will someone please describe lugging?

[ratropia]

TC 30.HST. 22hours.
I was mowing today with said tractor and a woods RM59 finnish mower, and got to wondering if I may be lugging the engine when I would go up inclines. I kept the throttle at the "540 pto" mark and mowing in 2 gear. The engine would whine a little only going up the inclines. Is that lugging? Or is that normal for the HST?
Also is second to fast to mow?
The manual say's not to lug the engine during break in period, so I do not want to do that. Thanks Rick T.
P.S. I did read the break in thread in the archives and seen also lugging is not good to do but no definintion. Sorry about the ignorant post. Thanks again Rick T.

 

[jbrumberg]

Ratropia:

Welcome to TBN and the Blue Forum ! HST's like to whine especially when they start to strain. You should back off on the foot throttle somewhat which essentially drops you a "gear" in your selected range. To me lugging is when the tractor is unable to keep selected RPM's and maintain groundspeed. The tractor appears to be straining. If you are lugging try your next lower gear range. For what it is worth IMHO. Jay

 

[irwin]

Think of a manual trans car traveling slowly up hill in 5th gear- this is lugging an engine.. or same manual trans car, taking off from stop in 3rd gear low rpm. Those are examples of lugging the engine.
Hope that helps..

 

[DocHeb]

If there's black smoke out the exhaust and your RPMs are dropping, you're lugging.

 

[Bird]

Look at the definitions of "lug" here that pertain to engines; i.e., running poorly, hesitating, jerky, etc. The engine may be "straining" a bit going uphill, but if it continues to run smoothly and doesn't drop much rpm, you aren't "lugging" it.

 

[SPYDERLK]

"Lugging" is too high of a load at too low of an RPM. The main reason this is bad is that the bearings in your engine are hydro-dynamic. They prevent metal to metal contact by the use of a viscous liquid between 2 surfaces that move wrt one another. The relative motion causes the fluid to be dragged between the surfaces and holds them separated. The viscosity of the fluid determnes how long any given volume of the fluid can hold them separated. This fluid is oil - and this hydrodynamic situation is happening everywhere in your running engine except for the valve seats.

Take the crank bearings -- There is oil in the clearance between the two sides. As the bearing begins to support a load the diameters no longer run concentric - the journal is forced toward the stationary plane bearing shell by the load. The oil, normally circulating at an equal pressure [that supplied by your oil pump] in the centered bearing, reacts automatically. The two surfaces approach contact in a way that causes clearance to diminish continually toward zero at a point. The oil, being propelled around the bearing by the relative motion, is swept thru this low clearance region more quickly than its viscosity will allow it to leak away. Pressure in the increasingly constrained flow rises to thousands of PSI and holds the surfaces separated - sometimes by only a few microns. If not there is contact and wear, soon to be catastrophic if continued. Things that will cause this contact are insufficient relative velocities in relation to the fluid viscosity. Maintaining relative velocities at a level sufficient to support the load is why you dont lug. Do not run a 2500 rated engine full throttle at 1000. Also, dont try playing with increasing viscosity beyond manufacturer recommendation in hopes of being safe in lugging situations. The flowing oil cools the bearing. Higher viscosity can cause very unpredictable problems, limiting adequate supply and causing thermal runaway in the bearing.
larry

 

[Soundguy]

In short.. if you can't gain rpms by adding throttle.. your load is too high and you are lugging... drop a gear.. or take a smaller bite so to speak..

Soundguy

 

[JerryG]

In short.. if you can't gain rpms by adding throttle.. your load is too high and you are lugging... drop a gear.. or take a smaller bite so to speak..

Soundguy

That's what I was always taught. If you can't accelerate, you are lugging.

 

[SPYDERLK]

In short.. if you can't gain rpms by adding throttle.. your load is too high and you are lugging... drop a gear.. or take a smaller bite so to speak..

Soundguy

Oh....

Far too simplistic. Use of maximum engine torque in the working RPM range of the engine is not lugging.
larry

 

[MikePA]

Far to simplistic. Use of maximum engine torque in the working RPM range of the engine is not lugging.
larry

Yeah, Chris, stop making posts that are understandable and describe a situation anyone who has ever driven a manual tranny car or tractor could relate to.

 

[SPYDERLK]

Yeah, Chris, stop making posts that are understandable and describe a situation anyone who has ever driven a manual tranny car or tractor could relate to.

Yeah. Understanding and relating to something that misses the key point is a good thing.

 

[MikePA]

Yeah. Understanding and relating to something that misses the key point is a good thing.

He didn't miss the point, nor did he post a bunch of professorial, Mech Eng college level gibberish. Why explain something in 2 or 3 sentences in English when a few paragraphs of mecheng technospeak will do.

What's lugging? Read Chris' reply.
Why is it bad? It can starve certain bearing of oil.

 

[SPYDERLK]

He didn't miss the point, nor did he post a bunch of professorial, Mech Eng college level gibberish. Why explain something in 2 or 3 sentences in English when a few paragraphs of mecheng technospeak will do.

What's lugging? Read Chris' reply.
Why is it bad? It can starve certain bearing of oil.

Sub nominal RPM [slow relative motion/spin rate between the two sides of the bearing] vs hi load is the point. He missed it. Sorry you didnt understand my gibberish. I was trying to describe the way oil lubricates by essentially separating the surfaces. Sorta like water skiing actually.
larry

 

[MikePA]

Sub nominal RPM vs hi load is the point. He missed it. Sorry you didnt understand my gibberish. I was trying to describe the way oil lubricates by essentially separating the surfaces. Sorta like water skiing actually.
larry

Thanks, I understand how oil works by forming a film between 2 surfaces. More like hydroplaning than water skiing.

BTW, how many people do you think use 'sub nominal' in everyday conversation?

By gibberish I didn't mean incorrect. I we don't communicate using words most people understand then we are not communicating. Sort of 'sub nominal' choice of words.

 

[SPYDERLK]

Quote MikePa: I we don't communicate using words most people understand then we are not communicating.

I recognize this and immediately edited my post to make it more clear - evidently while you were answering. Sub-nominal would be "below the manufacturers named values" - or in this case the named rpm range for engine use.

I also recognize that one has to write to the level of the reader and that this level varies widely. So its a near impossible task. I just try to cover all the pertinent issues clearly and correctly so that someone interested can dig thru it without an in depth knowledge of subject. If I fail to get it across with appropriate example and analogy there is always the option to ask a question prior to referring to the explanation as nonsense.

I would think that skiing is hydroplaning. What is the difference?
larry

 

[MikePA]

I didn't say it was nonsense, I said it was gibberish, i.e., it ddn't communicate.

Hydroplaning, a loss of steering control when a layer of water prevents direct contact between a vehicle's tires and the road surface, i.e., the water between the tire and road acts just like oil does between 2 surfaces in an engine. Three surfaces are involved in each situation;

Tire, water, road surface
Bearing, oil, crankshaft

Planing, a method by which the hull of a boat (or a water ski) skims over the surface of the water rather than plowing through it.

I don't see the analogy with water skiing.

 

[Soundguy]

Yeah, Chris, stop making posts that are understandable and describe a situation anyone who has ever driven a manual tranny car or tractor could relate to.

I know.. I know.. my bad... evn though I said 'in short'.. I should have typed out a 3 page disertation on all of the statics and dynamics on the flywheel.. loads.. motion, time and all.. and really made something that nothing but an engineer or a math major could read thru.. silly me for typing something a tractor newbie might understand.

I'll go stand in the corner.. now where's my pointy hat at??


Soundguy

 

[SPYDERLK]

I didn't say it was nonsense, I said it was gibberish, i.e., it ddn't communicate.

Hydroplaning, a loss of steering control when a layer of water prevents direct contact between a vehicle's tires and the road surface, i.e., the water between the tire and road acts just like oil does between 2 surfaces in an engine. Three surfaces are involved in each situation;

Tire, water, road surface
Bearing, oil, crankshaft

Planing, a method by which the hull of a boat (or a water ski) skims over the surface of the water rather than plowing through it.

I don't see the analogy with water skiing.

That is the trouble with far reaching analogies. They approximate, leading to the need for too much precise extrapolation by the interpreter in order to get the actual meaning. Many key points are issues of nuance, that if missed lead to things that dont add up right. That is why I dont try to convey a complex issue in a sound byte.

It seems, in my #6 above I introduced too much information, that altho I tried to connect together, didnt. Our carefree analogies tho, are too brief. In coddling the attention span they leave out too much. Viscosity is one thing. The differences in relative motion between tires rolling, planing, and a bearing turning is another. The rings sorta hydroplane/ski. The working of plain bearings is related. Both deserve a skeptical look in terms of comparison to the analogies using water as the fluid.
Its kind of like neglecting to move the "road" when testing aerodynamics of a car in a wind tunnel. How tedious - but must be done if you want your interpretatation to jibe with reality.
larry

 

[MikePA]

That is the trouble with far reaching analogies. They approximate, leading to the need for too much precise extrapolation by the interpreter in order to get the actual meaning. Many key points are issues of nuance, that if missed lead to things that dont add up right. That is why I dont try to convey a complex issue in a sound byte. It seems, in my #6 above I introduced too much information, that altho I tried to connect together, didnt. Our carefree analogies tho, are too brief. In coddling the attention span they leave out too much.

This is similar to the emails I get from engineers at work. Every issue is complex and filled with nuance. I ask them what time it is and they tell me how a watch works. Here at work, (may not be the case here) I think they respond with a dissertation so the recipient will be so snowed, that any conclusion can be drawn from their answer. Either that or they simply like showing off. "On the one hand, blah, blah, blah.Yet on the other hand, blah, blah, blah."

It's got nothing to do with 'coddling the attention span' it has to do with providing people with information they can use to make decisions or reach conclusions in a reasonable amount of time.

 

[jeffinsgf]

Well, I for one thought Larry's explanation was interesting and informative. I have known most of my life that "lugging" an engine was a bad thing -- but understanding why is helpful.

I also like the "if you can't accelerate, you're lugging..." shorthand. That really separates "lugging an engine" from "working an engine". When my grass is thick and I am going up hill with my 455, that sweet little Yanmar will snort a little black smoke and dig a little deeper -- but I can still push it harder without stalling -- that's working, not lugging.