieve the consistency I need. For my type of soil, I run my ford 1700 @ about 1300to 1600 RPM at whatever pto RPM it happens to be, that's enough to till my soil to powder consistency and the engine is just purring along. Saying that, the tractor is designed to operate the implement @ 540 rpm. For 1700 that means 2550 engine Rpm. Engine should be able to do that for hours on end if in good mechanical shape without any damage.

JC,

 

[North Dakota]

Thanks for the advice guys. I think everything is just fine then.

I Had to laugh at myself the other day. When I bought my tractor I put in the lowest gear it just crept along slower then a walk. I thought when would I ever use this gear? I found out it works real good for tilling unbroken ground.

 

[kbuegel]

The comment about running lower than 540 PTO rpm's makes me think of a related question - How often do you guys run attachments at 540 PTO rpm? Mowers, tillers, chippers, whatever. Seems to me the tractor is working pretty hard at high rpms, and using a lot of fuel. In many cases, I can run lower speed and the tractor seems to be a lot happier and still has power to do the job. Tractors don't last forever, so I try not to stress my engine for no reason. Running at 540 PTO rpm seems like its hard on the engine, and might shorten the life of the tractor if you do it for hours on end.

However, I understand how the governer on a diesel works - it adds fuel to keep the rpm at whatever you set it for (not really the same as a throttle on a gas engine). So in theory, the diesel with a fixed load uses almost the same amount of fuel at any rpm. But in practice, it sure sounds like its working hard at high rpms.

Can anyone shed light on this?

 

[North Dakota]

The comment about running lower than 540 PTO rpm's makes me think of a related question - How often do you guys run attachments at 540 PTO rpm? Mowers, tillers, chippers, whatever. Seems to me the tractor is working pretty hard at high rpms, and using a lot of fuel. In many cases, I can run lower speed and the tractor seems to be a lot happier and still has power to do the job. Tractors don't last forever, so I try not to stress my engine for no reason. Running at 540 PTO rpm seems like its hard on the engine, and might shorten the life of the tractor if you do it for hours on end.

However, I understand how the governer on a diesel works - it adds fuel to keep the rpm at whatever you set it for (not really the same as a throttle on a gas engine). So in theory, the diesel with a fixed load uses almost the same amount of fuel at any rpm. But in practice, it sure sounds like its working hard at high rpms.

Can anyone shed light on this?

My KK tiller manual says that the tiller was design to operate properly at 540 RPM only and warns of going above that. The only thing I could think that might happen with running at lower speeds then 540 RPM would be oil distrubition in the gear boxes on top and on the side of the machine might not splash around enough to get all the gears slopped with gear lube. It seems unlikely that that would be the case but at load under low rpms maybe damage could happen as the top gear in the side gear case of my tiller is quite a distance above the static oil level.

 

[pitt_md]

My Befco 66" tiller does not load down my tractor at all when all the down. I generally run in 2nd gear low range at about 2300 - 2400 rpms. The rpm's required to get 540 PTO speed is 2700. The fuel consumption between 2700 and 2400 is a lot and just seems to be less stress on the machine.

 

[ccsial]

I have a 1910 and use a 60" Howard rototiller. It will drop a few hundred RPM as well when the tiller is digging deep. I wouldn't worry.

 

[randy41]

I have a 1710 and pull a 48" tiller. it's a ford 105A tiller. I recently installed new blades and i notice the engine changes pitch slightly when the tiller is engaged. after the blades get worn it doesn't do this but it also doesn't till as well. so i would say the rpm drop is not significant.

 

[JC-jetro]

The only thing I could think that might happen with running at lower speeds then 540 RPM would be oil distrubition in the gear boxes on top and on the side of the machine might not splash around enough to get all the gears slopped with gear lube. It seems unlikely that that would be the case but at load under low rpms maybe damage could happen as the top gear in the side gear case of my tiller is quite a distance above the static oil level.

I tend to disagree with that statement. If you look at the level point (the hole that shows you had added adequate oil) in a gear driven KK tiller you'll notice the oil totally covers most of the lower gear , middle idler gear and half of the top gear... even @ 100 rpm of the tiller the gear will see adequate lubrication the same as set of bevel gears in the gear box above. What matters is quality of soil in general and the degree of tilling one needs. I don't drive at the speed limit because the sign says 65 MPH, I drive some where lower than 65 where I feel safe considering all the road conditions,..... kind of same logic with the PTO speed

JC,

 

[akazad1]

what is the reason behind high rpm drop in puddling application(pulverization of soil ) often used in wet land areas in southern Andhra pradesh ,INDIA

 

[Reg]

IMO "Lugging" is when the revs drop so low that a stall SEEMS imminent.
With a rototiller hitting a hard spot, or unusually large rock, it can actually stall the tractor.
Generally not good, sometimes disastrous.
SOME diesels can suffer all sorts of internal damage when stalled under heavy load and then additionally shock loaded - meaning a sudden additional load, e.g. a rock jam in the tiller.

So, if it is dropping WAY down, say below 2,000 on full throttle, decrease ground speed or decrease depth - almost that simple.

I think the slip clutch won't ALWAYS protect against stalling.
Well, if you have it so loose that it smokes like a burning off Harley rake, maybe,
but you don't want to run like that for very long.

 

[Reg]

My KK tiller manual says that the tiller was design to operate properly at 540 RPM only and warns of going above that. The only thing I could think that might happen with running at lower speeds then 540 RPM would be oil distrubition in the gear boxes on top and on the side of the machine might not splash around enough to get all the gears slopped with gear lube. It seems unlikely that that would be the case but at load under low rpms maybe damage could happen as the top gear in the side gear case of my tiller is quite a distance above the static oil level.

Pretty sure mine says at or below 540, i.e. no lower limit.
Trust me on this one; Oil climb isn't very dependent on speed, within some reasonable range, i.e. the oil will get everywhere it needs to at speeds as low as 50 RPM, probably lower.

Try it sometime.
Run the tiller high off the ground with the engine at idle for just a second or so.
Stop it, lower the 3 point, get out your tools and take the side cover off.
Betcha a week's pay there is still oil sliding down the insides of the cases (-:

 

[Mechanos]

Another consideration would be the direction of rotation of the tines. Some tillers rotate with the directions of travel, some rotate against the direction of travel and some are capable of operating in both modes.

 

[Dingeryote]

I run either a Woods 72 or a Kuhn 72 on our 1920.

Ground is either sandy loam or heavy black swamp muck, depending on the field.
2-300 rpm drop is normal when the tiller bites.

For what we do, running the PTO @ 540 and keeping forward travel good and slow for aeration, and busting up bits of organic matter into a fine and fluffy layer. Bogging happens down around 1500rpm in the clay/Marl around a couple ponds, and you WILL know "Bogging", when you hear it and feel the little Ford complaining.

Running the thing at 540 under a light to moderate load, doesn't wear the mill any more, than running it at a lower RPM.
Those nice Engineer folks at Shibura, optimized the torque curve, lubrication, cooling, and everything else for running at that speed under a load.

Some will argue that due to reduced lubrication and coolant flow, longer time with rings under pressure, and less flywheel effect, operating under a moderate load at lower rpms, MIGHT actually cause increased wear. I dunno. I ain't an engineer, and have heard from a couple slide rule types, that such things have been addressed on modern tractors, especially Deere, considering thier "E" PTO settings.

Tillers with gears get sufficient lube at any speed, if the gear oil isn't worn into watery consistency. Tine shaft gear, gets dunked and carries it to the idle gear, and then to the drive gear. Flinging 90-120 takes some doing, the stuff is tenacious, and it ain't happening at the speed the gears are spinning.

Set the thing for 540, and pick a gear that allows the Tiller to remain at a constant depth. If it's rising out of the cut or leaving clods, drop a gear.
If she wants to crawl while nibbling, let it crawl.

 

[oldballs]

Although new at tilling with a tractor, I found that the HST transmission allows me to immediately slow the ground speed down to allow the tiller to "catch up" when it bogs down in a heavier wet area....and then the engine smooths right out again.

 

[Reg]

Although new at tilling with a tractor, I found that the HST transmission allows me to immediately slow the ground speed down to allow the tiller to "catch up" when it bogs down in a heavier wet area....and then the engine smooths right out again.

Try it with a geared tractor - - SO much better ain't it ?

 

[RedNeckRacin]

I run either a Woods 72 or a Kuhn 72 on our 1920.

Some will argue that due to reduced lubrication and coolant flow, longer time with rings under pressure, and less flywheel effect, operating under a moderate load at lower rpms, MIGHT actually cause increased wear. I dunno. I ain't an engineer, and have heard from a couple slide rule types, that such things have been addressed on modern tractors, especially Deere, considering thier "E" PTO settings.

The "E" setting on a Deere runs the implement at 540 rpm though. Just in case anyone wasn't sure of that. It lets the motor turn at around 1700 and the pto to turn at the full 540. I really dont see any harm at running slower than 540, except that the implement was designed to work at that speed. I can think of a few conditions where you might want to slow a little or speed up a little.

To exaggerate a little; why in the world would you want to run an implement at idle instead of working it near its rated speed unless you like spending alot more time in the seat? Maybe it makes more sense with a tiller to slow it down incase you find a larger rock, but isn't that what shear bolts and correctly adjusted clutches are designed for?

As for the OP, a few hundred rpm drop just means the tractor is taking on load. If it continues to drop, thats lugging it down. The tractor should have enough power to maintain the speed on the tach and to get the full pto hp, you gotta run at the rated tach speed. Otherwise, your not putting all the hp to the dirt.