Here's my "take" on this. I have a Kubota 5030HST that redines at 2,700. I use it in my tree business, so I tend to do pretty much the same task with it day in and day out - moving logs and brush, all loader and 3ph lift work, and I have never once used the PTO. (Thinking of getting a PTO cement mixer for Margaritas and Pina Coladas though).
I tend to run it between 2,300 and 2,000, just to vary the engine speed a little for the sake of the engine. 2300 seems to be the sweet spot, and I have a feeling this is about where max. torque occurs on the torque chart. In fact, come to think of it, this is probably a darn good rule of thumb. Look on the torque chart for your engine, and hover around there. Why the heck not? Who needs extra RPM's without any additional torque? Hmm, just thought of who might. You'll probably get some extra HP by going with higher revs, for when you need HP even more than torque.
As far as idling down for tranport - I suppose that's OK, but I always keep the revs up for transport. of course, I have the hydro tranny to consider, and word is they like the higher hydraulic flows that they get at the higher rpms, so that clinched it for me. For gear tractors, I'd stil have to say keep the revs up pretty good. It just seems that speeds near 1000 are just too "luggy" for a diesel. Keep that baby thumping I say. And here's an interesting (IMHO) thought/observation I had a while ago about transport speeds and rpms. A friend of mine was telling me that near-idle speed was the way to go - told me for the zillionth time about "the farmer next door" /forums/images/graemlins/tongue.gif who knows EVERYTHING about tractors (he doesn't), and ALWAYS transports his tractors at close to low idle, to save wear and tear on the engine supposedly. Sounds to me like he lugs the cra& out of them. I got to thinking, "well your engine has to turn over X number of times to get from point A to point B, depending on what gear you're in. So does it really make much difference whether they're done slowly, over a longer period of time, or faster, for a shorter period of time?
And if you're running at slower rpm's (for gear tractors anyway, i'd have to think about hydros), you're probably going to be in a lower gear at the lower rpm's, so you're actually using MORE total engine revolutions to get between the two points. AND it just took you longer to get there (time is money). AND your engine is going to be happier operating (as another poster said here I think) at with a little bit of load on it.
There's also an excellent (long) thread here on lugging diesels.
Lugging diesels = bad or newfangled myth? Nine pages of REALLY good stuff. Bottom line? Lugging bad, letting the engine do its thing in a nice part of the power band good.
On <font color="blue"> And mostly I have been cruising around in B range, but I tried A and C for comparison. Seems A might be for tilling and C for just getting somewhere. </font>
On the Kubota it's L/M/H. I spend 90% of my time in M, 8% in H, and maybe 2% in L. As you, H for transport (and carrying logs on a paved surface), L for dragging heavy logs and trees/limbs, or budging something heavy with the front grapple, and M for everything else.
There's another must-read thread regarding engine care called
To idle or shut-off: Which is best?. What I took away from that thread and have put into practice are to start my engine at near idle, keep it there for about 3 -5 seconds, raise it to about 1500 and keep it there til I get to about 1/4 of operating temperature, then raise it up to about 1800-2000 and take off at a moderate pace to warm the engine up more quickly than if I just sat there idling. Warm engine = efficient, clean running engine. I don't do any real work until it's fully warmed up, but I see no downside to letting it warm up more quickly. It's being well-lubed, so who cares if it's not up to operating temperature yet, it soon (er) will be.
As to "idle or shut off" when you have to stop for a while: anything over a few minutes, just shut it off. Try not to let it cool down too much before you start using it again though (weather and time dependent), so this can affect the length of time you choose to let it idle instead. (Think Alaska pipeline).
Diesel engines at idle experience inefficient combustion and resulting unburned fuel migrating into the crankcase, sludge buildup, cylinder washing and a whole bunch of other nasty stuff. Let 'em rev a little, it's what they live for. As I said, my "idle" speed of choice is 1500.
So let her rip, and have fun! Sounds like a great machine, I came
this close to getting a 4710.
John D.
