DCS
Bronze Member
I have always heard that it is not good to "bog" down a diesel engine. What damage could occur to an engine by doing this?
"Bogging" down the engine
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chrisjbell
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The good news is that diesels do OK "bogged" because the way they ignite the air fuel mixture is pretty much like what you get when you hear knocking or pinging in a gas engine.
Better not to do it to any engine - means you're overloading it. Keep the revs up high enough for what you are doing so that doesn't happen.
There are those that suggest that running engines at lower RPM saves 'em from extra wear. I'm not of that school personally but can see where they're coming from.
Better not to do it to any engine - means you're overloading it. Keep the revs up high enough for what you are doing so that doesn't happen.
There are those that suggest that running engines at lower RPM saves 'em from extra wear. I'm not of that school personally but can see where they're coming from.
RoyJackson
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Worst thing I've ever heard (and who knows...maybe this is an old wives tale...or an old mechanic's tale) is bogging an engine can result in pounding the main bearings.
This would result in ovaling or flat spots at the bottom of the main (crankshaft) bearings, thus destroying their effectiveness and, ultimately, the crank.
Remember, the bearings require a thin oil film to work.
It's easy to prevent..just shift to a lower gear.
This would result in ovaling or flat spots at the bottom of the main (crankshaft) bearings, thus destroying their effectiveness and, ultimately, the crank.
Remember, the bearings require a thin oil film to work.
It's easy to prevent..just shift to a lower gear.
I also try to avoid bogging down diesel engines, but sometimes it happens and you can't help it.
I often find it happens when towing a heavy trailer in a high gear and you start going uphill. The engine dies down, and then recovers.
It is probably better to keep it revved up.
I often find it happens when towing a heavy trailer in a high gear and you start going uphill. The engine dies down, and then recovers.
It is probably better to keep it revved up.
Volfandt
Veteran Member
Several bad things happen when you bog down an engine. In both gas & diesel engines the crank and rod bearings bear the brunt of the pounding and additionally when a diesel bogs down the gov will call for more fuel to get the rpm's back up and all that additional fuel won't get combusted, it'll accumilate on the cylinder walls breaking down the thin film of lubricating oil and also collect in the oil pan diluting the oil.
Some engines are designed to run all day long at 2500 rpm, others at 3000 and still others at 3600 rpm. With tractors, it's best to "work" a tractor at it's designed rated pto speed.
In any case, it tain't good to continually bog an engine down when working it.
Some engines are designed to run all day long at 2500 rpm, others at 3000 and still others at 3600 rpm. With tractors, it's best to "work" a tractor at it's designed rated pto speed.
In any case, it tain't good to continually bog an engine down when working it.
jbrumberg
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DCS:
Shift to a lower gear and increase your RPM's. When your tractor is bogging down it is talking to you; it will happen on ocassion. Jay
Shift to a lower gear and increase your RPM's. When your tractor is bogging down it is talking to you; it will happen on ocassion. Jay
There are two things that are similar. One is when you have the throttle at 1/2 or 2/3 and you start to do something requiring more power. The RPM's will sag down some and the gov will start to give it more power. You can hear the extra power being generated. At that point the rpm's will stabilize or rise. That's normal even with a slight brown or black haze to the exhaust.
Bogging down is technically defined as the condition that exists when you pull the throttle down more and the engine is not able to increase the RPM's against the given load.
SO, if you are hitting a heavy load and hear the gov add fuel and you pull the throttle lever down and the RPM's don't change (or continue to drop), you are seriously overloading the engine. You can hear and feel the difference as it has a lower frequency with pronounced pounding. That is bogging it down and that is not good. The long term damage is typically a broken crank, spun bearing, bent rod, melted piston or even a thrown rod. Diesels are tough, but everything has it's limits. After a while you will get a feel for them and will add more throttle sooner and/or drop a gear.
When it happens on occasion, it's no big deal. It's when you make a practice of operating in a bogged condition that damage accumulates until your wallet bleeds.
jb
Bogging down is technically defined as the condition that exists when you pull the throttle down more and the engine is not able to increase the RPM's against the given load.
SO, if you are hitting a heavy load and hear the gov add fuel and you pull the throttle lever down and the RPM's don't change (or continue to drop), you are seriously overloading the engine. You can hear and feel the difference as it has a lower frequency with pronounced pounding. That is bogging it down and that is not good. The long term damage is typically a broken crank, spun bearing, bent rod, melted piston or even a thrown rod. Diesels are tough, but everything has it's limits. After a while you will get a feel for them and will add more throttle sooner and/or drop a gear.
When it happens on occasion, it's no big deal. It's when you make a practice of operating in a bogged condition that damage accumulates until your wallet bleeds.
jb
jbrumberg
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jb:
One of the best descriptions of bogging down a tractor and its consequences I have read
. Jay
One of the best descriptions of bogging down a tractor and its consequences I have read
. Jay
firedog
Gold Member
In addition to all previous statements; bogging causes the cylinder temperatures to increase dramatically. As the RPM drops the boost pressures also drops decreasing the amount of air (in non-turbo aspirated engines the effect is much the same - low mainfold pressure) and fuel delivery increases the cylinder temps skyrocket as well as the turbo temp.
bogging for long periods can do tremendous damage. Countless times I've had to drop a few gears when pulling thru the mountains. (sometimes even against a strong headwind)
bogging for long periods can do tremendous damage. Countless times I've had to drop a few gears when pulling thru the mountains. (sometimes even against a strong headwind)
dillo99
Gold Member
This was a very helpful post - something I always wondered about too!
Thanks all.
Thanks all.
DCS said:
I doubt you will do much damage to your engine (ever) from bogging. Just keep the throttle to where there is enough power to do the job and not over speed your application. That's hard with a gear tractor sometimes, but that's what defines an "operator" from a "user".
jb
DCS
Understanding the difference between bogging an engine and lugging an engine is important.
Engine bogging is different in that, the internal components are not subject to sudden rise and fall of pressure in a relative long duration as in engine lugging. Bogging is still a smooth operation as far as the engine is concerned although higher stress is present, as you would expect. More fuel more power more stress more heat. Only when the RPM falls significantly short of the torque range under heavy load will you need to fear engine damage.
Engine lugging happens when the operator pushes the engine to the point where the RPM is slow enough that the fuels burn cycle begins and ends before the piston has had time to accelerate smoothly into the exhaust stroke.
During ignition, expanding gasses force the piston down, quickly loading all connected components Rods, Crank, Bearings, Clutch, and so forth with a large amount of unused energy. Some of this energy is converted to heat until the fuel is spent and relative cooling of the combustion chamber begins. At this point, the unused energy is released back through the components allowing them to spring back causing a relaxed or low load state. A mild effect is heard as a low drone or in severe cases a rattle with a harsh shaking of the engine and equipment. Kinetic energy of the rotating mass and remaining hot gasses continue to push the piston through the remainder of the cycles.
The low RPM reduces the volume of oil supply reaching the Crank and Bearings taking an even larger toll on them. Pistons and Rings are also shocked, rocking the Piston hard to the major and minor thrust sides. Collapse Ring lands and Ring fracture, cracked or broken Cranks are also results of severe lugging.
You will know it when you feel it.
Some bogging is not hard on the engine. When bush-hogging thick brush. I start at PTO speed (2600 RPM) cruse along until I hit some heavy brush, when the engine bogs down to about 2200 I will compensate with ground speed to keep it within that range. (2200 to 2600RPM) This is where torque rise of the engine comes into play. From the manufactures information, I know that the peek torque is 2100 RPM. Any RPM lower than 2100 RPM under max load is leading to power loss because from that point (2100 RPM) the torque curve falls off in the lower RPM range. So, if you stay within 2200 to 2600 RPM while it belches dark gray exhaust is hurting nothing. There will be some expected temperature rise but nothing to indicate an over stressed engine on a well engineered and maintained tractor. You may want to find the torque curve for your 4310. Its there to use and makes tractor-n much more fun.
Understanding the difference between bogging an engine and lugging an engine is important.
Engine bogging is different in that, the internal components are not subject to sudden rise and fall of pressure in a relative long duration as in engine lugging. Bogging is still a smooth operation as far as the engine is concerned although higher stress is present, as you would expect. More fuel more power more stress more heat. Only when the RPM falls significantly short of the torque range under heavy load will you need to fear engine damage.
Engine lugging happens when the operator pushes the engine to the point where the RPM is slow enough that the fuels burn cycle begins and ends before the piston has had time to accelerate smoothly into the exhaust stroke.
During ignition, expanding gasses force the piston down, quickly loading all connected components Rods, Crank, Bearings, Clutch, and so forth with a large amount of unused energy. Some of this energy is converted to heat until the fuel is spent and relative cooling of the combustion chamber begins. At this point, the unused energy is released back through the components allowing them to spring back causing a relaxed or low load state. A mild effect is heard as a low drone or in severe cases a rattle with a harsh shaking of the engine and equipment. Kinetic energy of the rotating mass and remaining hot gasses continue to push the piston through the remainder of the cycles.
The low RPM reduces the volume of oil supply reaching the Crank and Bearings taking an even larger toll on them. Pistons and Rings are also shocked, rocking the Piston hard to the major and minor thrust sides. Collapse Ring lands and Ring fracture, cracked or broken Cranks are also results of severe lugging.
You will know it when you feel it.
Some bogging is not hard on the engine. When bush-hogging thick brush. I start at PTO speed (2600 RPM) cruse along until I hit some heavy brush, when the engine bogs down to about 2200 I will compensate with ground speed to keep it within that range. (2200 to 2600RPM) This is where torque rise of the engine comes into play. From the manufactures information, I know that the peek torque is 2100 RPM. Any RPM lower than 2100 RPM under max load is leading to power loss because from that point (2100 RPM) the torque curve falls off in the lower RPM range. So, if you stay within 2200 to 2600 RPM while it belches dark gray exhaust is hurting nothing. There will be some expected temperature rise but nothing to indicate an over stressed engine on a well engineered and maintained tractor. You may want to find the torque curve for your 4310. Its there to use and makes tractor-n much more fun.
Mickey_Fx
Veteran Member
Like with many things and terms, we all don't have the same understanding of those terms.
I think of the term lugging as in the description John Bud gave for bogging. If the engine is working so hard it can't respond to an increase in throttle, then I'm overloading, lugging, the engine. Time to change either the amount of work being done or changing gears to allow the engine to run at a higher speed.
I'm also in agreement with John Bud about throttle setting. There is a right amount of throttle and gearing for each task and I don't automatically run the engine at full gov speed. IMO there is no need to run WOT for simply moving the tractor with an additional small load. Reduced RPM and proper gear is more than adequate. My manual says operating engine speed is between 1800 and 2400 rpm. That is a large percentage to total engine speed range. No need for 2400 rpm for moving a bucket of brush to the burn pile. YMMV
I think of the term lugging as in the description John Bud gave for bogging. If the engine is working so hard it can't respond to an increase in throttle, then I'm overloading, lugging, the engine. Time to change either the amount of work being done or changing gears to allow the engine to run at a higher speed.
I'm also in agreement with John Bud about throttle setting. There is a right amount of throttle and gearing for each task and I don't automatically run the engine at full gov speed. IMO there is no need to run WOT for simply moving the tractor with an additional small load. Reduced RPM and proper gear is more than adequate. My manual says operating engine speed is between 1800 and 2400 rpm. That is a large percentage to total engine speed range. No need for 2400 rpm for moving a bucket of brush to the burn pile. YMMV
Lugging, bogging -- I may be using the terms loosely. Then again, it's just the way people talk about it around here....
I do agree completely with the explaination Posterboy gave. It's very readable! I sure hope he sticks around and gives us more than 4 posts a year.
jb
I do agree completely with the explaination Posterboy gave. It's very readable! I sure hope he sticks around and gives us more than 4 posts a year.
jb
Bob_Young
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OK, we seem to have some expertise here. At the risk of hijacking the thread, I'd like to ask a question about lugging(?) turbocharged engines.
I've run a large snowblower with a turbocharged NH with hydrostatic tranny (TV140). I'd set the throttle for 1000 PTO RPM and ease into the snow. At first the governor could hold the 1000 RPM steady as I increased groundspeed with the HST; but it would soon reach a point where it couldn't. I assume the throttle was being opened by the governor but it could only open it so far. If groundspeed increased further, the PTO RPM might drop down to say 700 RPM and you could tell the engine was laboring (or lugging or bogging???).
At this point it was possible to get the 1000 PTO RPM back by simply opening the hand throttle while holding groundspeed constant (at the speed that gave 700 PTO RPM with the lower throttle setting)....or even letting gspd increase WITH the throttle setting. In fact, you could repeat this process a few times before running out of hand throttle.
So, what was happening to the engine when this was done? lugging? overboosting? ...or what? It seems odd that the hand throttle could restore the 1000 PTO RPM after the governor had lost that ability....unless the governor was purposely limited in its response to protect the engine.
I only used this technique to a very limited degree as I had to get through the winter with the TV140 and couldn't afford damage it and tie it up in the shop.
I've asked this question before, but never really got an answer. Could be it's just an odd quirk of the TV140.
Bob
I've run a large snowblower with a turbocharged NH with hydrostatic tranny (TV140). I'd set the throttle for 1000 PTO RPM and ease into the snow. At first the governor could hold the 1000 RPM steady as I increased groundspeed with the HST; but it would soon reach a point where it couldn't. I assume the throttle was being opened by the governor but it could only open it so far. If groundspeed increased further, the PTO RPM might drop down to say 700 RPM and you could tell the engine was laboring (or lugging or bogging???).
At this point it was possible to get the 1000 PTO RPM back by simply opening the hand throttle while holding groundspeed constant (at the speed that gave 700 PTO RPM with the lower throttle setting)....or even letting gspd increase WITH the throttle setting. In fact, you could repeat this process a few times before running out of hand throttle.
So, what was happening to the engine when this was done? lugging? overboosting? ...or what? It seems odd that the hand throttle could restore the 1000 PTO RPM after the governor had lost that ability....unless the governor was purposely limited in its response to protect the engine.
I only used this technique to a very limited degree as I had to get through the winter with the TV140 and couldn't afford damage it and tie it up in the shop.
I've asked this question before, but never really got an answer. Could be it's just an odd quirk of the TV140.
Bob
Gomer,
The gov has a limited amount of movement and as you found out, when it reaches that limit the rpm's will drop. Adding more fuel with the hand lever helps, but it sounds like you are operating the tractor too agressively in the snow. I am assuming that the blower is a 1000 rpm attachment and not a 540 operated in an overspeed condition. With that assumption, it sounds like the blower is too large for the power of your tractor.
Are you in HST low range when this happens? Are you blowing pavement or trying to move mounds of blown/plowed snow? If you are just blowing a normal depth snow off the drive and it does this, you may have to take 1/2 width passes. It will take longer,but the tractor will like it better.
The gov has a limited amount of movement and as you found out, when it reaches that limit the rpm's will drop. Adding more fuel with the hand lever helps, but it sounds like you are operating the tractor too agressively in the snow. I am assuming that the blower is a 1000 rpm attachment and not a 540 operated in an overspeed condition. With that assumption, it sounds like the blower is too large for the power of your tractor.
Are you in HST low range when this happens? Are you blowing pavement or trying to move mounds of blown/plowed snow? If you are just blowing a normal depth snow off the drive and it does this, you may have to take 1/2 width passes. It will take longer,but the tractor will like it better.
RalphVa
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You can ruin the main bearings on ANY engine by running it too low an rpm. My grandpa was forever lugging his stick shift Plymouth V8. When my dad bought it from him, the bearings went out.
You need enough rpm to ensure good flow and pressure of oil through the bearings.
Some engines are quite smooth, like my VW, at low rpm and will give no indication of being lugged. Most do, emitting straining noises. Raise the rpm! Think it's best to keep well above 2,000 if much load at all is put on the engine. Heavy work needs rpms up closer to 3,000. Piddling around, 1,500 rpm seems okay and is the min shift point for my VW. (but it'll quietly lug down very low before starting to jerk; I don't do it but had a Japanese friend do it when driving it, while I was cringing)
Ralph
You need enough rpm to ensure good flow and pressure of oil through the bearings.
Some engines are quite smooth, like my VW, at low rpm and will give no indication of being lugged. Most do, emitting straining noises. Raise the rpm! Think it's best to keep well above 2,000 if much load at all is put on the engine. Heavy work needs rpms up closer to 3,000. Piddling around, 1,500 rpm seems okay and is the min shift point for my VW. (but it'll quietly lug down very low before starting to jerk; I don't do it but had a Japanese friend do it when driving it, while I was cringing)
Ralph
