Run @ 540 PTO RPM or faster when cutting?

Don't know who is right or wrong but I never run anything on the PTO faster than the 540 or 1000 mark on the tach, But what do I know

I think the conclusion is run your equipment at the manufacturers suggested speeds and loads.  Companies pay engineers a lot of money and spend millions in R&D to get maximum performance out of equipment.

This is Stan's original post:

Stan IL&TN wrote: Just wondering if you run faster engine RPM than the indicated 540 PTO speed when bush hogging or do you run her faster?  I ask because I was told to run her wide open for the best looking cut and it's easier on the engine not to lug it.  Just wondering what others do?

All comments regarding combines, silage blowers, lawn mowers, recutters, bailers... they're all irrelevant to Stan's posting.  His was about a 540rpm PTO-driven rotary mower.  As was posted earlier, comparing engine speeds of for-purpose engine-driven machinery (combines, lawn-mowers, etc) is irrelevant to the 540rpm implement.  The answer to the question of WHY is found in history, and engineering design and economics.

References to 'wide open' are improper terminology.  Throttles and injection pumps have 'wide open' positions of 'full fueling'.  These are GOVERNED engines, which by nature, are intended not only to limit engine speed, but hold it constant at a given speed.  Governors modulate throttle position to maintain governed speed.  A goverened engine will run at the desired speed with practically no throttle, when there is no load.  As load is applied, engine speed will drop off slightly, and the governor will BEGIN to increase throttle opening (technically referred by governor and engine-management engineers as 'sag')... the engine will only see 'full throttle' from a governor when the load is substantial enough to require all that the engine is capable of providing.  Once full throttle is reached, any additional load applied will slow the motor down BELOW the goverened speed, which is usually referred to by engineers as 'overload fall-off'.

Running an engines of for-purpose machines is irrelevant, because the machine is designed only for that purpose, and the engine governance, and all driven loads, are appropriately ratioed to their optimal speeds by drive mechanisms therin.  Engineers determine proper speed of all those pieces, assemble the drivetrain ratios, and then calculate the proper final drive ratio by comparing the prime mover's fuel and power curves, calculate performance lifespan and durability, and then apply the appropriate drive ratio, and set (now program) the engine speed governor accordingly.

540rpm PTO output systems on tractors have been well-standardized since the late 1950's.  Prior to that time, manufacturers made implements intended to be driven by their OWN tractors.  They Generally worked within the realm of ASAE standards of the mid '30's, wherin the common 540RPM PTO shaft operated at 540rpm +/- 10rpm, in a clockwise direction (when viewed at the output of the driving machine).  Through the late '50's, the expiration of Harry Ferguson's 3-point patents (there were many) gave the ASAE the ability to publish a 'standard' of hitching geometry, and they 'categorized' hitching sizes to tractor size.  At the same time, they published the PTO standards.

Once that occured, agricultural manufacturers both on the tractor end, and in the implement business, went to manufacturing implements to allow compatibility with other manufacturers.

Prior to the 60's, belt-driven implements were very common.  Belt-driven implements fell in their own neighborhood based on belt speed (in feet-per-minute), and the operator had to calculate a reasonable speed based on knowledge of the prior drive machine (oftentimes a steamer).  It isn't unusual, particularly after the late '30's for full-goverened speed to be bumped up... manufacturers did this as part of the 'horsepower wars' to improve package performance.  When doing so, the 540rpm PTO's final gearing either had to be altered (to accomodate the resulting higher speed), or the engine had to be slowed-down, and the PTO output tested (think Nebraska Tests) at less than full-goverened speed.  Manufacturers knew this would be a loss of performance-point (if the engine didn't create higher torque without the governed speed increase), however, it was a small price to pay vs. cost of tooling for lower PTO gear ratio.  Manufacturers also had to contend with belt hp performance, but towards the middle '60's. the importance of belt HP to the agricultural market fell off- most belt-driven implements were designed around lower-power tractors, hence, high belt-hp wasn't an incredible selling point.  That being the case, manufacturers didn't invest the engineering or production resources to alter belt-drive ratios, instead, they just left it as-was, and entrusted the operator to use due caution.  As time went on, and power demands increased, and PTO implements got big and mean, full-governed-speeds increased, manufacturers finally started revisiting rearend designs, PTO drive concepts (Cockshutt's live-PTO!), and PTO drive ratios to optimize PTO output power, especially on the Category II and III machines.  Agricultural engineers were constantly working to provide the highest PTO output numbers at the lowest fuel consumption and longest lifespan, it was not possible to make a drive ratio that yielded the desired output combination.  After the '60's, ROAD SPEED was also a consideration, and tractors were made with gearing and maximum governed speed to provide faster transit times between fields.

Amidst all this, was the implement manufacturer, who used the ASAE and ASME standards guidelines for selecting coupling equipment and calculating load applicability.  Once the design was done, proper implement manufacturers documented their products so that the operator would follow guidelines on operation.  Allis-Chalmers, for example, never made ANY implement, that didn't get passed to end user, without also being handed a book.

This is why, when you look at a tachometer, that SOME have the 540rpm 'window' in the same vicinity as full governed speed... while others, it's not.

How a person goes about using their equipment, is totally up to them, and totally determines how the driving force, and driven implement survive, and all the casual and catastrophic results that may occur.  The performance suggestions and safety mandates of the engineers of the machine-in-use should be abided by if you desire to get best performance, lifespan, and safety from the combination.  There is nothing wrong with telling another guy what YOU do, however, it is neither a wise nor honorable practice to do so without indicating that you're operating outside of the manufacturer's suggested realm, and it is an extreme disservice and liability to recomend to another a practice which occurs outside the envelope of the original design guidelines.  It is one thing to have equipment damage or injury due to one's own actions, it is totally another to suffer damage, injury, or death as a result of ill advise.  The damage to equipment and people can frequently be repaired, but the dead cannot be brought back to life.  The loss of friendship is irreplaceable. 

I have nobody to blame for my injuries except myself, and I plan on keeping it that way.  I would rather be the one injured, than to advise someone into peril.

Lets all put a fork in this topic!!

Just so everyone understands how lame this argument of PTO speed is I took my hand held tack that came with a 72  all crop combine my uncle bought years ago and checked some pto speeds in relation to the tach on 2 tractors. I only have 2 540 tractors one is on the mower so I took the 720 JD diesel at the 540 PTO mark on the tach which is roughly 3/4 throttle the pto speed is 600 and full throttle the pto speed is 620. On the second tractor a 210 with the famous  high hp 426 that doesnt last, yet this one has run 200 hp and we have never had a problem with it( but I digress)  at the 1000 rpm mark on the tach the pto speed is 1100 which is roughly 3/4 throttle again, and at wide open the speed was just under 1200 about 1175. So this argument about running PTO speed, or not, who is taking care of there tractor and who isnt, what your dad taught you, and I dont mean any disrespect to your parents at all, in fact my Grandpa was a slow runner and his fits about a wide open tractor, which lead to other problems I wont get into here are advise given based on nothing . The pto speeds arent even correct on the tach its over running on both tractors immediatly, and wide open didnt change the speeds hardly at all, less than 10%. You guys must think that wide open on your pto is like doubling the speed. I have another 9 tractors here I can test if you like the rest are all 1000 except the 8050 which I can swith but my guess is the out come is going to be the same.If someone has a tractor they want to know the speed tell me if there is one here or close by I can test I will. Heres another point what did they do when they chopped corn, baled or did other pto work with a WD45 there is no tach, so what were your parents grandparents etc baseing an over run on?

Lonn wrote: I agree with you victory except on the combine issue. You have to run them wide open and load them down to rated speed in order to get full efficiency and not leave crop in the field. On a gasoline engined combine the governor can't hold a constant speed very well unless you open it up.  This topic for some reason has hit some nerves and I can't figure out why.

X2 plus the walkers and sieves are designed to work best at full rated engine speed.

Amen Victoryallis!!!

Well to answer the original question, I run my 175D with the brushhog at the 540 rpm mark on the tach, throttle up as needed in the tough stuff, throttle back going down hills. I have done this for the last 7 years and probably could run the tractor without a tach as I can "feel" the correct range just by the sound and vibration. I've tried running faster, but I think it actually makes the cut worse and my fuel consumption just goes up. In rough conditions (rocks, rough ground) I throttle way back and the quality of cut doesn't change...and I stay more relaxed and in control.  Running wide open is just stressful to me.

D17JIM wrote: I keep seeing all of the discussion and remember 2 things Dad would kick my [IMG]uploads/1/censored.bmp"> for (not the only 2 by the way) Running pto equipment over pto speed and not running full throttle on heavy tillage loads.  It worked for him on every tractor from a square back WC to the 8070 and many in between.

This is the shortest and best advice I've heard.Been doing that for 35 years and haven't any problems.

I keep seeing all of the discussion and remember 2 things Dad would kick my for (not the only 2 by the way) Running pto equipment over pto speed and not running full throttle on heavy tillage loads.  It worked for him on every tractor from a square back WC to the 8070 and many in between.

Always run all my blower  tractors wide open , cause i hate unplugging pipes from an 80 foot silo .. 

In the case of your Loco with a cylinder not producing as much as the others, one dead or low cyl is reducing the maximum output from the engine, the operator then leans on the throttle more for a longer time. Fuel useage is up/economy is down. There again, pushing more fuel into it, more heat developed. Same load, engine not producing full power, RPM's down, more heat, taxing the cooling system....

ranger42 wrote: Great explanation Dave!....I appreciate the explanation from an enginerring perspective and common sense. From my experience I agree with you on every front. Also, I think we all can agree that there are instances where engines are "de-tuned" for longevity. One I know that has been discussed on this site in the past is the 426 in the N-6 combine. Where RPM's were dropped most often by private owners or AC mechanics who have them in for service and they had much more luck for durabilty stand point.

I don't know what the OEM rpm setting for the N-6 was, but the 426 wasn't happy at the 2550 rpm setting of the 7080.  The engine was much happier at the 2400 rpm setting of the 8070.

Dave, you dont have to worry abot me taking it personally, am always willing to learn something new, but I do know the XT has or had no problems in that sitation, other than it was not making full hp on a continuous bassis. If you ever ran a recutter its a heavy pto load like a dyno but it lasts for hours on end, rather than intermitant, like a hard spot in the field etc, so once the load starts its there for as long as you were grinding, which back than we would start it at 7 am shut down for lunch and start back up till about 4  so other than a small breather as the next wagon pulled in it was pretty much full load . The only difference between the 2 setups was one was full throttle and playing with the recutter, and 3/4 throttle and laboring on it. Now the out line you have decribed may have had something to do with it, but we have had no heating problems with that tractor in any situation other than a recutter at lowered rpms. Again not to beat a dead horse here, but I am not saying that every situation requires full rpms, but in a heavy load, the engine and implements were designed for full speed and you are not doing any damage to either by running it there. Nor is the engine or implements being damaged by a slower setting, a little common sence will go along way in this, every condition requires a different approach, but on the recutter full rpm was required . Its much like a semi tractor taking a hill if your pulling the hill in too high a gear the engine begins to labor the heat starts to rise, shift down a gear, bring the rpms up lower the load and the temp goes right back down. By some of your guys comments about full throttle settings hurting engines or being abusive is just so out in left field, if that was so there would be a million dead semis blown up on the side of any grade, becasue every trucker I know is going to have there foot in it for full power to take a hill. My last point here on this matter is again, if damage or abuse was occurring in full RPM the manufacture would not let the throttle go that far. Peace everyone.

Wow, this topic has taken off. On my 7050 I only pull a 4x18 plow so I usually only run about 1,900 rpm. It has never overheated or poured black smoke or whatnot. I could use the XT but the 7050 is much more comfortable and I like having all that available power. I also have run the XT at less than full rpm pulling a 9 shank Krause chisel plow without problems but the tractor will lug in the tough spots so I normally run at 2,200 rpm. My Dad rarely ever runs a tractor at full throttle unless whatever he's hooked to requires it and he made it through a lifetime of farming without blowing an engine. I tend to run a little faster than Dad and so far after about 30 years of field work never have had any problems either. I think everyone here knows their equipment pretty well so that they know what they can do and can't. Some run fast and some run a little slower.