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.