Stalling the engine under load?

[bikerdib]

I have a B7300 that I bought used and it serves me very well (previously had a B7100 and it did well also). Recently, I've been working on an area where I plan on making a small pond. This is an old creek bed and I'm already removing some sand with my FEL and dump cart because I want to build up some areas around my camphouse. I'm also pulling down some trees to make room for the pond work. First I use my sub-soiler to break as many feeder roots as possible. Then I use a ladder and get pretty high up on the trunk (depending on the size of the tree) to attach a cinch chain to which I then hook my pull chains. To give the tractor and chains some buffer I run the tractor at about 66% to 75% of max RPM. I have stalled the tractor a few times and that got me wondering. Am I doing the engine/transmission any damage by stalling it instead of running at max RPM and getting the extra torque? Would it be better on the engine and tranny to run the engine close to max RPM when pulling?

 

[beenthere]

Be better to not stall the engine.

Gear or HST tranny?

 

[RoyJackson]

I'd run it at a higher RPM...but if it does stall, start it right back up to keep the coolant flowing...

 

[Transit]

You dont want to be stalling the engine, its hard on the piston rings at the very least. Are you trying to control speed by running at 60-70% max rpm. If so, use a lower gear range and full rpms.

 

[bikerdib]

It's HST and I'm using low range to work so I'm not using throttle to control speed. In the last 8 hours run time I've stalled 3 or 4 times so it doesn't happen that often. I was just trying to reduce the load on everything but it seems the concensus is 'm doing more harm than good? Guess I'll give it full throttle.

 

[dex3361]

I would not stall the engine if at all possible. You are lugging the engine and that will beat the bearings out of the engine. As your RPMs drop below a certain point your oil pressure and flow is dropping very low, this is not good.
The HST relies on hydraulic pressure maintain a oil film between the piston glides and the swash plate and I would think this might allow metal to metal wear. I could be wrong but I wouldn't chance it.

 

[beenthere]

Sounds like the OP is not familiar with the HST operation.

Think of HST and the forward pedal as going from a lower to higher gear when pressing the forward pedal. Pushing harder on the pedal reduces the engine power and when you encounter higher/more load (filling the bucket with dirt for example), let off on the forward pedal to drop into lower gear (so to speak). That will avoid killing the engine.

 

[kuboman]

Sounds like the OP is not familiar with the HST operation.

Think of HST and the forward pedal as going from a lower to higher gear when pressing the forward pedal. Pushing harder on the pedal reduces the engine power and when you encounter higher/more load (filling the bucket with dirt for example), let off on the forward pedal to drop into lower gear (so to speak). That will avoid killing the engine.

Well said. It is a hydro!

 

[TripleR]

Yep, more RPM and less pedal.

On our HST and geared units both, I use enough RPM's and gearing to spin the tires without stalling. Working a tractor hard won't hurt it.

 

[bikerdib]

Yes, I understand about more peddle feed means a "higher ratio" and usually it does spin the tires when I encounter some harder work. That is not what caused the few stalls. I stalled the engine when I hit something unsuspected. I remember one instance, I was ripping a small root with the sub-soiler when I caught another larger root and the tractor pretty much immediately stopped as I reacted and released the peddle. I also think the peddle return damper might be getting more stiff (yes I keep everything lubed) causing the drive to keep pulling longer than I want at times like that. I plan on checking that out also. I do all this type of work slow and easy and that is why I thought that I might avoid trouble by not running the engine at max RPM. I was trying to give myself and the equipment an extra "safety margin". From what you guys say, it turns out I was just trying to save an inexpensive link by possibly hurting the major parts (like the engine). From now on, it's just under max RPM, low range and slow, slow, slow.

 

[brain55]

I'm not sure why people are afraid to run these machines at full throttle. If Kubota wanted you to run them at 3/4 throttle they would have governed them at 2000 RPM. Run it at full throttle and use all of the machine's power potential.

Just my opinion.

Brian

 

[TripleR]

You should hear how this thing is run.

 

[bikerdib]

Brian brought up a point I WAS unsure about. Like I said, I bought the B7300 used so I don't have a "baseline" to go by. Can I assume the engine has a Governor? I know that for using the PTO there is the recommended RPM mark on the tach. But for pulling and such, if I run the throttle control all the way to the stop, there is no chance on over revving the engine? Is that the recommended way to work it?

In my searching, I was never able to find what the recommended max RPM is and there is no red line mark on the tach.

 

[TripleR]

This is another one of those often debated issues. Though not exactly the same:

http://www.tractorbynet.com/forums/...6248-proper-power-take-off-revolutions-5.html

http://www.tractorbynet.com/forums/attachments/100068-correct-power-take-off-revolutions.html

Proper tractor setup can increase fuel efficiency

Given time and experience, you will be able to tell when you have the right combination of RPM and gearing for each task.

 

[beenthere]

I don't run full throttle, and once in a while I'm slow at getting off the forward pedal. But that is my slow reaction time and my fault. I try to learn from that and anticipate the engine load and do better the next time. All is about experience.

And more engine rpm won't hurt anything but your ears.

Just go easy on the pedal push. More tractor time needed.

That is the phenomena that Deere corrected with the ehydro tranny. Their is an engine load sensor that will back off on the forward motion so you cannot kill the engine. Nice feature but comes with a computer and more electronics to overcome the slow human reaction time.

 

[bikerdib]

I found one of the things causing the stalling engine issue. The pedal return damper was set to maximum. In other words, it was set to slow the pedal return and thus the time it took for the tranny to back off and stop. I have always listened to the engine to try and detect how much load was being put on it. Apparently, even though I would release the pedal, it sometimes still took too much time for the tractor to stop pulling and those times the engine stalled. Like I said, it wasn't a regular occurrence. Adjusting the damper should solve the issue but I will still run the engine at around 90% to 95% from now on when I know I will be putting a heavier pull load on the tractor.

 

[taborekle]

Yes, I understand about more peddle feed means a "higher ratio" and usually it does spin the tires when I encounter some harder work. That is not what caused the few stalls. I stalled the engine when I hit something unsuspected. I remember one instance, I was ripping a small root with the sub-soiler when I caught another larger root and the tractor pretty much immediately stopped as I reacted and released the peddle. I also think the peddle return damper might be getting more stiff (yes I keep everything lubed) causing the drive to keep pulling longer than I want at times like that. I plan on checking that out also. I do all this type of work slow and easy and that is why I thought that I might avoid trouble by not running the engine at max RPM. I was trying to give myself and the equipment an extra "safety margin". From what you guys say, it turns out I was just trying to save an inexpensive link by possibly hurting the major parts (like the engine). From now on, it's just under max RPM, low range and slow, slow, slow.

Just be prepared to stamp the clutch peddal when the engine is heading for cutoff. I've had to do this several times when tillering. You hit something unexpected and the engine starts to stall. For me it usually takes a second or two to stall the engine. If I'm quick with the foot, I can usually hit the clutch peddal to keep the engine from stalling.

 

[bikerdib]

I've used the clutch on a few occasions to stop, especially when mowing in tight areas.

Like I previously posted however, I found that the pedal return damper was set to maximum. I like my pedal set so that as soon as I let my foot off, the pedal returns. That's the way I always had previous HST equipment set to operate; from my old B7100 to the large equipment owed by the iron erection company I used to be a foreman for. I didn't know the damper on my B7300 had a setting, I found out through some searching. Now that I know, I'll set the damper to minimum so my foot has total control over movement. I don't mind the equipment stopping immediately and in fact prefer it that way. From my understanding, the only reason for dampened pedal return is to prevent tire wear and turf damage.

 

[funwithahoe]

I am surprised you can stall your engine pulling. My Kubota's have always lost traction before the engine ever sounded close to stalling - That's one advantage of a deisel which is lots of torque even as the RPM's slow. Maybe too high of a gear/range?

 

[Recoveryhill]

Plus one.

Hauling a 3/4 full Back Blade up hill at 2500 rpms in 4wd, tires loose traction, rpm remains at 2500 rpm.