Kubota Bx question

[Tractorrr]

I have noticed a few times that while mowing uphill in fairly thick grass that the RPM's have dropped from about 3400 to 3100 or so and return to 3400 at the top of the hill or in thinner grass. I noticed that it does this in high gear but not really in low. This is a pretty much new Kubota bx 2370-1 with about 35 hours on it.

Just looking for opinions on whether this is pretty normal or what. Is that considered lugging the engine to have a small drop in RPM's like that? I wouldn't think it is too harmful but thought it would be better to ask. Thanks

 

[wawajake]

When I cut grass with my BX2660 using my rear finish mower, I typically run the engine rpm at around 3000 at most , and I only cut in low gear, I would never attempt to cut in high gear unless it was very shallow grass cutting. I wouldn't even think of using high gear on a hill cutting deep grass. It would definitely bog down RPM in high gear. But that is just me maybe.

 

[oldballs]

Way back in 2009 when I owned a BX2660, I mowed "grass" in low gear. And IIRC the rpm was on the red line. I believe the High gear was for road travel IIRC.

 

[jeff9366]

What transmission does your BX have? HST or gear?

 

[Tractorrr]

What transmission does your BX have? HST or gear?

It's HST.

 

[jeff9366]

HST is most efficient at low RPMs: i.e. starting off.
The small drop you are experiencing is probably related HST operating a slight bit less efficiently as you power up hill at higher RPMs, working at a point slightly less efficient for the HST.

 

[Tractorrr]

Ok yeah I was thinking this is pretty normal. Thanks.

 

[Grandad4]

I have noticed a few times that while mowing uphill in fairly thick grass that the RPM's have dropped from about 3400 to 3100 or so and return to 3400 at the top of the hill or in thinner grass. I noticed that it does this in high gear but not really in low. This is a pretty much new Kubota bx 2370-1 with about 35 hours on it.

Just looking for opinions on whether this is pretty normal or what. Is that considered lugging the engine to have a small drop in RPM's like that? I wouldn't think it is too harmful but thought it would be better to ask. Thanks

Did the dealer tell you how to use the HST? When the engine is working hard, you BACK OFF the HST pedal instead of flooring it like you would the gas pedal in your car. That's because the pedal adjusts the gearing instead of the engine rpm. Light on the pedal = lower gear/more pulling power; heavy on the pedal = higher gear/faster ground speed. You may have a combination of slope and heavy grass that is bogging the engine a bit... adjust your driving technique and see if it helps. Others are right that going to Low range on a hill does the same thing. I've always used High range for mowing on generally level ground. It's about impossible to bog the engine, but you have to slow down to let the deck clear the discharge and cut all the stems.

 

[Tractorrr]

Did the dealer tell you how to use the HST? When the engine is working hard, you BACK OFF the HST pedal instead of flooring it like you would the gas pedal in your car. That's because the pedal adjusts the gearing instead of the engine rpm. Light on the pedal = lower gear/more pulling power; heavy on the pedal = higher gear/faster ground speed. You may have a combination of slope and heavy grass that is bogging the engine a bit... adjust your driving technique and see if it helps. Others are right that going to Low range on a hill does the same thing. I've always used High range for mowing on generally level ground. It's about impossible to bog the engine, but you have to slow down to let the deck clear the discharge and cut all the stems.

Yes I know about backing off the HST for more power. The engine didn't seem to bog in low gear but I would prefer to mow in high most the time. I guess I am wandering if bogging the engine a little bit while mowing is bad for it or not? Is a drop in 200 to 300 RPM's a bad thing?

 

[Code54]

On a hill in high, with the mower going and thick grass - yep totally normal. Should be shipping to low for that. It will give you a ton more power and keep the heat down. That is sort of like locking a car in overdrive going up the mountain, it may do it but it working really hard when there is a much better "gear" available.
We are very hilly and it is normal for me to shift from high to low a few times a day mowing on my BX25. kick in in low, do the steep hills then shift it to high for the fields. I even have to shift my 50hp on the big hills to a lower HST range if I am running the brushhog or something that takes power.

 

[dragoneggs]

OP, sounds normal to me in high gear... HST doesn't seem to have near the torque in high vs. low gear which is not surprising at all.

 

[JOHNTHOMAS]

On a hill in high, with the mower going and thick grass - yep totally normal. Should be shipping to low for that. It will give you a ton more power and keep the heat down. That is sort of like locking a car in overdrive going up the mountain, it may do it but it working really hard when there is a much better "gear" available.
We are very hilly and it is normal for me to shift from high to low a few times a day mowing on my BX25. kick in in low, do the steep hills then shift it to high for the fields. I even have to shift my 50hp on the big hills to a lower HST range if I am running the brushhog or something that takes power.

OP, sounds normal to me in high gear... HST doesn't seem to have near the torque in high vs. low gear which is not surprising at all.

Owned many Kubota BXs and Fs and Bs and some Ls and would never enter my mind to use them in high or rabbit when going up a semi steep hill and in fact I never put any of mine in high when they are "working". I only use high/rabbit when moving them up the fairly level street/road. I also have never tried driving my straight transmission cars/trucks in high 3rd/4th/5th/6th gear when pulling out or puttering around town or up steep hills.
It also doesn't sound like you are "lugging" your engine by a 200 rpm drop on a hill in deep grass but the simple answer is use the lower gear for high grass and steep hills and it shouldn't do much lowering rpms.

 

[dodge man]

I'd say there is nothing wrong with mowing on flat ground in high, I don't but it won't hurt anything. Do use low on hill though.

 

[massey driver]

Lugging a engine isn't what your describing. You have you RPM's up , to have it drop by a few 100 rpms is nothing this is a normal thing with all machines. Lugging your engine is when you have the rpms way down and are making the tractor work hard to the point its blowing black smoke and wanting to stall out. Having the rpms high and blowing black smoke and wanting to stall , is also lugging you engine. What your describing isn't lugging your engine. BTW use the low range when going up or down hills it's easier on your hydro.

 

[Tractorrr]

Thank you for all the replies.

 

[Henro]

Hi,

I will just add that it never occurred to me to be mowing with my BX in high gear...��

 

[nikerret]

Sounds normal. In these little BX's, it seems L is best for working and H is really just a transport gear.

 

[dragoneggs]

Sounds normal. In these little BX's, it seems L is best for working and H is really just a transport gear.

Yeppers!

 

[JOHNTHOMAS]

Hi,

I will just add that it never occurred to me to be mowing with my BX in high gear...��

Sounds normal. In these little BX's, it seems L is best for working and H is really just a transport gear.

Yeppers!

Add me to this list. Over the years I've seen some posters seem insulted if it's even suggested that they not use high gear all the time which has always confused me since I've rarely if ever needed to move faster across my yard (Not a lawn) than the lower (Turtle) "gear" in the BX. I do sometimes use the M "gear" in the B and Ls I've owned but only used the high on the paved street.

 

[JackyJ]

I'm curious what your HST temps are when mowing up hill in high range. As others have said, it's your transmission that's really getting the workout, not your engine. If you've got an infrared thermometer gun, you might want to aim the laser on the transmission case in front of the 3PH, especially the pump output on the upper left hand side. Kubota doesn't publish a max. temp specification, but you do not want to cook your fluid.