Do you mow at 540

[PineRidge]

I think this thread is a lot like the one asking at what temperature that you change your engine oil at. What's good for one member may not be good for another that's obvious with all the different replies that are coming in.

Still there are a few here that feel there is but one way to run a tractor (their way) and if you don't agree with them then you're destined for purgatory or worse.

 

[Doc_Bob]

I think this thread is a lot like the one asking at what temperature that you change your engine oil at. What's good for one member may not be good for another that's obvious with all the different replies that are coming in.

Still there are a few here that feel there is but one way to run a tractor (their way) and if you don't agree with them then you're destined for purgatory or worse.

Mike, it is just like draining hot oil (180), warm oil (100 degree), summer temp (70 degree) oil and winter (-20 degree) oil. Straight 30 W vs Multivis. So many variables, so little time.

I just hope I don't end up in "worse" .

 

[Soundguy]

While 540 may not be a magic number.. I would check the owners manual and do whatever it says for each implement. Those guys with the lab coats are doing something other than drawing a paycheck.

Vibration? perhaps a blade isn't swinging freely... I find that my mowers vibrate 'less' when up to speed.. That's probably a subjective issue.. as every piece of equipment.. even assembly line units tend to run just a bit differently depending on the individual unit.

Gearbox hot? Hot to a human hand is no big deal.. hot to darken paint is..

Whole weeds? It seems that might lead to a layer of thatch... I'm not looking for that.. I want mulched clippings than 'disolve' into nothing pretty quickly... I guess that is another subjective issue.. As I've found that cutting at lower rpm tends to leave grass balls, while cutting at correct rpm leaves an even mulched 'blanket'.. etc.

Can't really comment on the mower bogging.. except that you may have more mower than tractor.... I think ideally.. the equation is the other way around.. however.. sometimes it is hard to pass up a deal.. even if it is not 100% optimum conditions..

Soundguy

I don't think 540 RPM is a magic number. I think it's a very general guideline. I think you must adjust accordingly instead of blindly running at a particular speed. I think the 540 RPM spec was a compromise reached by implement and tractor makers many years ago, and not much more. Modern metallurgy and design changes the whole equation. I think it's almost impossible to under work a tractor or implement. I bet you that not many implements and tractors are brought to the dealer for repairs for being under worked.


Here's proof for me: Running my tractor and my brush hog at 540, there is a lot of stuff going on under the deck. The grass is being cut, re-cut, shredded, and big balls of grass are left in my wake. My tractror is straining a little bit, and fuel usage is high. My cutter's gearbox gets quite hot. At 425, there is little noise, banging, or vibration. The blades make a nice swishing noise as they cut. Grass and weeds come out mostly whole, and lay down evenly. Fuel usage is excellent. My gearbox is very warm, but not hot. My gearbox is rated for 55hp, my PTO hp is 30. All the signs point to 425 being more efficient than 540. I don't think I'm in any danger of under working anything! YMMV, of course!

 

[have_blue]

I find it absolutely astounding the number of members here who believe they're smarter than the engineers that design the equipment ! But then again, where would the repair shops be without them.......

//greg//

Greg, I want to stress 1 more point before I quit on this one. The 540rpm "standard" was probably a gentleman's agreement between implement manufacturers and tractor manufacturers so the implements could be rotated within a usable RPM range. I don't think a lot of engineering went into determining 540 RPM. It's not even addressed in any manual I've ever read. It's just a given, like lefty-loosy righty-tighty.

One more point and I promise I'll shut up. Equipment... engines, transmissions, gear boxes, etc. can be run 2 basic ways: To finish the job as fast as possible, or to cause the least wear and tear on the equipment. They are not 1 and the same! As RPM increases, wear and heat increase 2x to 4x more in proportion. Every 100rpm on the PTO probably doubles the heat and quadruples the wear on mower's a gear box. Reducing RPM is guaranteed to increase gear box and transmission life. I worked for years in failure analysis, and believe me, running higher RPM will always decrease component life.

When in doubt, I follow the Mfr's recommendations. When the Mfr's recommendations are missing or ill-explained, I rely on my own experience and "feel", for which there is no substitute.

 

[TrippleT]

When I posted I merely wanted to help, or suggest. As far as engineering data I am sure 540 is the standard and best at least on paper. However, after 40 years of working on machinery in the automotive industry I have learned that things are sometimes different. For instance I have had several problems with temp guages based on that I have some reservations as to the absolute accuracy of the 540 light on my tractor. The engine is screaming at that point and don't try to tell me that is good. I have rebuilt to many engines to buy into that. Not trying to be a smarty not every piece of machinery will work exactly the same. The picture is a small part of the yard I have to mow here at my place and this seems to be a pretty good cut to me. That is IF it comes through here.

 

[Farmwithjunk]

I think this thread is a lot like the one asking at what temperature that you change your engine oil at. What's good for one member may not be good for another that's obvious with all the different replies that are coming in.

Still there are a few here that feel there is but one way to run a tractor (their way) and if you don't agree with them then you're destined for purgatory or worse.

Well, next logical question. What temperature do you MOW at?

 

[have_blue]

Well, next logical question. What temperature do you MOW at?

Ideally, 70F. But it always seems to need mowing when it's 100F out!

 

[jeffinsgf]

On page 13 of the Owner's Manual for my Frontier RFM it says not once but three times to run at 540 rpm. Here are the last two quoted verbatim

Always operate trator PTO at 540 rpm to maintain proper blade speed and produce a clean cut.

Under certain conditions, trator tires may roll some grass down and prevent it from being cut at the same height as the surrounding area. When this occurs, reduce your ground speed, but maintain PTO at 540 rpm. The lower ground speed will permit grass to partially rebound.

Do whatever floats your boat, but if the manufacturer tells me three times in the space of half a page, I think I'll listen.

 

[cp1969]

... I worked for years in failure analysis, and believe me, running higher RPM will always decrease component life.

That's how accelerated wear testing is done, at higher speeds. If you want something to fail quicker, spin it faster.

 

[PineRidge]

On page 13 of the Owner's Manual for my Frontier RFM it says not once but three times to run at 540 rpm. Here are the last two quoted verbatim



Do whatever floats your boat, but if the manufacturer tells me three times in the space of half a page, I think I'll listen.

You'll also notice that the book qualifies "proper blade speed and produce a clean cut" they do not say that running the mower at less than 540 will be detrimental to your tractor or mower"

 

[JerryG]

540-RPM usage is only a general guideline. The same RPM is not the best for every piece of equipment. Do you think that a Jimi with a FarmPro cutter has the same wear characteristics as a JD with a Frontier cutter? Or a 1960 Allis with a Coop cutter?

 

[Doc_Bob]

You'll also notice that the book qualifies "proper blade speed and produce a clean cut" they do not say that running the mower at less than 540 will be detrimental to your tractor or mower"

Mike, you are such a detail freak !
Good point.
Bob

 

[Soundguy]

The tractor doesn't bog, the clippings are small and scattered, and I have probably cut 6 db from the noise level.

6 db huh? that can be a huge amount of SPL... you really think it cut your sound by a wide factor like that... considering sound is non linear.. etc

Soundguy

 

[Soundguy]

Does your tractor not reach 540 pto rpm untill full throttle? Most of mine hit it at about 2/3 throttle .. etc.

Soundguy

I just don't like hearing an engine running at full throttle unless their is a load on it, again just my opinion - right, wrong or indifferent.

 

[Soundguy]

the 540 light on my tractor. The engine is screaming at that point and don't try to tell me that is good. .

Unless otherwise stated in your manual.. do you have any reason to believe that your tractor won't operate a pto load for extended periods?

Ever seen engines running gensets? Ever see them run continously, 24-7-365... That is very common in many industries. Many even have provisions for oil changes without shutting the unit off.

Soundguy

 

[Soundguy]

With this kind of logic about reducing wear on your tractor etc.. a thought just occoured to me.

Why not leave your tractor parked int he barn 100% of the time and just not use it at all.. that will REALLY reduce the wear on it...

Come on guys.. there are big tough pieces of metal.. made to run in the sun and heat all day.. drinking fuel and get put away wet. If yardwork was so hard on tractors and killing them right an left then you wouldn't see tractors from the 40's still running around working... They had worse metalurgy, and lower technology, and worse lubes... and guess what.. with a little care.. lots of the oldies are still here.. why? because they were built to do the work... Just like our modern tractors are built to do the work...

Soundguy

Greg, I want to stress 1 more point before I quit on this one. The 540rpm "standard" was probably a gentleman's agreement between implement manufacturers and tractor manufacturers so the implements could be rotated within a usable RPM range. I don't think a lot of engineering went into determining 540 RPM. It's not even addressed in any manual I've ever read. It's just a given, like lefty-loosy righty-tighty.

One more point and I promise I'll shut up. Equipment... engines, transmissions, gear boxes, etc. can be run 2 basic ways: To finish the job as fast as possible, or to cause the least wear and tear on the equipment. They are not 1 and the same! As RPM increases, wear and heat increase 2x to 4x more in proportion. Every 100rpm on the PTO probably doubles the heat and quadruples the wear on mower's a gear box. Reducing RPM is guaranteed to increase gear box and transmission life. I worked for years in failure analysis, and believe me, running higher RPM will always decrease component life.

When in doubt, I follow the Mfr's recommendations. When the Mfr's recommendations are missing or ill-explained, I rely on my own experience and "feel", for which there is no substitute.

 

[jeffinsgf]

You'll also notice that the book qualifies "proper blade speed and produce a clean cut" they do not say that running the mower at less than 540 will be detrimental to your tractor or mower"

Like I said, do whatever floats your boat. I think you're splitting hairs that shouldn't be split.

Just to bring in an example from another field that I am much more familiar with. In woodworking, every tool should be run as fast as it can without causing friction burns. With an irregular shaped piece of wood on a lathe, it takes much less effort to cut at 500 rpm than it does at 200 rpm. When I am turning a bowl from a natural edge blank, I always turn the speed up to the point the piece is vibrating the lathe, and then back if off until the vibration settles down. Since my lathe weighs about 900 pounds, even a big out of round blank is probably turning 300+ rpm. If I work on a smaller lathe and have to start at 150 - 200 I can really tell the difference. When the piece is round and balanced, I kick the speed up to 1500 rpm.

A table saw that is turning too slow is much harder to work with, since each tooth is impacting a larger area.

I contend that JD didn't think that they had to ALSO list that running at lower rpm is bad for the equipment. I read "proper" blade speed to mean the best for the machine as well as for the cut.

I guess we'll see in 15 or 20 years. Check back with me then, and we'll see whose mower is in the best shape.

 

[PineRidge]

Guys look I'm not looking for an argument here. We can agree to disagree on this point and still be friends. I only made a comment that 2600RPM/540 PTO speed was a constant for me with the mower until I tried 2000 RPM. The engine raced less, the mower raced less, the grass was cut just as nice, and I used less fuel. How can that be so awful bad?

If you all want to run at PTO speed for mowing it ain't gonna affect those of us that choose to run at less RPM one way or another, it's just a different way of doing things, it still doesn't make us lepers.

 

[have_blue]

it's just a different way of doing things, it still doesn't make us lepers.

By definition efficiency is doing the most with the least power, wear, stress, and in my case noise and vibration. My tractor is not big and tough. It's only 35hp with a 6' brush hog with 55hp rated box. I don't have unlimited funds to fuel it and repair it, and sharpening very dull blades is not a favorite chore. So, I sacrifice about 1mph to go easy on my ears, the seat of my pants, and my wallet. Oh, and I rather mow grass than puree it and leave it in rows of balls. If that makes me a leper, I'll proudly wear a scarlet "L" on my forehead. Ehhhh... make that my ankle. Make that my brush hog.

If the weeds get away from me, or I have brush to mow, I will probably end up mowing at 540 and you guys can have a good laugh at my expense.

 

[Farmwithjunk]

Guys look I'm not looking for an argument here. We can agree to disagree on this point and still be friends. I only made a comment that 2600RPM/540 PTO speed was a constant for me with the mower until I tried 2000 RPM. The engine raced less, the mower raced less, the grass was cut just as nice, and I used less fuel. How can that be so awful bad?

If you all want to run at PTO speed for mowing it ain't gonna affect those of us that choose to run at less RPM one way or another, it's just a different way of doing things, it still doesn't make us lepers.

The entire thread reminds me of a time when I called my cousin to help me with my central air conditioner a few summers back. He works on HVAC full time. I was busy getting hay in, and the Mrs wasn't feeling too good. She was demanding the air be fixed. I called "cuz" over to bail me out.

He spent 5 hours tinkering with everything. I got a call from my wife wanting to know when he was going to have the house cooled down. I asked Taylor (my cuz) how things were going. He said," Well, the head pressure is perfect, The fan is running at the right speed, compressor is running fine, air flow seems to be good, Just about right temperature differential on pressuer and suction lines, looks good to me"!

"But Taylor, is it making cold air"? I asked.

"Well, not as far as I can tell"

Moral of the story? If it works, everything is OK. If it DOESN'T, try something different. No matter how much "by the book" you play it, the only thing that REALLY matters is the end result.

Mow at whatever RPM your heart desires everyone!