Have we been doing it wrong? High rpm's bad when not needed?

[5030]

If you let it 'slide', what will happen is when it fills up with burned ash (soot), the engine will either derate of the cannister will expand and push the front or rear sealing rings apart and then derate. Seen that happen on Class 8 big trucks many times and when it does, not only will the element have to be replaced because it cannot be cleaned as it's deformed plus the cannister and everything attached to it has to be replaced as well. In a big truck it's referred to as the 'one box' and the bare box itself is in the excess of 1500 bucks not including labor and it's not a warranty item either as it's considered abuse. Additionally, Rudy designed the diesel engine to produce maximum torque at a lower RPM than a gas motor, consequently, I'd never buy a post 4 tractor simply because high rpm causes excessive engine wear. I rarely run any of my tractors at rated RPM anyway unless the implement I have on requires it, like my discbine mowing heavy hay because I have to keep the forage flow going to the crimp rolls continuously.

Of course the 'genus's at the EPA don't take that into account.

 

[DarkBlack]

https://imgur.com/SV8D1zR

This graph shows soot production as a function of power and rpm. BMEP which is effectively torque is on the vertical axis and rpm on the horizontal axis. You can see there is a sweet spot of low soot right in the range where its putting out some power at a range of operating rpm. I don't know what engine its for or how much it changes for different engines but at least it's an idea of how it is for one engine.

You can tell that letting it idle with no load is going to generate many times more soot that working it.

Do you have supplemental information to go with this chart?
Normally BMEP maps are created from a specific quantity of fuel, like grams, or liters, etc. That would mean the lower the rpm on the plot , the less fuel would have been combusted for a given amount of time. We would need to know if the plot was compensated for this factor.
If the same quantity of fuel was combusted for each measured rpm point, then the lower rpm readings would have run longer to consume the fuel.
In other words, this may be a somewhat misleading plot without clarification

 

[5030]

One thing I don't worry about is fuel consumption. One, my off road diesel is not taxable and two what it is is an expense write off anyway. Far as my on road is concerned, that is also a write off as my truck is a farm related vehicle.

I'm alarmed at what they cost but it's the 'gotta have it' deal so I don't get excited.

 

[5030]

My Branson's tach has a green band from about 2000 to 2500 rpm. The manual says to keep the engine in that band for best DPF performance.

So you increase emissions longevity and decrease engine life from excessive RPM. Sounds counter productive to me...?

 

[Midniteoyl]

Curiously, what would happen if you just let it slide? Is it like a car with a check engine light where you can still drive it just fine for the most part, or does ignoring it cause serious problems?

If you ignore the regen light too long, or cancel it too many times, the ECM will go into a 'limp mode' and require the dealer to come out and reset it after doing the regen. I think Kubota is 3 or 4 skips.

Going too long without replacing/cleaning a clogging DPF means pretty much the same as a plugged catalytic converter as it plugs the exhaust. This can take thousands of hours though, unless you are constantly skipping regens.

 

[MarkMac]

If I’m pulling or plowing a given load “X”, the torque felt by the drivetrain will be the same regardless of engine RPM. Either the drive train is overcoming the load or it isn’t.

For instance, my pickup can drive a consistent 30 mph in 3rd, 4th, or 5th gear. The engine will be doing different RPMs based on the gear used, but the power to the ground, and the power felt by the components is the same. If the power were less, the pickup would slow down, and if it were more the pickup would speed up.

 

[dadohead]

You’re acting like you can predict all tractor designs and makes into a predetermined part lifespan, and that, you, or nobody can do.

Ha... it's done everyday.

The MBAs that run the ag companies treat every product they make as an appliance. They ask engineering/marketing to set very defined capabilities and life goals so they can remain competitive. Remember the first microwaves? Brand new technology then. They were big, faux walnut boxes that sat on the counter. Makers thought Americans would  cook with them. We didnt, just reheated stuff. Those old things just wouldn't die! Quickly though, manufacturers caught on and dialed it back to a 8-9 year life.... you can set your watch by it. Tractors are no different.

Engineers are taught to use 'perfect design'. Just like the human body, all compnents should hit that life goal. When we get old the eyes, joints, hearing, thinking, etc all decline at about the same rate. Perfect design. The diesel engine in your tractor is typically designed so it could go into multiple applications though: stationary pumps, gen sets, industrial machines, ag, marine, etc which many times have a higher life goal. The tractor transaxle, however, is one of the most expensive components in the tractor and designed just for its application. It is the weakest link.

If I’m pulling or plowing a given load “X”, the torque felt by the drivetrain will be the same regardless of engine RPM. Either the drive train is overcoming the load or it isn’t.

True!... from the motor back. From the pump forward it's not.

This shouldn't be this controversial. All I'm saying is it's better to error on the high side of throttle when you're working your tractor.

OP- Regular transaxle fluid changes per the OM is the single most important service your tractor gets.

 

[DarkBlack]

Ha... it's done everyday.

The MPAs that run the ag companies treat every product they make as an appliance. They ask engineering/marketing to set very defined capabilities and life goals so they can remain competitive. Remember the first microwaves? Brand new technology then. They were big, faux walnut boxes that sat on the counter. Makers thought Americans would  cook with them. We didnt, just reheated stuff. Those old things just wouldn't die! Quickly though, manufacturers caught on and dialed it back to a 8-9 year life.... you can set your watch by it. Tractors are no different.

Engineers are taught to use 'perfect design'. Just like the human body, all compnents should hit that life goal. When we get old the eyes, joints, hearing, thinking, etc all decline at about the same rate. Perfect design. The diesel engine in your tractor is typically designed so it could go into multiple applications though: stationary pumps, gen sets, industrial machines, ag, marine, etc which many times have a higher life goal. The tractor transaxle, however, is one of the most expensive components in the tractor and designed just for its application. It is the weakest link.

Just starting with your statement “the transaxle is the weakest link “ Is false on its own. Every tractor made, from every manufacturer, has weak and strong points. Pretty much any part failed, will put the tractor out of use.
If you open your mind up a bit, you would realize that starting batteries, followed by computer systems are the weakest link. Alternators, water pumps, fuel injectors, fuel pumps, are all much “weaker links “ in a tractor than the transmission.
Just pursue this site for failures..

And again , without knowing a specific load %, and without knowing where in the rpm range, the engine develops maximum torque, you can’t make a blanket statement that torque will go down and the transmission will last longer. That’s nonsense.
You’re also ignoring components that wear more from unnecessary rotations, such as alternators, oil seals, water pumps, camshafts, valves, valve springs, and on and on..

 

[LouNY]

Besides which tractors don't have transaxels.

 

[Torvy]

I always use a fuel treatment with cetane boost. I don't know when mine will regen. It's at 30 hours now.

I'm at 47 and change and no regen yet. I'm probably at 2000+ rpms at least 1/2 of the time. 2600 when mowing.

 

[Torvy]

If you ignore the regen light too long, or cancel it too many times, the ECM will go into a 'limp mode' and require the dealer to come out and reset it after doing the regen. I think Kubota is 3 or 4 skips.

Going too long without replacing/cleaning a clogging DPF means pretty much the same as a plugged catalytic converter as it plugs the exhaust. This can take thousands of hours though, unless you are constantly skipping regens.

That may be true with most of them. One reason I got a TYM/Kukje engine is to prevent the whole limp mode nonsense.

 

[rScotty]

Of course the 'genus's at the EPA don't take that into account.

They don't have to take it into account.

If someone prefers to run their diesel at a slower rpm, it's up to them to buy one that is pre-tier 4 and run it the way it was designed. That's what a lot of us do.
Or buy post tier 4 and run at high RPM.

Which design to buy is simply a market place decision; anyone can do it either way.

 

[CloverKnollFarms]

Kukje engines won't go limp

 

[CloverKnollFarms]

I use mine almost exclusively for tillage, so load and RPM are never an issue.

 

[DarkBlack]

Besides which tractors don't have transaxels.

I was going to mention I only associate that term with with riding mowers.

 

[Darth_DMack]

This is a good topic for me. I am a genuine NOOB to tractors. I bought my first tractor about 6 months ago or so... a 2023 Mahindra 5155. This is a bare bones, industrial type tractor with no bells / whistles. It does not use DEF, and has a small turbo. The 5145 and 5155 are the same tractor, only difference is the 5155 has the turbo, which gives it the 55 rated hp, over the 45 hp of the 5145.

I have right at 47 hours on it so far, using it to clear my property. I use the grapple mostly, box blade next, and bucket is the least used. It has two yellow marks on the tach, I'm assuming it's for the two different PTO settings. I typically run the tractor around the lower rpm yellow mark... or between the two. I believe it's about 1800 to 2000 rpm.

I've never had an issue with it, and the power has been perfect for me. I usually let the tractor idle for a few minutes before shutting it off. My tractor does not have a re-gen cycle nor does it use DEF, which is one reason why I chose it.

I'm still learning it, and I am very thankful for the wealth of knowledge on here.

 

[dadohead]

Just starting with your statement “the transaxle is the weakest link “ Is false on its own. Every tractor made, from every manufacturer, has weak and strong points. Pretty much any part failed, will put the tractor out of use.
If you open your mind up a bit, you would realize that starting batteries, followed by computer systems are the weakest link. Alternators, water pumps, fuel injectors, fuel pumps, are all much “weaker links “ in a tractor than the transmission.
Just pursue this site for failures..

And again , without knowing a specific load %, and without knowing where in the rpm range, the engine develops maximum torque, you can’t make a blanket statement that torque will go down and the transmission will last longer. That’s nonsense.
You’re also ignoring components that wear more from unnecessary rotations, such as alternators, oil seals, water pumps, camshafts, valves, valve springs, and on and on..

Wow... the parts you mention DON'T KILL THE TRACTOR. I think you know that.

We're NOT talking about a dyno pull at max power here... max engine curves have nothing to do with what is going on downstream. You can pick a high gear, pedal slow with high effort or you can pick a low gear, pedal fast with little effort... all to go the same speed.

Actually it IS a transaxle if the transmission has an integral axle.

 

[LouNY]

Wow... the parts you mention DON'T KILL THE TRACTOR. I think you know that.

We're NOT talking about a dyno pull at max power here... max engine curves have nothing to do with what is going on downstream. You can pick a high gear, pedal slow with high effort or you can pick a low gear, pedal fast with little effort... all to go the same speed.

Actually it IS a transaxle if the transmission has an integral axle.

The axles are in the rear end housing, the transmissions are ahead of that and often more then one.

 

[ruffdog]

As far as plugging a DPF, there are many factors that may cause the need to regen or clean the DPF. The use of modern diesel oil that is specifically made for low ash and soot will help. Fuels formulated to be cleaner will help. Some people still add snake oil from the 1960s to their fuel (sometimes in large amounts) thinking it will help lubricity when it may be plugging the DPF. And as mentioned, how it is used will make a difference.

 

[5030]

No plugging here, don't have any to plug. Far as turbo charged engines go, I always idle mine for a few minutes after using them to let the hot side of the turbo get fresh oil to the bearing and allow it to cool off. Turbo's all have a ceramic bearing on the hot side and conventional bearing on the cold side. Learned that with big trucks and big diesels. In fact my Western Star tractor has auto shutdown after a 3 minute no load idle. New turbo's aren't cheap today.