Hills and Hydrostatic Transmissions

[JonathanEngr]

Hi, everyone. I'm new here, and I've had this question nagging me since I bought my tractor back in the early 2000's.

I have a Kubota 3430 HSTC (34 HP hydrostatic transmission compact tractor with cab), and from the first day of ownership it has struggled going up slopes of 5% or more in medium range or any slope in high range. It climbs most hills just fine in low range--just very, very slowly. And, of course, it whines in protest. But if I get above 5% in medium it continues to slow down to about the speed it can move in low range. As far as high range goes, the ground has to almost be perfectly flat or it will eventually just stop.

I called my dealer after purchasing the tractor, and they said this is normal for a hydrostatic tractor. I've also heard this from other folks through the years. However, I've also been told that something is likely wrong with the hydrostat transmission/clutch/etc., for it to be *that* bad when just driving up a hill without using a PTO implement at the same time.

Don't get me wrong--I LOVE my hydrostatic transmission 95% of the time, but when my Dad an I are moving debris (piles of branches, etc.) to our "dump pile", we have to drive up a 5% or so grade after scooping a load. He has a 3430 GST (34 HP mechanical gear tractor) and can drive up the hill in high gear and leaves me in the dust. We usually do this every fall, and he probably carries 10 loads to my every 3.

I would love to hear from those who have hydrostatic transmissions to see if they have the same issues, or if there are folks with knowledge about whether this is normal behavior for a hydrostatic transmission. I do expect it to not be quite as good as a gear tractor, but should it be this extreme? Thanks!

 

[anomad]

I have a much smaller B2601 hydro. It climbs my steep driveway in M just fine. I use H on the paved hill coming back from my other lot where I can keep my speed up.

Struggling in L sounds like something isn't working right. But I only have my tractors to compare to.

My next tractor will probably be geared since bush hogging and grader work are my primary uses.

 

[jyoutz]

I have a much smaller B2601 hydro. It climbs my steep driveway in M just fine. I use H on the paved hill coming back from my other lot where I can keep my speed up.

Struggling in L sounds like something isn't working right. But I only have my tractors to compare to.

My next tractor will probably be geared since bush hogging and grader work are my primary uses.

Just get cruise control and your HST will work fine for mowing.

 

[GreensvilleJay]

What service has the HST seen in the past 20 years ?
I got a great deal on a similar 'cant' climb hills' green machine. Did the required service(as per HST mfr.NOT JD.) and it was like brand new again.

 

[85Hokie]

You may want to check the linkages - on my BX, there is a magic nut that will loosen over time and cause a slow down in forward and rear movements.

The BX is 2 speeds and in H range it is awful climbing a slight grade - in low it seems to want to climb a mountain.

I would think your machine would want to climb well in M - unless it is carrying a full FEL load.

 

[Tughill Tom]

Hi, everyone. I'm new here, and I've had this question nagging me since I bought my tractor back in the early 2000's.

I have a Kubota 3430 HSTC (34 HP hydrostatic transmission compact tractor with cab), and from the first day of ownership it has struggled going up slopes of 5% or more in medium range or any slope in high range. It climbs most hills just fine in low range--just very, very slowly. And, of course, it whines in protest. But if I get above 5% in medium it continues to slow down to about the speed it can move in low range. As far as high range goes, the ground has to almost be perfectly flat or it will eventually just stop.

I called my dealer after purchasing the tractor, and they said this is normal for a hydrostatic tractor. I've also heard this from other folks through the years. However, I've also been told that something is likely wrong with the hydrostat transmission/clutch/etc., for it to be *that* bad when just driving up a hill without using a PTO implement at the same time.

Don't get me wrong--I LOVE my hydrostatic transmission 95% of the time, but when my Dad an I are moving debris (piles of branches, etc.) to our "dump pile", we have to drive up a 5% or so grade after scooping a load. He has a 3430 GST (34 HP mechanical gear tractor) and can drive up the hill in high gear and leaves me in the dust. We usually do this every fall, and he probably carries 10 loads to my every 3.

I would love to hear from those who have hydrostatic transmissions to see if they have the same issues, or if there are folks with knowledge about whether this is normal behavior for a hydrostatic transmission. I do expect it to not be quite as good as a gear tractor, but should it be this extreme? Thanks!

Just asking, do lift off the HST peddle while going up the hill? If not, try it. It's almost as if you downshifted a geared machine.

 

[North Idaho Wolfman]

Yea what Tom sad, less pedal can equate to more speed.

Have you adjusted the clutch?

When was fluid and filters changed?

What fluid did you use?

 

[Magicman]

I found out very quickly that I had to keep the RPM's up on my M4900. It does not have the "lugging" power that the old 1530 John Deere still has.

 

[JonathanEngr]

Thanks for all of the replies! Okay... let me try to be sure I answer them all.

To begin, this behavior has existed ever since I purchased the tractor new from the dealer. At the dealership I tried the gear, glide and hydrostatic versions. I *loved* the HST due to easy maneuverability, cruise control, etc., and to me was worth the added cost. However, when it was delivered to my house with rolling hills the difficulties were immediately apparent. I called the dealer and was told that I needed to be in low gear for hills of any slope and the behavior was normal. I was so in love with the thing I really didn't care. And to be completely honest, it's not often that I really miss the uphill speed of my Dad's "geared" model, but his will go up the hill that mine can't do (except in low range) in his highest gear with zero problems.

Okay--servicing. For the first 10 years of my tractor's life it was serviced by the dealer. I had a larger piece of property and used it more often. Also, the dealer used to be 15 minutes away, but they moved and are now almost one hour away. I don't use it as much these days, and to be honest, I don't know if the hydraulic oil has *ever* been changed. I had a seal in one cylinder on my FEL burst several years back (I was aggressively trying to dig out a yellow jackets nest with my forks), and I checked the hydraulic fluid level after getting the cylinder repaired. It was a bit low, I topped it off with TSC hydraulic oil (and it was the type specified by Kubota--can't remember exactly what it was but I have most of the 5-gallon can left and can check if needed). My manual is long gone, but I think I downloaded a digital version. I'm up for changing it out completely--I just want to make sure I check and change *everything* that needs to be changed--filters, etc. So any tips on what to do, where to drain, the type/brand of hydraulic fluid you'd recommend as well as any filters, screens, etc., would be very much appreciated.

Clutch--I've never adjusted any part of the drivetrain. I regularly check my fluids, change my oil, grease all of the fittings, etc., but I haven't touched anything with the hydrostatic drive.

As for letting off the pedal, that's exactly what I do. When we're carrying our debris every fall I usually carry my load in neutral, and when I hit the hill I back down on the cruise control (basically let off of the pedal) until my rpms come back up. My Dad is already going faster, and when I back off on the cruise control he is completely gone.

As for the load during the "fall event" of carrying limbs, etc., my FEL is "full", but it's just a bunch of limbs. Maybe a couple of hundred pounds. It's definitely not like filling my bucket with dirt or gravel, so it's not something that's really adding a significant amount of weight that I have to carry up the slope.

Last, when I say "struggling in low", I mean the whine of the HST gets louder. In low it will climb most any slope that I'm comfortable taking the tractor on, but it's noticeably straining vs flatter ground. But if there's much of a slope medium gear typically requires me to back off on the pedal, and high gear is an absolute no-go.

I think I've addressed everyone's comments. Feel free to let me know your thoughts. I really appreciate it!

 

[rc51stierhoff]

Thanks for all of the replies! Okay... let me try to be sure I answer them all.

To begin, this behavior has existed ever since I purchased the tractor new from the dealer. At the dealership I tried the gear, glide and hydrostatic versions. I *loved* the HST due to easy maneuverability, cruise control, etc., and to me was worth the added cost. However, when it was delivered to my house with rolling hills the difficulties were immediately apparent. I called the dealer and was told that I needed to be in low gear for hills of any slope and the behavior was normal. I was so in love with the thing I really didn't care. And to be completely honest, it's not often that I really miss the uphill speed of my Dad's "geared" model, but his will go up the hill that mine can't do (except in low range) in his highest gear with zero problems.

Okay--servicing. For the first 10 years of my tractor's life it was serviced by the dealer. I had a larger piece of property and used it more often. Also, the dealer used to be 15 minutes away, but they moved and are now almost one hour away. I don't use it as much these days, and to be honest, I don't know if the hydraulic oil has *ever* been changed. I had a seal in one cylinder on my FEL burst several years back (I was aggressively trying to dig out a yellow jackets nest with my forks), and I checked the hydraulic fluid level after getting the cylinder repaired. It was a bit low, I topped it off with TSC hydraulic oil (and it was the type specified by Kubota--can't remember exactly what it was but I have most of the 5-gallon can left and can check if needed). My manual is long gone, but I think I downloaded a digital version. I'm up for changing it out completely--I just want to make sure I check and change *everything* that needs to be changed--filters, etc. So any tips on what to do, where to drain, the type/brand of hydraulic fluid you'd recommend as well as any filters, screens, etc., would be very much appreciated.

Clutch--I've never adjusted any part of the drivetrain. I regularly check my fluids, change my oil, grease all of the fittings, etc., but I haven't touched anything with the hydrostatic drive.

As for letting off the pedal, that's exactly what I do. When we're carrying our debris every fall I usually carry my load in neutral, and when I hit the hill I back down on the cruise control (basically let off of the pedal) until my rpms come back up. My Dad is already going faster, and when I back off on the cruise control he is completely gone.

As for the load during the "fall event" of carrying limbs, etc., my FEL is "full", but it's just a bunch of limbs. Maybe a couple of hundred pounds. It's definitely not like filling my bucket with dirt or gravel, so it's not something that's really adding a significant amount of weight that I have to carry up the slope.

Last, when I say "struggling in low", I mean the whine of the HST gets louder. In low it will climb most any slope that I'm comfortable taking the tractor on, but it's noticeably straining vs flatter ground. But if there's much of a slope medium gear typically requires me to back off on the pedal, and high gear is an absolute no-go.

I think I've addressed everyone's comments. Feel free to let me know your thoughts. I really appreciate it!

My B (and the BX I had before) is the same way. But I am rarely out t of L on either my B or MX and really no problem to speak of. You can let off the treadle pedal and seems like it helps on the margin…but that is about it IMO (most of us slow down if we try running up a hill too…not enough grunt for what we or the machine is being asked to do). It comes down to the difference in the transmissions and the power delivery. I love my HST, but they are not a geared a transmission, there is a place for them too. The easiest fix I think is come to terms with HST and lower your expectation in some situations or get a geared tractor….they each have plus and minus and each do some things better than the other. For a compact tractor (and their tasks and ease of use) I think the pluses of HST still outweigh a geared transmission for most people/uses….however I would not be so bold as to drag race a neighbor up a hill if they have a geared transmission…they are still the shit when the lady drops the handkerchief.

 

[Magicman]

I realized that my Reply #8 above was about a geared tractor rather than a Hydro, but you are talking about having to gear down. I also have to gear down to keep the RPM's up. To me it's the same situation. Gotta gear low enough to keep the revs up and the engine in the torque band.

 

[MountainMeadows]

My L2501 HST climbs a pretty steep hill on the main road in H with loaded tires, a 400# ballast box, and a bucket full of 2A modified without any problem. I do have to ease up on the pedal a bit to keep the rpms at about 2000. I've been extreamly impressed compared to my JD 655 on the same hill.

 

[North Idaho Wolfman]

MAN FALL'S ON FLOOR CLUTCHING CHEST!

To be honest, I don't know if the hydraulic oil has *ever* been changed.

I topped it off with TSC hydraulic oil

Clutch--I've never adjusted any part of the drivetrain. I regularly check my fluids, change my oil, grease all of the fittings, etc., but I haven't touched anything with the hydrostatic drive.

I appreciate your honesty, but where do I send the EMS bill?

WOW, Yea I would address all of those STAT!

I'll PM you a manual if you need it!
But you need new HST filter, new hydraulic filter, new hydraulic fluid KUBOTA SUDT2, NOT TSC, no where near Kubota SUDT2 standards, air filter, fuel filter, and oil filter and oil if that hasn't been done too, Heck I'd even do a radiator drain and fill!

And the clutch adjustment is the mechanical clutch and it runs the HST, it's not part of it.
If the mechanical clutch is out of adjustment and has been for that many hours it's possible that it's beyond adjustment, but the manual will tell you how, follow it.

 

[JonathanEngr]

Okay... so I didn't have a digital version of the owner's manual, but I did download the service manual for the L-series from kubotabooks at this link:

https://www.kubotabooks.com/AutoIndex/index.php?dir=Tractor%20Owners%20Manuals/&file=L3130%20-%205030%20WSM.pdf

Oddly enough, it doesn't have the cab version for the 3430. Perhaps they had discontinued it by the time this book was written (the book looks to be from 2003). I need to run out to my tractor and get the S/N to make sure I get the right manual with the right fluid volumes. North Idaho Wolfman--if you have the owners manual I'd really appreciate a copy. Can you send it through a PM, or should I PM you my email address?

As far as oil, oil filter and fuel filters go, I likely change them too often. By that I mean that I change them annually even though I likely don't use my tractor more than 10-20 hours per year at this point. As for the hydraulic oil and filter, I know that I've never changed them, but it could have been done when I used to get the tractor serviced. BUT... the last time it was at the dealer has likely been 10 years, so it's definitely time. I have never even considered it, and I don't know why.

Regarding the clutch, do you mean the physical clutch I press when shifting ranges? It has always seemed to work fine, and it even disengages the PTO when pressed. This may not be what you're talking about, however.

I've always wondered (and mind you--I do not know much about hydraulic systems and it may be about to show) if there's some way to "soup up" the hydraulics on the tractor to alleviate the slow uphill performance. For instance, if I move the FEL when driving up a hill it kills my forward momentum. After all, it's using the same hydraulic system (I assume). Would a higher capacity pump alleviate this? Would a higher capacity pump also alleviate the tendency for my tractor to struggle up hills in higher gears? I've always wondered what would happen if I got a hydraulic pump off of a large excavator and bolted it to my Kubota... LOL!!! It's pretty sad... I'm a Civil Engineer by trade, and I design "hydraulic" systems every day but with water. I'm sure there are similarities, but I've just never delved into true hydraulic systems.

It's good to hear that others have similar issues, but at the same time some users seem to have no problems at all (MountainMeadows--I'm looking/glaring at you). Of course, it's completely different tractor model and that's likely the reason for the disparity.

I think a good start is doing a proper maintenance on the hydraulic system and see if it makes a difference. I definitely don't mind lowering my expectations a bit using a HST on hills--I just want to do all that I can to make it as good as it can be.

 

[D2Cat]

Johnathan, in your post #9 when you said, " I topped it off with TSC hydraulic oil ...." I though that's the problem. However you only topped it up so it can't be as bad as a full oil change.

When a 5 gal. pail of oil say compatible with every machine ever made don't buy it! For your HST tractor only use Kubota SUDT2 hydraulic oil. Oh, it's not cheap but neither is your tractor. You need to change it like every 400 hrs. (check your manual).

Proper, clean hyd. fluid with new filters may be the solution to your problem.

 

[PoTreeBoy]

I've always wondered (and mind you--I do not know much about hydraulic systems and it may be about to show) if there's some way to "soup up" the hydraulics on the tractor to alleviate the slow uphill performance. For instance, if I move the FEL when driving up a hill it kills my forward momentum. After all, it's using the same hydraulic system (I assume). Would a higher capacity pump alleviate this? Would a higher capacity pump also alleviate the tendency for my tractor to struggle up hills in higher gears? I've always wondered what would happen if I got a hydraulic pump off of a large excavator and bolted it to my Kubota... LOL!!! It's pretty sad... I'm a Civil Engineer by trade, and I design "hydraulic" systems every day but with water. I'm sure there are similarities, but I've just never delved into true hydraulic systems.

Your issue is power, not volume. The engine drives the hydraulic pump and the hydrostatic pump, and its power is divided between the two. So, when you lift the loader bucket while traveling, some of the engine power is used by the loader and therefore not available at the wheels.

 

[JonathanEngr]

Got it. So I'd need to add the hydraulic pump AND the engine from the large excavator. I wonder if I could fit that under the current hood on my tractor

As for servicing the hydraulic system, I'll be driving by the dealership on Monday, and I'll pick up the oil and other items I'll need. I'll see if they can get me a copy of the manual, too, if I haven't secured a copy by then. I'll comb through youtube, as well, to see if anyone has made a video on servicing the hydraulic system on an L series.

 

[PoTreeBoy]

Got it. So I'd need to add the hydraulic pump AND the engine from the large excavator. I wonder if I could fit that under the current hood on my tractor

As for servicing the hydraulic system, I'll be driving by the dealership on Monday, and I'll pick up the oil and other items I'll need. I'll see if they can get me a copy of the manual, too, if I haven't secured a copy by then. I'll comb through youtube, as well, to see if anyone has made a video on servicing the hydraulic system on an L series.

There's a free WSM pdf at Kubotabooks. It covers the L3130 and others including the L3430. The General section has a maintenance interval chart as well as the procedures. I keep a copy of my equipment on my phone so it's always nearby.

 

[JonathanEngr]

Thanks! I did download that manual and made a donation to Kubotabooks. Pretty amazing site. I've been slowly going through it--it's over 600 pages! My only concern is that it doesn't have the 3430 cab model, but it's probably pretty likely that the non-cab 3430 HST is just like mine (fluid volumes, etc.). When I run by the dealership I'll check with them to make sure the values are correct.

I did find a few videos on Youtube for changing the hydraulic fluid. Most of them were for the new L series tractors, but I did see one for the 3430 HSTC like mine. However, they only changed one filter and opened two drain plugs. Maybe it's different on the newer models, but it appears they all have four drain plugs. Two at the differentials and two near the middle of the body. They also changed two filters--the hydraulic oil filter and the transmission filter.

 

[D2Cat]

Be sure to have a container that will hold all the hyd oil. It makes draining easier, to remove one plug, then just scoot the container to the next plug and let them all drain completely. Remove both filters, then install plug, new filters (mark date and hours with marker on filters). Fill with fluid.